Citation
Uptake and translocation of 85 Sr, 59 Fe, 185 W and 134 Cs by banana plants and coconut plants following foliar application.

Material Information

Title:
Uptake and translocation of 85 Sr, 59 Fe, 185 W and 134 Cs by banana plants and coconut plants following foliar application.
Creator:
Thomasson, Walter Neill 1940- ( Dissertant )
Bolch, Emmet William ( Thesis advisor )
Bevis, Herbert A. ( Reviewer )
Roessler, Charles E. ( Reviewer )
Dunovant, Billy G. ( Reviewer )
Uhrig, Robert E. ( Degree grantor )
Place of Publication:
Gainesville, Fla.
Publisher:
University of Florida
Publication Date:
Copyright Date:
1972
Language:
English
Physical Description:
xi, 141 leaves. illus. 28 cm.

Subjects

Subjects / Keywords:
Bananas ( jstor )
Cesium ( jstor )
Coconuts ( jstor )
Dosage ( jstor )
Fruit trees ( jstor )
Leaves ( jstor )
Plant roots ( jstor )
Radionuclides ( jstor )
Tracer bullets ( jstor )
Tungsten ( jstor )
Dissertations, Academic -- UF -- Environmental Engineering Sciences ( local )
Environmental Engineering Sciences thesis Ph. D. ( local )
Plants -- Effect of radiation on ( lcsh )

Notes

Abstract:
Bananas or plantains (cooking bananas) and coconuts comprise a significant part of the diets of the people residing in the areas of Panama and Colombia under consideration for a sea-level interoceanic canal. The coconut is also a major export commodity. Because of their importance in the area diet and economy, a mixed radiotracer experiment on a banana plant and a coconut plant was designed as a part of the evaluation of the radiological effects of a Plowshare project, such as the one proposed for construction of a sea-level interoceanic canal. In conjunction with the experiment, field and laboratory procedures were also developed. A second replicated field study was conducted to measure the rate of accumulation of 134 Cs in bananas following application of the isotope. Carrier-free, soluble tracers (85 Sr, 59 Fe, 185W, and 134 Cs) were applied to a portion of the foliage of both banana and coconut plants. Following foliar absorption, the translocation and distribution of these tracers within the plants were studied – with special emphasis on the fruit. It was found that only 134 Cs accumulated in the banana pulp and the coconut fruit (meat and water) following this type of foliar application. However, some of each radiotracer was detected in plant parts other than the treated foliage. The methodology employed to prevent contamination of the environment and to apply the tracers was very successful. The methodology included covering the ground with plastic sheeting, which in turn was covered with peat moss, and using a plastic bottle with a sponge applicator to treat the foliage. However, detectable levels of radioactivity were found in the banana plants, coconut plants, and weeds and grasses adjacent to the treated plants. Cesium-134 was translocated to adjacent plants in general, while 85 Sr, 59 Fe, and 185W were detected in the fruit of adjacent banana plants and second growth grasses and weeds near the base of the palm tree. The translocation resulted in slight accumulation of 59 Fe and 185W in the peels of the neighboring bananas in particular. This contamination was attributed to direct root-to-root translocation. Cesium-134 accumulation by bananas following foliar absorption was characterized by a first order kinetics function of the type C=Ce(1-e-kt). The rate constant (k) was determined to be -0.133 per day based on the least squares best fit of the data. The replicated experiment provided individual rate constant of -0.123, -0.158, and -0.122 per day for the three test plants. The equilibrium concentration values (Ce) expressed as a percentage of the concentration applied to the foliage were 0.04 percent, 0.80 percent, and 0.12 percent. The Ce varied as a function of the maturity of the fruit and the atmospheric conditions during and following tracer application. However, the rate constants were independent of the atmospheric conditions. As a result of these field experiments, it is evident that even with heavy rain during and following the period of fallout deposition radiologically significant amounts of radioactivitiy will be absorbed and retained by the foliage of banana and coconut plants. Using the results of this study, a model was developed to predict the yearly whole body dose to an individual who eats contaminated bananas. This model evaluates the dose as a function of 10 the concentration (μCi/m2) of fallout on the plant foliage; 2) the rate of consumption of contaminated bananas; and 3) the duration of consumption of the bananas.
General Note:
Typescript.
General Note:
Vita.
Thesis:
Thesis -- University of Florida.
Bibliography:
Bibliography: leaves 132-140.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
Copyright [name of dissertation author]. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Resource Identifier:
000580537 ( alephbibnum )
14050575 ( oclc )

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UPTAKE AND TRANSLOCATION OF
85Sr, 59Fe, 1R5W AND 134Cs BY BANANA PLANTS
AlNrD COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION












BY

HALTER NEILL TiOMiSSON


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY





UNIVERSITY OF FLORIDA
1972















ACKNOWLEDGEMENTS

The author wishes to thank Dr. Herbert A. Bevis and Dr. Emmett

Bolch, who alternately served as chairman of his supervisory committee,

for their direction, encouragement, and assistance. He also acknowl-

edges the help and encouragement of Drs. Charles E. Roessler and Billy

G. Dunavant who served on his committee. Particular thanks are extended

to Dr. John F. Gamble who spent many hours helping the author in the

field as well as providing invaluable guidance in the laboratory.

Mrs. Scott Zimmerman was indispensable in helping with the

radiological analyses. Mrs. Jo Anne Selin was helpful in performing

laboratory analyses, and Mrs. Effie Galbraith was of great help in

obtaining necessary laboratory equipment.

The author wishes to thank Mr. Laurin Wheeler, Dr. Sam Snedaker,

Mr. Harvey Norton, and Mr. Gordon Renshaw who provided help in the

field operations. Appreciation and thanks are also extended to the

personnel at the University of Florida's Sub-Tropical Experiment

Station at Homestead, Florida, particularly to Dr. Paul Orth, for their

assistance and for making their facilities available for the research.

Much thanks is due Mr. Wallace Manis, his personnel, and the United

States Department of Agriculture for the fine cooperation and the use

of the Plant Introduction Station, Miami, Florida.

The author also wants to recognize the general support and assist-

ance he received from the secretarial staff of the Soils Department of

the College of Agriculture and the Institute of Food and Agricultural









Sciences, University of Florida. Finally, the author wishes to thank

his wife, Lissie, who provided much help in the preparation of the

manuscript, translation of Spanish articles, editorial assistance, and

final preparation of figures.

This work was supported in part by United States Public Health

Service Training Grant No. 47013-03-68, and by the Institute of Food

and Agricultural Sciences, which was a sub-contractor of Battelle

Memorial Institute, Columbus, Ohio.













TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS .................................................... ii

LIST OF TABLES ......................................................... vi

LIST OF FIGURES .................................................... vii

ABSTRACT ................. ............................................ ix

CHAPTER

I. INTRODUCTION ............................................... 1

Sea-Level Canal Bioenvironmental and Radiological-
Safety Feasibility Study .............................. 1
Research Objectives .... ................................. 2

II. CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION .. 5

Introduction ............................ ................ 5
Plant Factors Affecting Foliar Absorption ............... 6
Environmental Factors Affecting Foliar Absorption ....... 8
Mechanisms of Ion Absorption ............................ 9
Rates of Absorption of Specific Ions .................... 10
Plant Characteristics Affecting Translocation ........... 14

III. PLANT NUTRITION .................. ......................... 16

Introduction ............................................ 16
Strontium .................................................. 17
Iron ....................................................... 18
Cesium ................ .................... .............. 19
Tungsten .............................. .................. 20
Nutrition of Banana Plants and Coconut Palms ............ 21
Fallout and Plant Nutrition ............................. 22

IV. METHODOLOGY ................................................ 23

Site Selection ......................................... 23
Selection of Tracers ............ ......................... 27
Field Procedures Mixed Tracer Experiment ............. 28
Field Procedures Kinetics Study Miami ................ 35
Laboratory Analyses .............. ....................... 42









Page


V. RESULTS ........................... ..................... 59

Introduction ............................................ 59
Environmental Control .................................. 59
Data Analyses Mixed Tracer Uptake ..................... 64
Data Analyses Kinetics Study Miami .................... 84

VI. DISCUSSION OF RESULTS .................................. 99

Efficacy of Field Experiments ........................... 99
Success of Environmental Protection Procedures .......... 100
Significance of Results in Relation to Radioactive
Fallout ............................................... 102
Evaluation of Allowable Activity on Plant Foliage ....... 105
Kinetics of Cesium Accumulation in the Banana Plant ..... 113
Effect of Rain .......................................... 116
Translocation of Radiotracers in Coconut and Banana
Plants ................................................ 117
Long-Term Effects of Foliar Contamination ............. 122

SUMMARY .............................. .. .... ..... ......... ......... 124

APPENDIX A: CHEMICAL SEPARATION PROCEDURE FOR TUNGSTEN ANALYSIS ... 128

APPENDIX B: DRY ASKING PROCEDURE PLANT TISSUE ................... 130

LIST OF REFERENCES ................................................... 132

BIOGRAPHICAL SKETCH ................................................ 141













LIST OF TABLES


Table Page

1. CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY,
MOBILITY, AND LEACHABILITY .................................. 12

2. RATES OF ABSORPTION .......... ................................. 13

3. SPECTROMETER CALIBRATION .................................... 55

4. COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED
PALM POSITIVE SAMPLES ..................................... 61

5. COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND
SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES ............ 62

6. TRACER COUNT RATES COCONUT FROND LEAFLETS AND
INFLORESCENCES 18 DAYS AFTER TREATMENT ...................... 65

7. TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER
TREATMENT ...................................................... 66

8. TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER
TREATMENT ...................................................... 67

9. RESULTS OF CHEMICAL SEPARATION FOR 185W ..................... 72

10. PARTIAL ELEMENT COMPOSITIONAL ANALYSES ...................... 82

11. SUMMARY OF 134Cs RATE OF UPTAKE EXPERIMENT .................. 86

12. EQUILIBRIUM CONCENTRATION VALUES Ce VERSUS AGE OF FRUIT ..... 91

13. COUNT RATE PER UNIT WEIGHT AS INDICATED BY PUNCH SAMPLES .... 92

14. CONCENTRATION OF 134Cs IN BANANA PLANT PARTS AND PEAT MOSS .. 94

15. RADIOACTIVITY IN ADJACENT FRUIT BEARING PLANTS AND NEARBY
GRASS .......................................................... 97

16. RELATIVE TRANSMISSION FACTORS .............................. 110













LIST OF FIGURES


Figure Page

1. FRUIT OF TREATED COCONUT PALM ............................... 24

2. FAST GLADE BANANA GROVE ..................................... 25

3. TREATED BANANA PLANT AT EAST GLADE .......................... 26

4. APPLICATION OF MIXED TRACERS TO COCONUT PALM ................ 30

5. REMOVAL OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING .. 32

6. HOMESTEAD COCONUT GROVE ..................................... 33

7. EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS ..... 34

8. USDA BANANA EXPERIMENT SITE .................................. 36

9. TREE 1 USDA BANANA SITE ................................... 37

10. PREPARED SITE USDA PLANT INTRODUCTION STATION TREE 2 AND
TREE 3 ....................................................... 39

11. EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER, AND
COUNTING CONTAINER AND SOLUTION APPLICATOR ................ 40

12. 134Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS .. 43

13. COUNTING CONTAINER IN POSITION OVER NaI(Tl) CRYSTAL PACKARD
LOW-BACKGROUND SYSTEM ....................................... 47

14. TUNGSTEN-185 STANDARD ....................................... 48

15. STRONTIUM-85 STANDARD ...................................... 49

16. CESIUM-134 STANDARD ......................................... 50

17. IRON-59 STANDARD ............................................... 51

18. POTASSIUM-40 STANDARD ....................................... 52

19. STANDARD CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr,
134Cs, AND 59Fe ............ ... ................. ............. 53









Figure Page

20. SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED ................ 71

21. SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1
SOLUBLE PORTION ...................................... ....... 73

22. SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1
INSOLUBLE PORTION ...................... ..................... 74

23. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1
SOLUBLE PORTION ................................................ 75

24. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1
INSOLUBLE PORTION ........................... ................... 76

25. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
SOLUBLE PORTION .................................................. 77

26. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
INSOLUBLE PORTION ............................................. 78

27. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
SOLUBLE PORTION ................................................ 79

28. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
INSOLUBLE PORTION ................... ............................ 80

29. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa walap TREE 1 ............................... 87

30. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa ralapuri Tree 2 ............................ 88

31. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa kullan TREE 3 ............................. 89

32. RELATIVE EQUILIBRIUM CONCENTRATION AS A FUNCTION OF FRUIT
MATURITY ................................................. ...... 95
137
33. MAXIMUM ALLOWABLE LEAF SURFACE CONCENTRATION OF 137Cs TO GIVE
A 0.17 REM ANNUAL WHOLE BODY DOSE AS A FUNCTION OF ASSUMED
DURATION OF INGESTION OF CONTAMINATED FRUIT ................... 112


viii
















Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of Doctor of Philosophy




UPTAKE AND TRANSLOCATION OF
85Sr, 59Fe, 185W AND 134Cs BY BANANA PLANTS
AND COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION



By

Walter Neill Thomasson

March, 1972


Chairman: William Emmett Bolch, PhD.
Major Department: Environmental Engineering

Bananas or plantains (cooking bananas) and coconuts comprise a

significant part of the diets of the people residing in the areas of

Panama and Colombia under consideration for a sea-level interoceanic

canal. The coconut is also a major export commodity. Because of their

importance in the area diet and economy, a mixed radiotracer experiment

on a banana plant and a coconut palm was designed as part of the eval-

uation of the radiological effects of a Plowshare project, such as the

one proposed for construction of a sea-level interoceanic canal. In

conjunction with the experiment, field and laboratory procedures were

also developed. A second replicated field study was conducted to meas-

ure the rate of accumulation of 134Cs in bananas following foliar

application of the isotope.









Carrier-free, soluble tracers (85Sr, 59Fe, 185W, and 134Cs) were

applied to a portion of the foliage of both banana and coconut plants.

Following foliar absorption, the translocation and distribution of

these tracers within the plants were studied with special emphasis on

the fruit. It was found that only 134Cs accumulated in the banana pulp

and the coconut fruit (meat and water) following this type of foliar

application. However, some of each radiotracer was detected in plant

parts other than the treated foliage.

The methodology employed to prevent contamination of the environ-

ment and to apply the tracers was very successful. The methodology

included covering the ground with plastic sheeting, which in turn was

covered with peat moss, and using a plastic bottle with a sponge appli-

cator to treat the foliage. However, detectable levels of radioactivity

were found in the banana plants, coconut plants, and weeds and grasses

adjacent to the treated plants. Cesium-134 was translocated to adja-

cent plants in general, while 59Fe, 85Sr, and 185W were detected in the

fruit of adjacent banana plants and second growth grasses and weeds near

the base of the palm tree. The translocation resulted in slight accumu-

lation of 59Fe and 185W in the peels of the neighboring bananas in

particular. This contamination was attributed to direct root-to-root

translocation.

Cesium-134 accumulation by bananas following foliar absorption was

characterized by a first order kinetics function of the type

C = Ce(l e-kt). The rate constant (k) was determined to be -0.133

per day based on.the least squares best fit of the data. The replicated

experiment provided individual rate constants of -0.123, -0.158, and

-0.122 per day for the three test plants. The equilibrium concentration

x









values (Ce) expressed as a percentage of the concentration applied to

the foliage were 0.40 percent, 0.80 percent, and 0.12 percent. The Ce

varied as a function of the maturity of the fruit and the atmospheric

conditions during and following tracer application. However, the rate

constants were independent of the atmospheric conditions.

As a result of these field experiments, it is evident that even

with heavy rain during and following the period of fallout deposition

radiologically significant amounts of radioactivity will be absorbed

and retained by the foliage of banana and coconut plants.

Using the results of this study, a model was developed to predict

the yearly whole body dose to an individual who eats contaminated

bananas. This model evaluates the dose as a function of 1) the

concentration (uCi/m2) of fallout on the plant foliage; 2) the rate of

consumption of contaminated bananas; and 3) the duration of consumption

of the bananas.















CHAPTER I

INTRODUCTION


The United States Atomic Energy Commission (AEC) has developed a

program, Plowshare, to investigate potential uses of nuclear devices

for peaceful purposes. These devices have been proposed for use in

excavating harbors, cutting railroad passes, developing water resources,

and excavating canals the most widely publicized use. Nuclear cratering

tests have been conducted at the Nevada Test Site in a program to develop

the technology and engineering design criteria required to utilize this

means of excavation. Lawrence Radiation Laboratory's Plowshare Division

has the primary responsibility for developing special nuclear devices for

engineering application.1



Sea-Level Canal Bioenvironmental and Radiological-Safety
Feasibility Study


The need for a new interoceanic sea-level canal has been well

demonstrated.2 Nuclear excavation is being considered for two of the

proposed new canal routes: 1) Route 17 in Panama's Darien Provence,

approximately 100 miles east of the existing canal, and 2) Route 25 in

northwestern Colombia, along the Panamanian-Colombian border.

The United States Congress passed Public Law 88-609 which authorized

the President to appoint a commission to investigate and to determine

the site and the best means of constructing a sea-level canal connecting

the Atlantic and Pacific Oceans. Nuclear excavation was proposed as a

1









possible method of constructing a new canal, and the AEC was given the

responsibility for investigating the problems associated with this

technique. The AEC subsequently awarded the prime contract for the

Bioenvironmental and Radiological-Safety Feasibility Study to Battelle

Memorial Institute, Columbus Laboratories. Battelle sub-contracted

various segments of the study to several research groups. The University

of Florida's International Programs of the Institute of Food and

Agricultural Sciences received the contract covering agricultural

ecology. This dissertation is part of the University of Florida study

and is concerned with two important components of the diets of the

ethnic groups in the canal study areas: the banana and the coconut.


Research Objectives


The objectives of this research were threefold: 1) develop method-

ology, 2) determine distribution patterns of radionuclides in the banana

and coconut plants following foliar application, and 3) study the kinetics

of cesium accumulation by the banana fruit following foliar absorption.

The first phase of the study was to develop methodology for perform-

ing low-level radiotracer experiments in the field while controlling the

radioisotopes with respect to the general environment. This was necessary

since most of the research concerning the accumulation of fallout by

crops has been devoted to 1) controlled greenhouse experiments in

nutrient solutions or pot studies and 2) field studies involving relatively

long-term uptake and concentration of fallout from nuclear tests.

The literature concerning comparison of field and greenhouse results

show that there is often poor agreement between parallel experiments in

the two environments. Russell and Milbourn3 reported that in greenhouse









pot studies the roots of the plants developed abnormal distribution

patterns. Handley et al.4 found that the amount of strontium absorbed

and the translocation patterns differed from greenhouse to the field.

Consequently, a field experiment was selected for this study because,

in the opinion of the investigator, actual field-environmental conditions

would provide more applicable data than would a greenhouse experiment,

particularly in view of the complex relationships involved in foliar

absorption.

The second objective of the study was to determine the distribution

patterns of radionuclides applied to aerial parts of banana and coconut

plants. The banana plant was selected for the study because up to 85

percent of the diet of people in the study areas is composed of bananas

or plantains. In fact, Dr. Torres de Arauz5 reported that as much as

approximately 12 kilograms (Kg) of bananas are consumed weekly per

individual. The coconut was selected because it is an important export

commodity in the economy of one of the local ethnic groups. Also,

coconuts provide a major portion of the fats in much of the populations'

diets. Overall, this fruit constitutes approximately 6 percent of the

total diet in Darien Provence.

Although much research has been conducted on uptake, translocation,

and concentration of strontium and cesium in the food chain, little work

has been done with the other radionuclides, particularly activation

products. In addition, there is no information concerning uptake,

translocation, and concentration patterns of fallout radionuclides by

either the banana or coconut plant. The field study undertaken here was

the first designed to produce data in this area.






4


A third objective of the study was to investigate the kinetics of

translocation of radiocesium by banana plants (as measured by the rate

of accumulation in the fruit). The banana plant was selected for this

study because 1) the banana comprises the bulk of the diet of the

populations in the study areas, 2) translocation of the radiotracers in

the initial phase of the field study was more rapid in the banana, and

3) the results of the initial study indicated that radiocesium would be

the more limiting radioisotope of the ones studied.
















CHAPTER II

CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION


Introduction


Foliar absorption is a complex phenomenon which is often utilized

to supply some of the minor, required nutrients to plants. Any substance

that can be absorbed by plant roots can be absorbed by the foliage more

efficiently.6 Foliar absorption, leaching, and'root absorption are

closely related, and all play significant.roles in radioactive contamina-

tion of crops. For instance, 1) foliar absorption can influence root

uptake of minerals by stimulating the plant's metabolism,7 2) leaching

of nutrients from the foliage also stimulates the rate of root absorption

and translocation of minerals through plants, and 3) once a mineral has

been absorbed by the plant, it is subject to foliar leaching by atmos-

pheric moisture.8'9

Contamination of fruit by above-ground deposition, other than direct

fruit deposition, involves two stages: 1) absorption by the foliage and

2) translocation from the absorption site to the fruit.10 Each element

is absorbed and translocated at rates specific to the element and plant

in question.6 The rates of absorption and translocation are closely

related; for example, tissue saturation at the site(s) of absorption may

occur if the absorbed material is slowly translocated, or remains

stationary.10 The distribution pattern in the plant is also character-

istic of the plant and the material.6

5









Plant Factors Affecting Foliar Absorption


The major work on foliar absorption has been conducted in temperate

climates with crops such as beans, corn, and apples. While these are

not the tropical banana plants nor coconut palms under consideration,

the studies on them have provided a very generalized concept of the

variables that affect foliar absorption.


Foliar Characteristics


As one would expect, the foliar characteristics of a plant play a

primary role in the rate of foliar absorption and the degree of absorp-

tion. Some factors which may affect absorption are leaf size, leaf

surface, the number and size of stomata (organs of respiration), and

the vascular system (xylem and phloem) of the leaf.

The leaf size is important because a large leaf provides more sur-

face area for foliar deposition and absorption and, therefore, will

increase absorption by the plant. The leaf surface is important because

it must be penetrated in order for a substance to be absorbed by the

foliage. Surface characteristics which may retard absorption are waxy

surfaces (cuticles), thick surfaces, and the occurrence of ion binding on

surfaces opposite the site of entry.11 Non-waxy cuticles, thin surfaces,

leaf wetness, and various leaf imperfections, such as hairs, injuries, or

protuberances, may aid, or encourage, absorption. The size, concentration,

and location of the stomata may also play a role in foliar absorption due

to 1) the surface area effect,12 2) thinner cuticles which line the

stomata,12 and 3) the location of the stomata relative to the venal

system.13 The vascular system (venal system), consisting of the xylem

and phloem, can also affect absorption. Plants with well-developed








vascular systems will absorb more, generally, than those with poorly

developed systems.


Plant Age


Foliar absorption is strongly associated with the age of the plant

and the phase of its growth cycle. As the leaf matures, its absorptive

capacity is reduced. Two events are responsible for this change: 1) the

permeability of the cuticle.decreases and 2) the rate of metabolism
14
increases to a maximum, then diminishes.4 There is some disagreement

as to the effect of leaf age on uptake, but this may be associated more

with the variation of nutrients and materials studied than with the

leaf itself. The cuticular development and concentration of stomata

change as the leaf matures, and this possibly accounts for some variation

in absorption.15 Generally, researchers have agreed that because of

thinner cuticles, young leaves absorb more foliar-applied nutrients than

mature leaves. This process is mainly irreversible in immature

leaves.16,17

Another important age-related factor is the time of contamination

with respect to the growth stage of the plant, since the greatest foliar

absorption of elements occurs during the flowering, or fruiting, stage

(when root absorption is negligible).6,18,19 If fallout occurs prior to

the flowering stage, the fruit will not be directly contaminated, and it

can only receive radioactivity from other plant parts via translocation.

On the other hand, if the fruit has begun to develop prior to the

deposition of fallout, direct surface contamination will result (the

fruit is capable of absorbing fallout).19'20






8


Other Plant Characteristics


Other plant characteristics which help determine the extent of fruit

contamination are the root structure morphological and physiological -

and the morphology of the foliage. Pseudostems may play a major role in

the absorption of fallout in the banana plant. Material collecting in the

axial (where the leaves come together forming the pseudostem) would not

be subject to washing or leaching and could be absorbed and held in the

hollow pseudostem, or between its leaf sheath layers. Banana (and also

coconut) plants have a central rib down each leaf which supports the

foliage this is termed the midrib. These are generally "U" shaped, and

in the banana plant they serve to channel runoff material to the axial.

Middleton21 and Handley et al.4 have noted the importance of the axial in

contamination of fruit by fallout.


Environmental Factors Affecting Foliar Absorption


Environmental conditions at the time of fallout formation and deposi-

tion strongly influence the amount of radioactivity available for absorp-

tion by plants. Wind velocity in conjunction with fractionization of fall-

out with respect to radionuclides and particle size will determine which

radioisotopes will be deposited in a given location. Rain during and

following fallout deposition decreases the fraction of fallout retained
22
by foliage. According to Tukey et al., up to 85 percent of foliar

contamination may be removed by a normal rain, and the amount retained is

decreased as the rain intensity increases.23 However, Russell and

Possingham24 concluded that rain, after the deposition period, had no

effect on retention of fallout by herbage.








Temperature and humidity are the primary factors that determine the

rate of drying of solutions on foliage, and the rate of absorption is

quite dependent on these parameters.4,23 High relative humidity, dew,

and general dampness act contrary to rain and increase, rather than

decrease, foliar absorption by maintaining the material in solution

longer. Ambler and Menzel25 ranked relative humidity as the single most

important variable controlling retention of 85Sr by foliage. But

according to the same authors, species variation, under identical environ-

mental conditions, may cause retention of fallout to vary from 10 to 90

percent. The species variation is a function of the surface wettability

of the foliage. As the relative humidity increases, the degree of hydra-

tion and cuticle permeability increase causing greater absorption.4'25

Similarly, Bukovac et al.26 reported that rewetting of the leaves

greatly increases absorption of fallout.

Although the most rapid absorption occurs under wet conditions, dry

state absorption does occur over extended time periods.27 Dry absorption

can be explained by the fact that although the surface appears dry, there

is a thin aqueous film of moisture created by the plant's transpiration.

This solvent may be more important than the nutrient-carrier solution.28


Mechanisms of Ion Absorption


There is some disagreement about the way in which ions deposited on

foliage pass into the plant's interior. Yamada29 has described the

passage of ions across the cuticle in a manner analogous to the classical

diffusion equation. Others28,30 have described continuous pathways

through the cuticle via surface imperfections. Generally, ion absorption

is a combination of passive and active processes. Initial penetration of









the cuticle and epidermis is by both passive and active means.16,22 The

passive component is absorption of nutrients into free space in the sub-

surface tissue by mass flow or diffusion; and the active processes are

ion exchange and transport into the protoplasm.16,31 For active absorp-

tion, an energy source is required, since energy is expended. Generally,

anion uptake is more energy dependent than cation absorption.32

After the initial absorptive phase, passage to the interior cells

is a two-phase process involving ion exchange and binding on the exterior

of cell walls, followed by an active uptake, which is metabolically

controlled by protoplasmic parts of the cell. Jyung et al.12 devised a

model for ion uptake using carrier concepts, which they feel is the most

likely overall uptake process by green leaves. The first phase of their

model involves a rapid, non-metabolic process, and the second phase, a

slower metabolically controlled step. According to them, a close fit to

a first order equation possibly indicates some passive uptake with the

initially rapid phase being more a function of existing environmental

conditions than of botanical characteristics.


Rates of Absorption of Specific Ions


Urea is reported to be the most rapidly foliar-absorbed material.10

Of the minerals, or nutrients, studied by other researchers, K, Na, and

Rb are the most rapidly absorbed. While Ca, Sr, Fe, and Mo are initially

absorbed fairly rapidly, the rate of absorption decreases sharply within

a few hours.10,33,34 This rate reduction may be associated with satura-

tion of the leaf tissue at the area of absorption coupled with an inabil-

ity to translocate these minerals from the leaf.10,35,36









Moorby37 related cesium absorption to sugar metabolism by the plant.
38
Thorne indirectly agreed with Moorby in suggesting that the negative

effect of shade on foliar absorption may be related to reduced carbohy-

drate concentrations during periods of low light intensity or darkness.

The most rapid absorption results when a mineral is in solution,14'15

and cations are absorbed more rapidly than anions.39 Absorption from

dilute acidic solutions (pH 4 to 5) is roughly linear with time until

evaporation and crystallization of the salts on the surface become

limiting.10 The hydrogen ion concentration plays a significant role in

the absorption of Sr, Fe, and W. At pH 4.5, four times as much strontium

is absorbed as at pH 2.5, and 40 times as much absorption occurs at pH

4.5 as at pH 8.2.40 Iron absorption is higher at acid pR since iron

hydroxides precipitate under alkaline conditions, Conversely, tungsten

will precipitate at neutral or acid pH. Lipid or oil solubility, in

particular, seems to play a major role in the uptake of minerals from

the foliage.41

Wittwer et al.20 have summarized and ranked various foliar nutrients

according to their relative rates of absorption, their degree of mobility

in the plant, and their leachability. Their own data and data of others

are shown in Table 1. Wittwer39 has also compiled data from various

researchers31,35,36 on rates of absorption of various elements. These

results and some from other authors are shown in Table 2 where the times

are the extremes from various studies when a time interval is indefinite.

It must be emphasized that these data only represent absorption and do

not indicate translocation rates nor rates of accumulation in edible

plant parts.
















TABLE 1

CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY, MOBILITY, AND
LEACHIABILITY20


Absorption Classa


Rapid:


Mobility Classb


Mobile:


Leachability Classc


Easily:


Urea N
Rb
Csc
Na
K
C1
S

Partially:


Immobile:


Na
Mn
Rbe
Csf
Ke


Moderate:


Difficult:


Wittwer and Teubner42
Bukovac and Wittwerl0
Tukey, Tukey, and Wittwer43
Wittwer39
Stenlid44
Olsen and Gate45


Urea N
Rb
Csd
Na
K
C1
Zn


Moderate:


Slow:


aAdapted
bAdapted
CAdapted
dAdapted
eAdapted
fAdapted


from
from
from
from
from
from










TABLE 2

'RATES OF ABSORPTION


Element


Cs



Sr



Mg

Ca

Mn

Fe

Zn

K

Mo



Cl

I

S



P



Urea N

(Banana)

(Banana)-


Time for
SAbsorption

24 Hours

142 Hours

24 Hours

142 Hours

10-24 Hours

10-94 Hours

1-2 Days

5-15 Days

1-2 Days

10-24 Hours

10-20 Days

5-15 Days

1-4 Days

10-20 Days

5-15 Days

5-10 Days

5-15 Days

5-10 Days

0.5-2 Hours

25 Minutes

30 Hours


*Percentage
Absorbed

45

80

10

40

50

50

50

50

50

50

50

50

50

50

50

50

50

50

50

65

100


Reference


26

26

26

26

39

39

39

7

39

39

39

7

39

39

7

39

7

39

39

46

47










A generalized qualitative indication of the relationship between

absorbability and mobility following foliar application is evident in

Table 1. Cesium is rapidly absorbed, and it is mobile. On the other

hand, Sr, Fe, and Mo are slowly absorbed; and strontium is considered

immobile while iron and molybdenum are translocated to some extent.

Possibly, the rate of absorption of iron and molybdenum controls the

mobility of the ions which in turn is gauged by the amount of ion

translocated from the point of absorption.


Plant Characteristics Affecting Translocation


Many factors that regulate or affect absorption of nutrients by

foliage also are important in the translocation processes, since the two

are so closely related. The translocation pattern is a function of

1) the plant age and/or stage of growth, 2) the rate of movement of each

radionuclide, and 3) the rate of concentration of the radioisotopes and

their congeners by a given plant part.23

The distribution pattern of various elements within the plant will

be different because of tissue barriers, specific coordinating substances,

and metabolic incorporation processes.38 Translocation occurs via the

plant's vascular system, which is composed of the xylem and the phloem.

Generally, the phloem is more highly developed as a conducting organ,

but the xylem is larger. The xylem generally carries material upward,

and the phloem carries substances downward from the foliage. For example,

it is commonly held that different compounds tend to be translocated by

different plant tissues: inorganic compounds, particularly water, via

the xylem; and organic compounds (products of photosynthesis) via the

phloem.16 Further, it is known that monovalent cations in the alkali









metal group move freely from the foliage to other plant parts via the

phloem,42 while the alkaline earths' divalent cations move only upwards

and will not translocate via the phloem.10,21,48

Translocation from the foliage may be related to the metabolism and

movement of carbohydrates.49 Moorby37 concluded that translocation

through leaf tissues to veins is a metabolically controlled step, and

discrimination against phloem mobile elements probably occurs at this

point in the translocation process. Biddulph50 has suggested that

chemical precipitation of elements in the extremities of the leaf's

veins may be the inhibiting mechanism of utilization and transport of

some elements.

During the active plant growth phase, nutrients translocated from

the leaf probably move via the phloem as opposed to movement via the

xylem (transpiration system) following root absorption.26 Leaf maturity

and metabolically active plant parts may be the primary factors that

determine the direction of translocation.51'52'53 While there is

greater absorption by younger leaves,15,42 the greatest translocation

is from the older leaves.54 The distribution of radionuclides is

proportional to the metabolic activity of the tissue,0 and the rate of

movement and final direction of translocation of ions are controlled by

internal mechanisms.55,56 Generally, mineral nutrients (or fallout) will

move towards the actively growing parts and nutrient storage organs such

as meristems, apical growth points, and fruit. Therefore, the distribu-

tion patterns depend on the relative rates of growth and the position of

the treated foliage and storage organs with respect to each other.42

Although there is more translocation when the fruit is young, the

increased movement is not necessarily to the fruit.15
















CHAPTER III

PLANT NUTRITION


Introduction


In this study the only required mineral nutrient employed as a

radiotracer was iron, which enters the plant's cytochrome respiratory

system.57 The other radiotracers used in the study have congeners

which are required mineral nutrients: strontium and calcium, tungsten

and molybdenum, and cesium and potassium. (The latter relationships are

not as definite and consistent as the strontium-calcium relationship.58)

Calcium is mainly utilized by plants in meristematic parts,59 such as

new leaves,6 and may be used to form calcium-pectate which provides cell

walls with their rigidity.58 Molybdenum acts as an electron-carrier in

the nitrate-reductase system,60 and potassium is associated with carbo-

hydrate utilization.58

Mineral requirements of all plants differ quantitatively, and plants

under unusual environmental conditions may exhibit specific requirements

for trace elements not ordinarily used.61 Differences exist even among

strains and varieties of a species because of their genetic composition.58

Mineral nutrients, except potassium and sodium, are most likely

absorbed and translocated as natural chelates.62 Chelates are regularly

employed to supply Fe, Zn, and Mn to valuable crops, such as fruit and

ornamentals.63









Strontium


Generally, strontium is not translocated from the site of foliar

absorption.30 However, Ambler15 reported that strontium translocated

from bean and corn leaves in both upward and downward directions, gener-

ally to other leaves. He concluded that this was reverse movement

through the xylem to the transpiring leaves since no strontium was

detected in the fruit or roots, as would have been the case if phloem

movement had occurred. In other studies slight, but measurable amounts

of strontium translocated to cherries and tomatoes from the plants'

foliage.64 Handley et al.4 have reported that 9 percent of the strontium

applied to the foliage translocated from the leaves to new tissue.

The small degree of strontium translocation from the foliage is in

contrast to its general translocation after absorption by the root

system. The uptake of strontium by plants from soil is related to the

following factors: 1) percentage organic matter in the soil; 2) calcium

content of the soil; 3) soil pH; 4) soil exchangeable cations; 5) soil

exchange capacity; 6) soil moisture; 7) soil nutrient status; 8) depth

of roots in the soil; and 9) cultivation techniques. Strontium absorbed

by the foliage is largely immobile,10,15,35 but strontium absorbed by the

roots is translocated to all the above-ground plant parts.18 However,

if contaminated foliage is allowed to accumulate on the ground beneath

the plants, significantly greater strontium contamination may occur than

if the fallout had directly contaminated the ground. For example,

Russell and Milbourn found that 25 percent more strontium was accumu-

lated by crops when contaminated stubble was fallowed under than when

land clear of stubble was cultivated. Thus, foliar-absorbed and immo-

bilized strontium in fallout became available to edible plant parts if

the vegetation was plowed under recycling the plant's nutrients.










Iron


Iron is a transition element with variable valence states, is easily

oxidized and reduced, and has a strong tendency to form organic

complexes.65 Plants require only small quantities of iron and use it in

the reduced state.66,67

Classically, iron has been considered to be slowly absorbed by

foliage and immobile after absorption.28,13 But recent research by

several investigators10,6869,70 has indicated that it may have limited

mobility from the foliage of plants, being translocated to young leaves

and meristem regions. Eddings and Brown13 attributed differences in

mobility of iron in three species of plants to variations in stomata and

venal organs. Biddulph48 determined that iron is immobilized through

precipitation as iron phosphate in veins at high pH and high phosphate

concentrations; while with low pH and low phosphate, iron is evenly

distributed in the plant. If iron is translocated, it probably enters

the leaf via the stomata and is then translocated across the mesophyl

to the phloem.13 Thus, the more cells through which it must pass before

reaching the phloem, the less it will be translocated. Simmons et al.,71

using nutrient solutions void of iron to grow bean plants, detected

foliar-to-root-to-solution translocation of iron, applied to the leaves

as iron sulfate, within a few days.

De et al.72 have shown that iron, chelated with ethylenediamine-

tetraacetic acid (EDTA), will penetrate the cuticle to a greater degree

than free ionic iron; however, chelated iron does not improve cellular

uptake by isolated cells. While the total iron absorbed is not increased

by chelation, the percentage translocated is improved.









Cesium


Cesium's physical and chemical properties enable it to enter readily

the food chains to man. There is an abundance of literature on the

cycling of radiocesium in the environment. Cesium is the most electro-

positive and active of all metals, and it forms strong bases and salts.73

Cesium is usually water soluble and is similar to potassium in its chem-

ical, physical, and physiological properties.73,74 (However, the cesium

to potassium congener relationship is not a good one in environmental or

biological studies.) Cesium is important in fallout because 1) it has

a high fission yield, 2) it has a long-lived radioisotope (137Cs), and

3) it is very soluble.

Radiocesium is more rapidly translocated than any other fission

product.75,76,77 The final distribution pattern of cesium in plants

varies with the plant species; however, when it is available during the

vegetative growth phase, it is mainly concentrated by the leaves and

flowers or fruit.78,79 Other authors21'30'80 have reported that

following foliar absorption, cesium moved freely throughout the plant

with the greatest accumulation in the stems. Moorby37 studied the

influence of light on the absorption and translocation of cesium, and he

concluded that absorption and translocation of cesium are related to the

plant's sugar metabolism. He stated that active metabolism and a

source of sugars in the treated foliage are a prerequisite for transloca-

tion of cesium. Moorby37 also found that a higher percentage of foliar-

applied cesium moved upward than toward the plant's base.










Tungsten


Essentially all cationic salts of tungsten are insoluble in water.

Some anionic salts of tungsten are quite soluble in water, and it is in

this form that tungsten usually enters into environmental chemical

processes.81 This element has been studied biologically least of any of

the Group VI B transition elements, and there is no available ecological

cycling information on it,82 nor could any botanical kinetics studies

related to it be found.

If it is assumed that tungsten will behave in a manner similar to

molybdenum, then the limited information about molybdenum may be useful

as a guide to the behavior of tungsten. Molybdenum has been reported to

be somewhat mobile following foliar treatment.10,83 One author10

suggested that it is translocated through the transpiration system

(xylem) to adjacent leaves in a manner similar to the way manganese is

moved. The only studies reported concerning tungsten and plants have

been involved with root absorption.81,84

While no information relative to foliar absorption of tungsten could

be found, various authors have shown that it is utilized by plants

following root uptake. Wilson and Cline84 found that potassium tungstate

provided tungsten in an easily available form as an anion in basic soil.

In acidic soil, tungsten was absorbed very little; therefore, these

authors concluded that tungsten must be in the form of tungstate, an anion,

before it can be absorbed by roots. They also concluded that tungsten

could be absorbed in biologically significant quantities from the soil,

but the uptake is very dependent on soil pH. Finally, Kaye and Crossley82

suggested that the movement of tungsten through food chains would

approximate the movement of cesium.









Essington et al.85 reported that radioisotopes of tungsten were the

most abundant radionuclides in fallout 167 days after the Sedan Plowshare

thermonuclear test. Studies by Romney and Rhoads86 and Romney et al.87

of tungsten accumulation by plants following the Sedan test showed that

radiotungsten was by far the dominant radioelement in plants grown on the

Sedan ejecta after three years of cropping. These investigators found

that the greatest concentration of radiotungsten occurred in the leaves

of these desert plants. Although this was root-absorbed tungsten, it

clearly showed the utilization of this element by one species of plant.


Nutrition of Banana Plants and Coconut Palms


According to Norton,88 little is known of the nutrition of bananas,

particularly the mineral nutrition. Generally, this plant exhibits

great flexibility in its cationic composition;89 this characteristic is

reflected in the fact that the mineral element concentration of banana

plant parts varies greatly during the plant's twelve-month growth cycle.

The most prominent compositional characteristic of the banana plant is

its high potassium content.

Most of the research on coconut palms has centered around the major

nutrients, of which potassium has been found to be the dominant cation

in the edible part of the coconut.90 According to Buchanan,90 there has

been a lack of interest in microelements in the past, and the literature

on coconut nutrition is relatively limited considering the importance of

this crop to human livelihood.






22


Fallout and Plant Nutrition


While considerable research has been conducted on foliar nutrition

using required trace elements, which are potential activation products

(e.g., Mg, Mn, and Fe), little research was conducted on uptake and

translocation of fission products by foliage prior to 1960.80 Then in

1963 Bukovac et al.26 concluded that aerial parts of plants are important

pathways for fission product absorption. Since then, substantial research

has been devoted to this topic.

No reference could be found in the literature concerning fission or

activation product absorption by banana plants or coconut palms. The

only references to mineral usage by these plants were concerned with

eliciting growth responses to a particular mineral element or to cure a

disease. No mention was made of rates of absorption or translocation by

these plants except for foliar nutrition of banana plants with urea.46,47

However, even these studies only developed rates of translocation to

other foliage and not to the fruit.
















CHAPTER IV

METHODOLOGY


Site Selection


The University of Florida's Sub-Tropical Experiment Station at

Homestead, Florida, was selected as the site for the initial mixed tracer

study. The United States Department of Agriculture's Plant Introduction

Station, Miami, Florida, was chosen for the kinetics study because 1) the

site was available for extended-term studies and 2) the site provided

excellent security.

The Homestead site was composed of two experimental locations. The

coconut experiment was conducted at the main site of the Sub-Tropical

Experiment Station where there were 12 trees in the coconut grove spaced

approximately 4.6 meters (m) apart. From these trees, a Malayan dwarf

coconut palm of the yellow variety was chosen for the study because it

presented a balanced distribution of maturing fruit.

The second site at Homestead was the East Glade Farm of the Sub-

Tropical Experiment Station. This farm was approximately eight miles

east and two miles south of Homestead. The East Glade banana grove had

24 clusters of banana plants in 4 rows of 6 clusters each. The spacing

was approximately 4.6 m within rows and 5.3 m between rows. The test

plant was selected because its fruit was estimated to be at least three

weeks from maturity. However, time showed that this estimate was quite

inaccurate (low). Figure 1 shows the coconut tree and its fruit, and

Figure 2 and Figure 3 show the banana grove and the treated banana plant.

23




























































FIGURE 1: FRUIT OF TREATED COCONUT PALM

















































i o




S.
*' *
\ t
* *" '


a.'p


I'


FIGURE 2: EAST GLADE BANANA GROVE



























































FIGURE 3: TREATED BANANA PLANT AT EAST GLADE









Selection of Tracers


In nuclear fission by thermal neutrons, fission products range from

mass numbers of 72 to 161.91 The most common fission products occur

around mass numbers 95 and 138. Of over 275 possible fission products,

only 13 significant isotopes are present singly or in combination

(e.g., Sr-Y) three months after a detonation.74 In addition, many other

nuclides may be produced through neutron activation of stable elements

in the nuclear device's components and in the surrounding soil. The

Relative Significance Index (RSI), developed by the Lawrence Radiation

Laboratory, University of California (the laboratory responsible for

designing and fabricating the nuclear devices to be employed in cratering

activities), ranked isotopes of 1) strontium and cesium (fission products)

and 2) iron and tungsten (activation products) among those which should

be considered in the environmental radiation hazards evaluation connected

with the Panama Canal feasibility study.

Generally, the selection of the isotopes was based on the desire to

have a mixture of gamma emitting radionuclides with minimum interference

among the respective photopeaks. The radionuclides of 85Sr and 134Cs were

chosen because they have much shorter half-lives (65 days and 2.1 years

respectively) than their longer-lived sisters (90Sr: 27 years; 137Cs:

30 years), which are the major long-lived fission products of concern.

(The shorter half-lives make these isotopes less hazardous to use in

tracer studies.) Strontium-90 is generally considered to be the most

hazardous and limiting fission product as far as man is concerned since

1) it accumulates in bone; 2) it has a fairly energetic beta particle;

and 3) its effective half-life in the body is long. Cesium-137 is the

other long-lived fission product that is generally considered to be of









concern in environmental radiation problems. It has a very penetrating

gamma ray and a beta particle; it is deposited throughout the body in

muscle tissue; and it has a long effective half-life. Both of these

radioisotopes are produced with high fission yields in nuclear devices.

Nothing is known of the distribution patterns, kinetics of absorption,

and assimilation of these isotopes by banana plants or coconut palms.

Iron (Fe-59) was chosen because 1) it is a required plant nutrient

and 2) considerable research has been devoted to iron utilization by

plants; therefore, this isotope would provide a means of judging these

results qualitatively with prior work.

Tungsten, while not a fission product, is expected to be the most

common activation product from the nuclear devices,92 as was indicated

in the Sedan Project. Although the half-lives of 181W and 185W are not

long (145 days and 74 days respectively), they are longer than the other

major activation products, and the quantities that are expected from

nuclear cratering devices make tungsten one of the most significant

radioelements.92 Little is known of its ecological relationships to

plants, and nothing is known of it with respect to banana or coconut

plants.


Field Procedures Mixed Tracer Experiment

Site Preparation


The coconut and banana sites were prepared in similar manners on

November 3, 1967. The area beneath each tree was cleared of all under-

brush, and the ground was covered with plastic sheeting (0.012 centimeter -

cm) out to a sufficient distance from the plant's stem to intercept all

drippage. Finally, the plastic was covered with approximately 7 cm of






29


peat moss. The plastic served as an impermeable barrier to percolation

to the ground, and the peat served as an absorbent. Background samples

of the fruit, vegetation, and soil were taken in the area of each test

tree.


Tracer Application


A mixture of four microcuries per milliliter (QCi/ml) each of 85Sr,

59Fe, and 134Cs and approximately 4 yCi/ml of 185W in a carrier-free,

soluble solution of NaEDTA was applied with a 5 cm wide paint brush. The

soluble, carrier-free tracers provided conservative results, since the

cratering fallout will not be entirely soluble nor carrier-free.

(Although the tracers were applied in soluble forms in order to be

conservative, the general conclusion found in the literature is that

fallout, other than that close-in, is in fairly soluble forms.) The

chelate prevented losses of the tracers on the sides of the container

and possibly made the 85Sr and 59Fe more available to the plant; thus,

conservatism was again maintained. A total of approximately 100 ml of

solution was applied to three fronds of the palm tree, and a total of

60 ml was applied to four leaves of the banana tree. A security fence

was constructed around each test tree, radiation warning signs were

posted, and the areas were surveyed with a Geiger counter. Figure 4

shows the application of the nuclides to the coconut palm. The treated

fronds can be seen in Figure 1; they are the three fronds in the fore-

ground above the withering frond.


Sampling


On'November 21, 1967, 18 days after treatment, the peat and plastic

were removed. The areas were then surveyed and decontaminated to a level






















































FIGURE 4: APPLICATION OF MIXED TRACERS TO COCONUT PALM









at most twice background, and then the samples were harvested. All the

contaminated waste was sealed in 55-gallon drums, which were subsequent-

ly buried in the University of Florida's waste disposal area. Figure 5

shows the removal of the peat and plastic.

All the coconut fruit, inflorescences (the plant part that produces

the flowers from which the fruit develop), treated fronds, and some

untreated fronds were collected, individually bagged, and returned to

the laboratory for analysis. The various parts of the banana tree and

its fruit were also individually bagged and returned to the laboratory.

In order to estimate the magnitude of zoological contamination which

might occur under these experimental conditions, samples were obtained

of 1) a lizard and a frog from the area of the banana tree and 2) ants,

a field mouse, a frog, and flying insects (collected with a light trap)

at the coconut site.

On December 14, 1967, 41 days after the test trees were treated,

additional fruit and soil were collected from adjacent trees at

both sites to determine the extent of radionuclide transport through the

.respective groves. Figure 6 and Figure 7 show where these samples were

obtained. Another environmental survey was conducted on June 5, 1968,

213 days after the tracer application, at the site of the coconut

experiment to be certain that there was no significant contamination of

the area. Samples of vegetation, soil, roots of the treated palm, and

earthworms were obtained to determine the extent of residual radio-

activity. Also, fruit was collected from an adjacent tree, and the area

was surveyed with a Geiger counter.




















*1(

LX


i .
. m. .-,' .


4~~F
a-, ~ '


404.


FIGURE 5: REMOVAL OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING











LEGEND:O Coconut Palms Sampled
O Treated Palm
9 Location of Treated Fronds
SOther Sampling Points
Q Other Positive Samples from Adjacent Palms

Roads Note: Palm trees were approximately 4.6 meters apart




0 O 0 0 0 0 xBxO O O O 0


FIGURE 6: HOMESTEAD COCONUT GROVE












D5




C5





B5

V



A5

V


D4
V



C4

0



B4

F I-



A4

V


Negative Samples Obtained
@ 12/14/67 41 days after
the study began
V Other Banana Trees Not
Sampled
F Test Tree Location


D3




C3

V



B3





A3

0


V


@


V


Positive Interplant
Translocation Samples
Obtained 11/21/67 18
days after the study
began
Other Positive Inter-
Splant Translocation
Samples Obtained
12/14/67 41 days after
the study began


FIGURE 7: EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS


A6

V

LEGEND:









Field Procedures Kinetics Study Miami


General


A second field experiment was conducted between May 10, 1968, and

June 5, 1968, at the United States Department of Agriculture's Plant

Introduction Station, Miami, Florida, to obtain data on the rate of

accumulation of 134Cs in the banana fruit after foliar absorption. The

experimental site was one of several 7.6 m square enclosures in a

structure originally designed for plant preservation and propagation.

Figure 8 shows the test area.

The banana plant was selected because 1) it is very important in the

diets of the ethnic groups in the canal study areas and 2) the transloca-

tion of cesium is fairly rapid in the banana plant. The banana plants

chosen for the study were of the species Musa and varieties walap

(Tree 1), rajapuri (Tree 2), and kullan (Tree 3). All three trees were

dwarf varieties. The fruit on Tree 1 was approximately two-thirds

mature; Tree 2 had fruit that was very young on an inflorescence which

had failed to emerge from the plant's axial causing the bananas to

develop in the axial; and fruit on Tree 3 was nearly mature (it ripened

after cutting). Figure 8 and Figure 9 show the general study area and

plants. Only 134Cs was selected for this study since 1) it was rapidly

and freely translocated through the banana plant in the mixed tracer

study, 2) in the previous study Sr, Fe, and W were generally rather

immobile after foliar absorption, and 3) cesium had been shown to be the

most critical fission product or activation product of concern in this

study.




















































FIGURE 8: USDA BANANA EXPERIMENT SITE





















































FIGURE 9: TREE 1 USDA BANANA SITE









Site Preparation


The site was prepared in a manner similar to that employed in the

previous experiment. One modification was that a slight mound of earth

was placed beneath the plastic sheeting around the periphery of each

tree, forming a bowl to help retain runoff in the event of a heavy rain.

A 1.8 m high, chain-link fence with a gate was constructed across the

front opening of the test enclosure providing permanent security. Radi-

ation warning signs were posted, and the area was surveyed for back-

ground radiation levels. Figure 10 shows the area beneath Tree 2 and

Tree 3 as it was prepared for the experiment.


Tracer Application


The solution applied to these banana plants contained 4 pCi/ml,

carrier-free 134Cs in a NaEDTA solution. In the laboratory, 50 ml of

the tracer solution was placed into each of three continuous-feeding,

plastic squeeze bottles with sponge applicators (5 cm x 1.3 cm). One

applicator was used on each tree. Figure 11 shows the plastic applica-

tor and the equipment used to process the samples in the laboratory.


Sampling

Immediately after the tracer solution was applied to each leaf, a

series of ten punch samples was taken with a hand paper punch in order

to quantitate the radioactivity per unit surface area. Similar samples

were obtained on the tenth and twenty-sixth days of the experiment. In

relation to this procedure, Freiberg and Payne46 had stated that, since

the banana leaf has such a large area, leaf samples could be taken with-

out significantly altering the total leaf photosynthetic activity.


























































FIGURE 10: PREPARED SITE USDA PLANT INTRODUCTION STATION
TREE 2 AND TREE 3

















^ Xhi
iit


FIGURE 11:


EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER,
AND COUNTING CONTAINER AND SOLUTION APPLICATOR









Selective sampling of the bananas as a function of time was accom-

plished by collecting five bananas every other day for 10 days and

collecting a final sample after 26 days. The bananas were cut from the

hands with a utility knife, which was washed after each sampling in

order to reduce cross-contamination of the fruit. No attempt was made

to seal the wound inflicted by the knife, since preliminary experiments

had indicated that there was negligible drippage of latex from this type

incision. (Latex is the banana plant juice that exudes from a wound in

the epidermis of a plant part.)

Before returning to the University of Florida laboratory, the first

four sets of samples were scanned at the University of Miami's Radiation

Biophysics Department with a scintillation detector ( 4.45 cm x 5.08 cm

NaI(TI) crystal with a 1.27 cm x 1.91 cm well) coupled to a photomulti-

plier tube with its output fed to a Nuclear Data 512-channel pulse-height

analyzer (Model ND 180M). The preliminary scanning was initiated to

insure that the sample size was large enough to enable quantification in

a reasonable counting time. It also revealed that the desired equilibrium

condition would not be achieved within 10 days; therefore, the experiment

was continued.

On the tenth day of the experiment, May 20, the site was cleared of

the peat and plastic sheeting, and new plastic and peat were laid, leaving

room for development of daughter shoots. The experiment was terminated

after 26 days, since the results from the preliminary scanning indicated

equilibrium had been reached. On June 5, 1968, the site was again cleared

of the peat and plastic, and the remaining fruit was harvested. Samples

of the treated leaves, the distal inflorescence bracts, pseudostems, and

untreated leaves were collected and returned to the laboratory for analyses.









The plants were then cut off at a point approximately 30 cm above the

soil so that transfer of the tracer from the rhizome storage organ (the

"root") to other developing fruit and new sword suckers (young plants

that originate from the rhizome) could be studied.

On September 13, 1968, samples of bananas, distal inflorescence

bracts, and grass were obtained from adjacent plants to determine the

extent of translocation to new daughter plants and to adjacent plants

from the rhizomes of the treated plants. The location of the test trees

and subsequent sampling points are shown in Figure 12.


Laboratory Analyses


Mixed Tracer Experiment Sample Preparation


All samples from the first experiment, except the shells and husks

of the coconuts, were processed to a homogeneous state. The banana pulp

and peels were individually prepared, and the coconut husks, shells, and

meat and water were analyzed separately. A heavy-duty paper cutter was

used to chop the samples, which were then blended in a 4.25 liter (L),

stainless-steel, food blender. The paper cutter, blender, and all

utensils were thoroughly washed after each set of samples was prepared in

order to prevent cross-contamination. The samples were prepared and

analyzed in the anticipated order of the lowest count rate to the highest.

Distilled water was added, as required, to the samples to facilitate

blending, and a few milliliters (ml) of formaldehyde were added as a

preservative. After blending, the samples were poured into 800 ml plastic

containers and weighed prior to low-level gamma scintillation counting.

The dry weights of all samples except the shells and husks were

obtained by drying three portions of each sample at 65-70 OC and











































LEGEND:
0: Denotes the location of banana plants.
D: Denotes the location of daughter plants.
X: Denotes a dead parent plant.

Notes: 1. Numerals are the numbers used to identify the banana plants
in the text.
2. Plants 1, 2, and 3 were the ones treated and sampled to study
the kinetics of 134Cs movement to the fruit from the foliage.
Plant 4 and Plant 5 were sampled once at the end of the study
(126 days).


FIGURE 12:


134Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS









averaging the percentage moistures. Wet weights of the samples were

corrected to dry weights using the percentage moisture correction factors.

Except for the coconuts, samples collected for determining inter-

plant translocation were placed in 800 ml counting containers and analyzed

in their fresh states without blending. Following analysis by gamma

spectroscopy, the samples were dried in an oven at 65-70 C to constant

dry weight.


Kinetics Study Sample Preparation


The samples (banana, leaf, pseudostem, and distal inflorescence

bract) were prepared in their fresh states to provide constant geometry

and uniform density. The unpeeled bananas were sliced and placed in

counting containers with sufficient distilled water added to fill all

voids to 800 ml. The pseudostem and inflorescence bract were individ-

ually chopped, blended with distilled water, and placed in 800 ml

counting containers. The leaf punch samples were placed in standard

glass liquid scintillation vials (7.9 cm x 2.2 cm) for low-level gamma

ray analysis. After analysis, the samples were dried at 65-70 OC until

constant dry weights were achieved.


Sample Counting


All samples prepared in the standard 800 ml geometry were analyzed

with a gamma scintillation spectrometer system (described later) in a

shielded, low-background facility. The following samples were analyzed

by the same instrumentation but were not analyzed in the standard geometry

assumed for this study: 1) coconut shells and husks from the treated palm

tree, 2) coconuts from the follow-up sampling to determine the extent of









radionuclide translocation to other trees, and 3) leaf punch samples from

the kinetics study.

The whole coconuts, coconut shells, and husks were counted in plastic

bags laid over the large crystal detector of the low-background analyzer

system. This geometry was used for two reasons: 1) reducing these samples

to a small enough volume to be counted in the standard geometry would

have necessitated ashing with possible loss of cesium through volatiliza-

tion and 2) the identification, or presence, of the radioisotopes in

these samples was more important than relative quantification of the

tracers. Identification was of primary interest because 1) the prelim-

inary analysis indicated that low levels (trace amounts) of isotopes

were involved; 2) the samples from the adjacent trees were analyzed only

to obtain translocation data for planning future studies; and 3) the fact

that interplant translocation occurred is of greater significance than

the amount, since so little radioactivity was involved.


Gamma Spectroscopy Systems


Except for the zoological samples, gamma ray spectroscopic analyses

were made using a 10.16 cm x 10.16 cm right-cylinder, NaI(Tl) scintilla-

tion crystal coupled to a photomultiplier tube. The base of the stand-

ard geometry 800 ml container was the same diameter as the scintillation

crystal. (A plastic centering ring was used to hold the containers in

constant position over the detector.) The photomultiplier was connected

to a Packard (Model 116) 400-channel multi-channel pulse-height analyzer.

The crystal was located inside a 51 cm x 51 cm x 61 cm high, tri-component

shield (5 cm thick lead sides, floor, and cover with graded cadmium and

copper lining). The entire analyzer system was housed in a large, low-level









activity, concrete semi-vault with 60 cm of concrete on all sides.

Figure 13 shows the large NaI(Tl) crystal inside the lead shield with

the standard 800 ml sample container in place.

The zoological samples were placed in plastic vials and analyzed

with a lead-shielded, 4.4 cm diameter x 5.08 cm thick NaI(Tl) well-

crystal with a 1.91 cm diameter x 3.8 cm deep well coupled to a photo-

multiplier tube. A 512-channel Nuclear Data pulse-height analyzer

(Model ND 180M) received the output from the photomultiplier.


Gamma Spectroscopy System Calibration


The low-level counting system was energy calibrated using a combina-

tion 137Cs and 60Co button-type check source, so that each of the 200

channels in a memory-half represented 10 Kev and full scale was 2.0 Mev.

The energy calibration and background were checked at the start and end

of each day or after counting any samples with high count rates.

Figure 14 through Figure 18 show the gamma scintillation spectra of

the energy calibration standards of each nuclide considered in this study.

The 40K was considered in the analyses since it is present in all biolog-

ical material, and the data must be corrected for its presence. Figure 19

shows the combined spectra of the tracers in a composite energy stand-

ard which contains roughly equal quantities of each radiotracer used.

The low-level counting system was calibrated for differences in

geometry with each of the four nuclides employed in this study. Starting

with a fixed amount of radiotracer and 10 ml of distilled water in the

800 ml container, the same amount of tracer was counted as successive

increments of distilled water were added to the container. All counting

was done on a relative basis in analyzing the results of the mixed tracer



















































.FIGURE 13: COUNTING CONTAINER IN POSITION OVER NaI(T1) CRYSTAL
PACKARD LOW-BACKGROUND SYSTEM













1,200

1,100


1,000

900

800

700

600

500

400

300

200

100


0,


80 100 120

Channel Number (10 Kev/Channel)

FIGURE 14: TUNGSTEN-185 STANDARD


140 160 180


20 40 60


200












2,400

2,200

2,000

1,800


1,600

1,400

1,200

1,000

800

600 -

400 -

200


0 10
0 10


30 50 70 90 110 130 150 170 190
Channel Number (10 Kev/Channel)

FIGURE 15: STRONTIUM-85 STANDARD






2,600


2,400

2,200

2,000

1,800

1,600

1,400

1,200


1,000

800

600

400

200


0
0


20 40 60 80 100 120 140 160 180

Channel Number (10 Kev/Channel)

FIGURE 16: CESIUM-134 STANDARD


200

















1,000


900

800 -


700 -

600

500 -

400

300

200

100

0
0


20 40 60 80 100 120 140 160 180
Channel Number (10 Kev/Channel)

FIGURE 17: IRON-59 STANDARD


200












600




500




400

o


S300
0)



S200
a



" 100




0
0 I I I I I !
0 20 40 60 80 100 120 140 160 180 200
Channel Number (10 Kev/Channel)

FIGURE 18: POTASSIUM-40 STANDARD l
(75 Grams KC1 in 750 ml water in standard 800 ml container over 10.08 cm x 10.08 cm NaI(T1) crystal)








85S
Sr


134Cs
Cs


134C


185W


59Fe


59Fe


20 40


FIGURE 19: STANDARD


60 80 100 120 -140 160 180

Channel Number (10 Kev/Channel)

CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr, 134Cs, AND 59Fe


200









study, since the relative distribution pattern of the tracers in the

plants was the primary purpose of the study. However, absolute counting.

of 134Cs was utilized in the kinetics study so that the total quantity

of cesium accumulated by the fruit could be estimated.

Calibration for geometry differences in counting the leaf punch

samples was based on the fact that the samples from the terminal sampling

of the banana leaves should have had the same count rate per unit weight

as the lamina tissue of the parent sample. Thus, the count rate per

unit weight was calculable for the two counting geometries involved

(standard 800 ml and scintillation vial over the large crystal). An

average correction factor was calculated which allowed correction of the

results of the leaf punch sample analyses for the non-standard geometry.


Data Analyses


The gamma ray analyzer (Packard system) output was an X-Y plot of

the gamma spectrum and a Monroe Digital printout of the number of counts

per channel (or energy band). The portions of the gamma spectra summed

to quantitate the photopeaks of the radionuclides and the photopeak

energies are shown in Table 3. Small spectrum shifts were corrected

when the channels were summed manually. The sums of counts under the

integrated photopeak regions were used in a computer program to separate

the mixed spectra into individual isotopic components.. The two photo-

peaks of 59Fe and 134Cs were summed to improve the sensitivity of detection.

The gamma spectrum of each sample was analyzed using a simultaneous

equations method of separating the components93 and the University of

Florida's. IBM 360 computer. The computer analysis involving simultaneous

equations was chosen as the method of separating the known components of















TABLE 3

SPECTROMETER CALIBRATION

94
Photopeak Energies
Mev

0.058

0.513

0.605

0.796

1.098

1.289


1.46


Channels Summed


4-9

42-63



50-90



100-139

135-155


Isotope.


185W

85Sr
134CS

5Cs


5Fe








the speetra because it is less sensitive than other methods to changes in

energy calibration of the spectrometer, and it can be used in conjunction

with manual methods of solving a set of simultaneous equations. The

computer output provided the net counts per minute (cpm) of 185W, 85Sr,

134Cs, 59Fe, and 4OK in each sample and also the two-sigma standard

error for each isotope in each sample.

Since the samples from the various segments of the Homestead coconut

and banana experiments were separated into sub-samples for analysis, the

final results of the individual sample components were summed to present

the composite average count rates in the given plant part. It was not

possible to treat these separate portions as replicates, since some had

more solids than others.

The data from the kinetics study were analyzed manually. The

channels summed for analysis of the 134Cs radiotracer were channels

50-70, which represented the 0.605 Mev photopeak. (The calculated

efficiency of detection over the range of this peak was 5.6 percent.)

These data were then used to obtain a model of the kinetics of 134Cs

accumulation by bananas following foliar absorption. A modified

Gauss-Newton, non-linear, least squares computer program was used to

obtain a curve of best fit to a first order kinetics function.95


Tungsten Separation


The 185W X-ray photopeak was in the low-energy region of the

spectrometer (59 Kev, or channel 6) where it encountered interference

from: 1) electronic noise and 2) backscatter and Compton continuum

associated with the higher energy photopeaks of the other radioisotopes.

Also, because of the very weak energy of this X-ray, the efficiency of


detection was low.









Since the 185W may have been masked by high. count rates or was below

the detectable and/or measurable limits of the whole sample, a chemical

separation procedure was developed to simplify the gamma spectra in order

to positively identify the tungsten, if it were present. The bases of

the procedure, which is outlined in Appendix A, were chemical precipita-

tion of tungsten using cinchonine96 (a selective precipitant for tungsten)

and a tungsten carrier combined with acid and alkali solubilities.

The counting geometry for these separated samples was 100 ml in the

standard 800 ml container, which was centered over the 10.16 cm x 10.16 cm

scintillation crystal. The smaller volume in conjunction with the

separation increased the efficiency for the detection of 185W by decreasing

the losses of X-rays through the sample container's sides, decreasing the

self-absorption losses, and simplifying the spectrum.

The specific samples separated were chosen because they included

1) edible parts (which were the primary samples of interest), 2) treated

foliage (the plant part to which tungsten had been applied), and 3) parts

to which tungsten might have been translocated untreated foliage,

distal inflorescence bract, and pseudostem.


Compositional Analyses


Stable element analyses for Ca, Mg, Mn, Fe, Cu, and Sr in vegetation

and crops from Panama and Colombia were determined at the Central

Analytical Laboratory, Institute of Food and Agricultural Sciences,

University of Florida (IFAS,UF) so that the mineral composition of fruit

from the bioenvironmental feasibility study area could be compared with

the composition of the plants and fruit in the Florida study. A

Beckman D. U. Flame Emission Spectrophotometer was used for these analyses.








Stewart Laboratories, Knoxville, Tennessee, analyzed banana, banana leaf,

coconut meat, coconut water, and frond samples from Homestead, Florida,

for Sr, 11n, Fe, and Cu using a Bausch and Lomb Spectrograph and for Ca,

Mg, and Zn using a Beckman Atomic Absorption Unit. The Tropical Soils

Laboratory (IFAS,UF) analyzed all the samples for potassium using a

Beckman D. U. Flame Emission Spectrophotometer and for phosphorus using

a Fisher Electrophotometer Colorimeter. The method by which the vegeta-

tion samples were prepared for these analyses is given in Appendix B.

Soil, coconut puree (meat and coconut water blended), and banana

samples from Homestead, and soil samples from Panama were analyzed for

stable W, Mo, and Cs by activation analysis at the University of Florida

Nuclear Science Center.
















CHAPTER V

RESULTS


Introduction


As indicated in the literature review, the process of foliar absorp-

tion and translocation of fallout is a complex phenomenon with many

physically and chemically interrelated factors. Botanical characteristics

of the plants as well as environmental factors play major roles in the

ultimate extent of absorption of material from the foliage (or more

generally, by the entire plant). The complex interrelationships are

evident in the results of these two experiments: 1) mixed tracer absorp-

tion and distribution and 2) kinetics of 134Cs accumulation in bananas

following foliar absorption.


Environmental Control


As was described in Chapter IV, plastic sheeting, peat moss, and

fencing were utilized to control the radioisotopes and to prevent contam-

ination of the general environment. Samples of vegetation (grass, weeds,

and roots), soil, insects, and small animals (mice, a lizard, and frogs)

were obtained from within and/or around the controlled areas to determine

the extent of spread of radioactivity to the general environment. In

addition, samples from adjacent banana plants (suckers, inflorescences,

and bananas) and coconuts from nearby palms were taken and analyzed to

investigate the possibility of interplant translocation (movement) of

the tracers.









The positive results of the sample analyses are presented in Table 4

and Table 5, Slight contamination was present in grass and weeds, local

soil, and in fruit from adjacent banana and coconut plants.

Samples of grass and weeds were obtained from all quadrants around

the treated palm in an effort to determine the mechanism of transfer of

material to the plants. The grass and weeds (Spanish nettle and a

succulent weed) have different type root systems; the more deeply rooted

weeds consistently showed higher concentrations of 134Cs than did the

shallow-rooted grass. Of these samples, the highest count rates were

in vegetation growing nearest the palm, even though they were from the

north side of the tree the side opposite the treated fronds. The

activity indicated in these samples is postulated to have traveled to

these plants via root-to-root transfer. This is suggested by the

higher activity in the roots of the treated palm tree. Soil samples

taken in the area were negative except for one sample taken at a point

on the periphery of the plastic sheeting where some rain water had

flowed to the unprotected ground. This contamination was removed in

soil excavated to a depth of about 8 cm in the contaminated area.

In Table 5 the indicated contamination of the soil was again by

root-to-root-to-soil movement and not by direct surface contamination.

The contaminated soil from the base of the test tree was from an area

near the treated plant's rhizome. The other positive soil samples were

taken from points adjacent to the plants, where the concentration of

roots would have been the greatest. In all cases, soil samples taken

directly under the treated foliage of the plants were negative, which

indicated no direct contamination from the experiment.











TABLE 4a


COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED PALM POSITIVE SAMPLES


Sample


PALM EAST OF TEST TREEb
Mature Fruit
Young Fruit
PALM WEST OF TEST TREEb
Mature Fruit
Young Fruit
Weeds S.W. Test Tree
SOUTH OF TEST TREEc
Spanish Nettle
Grass
Roots of Treated Palm
NORTH OF TEST TREE
Succulent Weed
Grass
EAST OF TEST TREE
Spanish Nettle
Grass
WEST OF TEST TREEc
Spanish Nettle
Grass
Chicken Weed


cpm/g 2a


0.002 0.01
0.004 + 0.002


0.005
0.008
-0.011

1.1
2.1
0.04


0.002
0.002
0.015

0.66
1.4
0.4


85Sr

cpm/g 20


-0.0002 0.003
0.0001 0.003


0.003
0.003
1.2

-0.22
-0.28
-0.24


0.003
0.009
0.10

2.3d
3.3d
3.0d
3.0


-0.04 0.7 0.92 4.2d
0.66 0.77 -0.23 + 3.5


1.3 0.64 -0.11
0.0 0.6 -0.57


0.28
-0.02
2.0


0.52
0.6
1.1


0.87
-0.20
-0.02


2.8d
1.9d
1.9


1.9
1.
5.


134Cs

cpm/g + 2a


0.01 0.001
0.007 0.001


0.02
0.1
1.7

2.9
3.4
12.


0.002
0.005
0.053

0.30
0.43
0.38


10. 0.54
6.6 0.45

4.7 0.36
2.3 0.25


1.9
1.5
12.


0.24
0.21
0.69


59Fe

cnm/g 2a


-0.0004 0.002
0.002 0.003


0.0007
-0.002
0.002

-0.22
-0.66
-0.13


Distance
From Test
Tree (Meters)


0.003
0.003
0.02


2.4
4.9
1.6


-0.17 2.7
-0.22 2.8

-0.10 2.4
-0.08 2.


-0.13
-0.24
-0.05


2.0
2.1
4.


3
3
2

0.2
1

2-3
2-3

2-3
2-3
1


aAll samples corrected for decay to November 3, 1967.
bSampled on December 14, 1967.
dSampled on June 5, 1968.
Qaulitative inspection of the gamma scintillation spectrum indicated the .presence of this radioisotope.












TABLE 5


COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES


185W
cpm/g 2a


85Sr
cpm/g 20


134cs
cpm/g 2a


5C
5Fe Location
com/g 2a (Figure 7)


Banana Pulpb
Banana Peelb
Soilc,d
Soilc,e
Suckerc,f

Banana Pulpc
Banana Peelc
Soil',g

Banana Pulpc
Banana Peelc
Soilc,d
Distal Inflor.


Bractb


0.019
0.034
0.02
0.04
0.005

-0.002
0.02
0.03

0.002
0.04
0.03
0.007


0.063
0.14
0.003
0.007
0.004

0.006
0.009
0.003

0.004
0.009
0.004
0.004


0.18
1.5
0.01
0.27
0.032

0.021
0.006
0.01

0.002
0.017
0.008
0.012


0.31
0.67
0.007
0.036
0.012

0.023
0.04
0.008

0.01
0.021
0.008
0.010


8.2
12
0.03
0.74
0.17

0.18
0.29
0.04

0.02
0.057
0.03
0.04


0.20
0.40
0.004
0.022
0.007

0.013
0.018
0.005

0.006
0.011
0.005
0.006


-0.052
1.5
0.02
0.16
0.005

0.006
0.015
0.02

-0.0006
0.036
0.02
0.005


aAll count data corrected for decay to November 3, 1967.
bSampled on November 21, 1967.
cSampled on December 14, 1967.
Radon daughters only as shown by qualitative identification of spectrum.
eFrom location of rhizome of treated plant.
Sucker developed from part of rhizome remaining from where treated parent was removed
gUncorrected for radon daughters, but spectroscopy indicated tracer peaks of 85sr and 13Cs.


Sample


0.091
0.22
0.004
0.011
0.007

0.01
0.016
0.004

0.007
0.015
0.006
0.006








Translocation to Other Trees


Translocation did occur between the treated trees and other trees

and plants in the areas, as is shown in Table 4 and Table 5. (The coconut

fruit samples were not counted in the standard geometry, since only

qualitative indication of translocation was desired.) The trees from

which the samples were taken are shown in Figure 6 (p. 33). Only the

adjacent palms on either side of the treated tree showed evidence of any

translocation. (Fruit of various ages were taken from each of the palm

trees to determine the extent of the intertree translocation.) The

results show that 134Cs was the most mobile radiotracer-between trees.

Slight amounts of 185W were translocated to the fruit of the adjacent

palms, and possibly some 85Sr and 59Fe moved to the adjacent plants.

The sites from which the follow-up samples were taken at the banana

grove are shown in Figure 7 (p. 34). The banana samples obtained on

November 21, 1967 (listed in Table 5) were composite from the banana

plants indicated by the asterisks in Figure 7. These samples were

counted in the standard geometry. Only the results of the positive

samples are shown in the table. All the radiotracers used were trans-

located to the adjacent banana plants. While 8Sr and 185W were not

detected in the fruit of the treated plant, these isotopes were trans-

located to the fruit of the adjacent trees.

Generally, the banana peels concentrated the 185W with possibly

only traces of it in the edible portion of the fruit. Iron-59 was also

translocated to the fruit of these plants. While all radiotracers were

translocated, 134Cs was translocated to other plants by a factor of

10 to 1,000 times greater than the other radiotracers.






64


Data Analyses Mixed Tracer Uptake


The application of the mixed tracers to a banana plant and a coconut

palm provided data on the relative distribution and concentration patterns

of each tracer within these plants. Since this was the major objective

of the study, no attempt was made to quantitate the tracers on the

treated foliage at the time of application. The data reported in Table 6,

Table 7, and Table 8 are the results of qualitative interpretation of the

gamma ray spectra and relative quantification of the data (i.e., not

absolute) using a simultaneous equations method of separating the

known components of the spectra.

The data are composite averages of several sub-samples of each listed

plant part that resulted from bagging, chopping, and homogenizing of the

plant parts. The data for the treated leaves are representative of the

radiotracer concentrations 17 days after treatment, but they were corrected

for decay to the day of tracer application since radiotracers with differ-

ent half-lives were used. It must be remembered that the 59Fe and 134Cs

data represent two major photopeaks each, while the 85Sr and 185W represent

only one photopeak each. This does not affect comparison of various parts,

but it does affect the comparison of count rates within a given sample.


Coconut Palm Results


As is evident in Table 6 and Table 7, only 134Cs was translocated

in significant amounts to any part of the palm. The very young fruit

had the greatest amounts of radioactivity, which would be expected since

it was the most rapidly developing plant part sampled. The largest amounts

of 134Cs were in the husks and shells of the coconuts, but direct

quantitative comparison of husks and/or shells with other plant parts is













TRACER COUNT RATES


Sample


Treated Frond

Untreated Frond (Above)

Untreated Frond (N. Side)

Inflorescence

Inflorescence

Inflorescence

Inflorescence

Inflorescence


- COCONUT FROND

185W
cpm/g 2a

NDb

0.6 0.4

-0.07 0.1

ND

2. 0.9

-0.13 0.3

0.02 0.2

-0.02 0.07


TABLE 6a

LEAFLETS AND INFLORESCENCES 18 DAYS AFTER TREATMENT

85Sr 134Cs 59Fe
cpm/g 2a cpm/g 20 cpm/g 2a

1,600 45 5,100 29 63 8.8C

75 3.0 180 2.1 ND

5.6 0.9 32 0.6 -0.15 0.16

120 8.4 500 5.2 ND

230 6.3 400 3.9 5.6 1.2

62 1.9 87 1.2 0.6 0.4

26 0.9 49 0.6 0.5 0.2

7.6 0.4 20 0.3 -0.06 0.1


aAll data corrected for decay to November 3, 1967.
bNot detectable when the 2a error term was included with the net count rate the result remained negative.
cAnalysis of chemically separated sub-sample indicated that this isotope was present.














TABLE 7a


TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER TREATMENT


Sample


YOUNG FRUITb
IfLMATURE FRUITd
Milk and Meat
Husks
IMMATURE FRUITe
Milk
Meat
Husks
MATURE FRUIT
Milk
Meat
Shell
Husks


185w
cpm/g 2a

NDc

ND
ND

0.014 0.018
ND
ND

ND
-0.06 0.06
ND
ND


85Sr
cpm/g 2a

-0.2 6.2

-0.3 0.3
-0.15 0.20


-0.02 0.1
ND
0.7 0.2

-0.07 0.1
-0.02 0.4
ND
0.5 0.1


134Cs
cpm/g 2a


350 4.0


2.4
46
17

5.6
13
21
10


59Fe
cpm/g 2a


0. 1.


0.2
0.1

0.1
0.5
+ 0.1


-0.02 0.02
ND
ND

ND
-0.05 0.09
ND
ND


aAll data corrected for decay to November 3, 1967.
bFruit about 3 to 6 centimeters in diameter.
CNot detectable when the 20 error term was included with the net count rate the result remained negative.
dShell only a thin layer of tissue with little meat developed.
eShell only a thin layer of tissue which was unseparable from the meat; fruit about 8 to 13 centimeters in
diameter.
Analysis of a chemically separated sub-sample indicated that this isotope was present.












TABLE 8a

TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER TREATMENT


185W
cpm/g 2a


85Sr
cpm/g 2a


134Cs
cpm/g 2a


59Fe
cpm/g 2a


TREATED PLANT PARTS
Lamina
Midrib
Axial
UNTREATED PLANT PARTS
Upper Pseudostem
Lower Pseudostem Interior
Lower Pseudostem Exterior
Rhizome
Lamina: Youngest
Midrib: Youngest
Inflorescence Stem
Distal Inflorescence Bract
Banana Pulp
Banana Peel
DAUGHTER PLANT PARTS
Upper Pseudostem
Lower Pseudostem
Lamina
Midrib


NDb, c
ND
ND

120 7
NDc
ND
ND
NDc
ND
ND
NDc
NDC
-5.2 5.8

ND
ND
ND
-1.4 2.3


Sample


280
100
42


14,000
3,500
2,400

3,200
90
90


180
66
28


6,400
900
300


36,000
9,300
3,800

3,100
1,400
1,100
960
1,900
1,800
4,800
15,000
3,400
3,200

1,800
1,700
2,500
1,400


510
600
74


ND
-0.34
750
140


69
23
8

11
4
4

4
5
11

7.1c
9


4
9
4


810
92
27
ND
84
41
91
NDc
-6.1
85 +

ND
-0.1
510 +
92


aAll data corrected for decay to November 3, 1967.
bNot detectable when the 2q error term was included with the net count rate the result remained negative.
CData from chemically separated sub-sample indicated that this isotope was present.










not possible because the former did not lend themselves to counting in

the standard geometry.

Strontium, iron, and tungsten did translocate from the treated fronds

on the south side of the tree to a younger frond on the north side. How-

ever, a much greater amount of 85Sr moved to an untreated frond directly

above the treated fronds.

The data for some of the inflorescences may be high because of direct

contamination since the rachises (the ribbing that supports the leaflets)

of the three fronds were treated as well as the leaflets. It is possible

that at the time of application some of the tracer solution was channeled

to the inflorescences which were associated with the treated fronds.

Also, the heavy rain (3.8 cm), which occurred within an hour of treatment,

may well have washed additional tracer down the rachises to the bases of

the treated fronds.

Although no attempt was made to relate the inflorescences to the

particular fronds with which they were associated, it is clear that the

134Cs (150 1 cpm/g fresh weight) measured in an inflorescence sampled

on December 14, 1967, as a follow-up sample resulted from translocation

from untreated parts since this inflorescence did not emerge until after

all treated parts were removed on November 21, 1967.


Banana Plant Results


In addition to the four leaves, the axial of the banana plant was

treated with some tracer solution. (The banana leaf is composed of four

distinct parts: 1) the leaf sheath, which helps form the pseudostem,

2) the petiole, the portion extending from the axial to where the "leaf"

tissue begins, 3) the lamina, the "leaf" photosynthetic area, and 4) the









midrib, the "channeled" ribbing which separates the lamina halves and is

an extension of the petiole.) In Table 8 the axial is considered to be

from about 5 cm below the pseudostem top to about 8 cm out on each

petiole. The untreated banana leaf was the youngest leaf on the plant,

and it was still in a vertical position well above the four treated

leaves; thus, it could not have been directly contaminated. The lower

pseudostem was a section from about 30 cm above the ground. This part

was separated into interior and exterior portions on the basis of tissue

color. The central, white core was termed the lower pseudostem

(interior), and the exterior part was that which contained some green

pigmentation. The rhizome was the entire subterranean base of the

parent plant. The daughter plant was a new growth with five leaves and

was about 2 m tall. It was to one side and slightly to the rear of the

area below the treated leaves.

Generally, there was greater translocation of all the radionuclides

by the banana plant than by the palm. Cesium-134 was very mobile through-

out the banana plant, and it particularly concentrated in the inflores-

cence and the fruit. The 134Cs concentration in the developing distal

inflorescence bract was four times greater than in the fruit.

Strontium-85 translocated to newly developing lamina tissue in the young

leaves of the parent and daughter plants. There is some indication that

59Fe was translocated to the bananas and that the peels concentrated this

isotope relative to the banana pulp (see Table 8). The chemical separa-

tion results did indicate the possible presence of 59Fe in the banana

pulp. However, this could have been slight contamination of the pulp

from the peels while separating the pulp from the peels of the green

bananas (which is quite difficult).









Chemical Separation


The chemical separation procedure outlined in Appendix A was used

to simplify the complex gamma ray spectra so that positive identifica-

tion could be made of tungsten in representative samples of fruit,

foliage, and other plant parts. Prior to separation, tungsten was

masked by electronic noise interference and Compton continuum from the

other radiotracers as shown in Figure 20. Following separation, the

samples' spectra were greatly simplified. If 185W were present, it was

in the NaOH soluble, HC1 insoluble portion of the separated sample,

while strontium and iron were in the NaOH insoluble, HC1 soluble

fraction. Although cesium was primarily in the NaOH soluble, HC1 soluble

portion, it was also present in the other three fractions of the

separated sample since cesium is amphoteric. Table 9 shows the general

results of the separation. Figure 21 through Figure 28 show the typical

spectra of 1) the chemically separated portions of the treated coconut

frond sub-sample (4 portions) and 2) the chemically separated portions

of the treated banana leaf sub-sample (4 portions).

Following the chemical separation, as expected, tungsten was

detectable on the treated foliage. Also, it was evident that 185W had

translocated to untreated foliage on both test plants and possibly to

the upper pseudostem (interior). For the latter, it is probable that

the activity in this sample originated from direct application, since

the petioles of the test tree were also treated and the radiotracer

solution probably "drained" into the pseudostem's upper section. The

edible parts of the fruit from both test trees and the distal inflores-

cence bract of the banana plant did not have any detectable radiotungsten.

The value of the chemical extraction is illustrated in Figure 20 through












1-- 40


o
36



0 20
32










a 16
CZ
4-4
28
















0 I I

0 20 40




FIGURE 20:


134Cs


60 80 100 120 140

Channel Number (10 Kev/Channel)

SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED
















TABLE 9

RESULTS OF CHEMICAL SEPARATION FOR 185W


Fraction

Supernatant

Precipitant

Supernatant

Precipitant


Tube

1

1

2

2


NaOH

Insoluble

Insoluble

Soluble

Soluble


HC1

Soluble

Insoluble

Soluble

Insoluble


Radioisotopea

85Sr, 59Fe, 134Cs

134CS

134Cs, 85Sr

185W, 134Cs


aln order of decreasing abundance.






5,200

4,800

4,400

4,000

3,600

3,200

2,800


2,400

2,000


1,600

1,200


134Cs


134Cs


20 40 60 80 100


FIGURE 21: SUB-SAMPLE


Channel Number (10 Kev/Channel)

- TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 SOLUBLE PORTION


85Sr


800

400





134Cs
2,800 -

2,600 -

2,400 -

2,200 -


2,000 -

1,800 134

. 1,600 -

S1,400 -


0 1,200 -

u 1,000 -

P 800


0 600

400 134C

200


0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)

FIGURE 22: SUB-SAMPLE- TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 INSOLUBLE PORTION




















134Cs


20 40 60 80 100


120


Channel Number (10 Kev/Channel)


SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1 SOLUBLE PORTION


200


FIGURE 23:













900


800 -

S 700 185W

600

-1
500

1-4
a 400

U 300

S200-3
200 134Cs

0 100


0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)

FIGURE 24: SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1 INSOLUBLE PORTION






5,20'


59Fe


4,800-

4,400- 8Sr

4,000- xi

3,600-

59
3,200- 59Fe

2,800-

S2,400--
134Cs
2,000-
1,6134Cs
S1,600-
S134Cs
4Cs
J 1,200-
0

800

400


0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)

FIGURE 25: SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 SOLUBLE PORTION











900


S800
134C
u
. 700 134Cs

600

S500
z 134
S400 -Cs

S300

200
0
lo / \ f \1346,
100 -134Cs

0 I I 1 1 I 1 .
0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)


SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 INSOLUBLE PORTION


FIGURE 26:

















80
8134
0
6 70
70

w 60 -

S50
4134
S40-

30 85Sr

~ 20


S10 134
Cs

0 0
S 0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)

FIGURE 27: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 SOLUBLE PORTION






3,500 -

3,250- 185W

3,000

2,750 -

2,500

S2,250

2,000
i-4
o 1,750

C)
S1,500

u 1,250

S1,000

o 750 134
03Cs

500 -
85 Sr 134cs

250 134Cs

0 1 I I I I
0 20 40 60 80 100 120 140 160 180 200

Channel Number (10 Kev/Channel)

FIGURE 28: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 INSOLUBLE PORTION o









Figure 24, which show the components of the unseparated coconut frond

and the spectra of the separated sample. In Figure 20, the tungsten is

undetectable, while Figure 24 clearly shows the presence of 185W.


Stable Element Data


Since this study was conducted in the sub-tropical climate of south

Florida, partial stable element analyses of the soil and vegetation

samples from south Florida and from Panama were made so that the applica-

tion of these tracer results might be extrapolated to the Panamanian

conditions. Table 10 shows the partial stable element compositional

analyses of various samples from south Florida and Panama.

The major elements are in reasonable agreement when one considers

what the data represent. The Panamanian samples represent data of the

mean of many samples, while those from Florida are determinations of at

most three samples. (The differences in the minor elements are typical

when comparing interlaboratory results of trace metal analyses as well

97
as plant tissue.97) In general, the elemental composition of plants vary

widely with age of tissue and environmental conditions prior to sampling.

Even so, there is generally good agreement among the banana pulp samples

from both locations and also between coconut meat samples. Notable

exceptions are in the 1) Fe, Mn, and Zn concentrations in the banana

leaf and pulp samples and 2) Fe, Mn, Zn, and Cu in the coconut plant

parts other than the coconut meat.

97
According to Gamble et al.,97 the soil compositions in south Florida

and Panama have similar tungsten concentrations. The cesium composition

of the soils in the two Homestead, Florida, experiments vary considerably.

The total cesium concentration in the soil at the coconut palm site was












TABLE 10a


PARTIAL ELEMENT COMPOSITIONAL ANALYSES


Element: Parts per million (ppm)


Sample

BANANA LEAF
East Glade
Panama Darienc

BANANA PULP
East Glade
Panama Darienc
USDA Miami 2e
USDA Miami 3e

SOIL
East Glade
Homestead

COCONUT MEAT
Homestead
Panama Dariene


Ca Sr


5,200
8,700


170
230
530
190


NA
NA


1.4
1.8
6.9
1.7


NA
NA


Fe Mg


2.6b
420


9.1
31
14
0.14


NA
NA


620 0.77 22
220 1.0 17


COCONUT FROND
Homestead 5,500 30
Panama DarienC 3,700 15


COCONUT HUSK
Homestead
Panama Darienc


2,300 13
1,100 12


2,400
4,200


1,000
1,000
840
730


NA
NA


Mn Zn Cu P K


15b
310


0.78
19
0.19
0.14


NA
NA


50 27b
0.8 16


14 4.
0.7 9.
54 3.
2.3 0.


NA N
NA N


1,000 12 24
1,200 5.8 16


1,300 7.0 62
4,000 68 19


690 0.19 40
1,100 10 11


3
0
L
14


780
1,900


1,800
1,200
NA
NA


NA
NA


13 2,400
4.0 2,000


30 1,600
8.0 980


11,000
25,000


7,200b
11,000
8,800
10,000


NA
NA


Cs Mo W


NA
NA


0.014d
NA
NA
NA


0.069f
2.9f


9,000 0.044f
5,700 NA


NA
NA


1.0d
NA
NA
NA


1.89
4.5g


1.0d
NA


6,100
7,000


18 740 11,000
2.5 280 11,000


NA
NA


0.015d
NA
NA
NA


0.25d
1.d


0.015d
NA










aExcept where noted, all values are averages of three determinations.

bValues are averages of two determinations.

CMean of all samples from Darien Provence, Panama.

Activation analysis determination 5%.

eAll values based on one determination only.

Activation analysis determination 4%.

gActivation analysis determination 2.9%.

hActivation analysis determination 2.5%.

NA indicates the samples were not analyzed for this element.






84


.42 times that in the East Glade soil. However, the stable cesium concen-

tration in the coconut meat was only three times that in the banana pulp.

Since the available cesium concentration in each location is unknown,

an explanation of this concentration difference is not possible.


Data Analyses Kinetics Study Miami


Cesium-134 Accumulation


The kinetics of cesium movement from the banana plant's foliar sur-

face to the fruit was determined by measuring the rate of 134Cs accumu-

lation in the fruit. The accumulation rate derived in this study can be

characterized by a first order kinetics function of the type_


dCt
dt


dCt

dt


=k(Ce Ct)


134
=the change in the 1Cs concentration in

the banana fruit with time;


= the rate constant in units of

= the equilibrium concentration

134Cs in the fruit;

134
= the concentration of Cs in

at time "t."


days-1

value of




the fruit


The solution to Equation (1)

Ct

where


Ce(1 e-kt)


t = the time after treatment of the foliage.


where










The rate constants (k), which are presented in Table 11 and are

shown on Figure 29 through Figure 31 for the respective trees, represent

an overall uptake and translocation to the fruit, or rate of accumulation

in the fruit. The data from the three banana plants were also treated

as replicates, and an average rate constant (k) was calculated for the

rate of cesium accumulation in bananas following foliar absorption. The

rate constants for Tree 1 and Tree 3 were essentially the same, even

though the plants were of different varieties and the fruit were in

different stages of development. It is postulated that the slightly

higher rate constant for Tree 2 was a result of the abnormal condition

of the inflorescence of this plant, which caused the fruit to develop

in the axial; thus, the distance over which the translocation had to

take place was significantly shorter than in Tree 1 and Tree 3. (The

tracer was applied to the lamina, leaf, midrib, and petioles of all

three trees and not just to the lamina.) Generally, there is good

agreement among all three trees' rate constants, and the calculated

combined rate constant of -0.133 per day is only approximately 10

percent higher than the individual constants for Tree 1 and Tree 3.

The engineering significance of these results will be discussed in

the next chapter.


Rain Effect on Equilibrium Concentration


The effect of rain wash-off played a significant role in estab-

lishing the equilibrium concentration (Ce) level in the fruit. No

rain fell during the process of applying the tracer to Tree 1; a light

rain began while treating Tree 2; and by the time Tree 3 was treated, a

tropical downpour was occurring. While Tree 1 received more tracer than

the other trees, Tree 2 attained a Ce of approximately twice that for






86








TABLE 11
134
SUMMARY OF 134Cs RATE OF UPTAKE EXPERIMENT


Banana Tree k Ce Time to Treated Activity
50 % Ce Area Applied
(day-1) (pCi/g) (days) (cm2) (pCi)

Tree 1: Musa walap -0.123 16,000 5.8 13,900 175

Tree 2: Musa rajapuri -0.158 32,000 4.3 10,800 147

Tree 3: Musa kullan -0.122 5,000 5.8 21,800 150







87











100








o C/Ce = 100 ( 1 e-0123t )

C)

u -







00
u









M


p-,
1
P4












0.1 I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24 26

Time: Days

FIGURE 29: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa walap
TREE 1


















100







ce
c/ce = 100( 1 e-0"158t )



CO














0.1
10





C-,


















0 2 4 6 8 10 12 14 16 18 20 22 24 26

Time: Days

FIGURE 30; RATE OF ACCUZILATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa rajapuri
TREE 2
**


























TREE 2







89











100







SC/C = 100( 1 e-0.122t )

a e

u

10





H






















0.1
0 2 4 6 8 10 12 14 16 18 20 22 24 26

Time: Days

FIGURE 31: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa kullan
TREE 3




Full Text
CHEMICAL SEPARATION PROCEDURE FOR TUNGSTEN ANALYSIS
1) Dry a few grams of the sample.
2) Ash 2-3 grams at 550 C to whiteness (overnight).
3) Dissolve the ash in 5 ml of 6N NaOH and bring to gentle boil for
15 minutes.
4) Wash sample into centrifuge tube with distilled water and centrifuge
the tube.
5) Pour supernatant into another centrifuge tube (Tube 2); (Tube 1
contains the NaOH insoluble precipitate, and Tube 2 contains the
NaOH soluble supernatant).
6) Add 16 mg tungstate carrier and 8 mg cinchonine to Tube 2 and mix
well.
7) Add 5 ml concentrated HC1 (8N) to both centrifuge tubes and mix well
check pH; if not acidic, add more HC1.
8) Centrifuge both portions Tube 1 and Tube 2.
9) Pour supernatants into separate 800 ml counting containers and add
distilled water to 100 ml volume.
10) Wash precipitates into separate 800 ml counting containers and add
distilled water to 100 ml.
11) Count all four sample portions using the Packard gamma scintillation
spectrometer.
12) Sum activities in all four samples over each photopeak region; solve
by method of simultaneous equations to quantitate.
129


APPENDIX B


10
the cuticle and epidermis is by both passive and active means.16,22 The
passive component is absorption of nutrients into free space in the sub
surface tissue by mass flow or diffusion; and the active processes are
ion exchange and transport into the protoplasm.16,31 por active absorp
tion, an energy source is required, since energy is expended. Generally,
anion uptake is more energy dependent than cation absorption.^2
After the initial absorptive phase, passage to the interior cells
is a two-phase process involving ion exchange and binding on the exterior
of cell walls, followed by an active uptake, which is metabolically
controlled by protoplasmic parts of the cell. Jyung et al. devised a
model for ion uptake using carrier concepts, which they feel is the most
likely overall uptake process by green leaves. The first phase of their
model involves a rapid, non-metabolic process, and the second phase, a
slower metabolically controlled step. According to them, a close fit to
a first order equation possibly indicates some passive uptake with the
initially rapid phase being more a function of existing environmental
conditions than of botanical characteristics.
Rates of Absorption of Specific Ions
Urea is reported to be the most rapidly foliar-absorbed material.^
Of the minerals, or nutrients, studied by other researchers, K, Na, and
Rb are the most rapidly absorbed. While Ca, Sr, Fe, and Mo are initially
absorbed fairly rapidly, the rate of absorption decreases sharply within
a few hours.I,33,34 This rate reduction may be associated with satura
tion of the leaf tissue at the area of absorption coupled with an inabil
ity to translocate these minerals from the leaf.10>35,36


116
are the two most rapidly translocated minerals (see Table 1, p. 12), a 4-
to 6-day time to 50 percent equilibrium for cesium accumulation in the
fruit of the banana plant is reasonable. All the other data in the
literature are concerned with rates of absorption by the foliage and
not translocation rates.
Effect of Rain
Although determining the effects of rain on the fate of fallout on
tropical fruit plants was not an objective of this research, the field -
study provided significant data on these effects which will be very
important in predicting the radiological consequences of a Plowshare
event in the tropics. In the mixed tracer study, for instance, approxi
mately twice as much mixed tracer solution was applied to the three fronds
of the palm as was applied to the banana leaves; yet, at the end of the
experiment the treated banana leaves had roughly ten times the concen
tration of radiotracers on them as did the palm leaflets. (The East Glade
banana plant was treated following a light shower, but no additional rain
fell afterwards until near the end of the experiment; on the other hand,
a 3.8 cm rainfall occurred within an hour of treating the palm fronds.)
While part of the concentration difference was probably related to
botanical variations between the coconut palm and the banana plant, the
rain wash-off effect probably was a major factor.
The kinetics of x'54Cs accumulation experiment provided an even greater
illustration of the importance of rain on the absorption of foliar-deposited
fallout. Tree 1 was treated when no rain was falling, treatment of Tree 2
was during a light rain, and by the time Tree 3 was treated, a regular
downpour was in progress. This had a significant effect on the equilibrium


68
not possible because the former did not lend themselves to counting in
the standard geometry.
Strontium, iron, and tungsten did translocate from the treated fronds
on the south side of the tree to a younger frond on the north side. How
ever, a much greater amount of 5gr moved to an untreated frond directly
above the treated fronds.
The data for some of the inflorescences may be high because of direct
contamination since the rachises (the ribbing that supports the leaflets)
of the three fronds were treated as well as the leaflets. It is possible
that at the time of application some of the tracer solution was channeled
to the inflorescences which were associated with the treated fronds.
Also, the heavy rain (3.8 cm), which occurred within an hour of treatment,
may well have washed additional tracer down the rachises to the bases of
the treated fronds.
Although no attempt was made to relate the inflorescences to the
particular fronds with which they were associated, it is clear that the
^^Cs (150 1 cpm/g fresh x^eight) measured in an inflorescence sampled
on December 14, 1967, as a follow-up sample resulted from translocation
from untreated parts since this inflorescence did not emerge until after
all treated parts were removed on November 21, 1967.
Banana Plant Results
In addition to the four leaves, the axial of the banana plant was
treated with some tracer solution. (The banana leaf is composed of four
distinct parts: 1) the leaf sheath, which helps form the pseudostem,
2) the petiole, the portion extending from the axial to where the "leaf"
tissue begins, 3) the lamina, the "leaf" photosynthetic area, and 4) the


63
Translocation to Other Trees
Translocation did occur between the treated trees and other trees
and plants in the areas, as is shown in Table 4 and Table 5. (The coconut
fruit samples were not counted in the standard geometry, since only
qualitative indication of translocation was desired.) The trees from
which the samples were taken are shown in Figure 6 (p. 33). Only the
adjacent palms on either side of the treated tree showed evidence of any
translocation. (Fruit of various ages were taken from each of the palm
trees to determine the extent of the intertree translocation.) The
results show that L~54Cs was the most mobile radiotracer-between trees.
Slight amounts of were translocated to the fruit of the adjacent
palms, and possibly some -*Sr and -^Fe moved to the adjacent plants.
The sites from which the follow-up samples were taken at the banana
grove are shown in Figure 7 (p. 34). The banana samples obtained on
November 21, 1967 (listed in Table 5) were composited from the banana
plants indicated by the asterisks in Figure 7. These samples were
counted in the standard geometry. Only the results of the positive
samples are shown in the table. All the radiotracers used were trans
located to the adjacent banana plants. While "*Sr and were not
detected in the fruit of the treated plant, these isotopes were trans
located to the fruit of the adjacent trees.
185
Generally, the banana peels concentrated the W with possibly
only traces of it in the edible portion of the fruit. Iron-59 was also
translocated to the fruit of these plants. While all radiotracers were
translocated, ^Cs was translocated to other plants by a factor of
10 to 1,000 times greater than the other radiotracers.


36
FIGURE 8: USDA BANANA EXPERIMENT SITE


39
FIGURE 10: PREPARED SITE USDA PLANT INTRODUCTION STATION
TREE 2 AND TREE 3


LIST OF TABLES
Table Page
1. CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY,
MOBILITY, AND LEACHABILITY 12
2. RATES OF ABSORPTION 13
3. SPECTROMETER CALIBRATION 55
4. COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED
PALM POSITIVE SAMPLES 61
5. COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND
SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES 62
6. TRACER COUNT RATES COCONUT FROND LEAFLETS AND
INFLORESCENCES 18 DAYS AFTER TREATMENT 65
7. TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER
TREATMENT 66
8. TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER
TREATMENT 67
9. RESULTS OF CHEMICAL SEPARATION FOR 185W 72
10. PARTIAL ELEMENT COMPOSITIONAL ANALYSES 82
11. SUMMARY OF 134Cs RATE OF UPTAKE EXPERIMENT 86
12. EQUILIBRIUM CONCENTRATION VALUES Ce VERSUS AGE OF FRUIT 91
13. COUNT RATE PER UNIT V7EIGHT AS INDICATED BY PUNCH SAMPLES .... 92
14. CONCENTRATION OF 134Cs IN BANANA PLANT PARTS AND PEAT MOSS .. 94
15. RADIOACTIVITY IN ADJACENT FRUIT BEARING PLANTS AND NEARBY
GRASS 97
16. RELATIVE TRANSMISSION FACTORS 110
Vi


57
Since the may have been masked by high, count rates or was below
the detectable and/or measurable limits of the whole sample, a chemical
separation procedure was developed to simplify the gamma spectra in order
to positively identify the tungsten, if it were present. The bases of
the procedure, which is outlined in Appendix A, were chemical precipita
tion of tungsten using cinchonine^ (a selective precipitant for tungsten)
and a tungsten carrier combined with acid and alkali solubilities.
The counting geometry for these separated samples was 100 ml in the
standard 800 ml container, which was centered over the 10.16 cm x 10.16 cm
scintillation crystal. The smaller volume in conjunction with the
separation increased the efficiency for the detection of -*-^W by decreasing
the losses of X-rays through the sample containers sides, decreasing the
self-absorption losses, and simplifying the spectrum.
The specific samples separated were chosen because they included
1) edible parts (which were the primary samples of interest), 2) treated
foliage (the plant part to which tungsten had been applied), and 3) parts
to which tungsten might have been translocated untreated foliage,
distal inflorescence bract, and pseudostem.
Compositional Analyses
Stable element analyses for Ca, Mg, Mn, Fe, Cu, and Sr in vegetation
and crops from Panama and Colombia were determined at the Central
Analytical Laboratory, Institute of Food and Agricultural Sciences,
University of Florida (IFAS,UF) so that the mineral composition of fruit
from the bioenvironmental feasibility study area could be compared with
the composition of the plants and fruit in the Florida study. A
Beckman D. U. Flame Emission Spectrophotometer was used for these analyses.


DRY ASHING PROCEDURE PLANT TISSUE101
1) Dry the samples at 100 C.
2) Ash about 2 grams at 550 C until ash becomes gray (overnight).
3) Cool, add excess concentrated HC1 (reagent grade), evaporate excess
acid carefully.
4) Reheat to 550 C for 1-2 hours to whiteness.
5) If ash is not white, cool, add 25 percent HNO^, re-evaporate
carefully to dryness.
6) Heat to 550 C and cool.
7) Add a few drops of concentrated HC1, dilute with demineralized water
to 50 ml.
131


Counts per Channel in 60 Minutes
FIGURE 17: IRON-59 STANDARD


CHAPTER IV
METHODOLOGY
Site Selection
The University of Florida's Sub-Tropical Experiment Station at
Homestead, Florida, was selected as the site for the initial mixed tracer
study. The United States Department of Agriculture's Plant Introduction
Station, Miami, Florida, was chosen for the kinetics study because 1) the
site was available for extended-term studies and 2) the site provided
excellent security.
The Homestead site was composed of two experimental locations. The
coconut experiment was conducted at the main site of the Sub-Tropical
Experiment Station where there were 12 trees in the coconut grove spaced
approximately 4.6 meters (m) apart. From these trees, a Malayan dwarf
coconut palm of the yellow variety was chosen for the study because it
presented a balanced distribution of maturing fruit.
The second site at Homestead was the East Glade Farm of the Sub-
Tropical Experiment Station. This farm was approximately eight miles
east and two miles south of Homestead. The East Glade banana grove had
24 clusters of banana plants in 4 rows of 6 clusters each. The spacing
was approximately 4.6 m within rows and 5.3 m between rows. The test
plant was selected because its fruit was estimated to be at least three
weeks from maturity. However, time showed that this estimate was quite
inaccurate (low). Figure 1 shows the coconut tree and its fruit, and
Figure 2 and Figure 3 show the banana grove and the treated banana plant.
23


Sciences, University of Florida. Finally, the author wishes to thank
his wife, Lissie, who provided much help in the preparation of the
manuscript, translation of Spanish articles, editorial assistance, and
final preparation of figures.
This work was supported in part by United States Public Health
Service Training Grant No. 47013-03-68, and by the Institute of Food
and Agricultural Sciences, xhich was a sub-contractor of Battelle
Memorial Institute, Columbus, Ohio.
iii


54
study, since the relative distribution pattern of the tracers in the
plants was the primary purpose of the study. However, absolute counting,
of 4Cs was utilized in the kinetics study so that the total quantity
of cesium accumulated by the fruit could be estimated.
Calibration for geometry differences in counting the leaf punch
samples was based on the fact that the samples from the terminal sampling
of the banana leaves should have had the same count rate per unit weight
as the lamina tissue of the parent sample. Thus, the count rate per
unit weight was calculable for the two counting geometries involved
(standard 800 ml and scintillation vial over the large crystal). An
average correction factor was calculated which allowed correction of the
results of the leaf punch sample analyses for the non-standard geometry.
Data Analyses
The gamma ray analyzer (Packard system) output was an X-Y plot of
the gamma spectrum and a Monroe Digital printout of the number of counts
per channel (or energy band). The portions of the gamma spectra summed
to quantitate the photopeaks of the radionuclides and the photopeak
energies are shown in Table 3. Small spectrum shifts were corrected
when the channels were summed manually. The sums of counts under the
integrated photopeak regions were used in a computer program to separate
the mixed spectra into individual isotopic components.. The two photo
peaks of *^Fe and ^^Cs were summed to improve the sensitivity of detection.
The gamma spectrum of each sample was analyzed using a simultaneous
equations method of separating the components^ and the University of
Florida's. IBM 360 computer. The computer analysis involving simultaneous
equations was chosen as the method of separating the known components of


2
possible method of constructing a new canal, and the AEC was given the
responsibility for investigating the problems associated with this
technique. The AEC subsequently awarded the prime contract for the
Bioenvironmental and Radiological-Safety Feasibility Study to Battelle
Memorial Institute, Columbus Laboratories. Battelle sub-contracted
various segments of the study to several research groups. The University
of Florida's International Programs of the Institute of Food and
Agricultural Sciences received the contract covering agricultural
ecology. This dissertation is part of the University of Florida study
and is concerned with two important components of the diets of the
ethnic groups in the canal study areas: the banana and the coconut.
Research Objectives
The objectives of this research were threefold: 1) develop method
ology, 2) determine distribution patterns of radionuclides in the banana
and coconut plants following foliar application, and 3) study the kinetics
of cesium accumulation by the banana fruit following foliar absorption.
The first phase of the study was to develop methodology for perform
ing low-level radiotracer experiments in the field while controlling the
radioisotopes with respect to the general environment. This was necessary
since most of the research concerning the accumulation of fallout by
crops has been devoted to 1) controlled greenhouse experiments in
nutrient solutions or pot studies and 2) field studies involving relatively
long-term uptake and concentration of fallout from nuclear tests.
The literature concerning comparison of field and greenhouse results
show that there is often poor agreement between parallel experiments in
3
the two environments. Russell and Milbourn reported that in greenhouse


Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 25: SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 SOLUBLE PORTION


31
at moat twice background, and then the samples were harvested. All the
contaminated waste was sealed in 55-gallon drums, which were subsequent
ly buried in the University of Florida's waste disposal area. Figure 5
shows the removal of the peat and plastic.
All the coconut fruit, inflorescences (the plant part that produces
the flowers from which the fruit develop), treated fronds, and some
untreated fronds were collected, individually bagged, and returned to
the laboratory for analysis. The various parts of the banana tree and
its fruit were also individually bagged and returned to the laboratory.
In order to estimate the magnitude of zoological contamination which
might occur under these experimental conditions, samples were obtained
of 1) a lizard and a frog from the area of the banana tree and 2) ants,
a field mouse, a frog, and flying insects (collected with a light trap)
at the coconut site.
On December 14, 1967, 41 days after the test trees were treated,
additional fruit and soil were collected from adjacent trees at
both sites to determine the extent of radionuclide transport through the
.respective groves. Figure 6 and Figure 7 show where these samples were
obtained. Another environmental survey was conducted on June 5, 1968,
213 days after the tracer application, at the site of the coconut
experiment to be certain that there was no significant contamination of
the area. Samples of vegetation, soil, roots of the treated palm, and
earthworms were obtained to determine the extent of residual radio
activity. Also, fruit was collected from an adjacent tree, and the area
was surveyed with a Geiger counter.


LEGEND: O Coconut Palms Sampled
Treated Palm
B Location of Treated Fronds
)( Other Sampling Points
(3 Other Positive Samples from Adjacent Palms
Roads
Note: Palm trees were approximately 4.6 meters apart
O O O O O OxBxO o ooo
X
X X
FIGURE 6: HOMESTEAD COCONUT GROVE


12
TABLE 1
CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY, MOBILITY, AND
LEACHABILITY20
Absorption Class3 Mobility Class^ Teachability Class0
Rapid: Mobile; Easily:
Urea N
Rb
Csd
Na
K
Cl
Zn
Moderate;
Ca
S
Ba
P
Mn
B
Slow:
Mg
Sr
Fe
Cu
Mo
Urea N
Rb
Csc
Na
K
Cl
S
Partially;
Zn
Cu
Mn
Fe
Mo
B
Immobile:
Mg
Ca
Ba
Sr
Na
Mn
Rbe
Csf
Ke
Modrate:
Ca
Mg
S
K
Sr
Difficult:
Fe
Zn
Cl
P
aAdapted from Wittwer and Teubner^2
^Adapted from Bukovac and Wittwer^
cAdapted from Tukey, Tukey, and Wittwer^
^Adapted from Wittwer^
eAdapted from Stenlid^
Adapted from Olsen and Cate


134
23. Middleton, L. J., "Radioisotopes in Plants: Practical Aspects of
Aerial Contamination with Strontium-89 and Caesium-137" (A
Symposium on) Radioisotopes in the Biosphere, Edited by Richard
S. Caldecott and Leon A. Snyder. Minneapolis: Center for
Continuation Study, University of Minnesota, 1960.
24. Russell, R. S. and J. V. Possingham, "Physical Characteristics of
Fallout and Its Retention on Herbage," United Kingdom Atomic
Energy Weapons Research Establishment Report T 57-58, 1959.
25. Ambler, J. E. and R. G. Menzel, "Retention of Foliar Applications
of Sr^ by Several Plant Species as Affected by Temperature
and Relative Humidity of the Air," Radiation Botany, 6:
219-223 (1966). .
26. Bukovac, M. J., S. H. Wittwer, and H. B. Tukey, "Aboveground Plant
Parts as a Pathway for Entry of Fission Products into the Food
Chain with Special Reference to sr^9~90 an(j cs137^n Michigan
State University, USAEC TID 17977 (1963).
27. Eggert, R., L. T. Kardos, and R. D. Smith, "The Relative Absorption
by Apple Trees and Fruits from Foliar Sprays and from Soil
Applications of Fertilizers Using Radioactive Phosphorus as a
Tracer," Proceedings of the American Society of Horticultural
Science, 60: 75-86 (1952).
28. Boynton, Damon, "Nutrition by Foliar Application," Annual Review of
Plant Physiology, 5: 31-54 (1954).
29. Yamada, Y., "Studies on Foliar Absorption of Nutrients Using
Radioisotopes," PhD Thesis, Kyoto University, Kyoto, Japan
(1962).
30. Biddulph, 0., "Radioisotopes in Plants: Foliar Entry and
Distribution" (A Symposium on) Radioisotopes in the Biosphere.
Edited by Richard S. Caldecott and Leon A. Snyder, Minneapolis:
Center for Continuation Study, University of Minnesota, 1960.
31. Jyung, W. H. and S. H. Wittwer, "Foliar Absorption Active Uptake
Process," American Journal of Botany, 51: 437-444 (1964).
32. Epstein, E., D. W. Rains, and W. E. Schmid, "Course of Cation
Absorption by Plant Tissue," Science, 136: 1051-1052 (1962).
33. Fisher, E. G. and D. R. Walker, "The Apparent Absorption of
. Phosphorus and Magnesium from Sprays Applied to the Lower
Surface of McIntosh Apple Leaves," Proceedings of the American
Society of Horticultural Science, 65: 17-24 (1955).
34. Oland, K. and T. B. Opland, "Uptake of Magnesium by Apple Leaves,"
Physiologia Plantarum, 9: 401-411 (1956).


106
137
The whole-body dose resulting from intake of Cs through the
consumption of bananas is a function of the rate of intake (R), the
duration of ingestion, and the biological half-life of ^^Cs. Since
the physical half-life is so long (30 years), the biological half-life
determines the rate of decrease of the body burden (B) of AJ/Cs. The
dose received during the period of ingestion is a function of the rate
of ingestion and the biological elimination constant (k), while the
dose received following the termination of ingestion is determined by
the body burden (B) of LJ/Cs accumulated during the ingestion phase
and the biological elimination constant. Equation (3) shows how the
body burden varies with the duration of intake:
= R kB (3)
dt
where
B
R
k
dB
dt
the body burden of Cs in yCi;
the rate of AJ/Cs ingestion in pCi/day;
the biological elimination constant for ^^^Cs in the
body: 0.0099 days-^ assuming a biological half-life of
70 days;
the change in the body burden as a function of time.
The solution to Equation (3) is
B = -|-(1 e~kt) (4)
In addition to the other variables previously mentioned which
determine the dose due to the intake of radiocesium, the dose is inversely
proportional to the mass of the body since the whole body is the critical
no
organ for radiocesium. Thus, the dose rate during the consumption
period can be expressed as:


55
Isotope.
185
W
85 c
'Sr
134
Cs
59
Fe
40
TABLE 3
SPECTROMETER CALIBRATION
Photopeak Energies
Mev
0.058
0.513
0.605
0.796
1.098
1.289
94
Channels Summed
4-9
42-63
50-90
100-139
K
1.46
135-155


41
Selective sampling of the bananas as a function of time was accom
plished by collecting five bananas every other day for 10 days and
collecting a final sample after 26 days. The bananas were cut from the
hands with a utility knife, which was washed after each sampling in
order to reduce cross-contamination of the fruit. No attempt was made
to seal the wound inflicted by the knife, since preliminary experiments
had indicated that there was negligible drippage of latex from this type
incision. (Latex is the banana plant juice that exudes from a wound in
the epidermis of a plant part.)
Before returning to the University of Florida laboratory, the first
four sets of samples were scanned at the University of Miami's Radiation
Biophysics Department with a scintillation detector ( 4.45 cm x 5.08 cm
Nal(Tl) crystal with a 1.27 cm x 1.91 cm well) coupled to a photomulti
plier tube with its output fed to a Nuclear Data 512-channel pulse-height
analyzer (Model ND 180M). The preliminary scanning was initiated to
insure that the sample size was large enough to enable quantification in
a reasonable counting time. It also revealed that the desired equilibrium
condition would not be achieved within 10 days; therefore, the experiment
was continued.
On the tenth day of the experiment, May 20, the site was cleared of
the peat and plastic sheeting, and new plastic and peat were laid, leaving
room for development of daughter shoots. The experiment was terminated
after 26 days, since the results from the preliminary scanning indicated
equilibrium had been reached. On June 5, 1968, the site was again cleared
of the peat and plastic, and the remaining fruit was harvested. Samples
of the treated leaves, the distal inflorescence bracts, pseudostems, and
untreated leaves were collected and returned to the laboratory for analyses


92
TABLE 13
COUNT RATE PER UNIT WEIGHT AS INDICATED BY PUNCH SAMPLES3
Date of Sampling Tree 1
Bffi/jg.
Tree 2 Tree 3
PCi/g pCi/g
10 May 1968
985,000
410,000
244,000
20 May 1968
22,300
51,000
15,300
5 June 1968 15,200
8,300
13,500
Q
Adjusted for geometry by applying an average geometry correction factor
since these samples were counted in non-standard geometry.


14
A generalized qualitative indication of the relationship between
absorbability and mobility following foliar application is evident in
Table 1. Cesium is rapidly absorbed, and it is mobile. On the other
hand, Sr, Fe, and Mo are slowly absorbed; and strontium is considered
immobile while iron and molybdenum are translocated to some extent.
Possibly, the rate of absorption of iron and molybdenum controls the
mobility of the ions which in turn is gauged by the amount of ion
translocated from the point of absorption.
Plant Characteristics Affecting Translocation
Many factors that regulate or affect absorption of nutrients by
foliage also are important in the translocation processes, since the two
are so closely related. The translocation pattern is a function of
1) the plant age and/or stage of growth, 2) the rate of movement of each
radionuclide, and 3) the rate of concentration of the radioisotopes and
23
their congeners by a given plant part.
The distribution pattern of various elements within the plant will
be different because of tissue barriers, specific coordinating substances,
OO
and metabolic incorporation processes. Translocation occurs via the
plant's vascular system, which is composed of the xylem and the phloem.
Generally, the phloem is more highly developed as a conducting organ,
but the xylem is larger. The xylem generally carries material upward,
and the phloem carries substances downward from the foliage. For example,
it is commonly held that different compounds tend to be translocated by
different plant tissues: inorganic compounds, particularly water, via
the xylem; and organic compounds (products of photosynthesis) via the
phloem.^ Further, it is known that monovalent cations in the alkali


133
12* Jyung, W. H., S. H. Wittwer, Y. Yamada, and M. J. Bukovac, "Pathways
and Mechanisms for Foliar Absorption of Mineral Nutrients A
Review," Michigan State University, USAEC Report COO-888-47
(1964).
13. Eddings, J. L. and A. L. Brown, "Absorption and Translocation of
Foliar-Applied Iron," Thesis, Michigan State University (1963).
14. Kaindl, K., "Foliar Fertilization with Phosphatic Nutrient Labeled
with p32," Proceedings of the Second Radioisotope Conference
1954, Oxford, July 19-23, 1954. Edited by J. E. Johnston,
R. A. Faires, and R. L. Millett. London: Butterworths
Publications, Ltd., 1954.
15. Ambler, John E., "Translocation of Strontium from Leaves of Bean and
Corn Plants," Radiation Botany, 4: 259-265 (1964).
16. Tukey, H. B., S. H. Wittwer, W. G. Long, and F. G. Teubner,
"Absorption of Radionuclides through the Above-Ground Parts of
Plants, with Special Reference to Products of Nuclear Fission,"
Michigan State University, East Lansing, Michigan, USAEC Report
AECU-3847 (1955).
17. Ticknor, Robert Lewis, "The Entry of Nutrients through the Bark and
Leaves of Deciduous Fruit Trees as Indicated by Radioactive
Isotopes," Michigan State College of Agriculture and Applied
Science Report AECU-2753 (1953).
18. Wittwer, S. H., M. J. Bukovac, and H. B. Tukey, "Advances in Foliar
Feeding of Fertilizer Materials to Plants," Agricultural
Chemicals. 17: 20-22 (1962).
19. Tukey, H. B., S. H. Wittwer, F. G. Teubner, and W. G. Long,
"Utilization of Radioactive Isotopes in Resolving the Effec
tiveness of Foliar Absorption of Plant Nutrients," Proceedings
of the International Conference on the Peaceful Uses of Atomic
Energy. Vol. 12: Radioactive Isotopes and Ionizing R.adiation
in Agriculture, Physiology, and Biochemistry, Geneva, August
8-20, 1955. New York: United Nations (1956).
20. Wittwer, S. H., H. B. Tukey, and M. J. Bukovac, "Absorption of
Radionuclides Applied to Above-Ground Plant Parts," Terminal
Report AECU-4597, UC-48 (1959)..
21. Middleton, L. J., "Radioactive Strontium and Caesium in the Edible
Parts of Crop Plants after Foliar' Contamination," International
Journal of Radiation Biology, 1-2: 387-402 (1959).
22. Tukey, H. B,, S. H. Wittwer, and M. J. Bukovac, "Absorption of
Radionuclides by Aboveground Plant Parts and Movement within
the Plant," Journal of Agricultural and Food Chemistry, 9:
106-113 (1961).


120
The concentration of the various isotopes varied considerably in the
banana plant from one plant part to another showing a definite difference
in the translocation of the isotopes. Evidently, the upper pseudostem just
below the axial concentrated the tracers that reached it directly from the
axial, since the amounts of Sr, J7Fe, and JW there were considerably
greater than in the axial (see Table 8, p. 67). (The axial received some
directly applied tracer in addition to that drained to it from the midribs
of the treated leaves and that which translocated from the leaves.) Cesium
was translocated throughout the plant concentrating in equal amounts in the
fruit and lamina, but the distal inflorescence bract had a ^-^Cs concen
tration at least three times that of any other untreated plant part. This
high ^"^Cs concentration was a result of a higher rate of metabolism and
growth in the distal inflorescence bract where the banana "flowers" were
developing. The banana peels contained as much *^Fe as did the untreated
lamina, and -*Sr and **^Fe were translocated from the axial to the growing
plant parts such as the younger lamina of the new leaf and the developing
daughter plant where they were preferentially concentrated in the lamina.
The iron which was translocated from the banana foliage was probably
72
influenced by two factors. First, the iron was chelated; other authors
have shown that a greater fraction of foliar-absorbed iron is translocated
when it is applied as a chelate. Secondly, the morphology and physiology
of the treated banana plant probably played a significant role in deter
mining the amount of radioiron translocated from the foliage.
Interplant Translocation
The mechanism of translocation of the radionuclides from the test
trees to the neighboring plants is postulated to have occurred through


101
entirely unexpected. The environmental protection provided by the
plastic and peat moss was successful in preventing direct soil contam
ination beneath the treated foliage. The same conclusions are valid
for the mixed tracer study where soil contamination was associated only
with the area adjacent to the rhizomes of the plants which had activity
translocated to them and to the soil around the bases of the treated
trees (see Table 4 and Table 5). It should be emphasized that the
levels of radioactivity in the soil and these plants were such that
they were detectable only through low-level gamma spectroscopy no
contamination was indicated by a Geiger counter survey. Even in the
cases where the soil was slightly contaminated, the contamination could
have been eliminated by removing the soil in the area immediately
adjacent to the "contaminated" plants, if it had been deemed necessary.
The radiotracers in the adjacent banana or coconut plants were probably
a result of transfer of material through root-to-root contact.
Care must continually be exercised over the ingress and egress to
the study area when conducting a field study in order to prevent contam
ination of the environment. The most important key to the successful
completion of an environmental tracer study, such as this, is detailed
consideration prior to entering the field of all possible modes of
losing control of the radioactivity and careful planning to avoid the
hazards envisioned.
The logistic problems of conducting environmental radiotracer
studies are considerable. In particular, the amount of material
requiring disposal is large because of the peat, plastic, and large
volume of the plants. If better statistical designs involving replica
tion were attempted, the volume of waste would be vastly increased;


93
Tree 2 during this period is unclear, but it is suspected that an
untreated portion of the leaves was included in the final leaf sample
(Table 14 treated leaves) from which the terminal punch samples were
obtained.
Other Factors Affecting the Equilibrium Concentrations
The other factors which probably influenced the Ce values were
plant morphology and fruit maturity. As previously discussed, the
inflorescence of Tree 2 had failed to emerge from the axial. Thus, the
relative importance of the tracer applied to the leaf ribbing, petiole,
and axial was greater for Tree 2 since this activity was much nearer to
the base of the fruit's inflorescence.
The effect of fruit maturity is shown in Table 14 and in Figure 32,
which shows that the normalized equilibrium concentration was roughly
inversely proportional to the age of the fruit. In all cases ^^Cs
translocated to other parts of Tree 1 in greater quantities than in
Tree 3 on a percentage basis. This reflects the general slowing of
metabolism of Tree 3 as the fruit reached maturity. The most significant
point here is the concentrations in the distal inflorescence bracts. As
in the fruit, the concentration in the bract of Tree 2 was twice that of
the bract from Tree 1 and ten times that in the bract on Tree 3. In the
latter case, the distal inflorescence bract had withered by the end of
the experiment. The ^-^Cs concentration in the youngest distal bract
(Tree 2) was 48.5 percent of the concentration in the treated leaves
after 26 days. In comparison, the distal bract of Tree 3, whose fruit
began to ripen by the termination of the study, had a concentration only
3 percent of the treated leaves; and the distal bract of Tree 1, whose


24
FIGURE 1: FRUIT OF TREATED COCONUT PALM


109
where
C(f) = the concentration of in the fruit: yCi/g;
M = the mass of fruit consumed per day g/day;
RTF = the relative transmission factor;
C(L) = the concentration of on the leaf: yCi/g.
Equation (13) can be rearranged and solved for C(L) after substituting
for "R" and "C(f)M as shorn by Equation (14):
C(L) (yCi/g) = D(T) W k2 (14)
(DCF)(M)(RTF)[(tk + e_kt 1) + (i e~kt)(1 -ek0)] -
The data developed in this study have provided a measure of the RTF.
As shown in Table 16, the RTF varied according to the maturity of the
banana plant's fruit and environmental conditions the fruit on Tree 1
and Tree 2 were immature, while the fruit on Tree 3 was mature. The RTF
for Tree 1 through Tree 3 are based on the leaf punch samples taken on the
tenth day of the study, since the later data for Tree 2 probably were
affected by inclusion of untreated foliage which resulted in a lower
calculated residual concentration in the treated leaf at the end of the
study.
Although the RTF is based on the ratio of the -*--^Cs concentration
in the fruit to the residual concentration on the foliage rather than
on the foliar concentration immediately after treatment, the estimates
of allowable leaf concentrations will be conservative since the
(yCi/g leaf)residual is smaller than the (yCi/g leaf)initial; thus, the
RTF based on the residual activity is larger, which results in smaller
allowable leaf surface concentrations as calculated by Equation (14).
Equation (14) can be evaluated for the critical population group
in Darien Provence, Panama, if the following assumptions are made:


Counts per Channel in 15 Minutes (Thousands)
FIGURE 20: SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED


44
averaging the percentage moistures. Wet weights of the samples were
corrected to dry weights using the percentage moisture correction factors.
Except for the coconuts, samples collected for determining inter
plant translocation were placed in 800 ml counting containers and analyzed
in their fresh states without blending. Following analysis by gamma
spectroscopy, the samples were dried in an oven at 65-70 C to constant
dry weight.
Kinetics Study Sample Preparation
The samples (banana, leaf, pseudostem, and distal inflorescence
bract) were prepared in their fresh states to provide constant geometry
and uniform density. The unpeeled bananas were sliced and placed in
counting containers with sufficient distilled water added to fill all
voids to 800 ml. The pseudostem and inflorescence bract were individ
ually chopped, blended with distilled water, and placed in 800 ml
counting containers. The leaf punch samples were placed in standard
glass liquid scintillation vials (7.9 cm x 2.2 cm) for low-level gamma
ray analysis. After analysis, the samples were dried at 65-70 C until
constant dry weights were achieved.
Sample Counting
All samples prepared in the standard 800 ml geometry were analyzed
with a gamma scintillation spectrometer system (described later) in a
shielded, low-background facility. The following samples were analyzed
by the same instrumentation but were not analyzed in the standard geometry
assumed for this study: 1) coconut shells and husks from the treated palm
tree, 2) coconuts from the foilow-up sampling to determine the extent of


86
TABLE 11
134
SUMMARY OF Cs RATE OF UPTAKE EXPERIMENT
Banana Tree
k
(day-1)
ce
(pCi/g)
Time to
50 % Ce
(days)
Treated
Area
(cm^)
Activity
Applied
(yCi)
Tree
1: Musa walap
-0.123
16,000
5.8
13,900
175
Tree
2: Musa ra.japuri
-0.158
32,000
4.3
10,800
147
Tree
3: Musa kullan
-0.122
5,000
5.8
21,800
150


Carrier-free, soluble tracers (^Sr, ^Fe, 185^ and 134^sj were
applied to a portion of the foliage of both banana and coconut plants.
Following foliar absorption, the translocation and distribution of
these tracers within the plants were studied with special emphasis on
the fruit. It was found that only LjqCs accumulated in the banana pulp
and the coconut fruit (meat and water) following this type of foliar
application. However, some of each radiotracer was detected in plant
parts other than the treated foliage.
The methodology employed to prevent contamination of the environ
ment and to apply the tracers was very successful. The methodology
included covering the ground with plastic sheeting, which in turn was
covered with peat moss, and using a plastic bottle with a sponge appli
cator to treat the foliage. However, detectable levels of radioactivity
were found in the banana plants, coconut plants, and weeds and grasses
adjacent to the treated plants. Cesium-134 was translocated to adja
cent plants in general, while ^^Fe, ^Sr, and 185y Were detected in the
fruit of adjacent banana plants and second growth grasses and weeds near
the base of the palm tree. The translocation resulted in slight accumu
lation of -*^Fe an 185y the peels of the neighboring bananas in
particular. This contamination was attributed to direct root-to-root
translocation.
Cesium-134 accumulation by bananas following foliar absorption was
characterized by a first order kinetics function of the type
C *= Ce(l e-kt). The rate constant (k) was determined to be -0.133
per day based on.the least squares best fit of the data. The replicated
experiment provided individual rate constants of -0.123, -0.158, and
-0.122 per day for the three test plants. The equilibrium concentration
x


137
62. Stewart, Ivan, "Chelation in the Absorption and Translocation of
Mineral Elements," Annual Review of Plant Physiology, 14: 295-311
(1963).
63. Haerth, E. J., "Metal Chelates in Plant Nutrition," Journal of
- Agricultural and Pood Chemistry, 11: 108-111 (1963).
64. Michigan State University, "Mechanisms of Uptake of Ions by Above
Ground Plant Parts and Their Subsequent Transport and Redistrib
ution within the Plant," Technical Progress Report USAEC
TID 14476 (1961).
65. Lowman, E. G., "Iron and Cobalt in Ecology," Radioecology. Edited by
Vincent Schultz and Alfred W. Element, Jr. (Proceedings of the
Eirst National Symposium on Radioecology, Colorado State
University, Eort Collins, Colorado, September 10-15, 1961).
New York: Reinhold Publishing Corporation, 1963.
66. Biddulph, 0., "Translocation of Minerals in Plants," Mineral
Nutrition of Plant. Edited by E. Truog. Madison, Wisconsin:
University of Wisconsin Press, 1951.
67. Meyer, B. S., D. B. Anderson, and R. H. Bonning, Introduction to
Plant Physiology. Princeton, New Jersey: D. van Nostrand
Company, I960,
68. Branton, D. and L. Jacobson, "Iron Transport in Pea Plants," Plant
Physiology, 37: 539-545 (1962).
69. Brown, A. L., S. Yamaguchi, and J. Leal-Diaz, "Evidence for
Translocation of Iron in Plants," Plant Physiology, 40: 35-38
(1965).
70. Doney, R. C., R. L. Smith, and H. H. Wiebe, "Effects of Various
, Levels of Bicarbonate, Phosphorus and pH on the Translocation
of Eoliar-Applied Iron in Plants," Soil Science, 89: 269-275
(1960).
71. Simmons, J. N., R. Swidler, and H. M. Benedict, "Absorption of
Chelated Iron by Soybean Roots in Nutrient Solutions," Plant
Physiology, 37: 460-466 (1962).
72. De, Raja^, S. H. Wittwer, and S. Kannon, "Uptake and Transport of
Ee~> by Intact Leaves and Enzymatically Isolated Leaf Cells of
the Bean Plant (Phaseolus vulgaris)," Michigan State
University, USAEC Report COO-88-48 (1965).
73. Davis, J. J., "Cesium and Its Relationship to Potassium in Ecology,"
Radioecology. Edited by Vincent Schultz and Alfred W. Element,
Jr. (Proceedings of the Eirst National Symposium on Radio
ecology Colorado State University, September 10-15, 1961).
New York: Reinhold Publishing Corporation, 1963.


58
Stewart Laboratories, Knoxville, Tennessee, analyzed banana, banana leaf,
coconut meat, coconut-water, and frond samples from Homestead, Florida,
for Sr, Mn, Fe, and Cu using a Bausch and Lomb Spectrograph and for Ca,
Mg, and Zn using a Beckman Atomic Absorption Unit. The Tropical Soils
Laboratory (1FAS,UF) analyzed all the samples for potassium using a
Beckman D. U. Flame Emission Spectrophotometer and for phosphorus using
a Fisher Electrophotometer Colorimeter. The method by which the vegeta
tion samples were prepared for these analyses is given in Appendix B.
Soil, coconut puree (meat and coconut water blended), and banana
samples from Homestead, and soil samples from Panama were analyzed for
stable W, Mo, and Cs by activation analysis at the University of Florida
Nuclear Science Center.
0


32
FIGURE 5: REMOVAL OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING


TABLE 6a
TRACER COUNT RATES COCONUT FROND LEAFLETS AND INFLORESCENCES 18 DAYS AFTER TREATMENT
Sample
185W
cpm/g 2a
85 sr
cpm/g :
2a
134Cs
cpm/g
2a
59Fe
cpm/g
2a
Treated Frond
NDb
1,600

45
5,100

29
63
+
8.8C
Untreated Frond
(Above)
0.6 0.4
75
+
3.0
180
+
2.1
ND
Untreated Frond
(N. Side)
-0.07 0.1
5.6
+
0.9
32
+
0.6
-0.15
+
0.16
Inflorescence
ND
120
+
8.4
500
+
5.2
ND
Inflorescence
2. 0.9
230
+
6.3
400
+
3.9
5.6
+
1.2
Inflorescence
-0.13 0.3
62
+
1.9
87
+
1.2
0.6
+
0.4
Inflorescence
0.02 0.2
26

0.9
49
+
0.6
0.5
+
0.2
Inflorescence
-0.02 0.07
7.6

0.4
20
+
0.3
-0.06

0.1
aAll data corrected for decay to November 3, 1967.
^Not detectable when the 2a error term was included with the net count rate the result remained negative
cAnalysis of chemically separated sub-sample indicated that this isotope was present.


113
for a critical population group composed of "standard men" who consume
1,700 g of bananas per day, Equation (15) can be used to calculate either
the allowable leaf surface concentration to yield an allowable dose or to
evaluate the projected dose due to an estimated fallout density for any
size man, any rate of intake, or duration of intake.
Two factors add some conservatism to these calculations: 1) the
radiotracers were applied in soluble form, which increased the percentage
of absorption and 2) the RTF for the three kinetics study plants were
conservative since the residual concentrations were significantly reduced
by rain.
However, the limitations of this calculation cannot be stressed too
strongly for the following reasons: 1) the calculations assume that the
entire inventory of the radionuclide which reach the edible plant parts
was derived from foliar-absorption; (it is the belief of the author that
the contribution of axial-absorbed radioactivity in the banana plant will
be as significant as that due to leaf absorption;) 2) the Cl are based on
the assumption that the entire body burden and resulting doses are derived
from the ^37cs in the bananas ingested; and 3) the total exposure of the
population to all fallout in combination must be considered and not just
Kinetics of Cesium Accumulation in the Banana Plant
This is the only study known to the author in which a model was
developed to measure the overall kinetics of accumulation of an element
from the foliage to the fruit of a banana plant, or any other plant.
Historically, only the rate of absorption by the foliage and/or the
distribution patterns have been studied. It is significant that the


SUMMARY
This study has demonstrated that 1) environmental radiotracer exper
iments can be safely conducted using the techniques employed and 2) valu
able knowledge regarding rain effects and interplant translocation can
be obtained by performing the experiments in the field. These experiments
were conducted in south Florida fields using the following techniques:
1) the area beneath the foliage to be treated was cleared of all vegeta
tion, 2) plastic sheeting was spread over the cleared area, 3) peat moss
was spread over the plastic to absorb all drippage and wash-off, and
4) the areas around each treated plant were secured by fencing.
Four banana leaves and three coconut fronds were treated with a
carrier-free solution of mixed radiotracers: ^Sr, 185^ and 134cs.
The study showed that ^4qs was 1) rapidly translocated from the banana
leaves, 2) more uniformly distributed than the other radionuclides used
in the study, and 3) accumulated in the fruit, while Fe, Sr, and W were
not. Cesium nd iron also accumulated in the other actively growing
plant parts new leaves and daughter plants.
Strontium-85, tungsten-185, and iron-59 were absorbed by the
banana leaves, but their mobility was much less than that of cesium.
Strontium translocated in small amounts to newly developing leaves and
young leaves where its congener, calcium, is used in cell wall formation.
The which translocated in the treated plant, was detected in the
youngest banana leaf and the lower pseudostem; and ~^Fe accumulated in
the actively grox^ing plant parts the young lamina, banana peels
inflorescence, and the daughter plant.
124


UPTAKE AND IRANHLOCATION OF
85Sr, 59Fe> 1H5W AND 134Cs BY BANANA PLANTS
AND COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION
BY
WALTER NEILL THOMASSON
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1972

ACKNOWLEDGEMENTS
The author wishes to thank Dr. Herbert A. Bevis and Dr. Emmett
Bolch, who alternately served as chairman of his supervisory committee,
for their direction, encouragement, and assistance. He also acknowl
edges the help and encouragement of Drs. Charles E. Roessler and Billy
G. Dunavant who served on his committee. Particular thanks are extended
to Dr. John F. Gamble who spent many hours helping the author in the
field as well as providing invaluable guidance in the laboratory.
Mrs. Scott Zimmerman was indispensable in helping with the
radiological analyses. Mrs. Jo Anne Selin was helpful in performing
laboratory analyses, and Mrs. Effie Galbraith was of great: help in
obtaining necessary laboratory equipment.
The author wishes to thank Mr. Laurin Wheeler, Dr. Sam Snedaker,
Mr. Harvey Norton, and Mr. Gordon Renshaw who provided help in the
field operations. Appreciation and thanks are also extended to the
personnel at the University of Floridas Sub-Tropical Experiment
Station at Homestead, Florida, particularly to Dr. Paul Orth, for their
assistance and for making their facilities available for the research.
Much thanks is due Mr. Wallace Manis, his personnel, and the United
States Department of Agriculture for the fine cooperation and the use
of the Plant Introduction Station, Miami, Florida.
The author also wants to recognize the general support and assist
ance he received from the secretarial staff of the Soils Department of
the College of Agriculture and the Institute of Food and Agricultural
ii

Sciences, University of Florida. Finally, the author wishes to thank
his wife, Lissie, who provided much help in the preparation of the
manuscript, translation of Spanish articles, editorial assistance, and
final preparation of figures.
This work was supported in part by United States Public Health
Service Training Grant No. 47013-03-68, and by the Institute of Food
and Agricultural Sciences, xhich was a sub-contractor of Battelle
Memorial Institute, Columbus, Ohio.
iii

TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ii
LIST OF TABLES vi
LIST OF FIGURES vii
ABSTRACT ix
CHAPTER
I. INTRODUCTION 1
Sea-Level Canal Bioenvironmental and Radiological-
Safety Feasibility Study 1
Research Objectives 2
II. CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION .. 5
Introduction 5
Plant Factors Affecting Foliar Absorption 6
Environmental Factors Affecting Foliar Absorption 8
Mechanisms of Ion Absorption 9
Rates of Absorption of Specific Ions 10
Plant Characteristics Affecting Translocation 14
III. PLANT NUTRITION 16
Introduction 16
Strontium 17
Iron 18
Cesium 19
Tungsten 20
Nutrition of Banana Plants and Coconut Palms 21
Fallout and Plant Nutrition 22
IV. METHODOLOGY 23
Site Selection 23
Selection of Tracers .' 27
Field Procedures Mixed Tracer Experiment 28
Field Procedures Kinetics Study Miami 35
Laboratory Analyses 42
iv

Page
V. RESULTS 59
Introduction 59
Environmental Control 59
Data Analyses Mixed Tracer Uptake 64
Data Analyses Kinetics Study Miami 84
VI. DISCUSSION OF RESULTS 99
Efficacy of Field Experiments 99
Success of Environmental Protection Procedures 100
Significance of Results in Relation to Radioactive
Fallout 102
Evaluation of Allowable Activity on Plant Foliage 105
Kinetics of Cesium Accumulation in the Banana Plant ..... 113
Effect of Rain 116
Translocation of Radiotracers in Coconut and Banana
Plants 117
Long-Term Effects of Foliar Contamination 122
SUMMARY 124
APPENDIX A: CHEMICAL SEPARATION PROCEDURE FOR TUNGSTEN ANALYSIS ... 128
APPENDIX B: DRY ASHING PROCEDURE PLANT TISSUE 130
LIST OF REFERENCES 132
BIOGRAPHICAL SKETCH 141
v

LIST OF TABLES
Table Page
1. CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY,
MOBILITY, AND LEACHABILITY 12
2. RATES OF ABSORPTION 13
3. SPECTROMETER CALIBRATION 55
4. COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED
PALM POSITIVE SAMPLES 61
5. COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND
SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES 62
6. TRACER COUNT RATES COCONUT FROND LEAFLETS AND
INFLORESCENCES 18 DAYS AFTER TREATMENT 65
7. TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER
TREATMENT 66
8. TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER
TREATMENT 67
9. RESULTS OF CHEMICAL SEPARATION FOR 185W 72
10. PARTIAL ELEMENT COMPOSITIONAL ANALYSES 82
11. SUMMARY OF 134Cs RATE OF UPTAKE EXPERIMENT 86
12. EQUILIBRIUM CONCENTRATION VALUES Ce VERSUS AGE OF FRUIT 91
13. COUNT RATE PER UNIT V7EIGHT AS INDICATED BY PUNCH SAMPLES .... 92
14. CONCENTRATION OF 134Cs IN BANANA PLANT PARTS AND PEAT MOSS .. 94
15. RADIOACTIVITY IN ADJACENT FRUIT BEARING PLANTS AND NEARBY
GRASS 97
16. RELATIVE TRANSMISSION FACTORS 110
Vi

LIST OF FIGURES
Figure Page
1. FRUIT OF TREATED COCONUT PALM 24
2. FAST GLADE BANANA GROVE 25
3. TREATED BANANA PLANT AT EAST GLADE 26
4. APPLICATION OF MIXED TRACERS TO COCONUT PALM 30
5. REMOVAI. OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING .. 32
6. HOMESTEAD COCONUT GROVE 33
7. EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS 34
8. USDA BANANA EXPERIMENT SITE 36
9. TREE 1 USDA BANANA SITE .' 37
10. PREPARED SITE USDA PLANT INTRODUCTION STATION TREE 2 AND
TREE 3 39
11. EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER, AND
COUNTING CONTAINER AND SOLUTION APPLICATOR 40
12. 134Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS .. 43
13. COUNTING CONTAINER IN POSITION OVER Nal(Tl) CRYSTAL PACKARD
LOW-BACKGROUND SYSTEM 47
14. TUNGSTEN-185 STANDARD 48
15. STRONTIUM-85 STANDARD 49
16. CESIUM-134 STANDARD 50
17. IRON-59 STANDARD 51
18. POTASSIUM-40 STANDARD 52
19. STANDARD CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr,
134Cs, AND 59Fe 53
vii

Figure Page
20. SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED 71
21. SUB-SAMPLE TREATED PALM LEAFLETS NaOIl INSOLUBLE, HC1
SOLUBLE PORTION 73
22. SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, EC1
INSOLUBLE PORTION 74
23. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1
SOLUBLE PORTION 75
24. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, IICl
INSOLUBLE PORTION 76
25. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
SOLUBLE PORTION 77
26. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
INSOLUBLE PORTION 78
27. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
SOLUBLE PORTION 79
28. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
INSOLUBLE PORTION 80
29. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa walap TREE 1 87
30. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa ra;japuri Tree 2 88
31. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa kullan TREE 3 89
32. RELATIVE EQUILIBRIUM CONCENTRATION AS A FUNCTION OF FRUIT
MATURITY 95
33. MAXIMUM ALLOWABLE LEAF SURFACE CONCENTRATION OF 137Cs TO GIVE
A 0.17 REM ANNUAL WHOLE BODY DOSE AS A FUNCTION OF ASSUMED
DURATION OF INGESTION OF CONTAMINATED FRUIT 112
viii

Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of Doctor of Philosophy
UPTAKE AND TRANSLOCATION OF
85Sr, 5^Fe, 185W AND 184cs BY BANANA PLANTS
AND COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION
By
Walter Neill Thomasson
March, 1972
Chairman: William Emmett Bolch, PhD.
Major Department: Environmental Engineering
Bananas or plantains (cooking bananas) and coconuts comprise a
significant part of the diets of the people residing in the areas of
Panama and Colombia under consideration for a sea-level interoceanic
canal. The coconut is also a major export commodity. Because of their
importance in the area diet and economy, a mixed radiotracer experiment
on a banana plant and a coconut palm was designed as part of the eval
uation of the radiological effects of a Plowshare project, such as the
one proposed for construction of a sea-level interoceanic canal. In
conjunction with the experiment, field and laboratory procedures were
also developed. A second replicated field study was conducted to meas
ure the rate of accumulation of -*-8^Cs in bananas following foliar
application of the isotope.
ix

Carrier-free, soluble tracers (^Sr, ^Fe, 185^ and 134^sj were
applied to a portion of the foliage of both banana and coconut plants.
Following foliar absorption, the translocation and distribution of
these tracers within the plants were studied with special emphasis on
the fruit. It was found that only LjqCs accumulated in the banana pulp
and the coconut fruit (meat and water) following this type of foliar
application. However, some of each radiotracer was detected in plant
parts other than the treated foliage.
The methodology employed to prevent contamination of the environ
ment and to apply the tracers was very successful. The methodology
included covering the ground with plastic sheeting, which in turn was
covered with peat moss, and using a plastic bottle with a sponge appli
cator to treat the foliage. However, detectable levels of radioactivity
were found in the banana plants, coconut plants, and weeds and grasses
adjacent to the treated plants. Cesium-134 was translocated to adja
cent plants in general, while ^^Fe, ^Sr, and 185y Were detected in the
fruit of adjacent banana plants and second growth grasses and weeds near
the base of the palm tree. The translocation resulted in slight accumu
lation of -*^Fe an 185y the peels of the neighboring bananas in
particular. This contamination was attributed to direct root-to-root
translocation.
Cesium-134 accumulation by bananas following foliar absorption was
characterized by a first order kinetics function of the type
C *= Ce(l e-kt). The rate constant (k) was determined to be -0.133
per day based on.the least squares best fit of the data. The replicated
experiment provided individual rate constants of -0.123, -0.158, and
-0.122 per day for the three test plants. The equilibrium concentration
x

values (Ce) expressed as a percentage of the concentration applied to
the foliage were 0.40 percent, 0.80 percent, and 0.12 percent. The Ce
varied as a function of the maturity of the fruit and the atmospheric
conditions during and following tracer application. However, the rate
constants were independent of the atmospheric conditions.
As a result of these field experiments, it is evident that even
with heavy rain during and following the period of fallout deposition
radiologically significant amounts of radioactivity will be absorbed
and retained by the foliage of banana and coconut plants.
Using the results of this study, a model was developed to predict
the yearly whole body dose to an individual who eats contaminated
bananas. This model evaluates the dose as a function of 1) the
concentration (yCi/m^) of fallout on the plant foliage; 2) the rate of
consumption of contaminated bananas; and 3) the duration of consumption
of the bananas.
xi

CHAPTER I
INTRODUCTION
The United States Atomic Energy Commission (AEC) has developed a
program, Plowshare, to investigate potential uses of nuclear devices
for peaceful purposes. These devices have been proposed for use in
excavating harbors, cutting railroad passes, developing water resources,
and excavating canals the most widely publicized use. Nuclear cratering
tests have been conducted at the Nevada Test Site in a program to develop
the technology and engineering design criteria required to utilize this
means of excavation. Lawrence Radiation Laboratory's Plowshare Division
has the primary responsibility for developing special nuclear devices for
engineering application.^
Sea-Level Canal Bioenvironmental and Radiological-Safety
Feasibility Study
The need for a new interoceanic sea-level canal has been well
demonstrated. Nuclear excavation is being considered for two of the
proposed new canal routes: 1) Route 17 in Panama's Darien Provence,
approximately 100 miles east of the existing canal, and 2) Route 25 in
northwestern Colombia, along the Panamanian-Colombian border.
The United States Congress passed Public Law 88-609 which authorized
the President to appoint a commission to investigate and to determine
the site and the best means of constructing a sea-level canal connecting
the Atlantic and Pacific Oceans. Nuclear excavation was proposed as a
1

2
possible method of constructing a new canal, and the AEC was given the
responsibility for investigating the problems associated with this
technique. The AEC subsequently awarded the prime contract for the
Bioenvironmental and Radiological-Safety Feasibility Study to Battelle
Memorial Institute, Columbus Laboratories. Battelle sub-contracted
various segments of the study to several research groups. The University
of Florida's International Programs of the Institute of Food and
Agricultural Sciences received the contract covering agricultural
ecology. This dissertation is part of the University of Florida study
and is concerned with two important components of the diets of the
ethnic groups in the canal study areas: the banana and the coconut.
Research Objectives
The objectives of this research were threefold: 1) develop method
ology, 2) determine distribution patterns of radionuclides in the banana
and coconut plants following foliar application, and 3) study the kinetics
of cesium accumulation by the banana fruit following foliar absorption.
The first phase of the study was to develop methodology for perform
ing low-level radiotracer experiments in the field while controlling the
radioisotopes with respect to the general environment. This was necessary
since most of the research concerning the accumulation of fallout by
crops has been devoted to 1) controlled greenhouse experiments in
nutrient solutions or pot studies and 2) field studies involving relatively
long-term uptake and concentration of fallout from nuclear tests.
The literature concerning comparison of field and greenhouse results
show that there is often poor agreement between parallel experiments in
3
the two environments. Russell and Milbourn reported that in greenhouse

3
pot studies the roots of the plants developed abnormal distribution
patterns. Handley et al.^ found that the amount of strontium absorbed
and the translocation patterns differed from greenhouse to the field.
Consequently, a field experiment was selected for this study because,
in the opinion of the investigator, actual field-environmental conditions
would provide more applicable data than would a greenhouse experiment,
particularly in view of the complex relationships involved in foliar
absorption.
The second objective of the study was to determine the distribution
patterns of radionuclides applied to aerial parts of banana and coconut
plants. The banana plant was selected for the study because up to 85
percent of the diet of people in the study areas is composed of bananas
or plantains. In fact, Dr. Torres de Arauz^ reported that as much as
approximately 12 kilograms (Kg) of bananas are consumed weekly per
individual. The coconut was selected because it is an important export
commodity in the economy of one of the local ethnic groups. Also,
coconuts provide a major portion of the fats in much of the populations'
diets. Overall, this fruit constitutes approximately 6 percent of the
total diet in Darien Provence.^
Although much research has been conducted on uptake, translocation,
and concentration of strontium and cesium in the food chain, little work
has been done xjith the other radionuclides, particularly activation
products. In addition, there is no information concerning uptake,
translocation, and concentration patterns of fallout radionuclides by
either the banana or coconut plant. The field study undertaken here was
the first designed to produce data in this area.

A third objective of the study was to investigate the kinetics of
translocation of radiocesium by banana plants (as measured by the rate
of accumulation in the fruit). The banana plant was selected for this
study because 1) the banana comprises the bulk of the diet of the
populations in the study areas, 2) translocation of the radiotracers in
the initial phase of the field study was more rapid in the banana, and
3) the results of the initial study indicated that radiocesium would be
the more limiting radioisotope of the ones studied.

CHAPTER II
CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION
Introduction
Foliar absorption is a complex phenomenon which is often utilized
to supply some of the minor, required nutrients to plants. Any substance
that can be absorbed by plant roots can be absorbed by the foliage more
efficientlyFoliar absorption, leaching, and root absorption are
closely related, and all play significant roles in radioactive contamina
tion of crops. For instance, 1) foliar absorption can influence root
uptake of minerals by stimulating the plants metabolism,^ 2) leaching
of nutrients from the foliage also stimulates the rate of root absorption
and translocation of minerals through plants, and 3) once a mineral has
been absorbed by the plant, it is subject to foliar leaching by atmos-
pherxc moisture.
Contamination of fruit by above-ground deposition, other than direct
fruit deposition, involves two stages: 1) absorption by the foliage and
2) translocation from the absorption site to the fruit.Each element
is absorbed and translocated at rates specific to the element and plant
in question.^ The rates of absorption and translocation are closely
related; for example, tissue saturation at the site(s) of absorption may
occur if the absorbed material is slowly translocated, or remains
stationary.The distribution pattern in the plant is also character
istic of the plant and the material.^
5

6
Plant Factors Affecting Foliar Absorption
The major work on foliar absorption has been conducted in temperate
climates with crops such as beans, corn, and apples. While these are
not the tropical banana plants nor coconut palms under consideration,
the studies on them have provided a very generalized concept of the
variables that affect foliar absorption.
Foliar Characteristics
As one would expect, the foliar characteristics of a plant play a
primary role in the rate of foliar absorption and the degree of absorp
tion. Some factors which may affect absorption are leaf size, leaf
surface, the number and size of stomata (organs of respiration), and
the vascular system (xylem and phloem) of the leaf.
The leaf size is important because a large leaf provides more sur
face area for foliar deposition and absorption and, therefore, will
increase absorption by the plant. The leaf surface is important because
it must be penetrated in order for a substance to be absorbed by the
foliage. Surface characteristics which may retard absorption are waxy
surfaces (cuticles), thick surfaces, and the occurrence of ion binding on
surfaces opposite the site of entry.^ Non-waxy cuticles, thin surfaces,
leaf wetness, and various leaf imperfections, such as hairs, injuries, or
protuberances, may aid, or encourage, absorption. The size, concentration,
and location of the stomata may also play a role in foliar absorption due
1 2
to 1) the surface area effect, 2) thinner cuticles which line the
12
stomata, and 3) the location of the stomata relative to the venal
13
system. The vascular system (venal system), consisting of the xylem
and phloem, can also affect absorption. Plants with well-developed

7
vascular systems will absorb more, generally, than those with poorly
developed systems.
Plant Age
Foliar absorption is strongly associated with the age of the plant
and the phase of its growth cycle. As the leaf matures, its absorptive
capacity is reduced. Two events are responsible for this change: 1) the
permeability of the cuticle decreases and 2) the rate of metabolism
14
increases to a maximum, then diminishes. There is some disagreement
as to the effect of leaf age on uptake, but this may be associated more
with the variation of nutrients and materials studied than with the
leaf itself. The cuticular development and concentration of stomata
change as the leaf matures, and this possibly accounts for some variation
1 s
in absorption. Generally, researchers have agreed that because of
thinner cuticles, young leaves absorb more foliar-applied nutrients than
mature leaves. This process is mainly irreversible in immature
leaves.^
Another important age-related factor is the time of contamination
with respect to the growth stage of the plant, since the greatest foliar
absorption of elements occurs during the flowering, or fruiting, stage
(when root absorption is negligible) If fallout occurs prior to
the flowering stage, the fruit will not be directly contaminated, and it
can only receive radioactivity from other plant parts via translocation.
On the other hand, if the fruit has begun to develop prior to the
deposition of fallout, direct surface contamination will result (the
19 20
fruit is capable of absorbing fallout).

8
Other Plant Characteristics
Other plant characteristics which help determine the extent of fruit
contamination are the root structure morphological and physiological -
and the morphology of the foliage. Pseudostems may play a major role in
the absorption of fallout in the banana plant. Material collecting in the
axial (where the leaves come together forming the pseudostem) would not
he subject to washing or leaching and could be absorbed and held in the
hollow pseudostem, or between its leaf sheath layers. Banana (and also
coconut) plants have a central rib down each leaf which supports the
foliage this is termed the midrib. These are generally "U" shaped, and
in the banana plant they serve to channel runoff material to the axial.
21 a
Middleton^ and Handley et_ al have noted the importance of the axial in
contamination of fruit by fallout.
Environmental Factors Affecting Foliar Absorption
Environmental conditions at the time of fallout formation and deposi
tion strongly influence the amount of radioactivity available for absorp
tion by plants. Wind velocity in conjunction with fractionization of fall
out with respect to radionuclides and particle size will determine which
radioisotopes will be deposited in a given location. Rain during and
following fallout deposition decreases the fraction of fallout retained
22
by foliage. According to Tukey ert al., up to 85 percent of foliar
contamination may be removed by a normal rain, and the amount retained is
23
decreased as the rain intensity increases. However, Russell and
24
Possingham concluded that rain, after the deposition period, had no
effect on retention of fallout by herbage,

9
Temperature and humidity are the primary factors that determine the
rate of drying of solutions on foliage, and the rate of absorption is
quite dependent on these parameters.^^3 High relative humidity, dew,
and general dampness act contrary to rain and increase, rather than
decrease, foliar absorption by maintaining the material in solution
O C
longer. Ambler and Menzel J ranked relative humidity as the single most
important variable controlling retention of 85gr by foliage. But
according to the same authors, species variation, under identical environ
mental conditions, may cause retention of fallout to vary from 10 to 90
percent. The species variation is a function of the surface wettability
of the foliage. As the relative humidity increases, the degree of hydra
tion and cuticle permeability increase causing greater absorption.^5^
Similarly, Bukovac eh al.^6 reported that rewetting of the leaves
greatly increases absorption of fallout.
Although the most rapid absorption occurs under wet conditions, dry
27
state absorption does occur over extended time periods. Dry absorption
can be explained by the fact that although the surface appears dry, there
is a thin aqueous film of moisture created by the plant's transpiration.
28
This solvent may be more important than the nutrient-carrier solution.
Mechanisms of Ion Absorption
There is some disagreement about the way in which ions deposited on
foliage pass into the plant's interior. Yamada^ has described the
passage of ions across the cuticle in a manner analogous to the classical
po pn
diffusion equation. Others have described continuous pathways
through the cuticle via surface imperfections. Generally, ion absorption
is a combination of passive and active processes. Initial penetration of

10
the cuticle and epidermis is by both passive and active means.16,22 The
passive component is absorption of nutrients into free space in the sub
surface tissue by mass flow or diffusion; and the active processes are
ion exchange and transport into the protoplasm.16,31 por active absorp
tion, an energy source is required, since energy is expended. Generally,
anion uptake is more energy dependent than cation absorption.^2
After the initial absorptive phase, passage to the interior cells
is a two-phase process involving ion exchange and binding on the exterior
of cell walls, followed by an active uptake, which is metabolically
controlled by protoplasmic parts of the cell. Jyung et al. devised a
model for ion uptake using carrier concepts, which they feel is the most
likely overall uptake process by green leaves. The first phase of their
model involves a rapid, non-metabolic process, and the second phase, a
slower metabolically controlled step. According to them, a close fit to
a first order equation possibly indicates some passive uptake with the
initially rapid phase being more a function of existing environmental
conditions than of botanical characteristics.
Rates of Absorption of Specific Ions
Urea is reported to be the most rapidly foliar-absorbed material.^
Of the minerals, or nutrients, studied by other researchers, K, Na, and
Rb are the most rapidly absorbed. While Ca, Sr, Fe, and Mo are initially
absorbed fairly rapidly, the rate of absorption decreases sharply within
a few hours.I,33,34 This rate reduction may be associated with satura
tion of the leaf tissue at the area of absorption coupled with an inabil
ity to translocate these minerals from the leaf.10>35,36

11
37
Moorby related cesium absorption to sugar metabolism by the plant.
38
ThorneJ indirectly agreed with Moorby in suggesting that the negative
effect of shade on foliar absorption may be related to reduced carbohy
drate concentrations during periods of low light intensity or darkness.
The most rapid absorption results when a mineral is in solution,H
and cations are absorbed more rapidly than anions.^9 Absorption from
dilute acidic solutions (pH 4 to 5) is roughly linear with time until
evaporation and crystallization of the salts on the surface become
limiting.The hydrogen ion concentration plays a significant role in
the absorption of Sr, Fe, and W. At pH 4.5, four times as much strontium
is absorbed as at pH 2.5, and 40 times as much absorption occurs at pH
4.5 as at pH 8.2.^ iron absorption is higher at acid pH since iron
hydroxides precipitate, under alkaline conditions. Conversely, tungsten
will precipitate at neutral or acid pH. Lipid or oil solubility, in
particular, seems to play a major role in the uptake of minerals from
the foliage.^
20
Wittwer et_ al. have summarized and ranked various foliar nutrients
according to their relative rates of absorption, their degree of mobility
in the plant, and their leachability. Their own data and data of others
39
are shown in Table 1. Wittwer has also compiled data from various
o or q£
researchers'5 ~5 on rates of absorption of various elements. These
results and some from other authors are shown in Table 2 where the times
are the extremes from various studies when a time interval is indefinite.
It must be emphasized that these data only represent absorption and do
not indicate translocation rates nor rates of accumulation in edible
plant parts.

12
TABLE 1
CLASSIFICATION OF ELEMENTS AS TO ABSORBABILITY, MOBILITY, AND
LEACHABILITY20
Absorption Class3 Mobility Class^ Teachability Class0
Rapid: Mobile; Easily:
Urea N
Rb
Csd
Na
K
Cl
Zn
Moderate;
Ca
S
Ba
P
Mn
B
Slow:
Mg
Sr
Fe
Cu
Mo
Urea N
Rb
Csc
Na
K
Cl
S
Partially;
Zn
Cu
Mn
Fe
Mo
B
Immobile:
Mg
Ca
Ba
Sr
Na
Mn
Rbe
Csf
Ke
Modrate:
Ca
Mg
S
K
Sr
Difficult:
Fe
Zn
Cl
P
aAdapted from Wittwer and Teubner^2
^Adapted from Bukovac and Wittwer^
cAdapted from Tukey, Tukey, and Wittwer^
^Adapted from Wittwer^
eAdapted from Stenlid^
Adapted from Olsen and Cate

13
TABLE 2
RATES OF ABSORPTION
Element
Time for
Absorption
Percentage
Absorbed
Reference
Cs
24 Hours
45
26
142 Hours
80
26
Sr
24 Hours
10
26
142 Hours
40
26
Mg
10-24 Hours
50
39
Ca
10-94 Hours
50
39
Mn
1-2 Bays
50
39
Fe
5-15 Days
50
7
Zn
1-2 Days
50
39
K
10-24 Hours
50
39
Mo
10-20 Days
50
39
5-15 Days
50
7
Cl
1-4 Days
50
39
I
10-20 Days
50
39
S
5-15 Days
50
7
5-10 Days
50
39
P
5-15 Days
50
7
5-10 Days
50
39
Urea N
0.5-2 Hours
50
39
(Banana)
25 Minutes
65
46
(Banana)
30 Hours
100
47

14
A generalized qualitative indication of the relationship between
absorbability and mobility following foliar application is evident in
Table 1. Cesium is rapidly absorbed, and it is mobile. On the other
hand, Sr, Fe, and Mo are slowly absorbed; and strontium is considered
immobile while iron and molybdenum are translocated to some extent.
Possibly, the rate of absorption of iron and molybdenum controls the
mobility of the ions which in turn is gauged by the amount of ion
translocated from the point of absorption.
Plant Characteristics Affecting Translocation
Many factors that regulate or affect absorption of nutrients by
foliage also are important in the translocation processes, since the two
are so closely related. The translocation pattern is a function of
1) the plant age and/or stage of growth, 2) the rate of movement of each
radionuclide, and 3) the rate of concentration of the radioisotopes and
23
their congeners by a given plant part.
The distribution pattern of various elements within the plant will
be different because of tissue barriers, specific coordinating substances,
OO
and metabolic incorporation processes. Translocation occurs via the
plant's vascular system, which is composed of the xylem and the phloem.
Generally, the phloem is more highly developed as a conducting organ,
but the xylem is larger. The xylem generally carries material upward,
and the phloem carries substances downward from the foliage. For example,
it is commonly held that different compounds tend to be translocated by
different plant tissues: inorganic compounds, particularly water, via
the xylem; and organic compounds (products of photosynthesis) via the
phloem.^ Further, it is known that monovalent cations in the alkali

15
metal group move freely from the foliage to other plant parts via the
phloem, while the alkaline earths divalent cations move only upwards
and will not translocate via the phloem.10*21,48
Translocation from the foliage may be related to the metabolism and
movement of carbohydrates.^ Moorby*^ concluded that translocation
through leaf tissues to veins is a metabolically controlled step, and
discrimination against phloem mobile elements probably occurs at this
point in the translocation process. Biddulph^ has suggested that
chemical precipitation of elements in the extremities of the leaf's
veins may be the inhibiting mechanism of utilization and transport of
some elements.
During the active plant growth phase, nutrients translocated from
the leaf probably move via the phloem as opposed to movement via the
xylem (transpiration system) following root absorption. Leaf maturity
and metabolically active plant parts may be the primary factors that
SI S2 S3
determine the direction of translocation. 5 5 While there is
. r ^ ^
greater absorption by younger leaves, the greatest translocation
54
is from the older leaves. The distribution of radionuclides is
proportional to the metabolic activity of the tissue,^ and the rate of
movement and final direction of translocation of ions are controlled by
C C C/f
internal mechanisms. Generally, mineral nutrients (or fallout) will
move towards the actively growing parts and nutrient storage organs such
as meristems, apical growth points, and fruit. Therefore, the distribu
tion patterns depend on the relative rates of growth and the position of
t 2
the treated foliage and storage organs with respect to each other.
Although there is more translocation when the fruit is young, the
increased movement is not necessarily to the fruit.^

CHAPTER III
PLANT NUTRITION
Introduction
In this study the only required mineral nutrient employed as a
radiotracer was iron, which enters the plant's cytochrome respiratory
system.57 The other radiotracers used in the study have congeners
which are required mineral nutrients: strontium and calcium, tungsten
and molybdenum, and cesium and potassium. (The latter relationships are
CO
not as definite and consistent as the strontium-calcium relationship. )
cn
Calcium is mainly utilized by plants in meristematic parts, such as
new leaves,^ and may be used to form calcium-pectate which provides cell
CO
walls with their rigidity. Molybdenum acts as an electron-carrier in
the nitrate-reductase system,and potassium is associated with carbo-
c O
hydrate utilization.
Mineral requirements of all plants differ quantitatively, and plants
under unusual environmental conditions may exhibit specific requirements
for trace elements not ordinarily used.Differences exist even among
CO
strains and varieties of a species because of their genetic composition.
Mineral nutrients, except potassium and sodium, are most likely
f\ 9
absorbed and translocated as natural chelates. Chelates are regularly
employed to supply Fe, Zn, and Mn to valuable crops, such as fruit and
ornamentals.63
16

17
Strontium
Generally, strontium is not translocated from the site of foliar
absorption.However, Ambler^ reported that strontium translocated
from bean and corn leaves in both upward and downward directions, gener
ally to other leaves. He concluded that this was reverse movement
through the xylem to the transpiring leaves since no strontium was
detected in the fruit or roots, as would have been the case if phloem
movement had occurred. In other studies slight, but measurable amounts
of strontium translocated to cherries and tomatoes from the plants'
foliage.^ Handley et al.^ have reported that 9 percent of the strontium
applied to the foliage translocated from the leaves to new tissue.
The small degree of strontium translocation from the foliage is in
contrast to its general translocation after absorption by the root
system. The uptake of strontium by plants from soil is related to the
following factors: 1) percentage organic matter in the soil; 2) calcium
content of the soil; 3) soil pH; 4) soil exchangeable cations; 5) soil
exchange capacity; 6) soil moisture; 7) soil nutrient status; 8) depth
of roots in the soil; and 9) cultivation techniques. Strontium absorbed
by the foliage is largely immobile,^but strontium absorbed by the
18
roots is translocated to all the above-ground plant parts. However,
if contaminated foliage is allowed to accumulate on the ground beneath
the plants, significantly greater strontium contamination may occur than
if the fallout had directly contaminated the ground. For example,
3
Russell and Milbourn found that 25 percent more strontium was accumu
lated by crops when contaminated stubble was fallowed under than when
land clear of stubble was cultivated. Thus, foliar-absorbed and immo
bilized strontium in fallout became available to edible plant parts if
the vegetation was plowed under recycling the plant's nutrients.

18
Iron
Iron is a transition element with variable valence states, is easily
oxidized and reduced, and has a strong tendency to form organic
complexes.Plants require only small quantities of iron and use it in
the reduced state.^^
Classically, iron has been considered to be slowly absorbed by
28 1 8
foliage and immobile after absorption. But recent research by
several investigators^->68,69,70 indicated that it may have limited
mobility from the foliage of plants, being translocated to young leaves
13
and meristem regions. Eddings and Brown attributed differences in
mobility of iron in three species of plants to variations in stomata and
venal organs. Biddulph determined that iron is immobilized through
precipitation as iron phosphate in veins at high pH and high phosphate
concentrations; while with low pH and low phosphate, iron is evenly
distributed in the plant. If iron is translocated, it probably enters
the leaf via the stomata and is then translocated across the mesophyl
to the phloem. Thus, the more cells through which it must pass before
reaching the phloem, the less it will be translocated. Simmons et al.,^
using nutrient solutions void of iron to grow bean plants, detected
foliar-to-root-to-solution translocation of iron, applied to the leaves
as iron sulfate, within a few days.
72
De 1L have shown that iron, chelated with ethylenediamine-
tetraacetic acid (EDTA), will penetrate the cuticle to a greater degree
than free ionic iron; however, chelated iron does not improve cellular
uptake by isolated cells. While the total iron absorbed is not increased
by chelation, the percentage translocated is improved.

19
Cesium
Cesium's physical and chemical properties enable it to enter readily
the food chains to man. There is an abundance of literature on the
cycling of radiocesium in the environment. Cesium is the most electro
positive and active of all metals, and it forms strong bases and salts.^
Cesium is usually water soluble and is similar to potassium in its chem
ical, physical, and physiological properties.^(However, the cesium
to potassium congener relationship is not a good one in environmental or
biological studies.) Cesium is important in fallout because 1) it has
a high fission yield, 2) it has a long-lived radioisotope ('37cs)> and
3) it is very soluble.
Radiocesium is more rapidly translocated than any other fission
product.75,76,77 The final distribution pattern of cesium in plants
varies with the plant species; however, when it is available during the
vegetative growth phase, it is mainly concentrated by the leaves and
flowers or fruit. ^>^9 Other authors^ >30 80 jjave reported that
following foliar absorption, cesium moved freely throughout the plant
with the greatest accumulation in the stems. Moorby^ studied the
influence of light on the absorption and translocation of cesium, and he
concluded that absorption and translocation of cesium are related to the
plant's sugar metabolism. He stated that active metabolism and a
source of sugars in the treated foliage are a prerequisite for transloca-
37
tion of cesium. Moorby also found that a higher percentage of foliar-
applied cesium moved upward than toward the plant's base.

20
Tungsten
Essentially all cationic salts of tungsten are insoluble in water.
Some anionic salts of tungsten are quite soluble in water, and it is in
this form that tungsten usually enters into environmental chemical
o-i
processes. This element has been studied biologically least of any of
the Group VI B transition elements, and there is no available ecological
82
cycling information on it, nor could any botanical kinetics studies
related to it be found.
If it is assumed that tungsten will behave in a manner similar to
molybdenum, then the limited information about molybdenum may be useful
as a guide to the behavior of tungsten. Molybdenum has been reported to
be somewhat mobile following foliar treatment.One author^
suggested that it is translocated through the transpiration system
(xylem) to adjacent leaves in a manner similar to the way manganese is
moved. The only studies reported concerning tungsten and plants have
81 84
been involved with root absorption.
While no information relative to foliar absorption of tungsten could
be found, various authors have shown that it is utilized by plants
84
following root uptake. Wilson and Cline found that potassium tungstate
provided tungsten in an easily available form as an anion in basic soil.
In acidic soil, tungsten was absorbed very little; therefore, these
authors concluded that tungsten must be in the form of tungstate, an anion,
before it can be absorbed by roots. They also concluded that tungsten
could be absorbed in biologically significant quantities from the soil,
but the uptake is very dependent on soil pH. Finally, Kaye and Crossley^
suggested that the movement of tungsten through food chains would
approximate the movement of cesium.

21
85
Essington et al. reported that radioisotopes of tungsten were the
most abundant radionuclides in fallout 167 days after the Sedan Plowshare
thermonuclear test. Studies by Romney and Rhoads^ and Romney et al.^
of tungsten accumulation by plants following the Sedan test showed that
radiotungsten was by far the dominant radioelement in plants grovro on the
Sedan ejecta after three years of cropping. These investigators found
that the greatest concentration of radiotungsten occurred in the leaves
of these desert plants. Although this was root-absorbed tungsten, it
clearly showed the utilization of this element by one species of plant.
Nutrition of Banana Plants and Coconut Palms
O Q
According to Norton, little is known of the nutrition of bananas,
particularly the mineral nutrition. Generally, this plant exhibits
great flexibility in its cationic composition;^ this characteristic is
reflected in the fact that the mineral element concentration of banana
plant parts varies greatly during the plant's twelve-month growth cycle.
The most prominent compositional characteristic of the banana plant is
its high potassium content.
Most of the research on coconut palms has centered around the major
nutrients, of which potassium has been found to be the dominant cation
in the edible part of the coconut.^ According to Buchanan,there has
been a lack of interest in microelements in the past, and the literature
on coconut nutrition is relatively limited considering the importance of
this crop to human livelihood.

22
Fallout and Plant Nutrition
While considerable research has been conducted on foliar nutrition
using required trace elements, which are potential activation products
(e.g., Mg, Mn, and Fe) little research was conducted on uptake and
80
translocation of fission products by foliage prior to 1960. Then in
n /
1963 Bukovac et_ al. 0 concluded that aerial parts of plants are important
pathways for fission product absorption. Since then, substantial research
has been devoted to this topic.
No reference could be found in the literature concerning fission or"
activation product absorption by banana plants or coconut palms. The
only references to mineral usage by these plants were concerned with
eliciting growth responses to a particular mineral element or to cure a
disease. No mention was made of rates of absorption or translocation by
these plants except for foliar nutrition of banana plants with urea.^s47
However, even these studies only developed rates of translocation to
other foliage and not to the fruit.

CHAPTER IV
METHODOLOGY
Site Selection
The University of Florida's Sub-Tropical Experiment Station at
Homestead, Florida, was selected as the site for the initial mixed tracer
study. The United States Department of Agriculture's Plant Introduction
Station, Miami, Florida, was chosen for the kinetics study because 1) the
site was available for extended-term studies and 2) the site provided
excellent security.
The Homestead site was composed of two experimental locations. The
coconut experiment was conducted at the main site of the Sub-Tropical
Experiment Station where there were 12 trees in the coconut grove spaced
approximately 4.6 meters (m) apart. From these trees, a Malayan dwarf
coconut palm of the yellow variety was chosen for the study because it
presented a balanced distribution of maturing fruit.
The second site at Homestead was the East Glade Farm of the Sub-
Tropical Experiment Station. This farm was approximately eight miles
east and two miles south of Homestead. The East Glade banana grove had
24 clusters of banana plants in 4 rows of 6 clusters each. The spacing
was approximately 4.6 m within rows and 5.3 m between rows. The test
plant was selected because its fruit was estimated to be at least three
weeks from maturity. However, time showed that this estimate was quite
inaccurate (low). Figure 1 shows the coconut tree and its fruit, and
Figure 2 and Figure 3 show the banana grove and the treated banana plant.
23

24
FIGURE 1: FRUIT OF TREATED COCONUT PALM

25
FIGURE 2: EAST GLADE BANANA GROVE

26
FIGURE 3: TREATED BANANA PLANT AT EAST GLADE

27
' Selection of Tracers
In miclear fission by thermal neutrons, fission products range from
mass numbers of 72 to 161. ^ The most common fission products occur
around mass numbers 95 and 138. Of over 275 possible fission products,
only 13 significant isotopes are present singly or in combination
(e.g., Sr-Y) three months after a detonation.^ In addition, many other
nuclides may be produced through neutron activation of stable elements
in the nuclear device's components and in the surrounding soil. The
Relative Significance Index (RSI), developed by the Lawrence Radiation
Laboratory, University of California (the laboratory responsible for
designing and fabricating the nuclear devices to be employed in cratering
activities), ranked isotopes of 1) strontium and cesium (fission, products)
and 2) iron and tungsten (activation products) among those which should
be considered in the environmental radiation hazards evaluation connected
with the Panama Canal feasibility study.
Generally, the selection of the isotopes was based on the desire to
have a mixture of gamma emitting radionuclides with minimum interference
among the respective photopeaks. The radionuclides of ^Sr and ^^Cs were
chosen because they have much shorter half-lives (65 days and 2.1 years
respectively) than their longer-lived sisters (^Sr: 27 years; ^^Cs:
30 years), which are the major long-lived fission products of concern.
(The shorter half-lives make these isotopes less hazardous to use in
tracer studies.) Strontium-90 is generali.y considered to be the most
hazardous and limiting fission product as far as man is concerned since
1) it accumulates in bone; 2) it has a fairly energetic beta particle;
and 3) its effective half-life in the body is long. Cesium-137 is the
other long-lived fission product that is generally considered to be of

28
concern in environmental radiation problems. It has a very penetrating
gamma ray and a beta particle; it is deposited throughout the body in
muscle tissue; and it has a long effective half-life. Both of these
radioisotopes are produced with high fission yields in nuclear devices.
Nothing is known of the distribution patterns, kinetics of absorption,
and assimilation of these isotopes by banana plants or coconut palms.
Iron (Fe-59) was chosen because 1) it is a required plant nutrient
and 2) considerable research has been devoted to iron utilization by
plants; therefore, this isotope would provide a means of judging these
results qualitatively with prior work.
Tungsten, while not a fission product, is expected to be the most
no
common activation product from the nuclear devices, as was indicated
in the Sedan Project. Although the half-lives of and are not
long (145 days and 74 days respectively), they are longer than the other
major activation products, and the quantities that are expected from
nuclear cratering devices make tungsten one of the most significant
radioelements.^2 Little is known of its ecological relationships to
plants, and nothing is known of it with respect to banana or coconut
plants.
Field Procedures Mixed Tracer Expriment
Site Preparation
The coconut and banana sites were prepared in similar manners on
November 3, 1967. The area beneath each tree was cleared of all under
brush, and the ground was covered with plastic sheeting (0.012 centimeter
cm) out to a sufficient distance from the plant's stem to intercept all
drippage. Finally, the plastic was covered with approximately 7 cm of

29
peat moss. The plastic served as an impermeable barrier to percolation
to the ground, and the peat served as an absorbent. Background samples
of the fruit, vegetation, and soil were taken in the area of each test
tree.
Tracer Application
85
A mixture of four microcuries per milliliter (yCi/ml) each of JSr,
^Fe, and and approximately 4 yCi/ml of in a carrier-free,
soluble solution of NaEDTA was applied with a 5 cm wide paint brush. The
soluble, carrier-free tracers provided conservative results, since the
cratering fallout will not be entirely soluble nor carrier-free.
(Although the tracers were applied in soluble forms in order to be
conservative, the general conclusion found in the literature is that
fallout, other than that close-in, is in fairly soluble forms.) The
chelate prevented losses of the tracers on the sides of the container
and possibly made the ^Sr an 59pe more available to the plant; thus,
conservatism was again maintained. A total of approximately 100 ml of
solution was applied to three fronds of the palm tree, and a total of
60 ml was applied to four leaves of the banana tree. A security fence
was constructed around each test tree, radiation warning signs were
posted, and the areas were surveyed with a Geiger counter. Figure 4
shows the application of the nuclides to the coconut palm. The treated
fronds can be seen in Figure 1; they are the three fronds in the fore
ground above the withering frond.
Sampling
OnNovember 21, 1967, 18 days after treatment, the peat and plastic
were removed. The areas were then surveyed and decontaminated to a level

FIGURE 4: APPLICATION OF MIXED TRACERS TO COCONUT PALM

31
at moat twice background, and then the samples were harvested. All the
contaminated waste was sealed in 55-gallon drums, which were subsequent
ly buried in the University of Florida's waste disposal area. Figure 5
shows the removal of the peat and plastic.
All the coconut fruit, inflorescences (the plant part that produces
the flowers from which the fruit develop), treated fronds, and some
untreated fronds were collected, individually bagged, and returned to
the laboratory for analysis. The various parts of the banana tree and
its fruit were also individually bagged and returned to the laboratory.
In order to estimate the magnitude of zoological contamination which
might occur under these experimental conditions, samples were obtained
of 1) a lizard and a frog from the area of the banana tree and 2) ants,
a field mouse, a frog, and flying insects (collected with a light trap)
at the coconut site.
On December 14, 1967, 41 days after the test trees were treated,
additional fruit and soil were collected from adjacent trees at
both sites to determine the extent of radionuclide transport through the
.respective groves. Figure 6 and Figure 7 show where these samples were
obtained. Another environmental survey was conducted on June 5, 1968,
213 days after the tracer application, at the site of the coconut
experiment to be certain that there was no significant contamination of
the area. Samples of vegetation, soil, roots of the treated palm, and
earthworms were obtained to determine the extent of residual radio
activity. Also, fruit was collected from an adjacent tree, and the area
was surveyed with a Geiger counter.

32
FIGURE 5: REMOVAL OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING

LEGEND: O Coconut Palms Sampled
Treated Palm
B Location of Treated Fronds
)( Other Sampling Points
(3 Other Positive Samples from Adjacent Palms
Roads
Note: Palm trees were approximately 4.6 meters apart
O O O O O OxBxO o ooo
X
X X
FIGURE 6: HOMESTEAD COCONUT GROVE

34
D6
D5
D4
D3
D2
D1


V

V

C6
C5
C4
C3
C2
Cl
V
V
O
V


B6
B5
B4
B3
B2
B1

V
X- 0
*o
V

A6
A5
A4
A3
A2
A1
V
V
V
O

V
Negative Samples Obtained
LEGEND: ^3) 12/14/67 41 days after
the study began
V Other Banana Trees Not
Sampled
( pj Test Tree Location
Positive Interplant
y Translocation Samples
^ Obtained 11/21/67 18
days after the study
began
Other Positive Inter-
O plant Translocation
Samples Obtained
12/14/67 41 days after
the study began
FIGURE 7: EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS

35
Field Procedures Kinetics Study Miami
General
A second field experiment was conducted between May 10, 1968, and
June 5, 1968, at the United States Department of Agricultures Plant
Introduction Station, Miami, Florida, to obtain data on the rate of
accumulation of ^^Cs in the banana fruit after foliar absorption. The
experimental site was one of several 7.6 m square enclosures in a
structure originally designed for plant preservation and propagation.
Figure 8 shows the test area.
The banana plant was selected because 1) it is very important in the
diets of the ethnic groups in the canal study areas and 2) the transloca
tion of cesium is fairly rapid in the banana plant. The banana plants
chosen for the study x^ere of the species Musa and varieties walap
CTree 1), rajapuri (Tree 2), and kullan (Tree 3). All three trees were
dwarf varieties. The fruit on Tree 1 was approximately two-thirds
mature; Tree 2 had fruit that was very young on an inflorescence which
had failed to emerge from the plants axial causing the bananas to
develop in the axial; and fruit on Tree 3 was nearly mature (it ripened
after cutting). Figure 8 and Figure 9 show the general study area and
plants. Only ^^Cs was selected for this study since 1) it was rapidly
and freely translocated through the banana plant in the mixed tracer
study, 2) in the previous study Sr, Fe, and W were generally rather
immobile after foliar absorption, and 3) cesium had been shown to be the
most critical fission product or activation product of concern in this
study.

36
FIGURE 8: USDA BANANA EXPERIMENT SITE

37
FIGURE 9: TREE 1 USDA BANANA SITE

38
Site Preparation
The site was prepared in a manner similar to that employed in the
previous experiment. One modification was that a slight mound of earth
was placed beneath the plastic sheeting around the periphery of each
tree, forming a bowl to help retain runoff in the event of a heavy rain.
A 1.8 m high, chain-link fence with a gate was constructed across the
front opening of the test enclosure providing permanent security. Radi
ation warning signs were posted, and the area was surveyed for back
ground radiation levels. Figure 10 shows the area beneath Tree 2 and
Tree 3 as it was prepared for the experiment.
Tracer Application
The solution applied to these banana plants contained 4 yCi/ml,
carrier-free ^^Cs in a NaEDTA solution. In the laboratory, 50 ml of
the tracer solution was placed into each of three continuous-feeding,
plastic squeeze bottles with sponge applicators (5 cm x 1.3 cm). One
applicator was used on each tree. Figure 11 shows the plastic applica
tor and the equipment used to process the samples in the laboratory.
Sampling
Immediately after the tracer solution was applied to each leaf, a
series of ten punch samples was taken with a hand paper punch in order
to quantitate the radioactivity per unit surface area. Similar samples
were obtained on the tenth and twenty-sixth days of the experiment. In
relation to this procedure, Freiberg and Payne^ had stated that, since
the banana leaf has such a large area, leaf samples could be taken with
out significantly altering the total leaf photosynthetic activity.

39
FIGURE 10: PREPARED SITE USDA PLANT INTRODUCTION STATION
TREE 2 AND TREE 3

40
FIGURE 11: EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER,
AND COUNTING CONTAINER AND SOLUTION APPLICATOR

41
Selective sampling of the bananas as a function of time was accom
plished by collecting five bananas every other day for 10 days and
collecting a final sample after 26 days. The bananas were cut from the
hands with a utility knife, which was washed after each sampling in
order to reduce cross-contamination of the fruit. No attempt was made
to seal the wound inflicted by the knife, since preliminary experiments
had indicated that there was negligible drippage of latex from this type
incision. (Latex is the banana plant juice that exudes from a wound in
the epidermis of a plant part.)
Before returning to the University of Florida laboratory, the first
four sets of samples were scanned at the University of Miami's Radiation
Biophysics Department with a scintillation detector ( 4.45 cm x 5.08 cm
Nal(Tl) crystal with a 1.27 cm x 1.91 cm well) coupled to a photomulti
plier tube with its output fed to a Nuclear Data 512-channel pulse-height
analyzer (Model ND 180M). The preliminary scanning was initiated to
insure that the sample size was large enough to enable quantification in
a reasonable counting time. It also revealed that the desired equilibrium
condition would not be achieved within 10 days; therefore, the experiment
was continued.
On the tenth day of the experiment, May 20, the site was cleared of
the peat and plastic sheeting, and new plastic and peat were laid, leaving
room for development of daughter shoots. The experiment was terminated
after 26 days, since the results from the preliminary scanning indicated
equilibrium had been reached. On June 5, 1968, the site was again cleared
of the peat and plastic, and the remaining fruit was harvested. Samples
of the treated leaves, the distal inflorescence bracts, pseudostems, and
untreated leaves were collected and returned to the laboratory for analyses

42
The plants were then cut off at a point approximately 30 cm above the
soil so that transfer of the tracer from the rhizome storage organ (the
"root") to other developing fruit and new sword suckers (young plants
that originate from the rhizome) could be studied.
On September 13, 1968, samples of bananas, distal inflorescence
bracts, and grass were obtained from adjacent plants to determine the
extent of translocation to new daughter plants and to adjacent plants
from the rhizomes of the treated plants. The location of the test trees
and subsequent sampling points are shown in Figure 12.
Laboratory Analyses
Mixed Tracer Experiment Sample Preparation
All samples from the first experiment, except the shells and husks
of the coconuts, were processed to a homogeneous state. The banana pulp
and peels were individually prepared, and the coconut husks, shells, and
meat and water were analyzed separately. A heavy-duty paper cutter was
used to chop the samples, which were then blended in a 4.25 liter (L),
stainless-steel, food blender. The paper cutter, blender, and all
utensils were thoroughly washed after each set of samples was prepared in
order to prevent cross-contamination. The samples were prepared and
analyzed in the anticipated order of the lowest count rate to the highest.
Distilled water was added, as required, to the samples to facilitate
blending, and a few milliliters (ml) of formaldehyde were added as a
preservative. After blending, the samples were poured into 800 ml plastic
containers and weighed prior to low-level gamma scintillation counting.
The dry weights of all samples except the shells and husks were
obtained by drying three portions of each sample at 65-70 C and

43
LEGEND:
O: Denotes the location of banana plants.
D: Denotes the location of daughter plants.
X: Denotes a dead parent plant.
Notes: 1. Numerals are the numbers used to identify the banana plants
in the text.
2. Plants 1, 2, and 3 were the ones treated and sampled to study
the kinetics of -^^Cs movement to the fruit from the foliage.
Plant 4 and Plant 5 were sampled once at the end of the study
(126 days).
134
FIGURE 12:
Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS

44
averaging the percentage moistures. Wet weights of the samples were
corrected to dry weights using the percentage moisture correction factors.
Except for the coconuts, samples collected for determining inter
plant translocation were placed in 800 ml counting containers and analyzed
in their fresh states without blending. Following analysis by gamma
spectroscopy, the samples were dried in an oven at 65-70 C to constant
dry weight.
Kinetics Study Sample Preparation
The samples (banana, leaf, pseudostem, and distal inflorescence
bract) were prepared in their fresh states to provide constant geometry
and uniform density. The unpeeled bananas were sliced and placed in
counting containers with sufficient distilled water added to fill all
voids to 800 ml. The pseudostem and inflorescence bract were individ
ually chopped, blended with distilled water, and placed in 800 ml
counting containers. The leaf punch samples were placed in standard
glass liquid scintillation vials (7.9 cm x 2.2 cm) for low-level gamma
ray analysis. After analysis, the samples were dried at 65-70 C until
constant dry weights were achieved.
Sample Counting
All samples prepared in the standard 800 ml geometry were analyzed
with a gamma scintillation spectrometer system (described later) in a
shielded, low-background facility. The following samples were analyzed
by the same instrumentation but were not analyzed in the standard geometry
assumed for this study: 1) coconut shells and husks from the treated palm
tree, 2) coconuts from the foilow-up sampling to determine the extent of

45
radionuclide translocation to other trees, and 3) leaf punch samples from
the kinetics study.
The whole coconuts, coconut shells, and husks were counted in plastic
hags laid over the large crystal detector of the low-background analyzer
system. This geometry was used for two reasons: 1) reducing these samples
to a small enough volume to be counted in the standard geometry would
have necessitated ashing with possible loss of cesium through volatiliza
tion and 2) the identification, or presence, of the radioisotopes in
these samples was more important than relative quantification of the
tracers. Identification was of primary interest because 1) the prelim
inary analysis indicated that low levels (trace amounts) of isotopes
were involved; 2) the samples from the adjacent trees were analyzed only
to obtain translocation data for planning future studies; and 3) the fact
that interplant translocation occurred is of greater significance than
the amount, since so little radioactivity was involved.
Gamma Spectroscopy Systems
Except for the zoological samples, gamma ray spectroscopic analyses
were made using a 10.16 cm x 10.16 cm right-cylinder, Nal(Tl) scintilla
tion crystal coupled to a photomultiplier tube. The base of the stand
ard geometry 800 ml container was the same diameter as the scintillation
crystal. (A plastic centering ring was used to hold the containers in
constant position over the detector.) The photomultiplier was connected
to a Pckard (Model 116) 400-channel multi-channel pulse-height analyzer.
The crystal was located inside a 51 cm x 51 cm x 61 cm high, tri-component
shield (5 cm thick lead sides, floor, and cover with graded cadmium and
copper lining). The entire analyzer system was housed in a large, low-level

46
activity, concrete semi-vault with 60 cm of concrete on all sides.
Figure 13 shows the large NaI(Tl) crystal inside the lead shield with
the standard 800 ml sample container in place.
The zoological samples were placed in plastic vials and analyzed
with a lead-shielded, 4.4 cm diameter x 5.08 cm thick Nal(Tl) well-
crystal with a 1.91 cm diameter x 3.8 cm deep well coupled to a photo
multiplier tube. A 512-channel Nuclear Data pulse-height analyzer
(Model ND 180M) received the output from the photomultiplier.
Gamma Spectroscopy System Calibration
The low-level counting system was energy calibrated using a combina
tion ^^Cs and ^Co button-type check source, so that each of the 200
channels in a memory-half represented 10 Kev and full scale was 2.0 Mev.
The energy calibration and background were checked at the start and end
of each day or after counting any samples with high count rates.
Figure 14 through Figure 18 show the gamma scintillation spectra of
the energy calibration standards of each nuclide considered in this study.
The was considered in the analyses since it is present in all biolog
ical material, and the data must be corrected for its presence. Figure 19
shows the combined spectra of the tracers in a composite energy stand
ard which contains roughly equal quantities of each radiotracer used.
The low-level counting system was calibrated for differences in
geometry with each of the four nuclides employed in this study. Starting
with a fixed amount of radiotracer and 10 ml of distilled water in the
800 ml container, the same amount of tracer was counted as successive
increments of distilled water were added to the container. All counting
was done on a relative basis in analyzing the results of the mixed tracer

47
FIGURE 13: COUNTING CONTAINER IN POSITION OVER Nal(Tl) CRYSTAL
PACKARD LOW-BACKGROUND SYSTEM

Counts per Channel in 60 Minutes
Channel Number (10 Kev/Channel)
FIGURE 14: TUNGSTEN-185 STANDARD
-CN
CO

Counts per Channel in 60 Minutes
190
FIGURE 15: STRONTIUM-85 STANDARD
VO

Counts per Channel in 60 Minutes
Channel Number (10 Kev/Channel)
FIGURE 16: CESIUM-134 STANDARD
Ul
o

Counts per Channel in 60 Minutes
FIGURE 17: IRON-59 STANDARD

400
300
200
100
0
FIGURE 18: POTASSIUM-40 STANDARD
(75 Grams KC1 in 750 ml water in standard 800 ml container over 10.08 cm x 10.08 cm Nal(Tl) crystal)
Ul
to

Counts per Channel in 60 Minutes (Thousands)
Channel Number (10 Kev/Channel)
FIGURE 19: STANDARD CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr, 13tCs, AND 59Fe
Ui

54
study, since the relative distribution pattern of the tracers in the
plants was the primary purpose of the study. However, absolute counting,
of 4Cs was utilized in the kinetics study so that the total quantity
of cesium accumulated by the fruit could be estimated.
Calibration for geometry differences in counting the leaf punch
samples was based on the fact that the samples from the terminal sampling
of the banana leaves should have had the same count rate per unit weight
as the lamina tissue of the parent sample. Thus, the count rate per
unit weight was calculable for the two counting geometries involved
(standard 800 ml and scintillation vial over the large crystal). An
average correction factor was calculated which allowed correction of the
results of the leaf punch sample analyses for the non-standard geometry.
Data Analyses
The gamma ray analyzer (Packard system) output was an X-Y plot of
the gamma spectrum and a Monroe Digital printout of the number of counts
per channel (or energy band). The portions of the gamma spectra summed
to quantitate the photopeaks of the radionuclides and the photopeak
energies are shown in Table 3. Small spectrum shifts were corrected
when the channels were summed manually. The sums of counts under the
integrated photopeak regions were used in a computer program to separate
the mixed spectra into individual isotopic components.. The two photo
peaks of *^Fe and ^^Cs were summed to improve the sensitivity of detection.
The gamma spectrum of each sample was analyzed using a simultaneous
equations method of separating the components^ and the University of
Florida's. IBM 360 computer. The computer analysis involving simultaneous
equations was chosen as the method of separating the known components of

55
Isotope.
185
W
85 c
'Sr
134
Cs
59
Fe
40
TABLE 3
SPECTROMETER CALIBRATION
Photopeak Energies
Mev
0.058
0.513
0.605
0.796
1.098
1.289
94
Channels Summed
4-9
42-63
50-90
100-139
K
1.46
135-155

56
the spectra hecause it is less sensitive than other methods to changes in
energy calibration of the spectrometer, and it can be used in conjunction
with manual methods of solving a set of simultaneous equations. The
computer output provided the net counts per minute (cpm) of -*Sr,
i^Cs, 59Fe, and 40K in each sample and also the two-sigma standard
error for each isotope in each sample.
Since the samples from the various segments of the Homestead coconut
and banana experiments were separated into sub-samples for analysis, the
final results of the individual sample components were summed to present
the composite average count rates in the given plant part. It was not
possible to treat these separate portions as replicates, since some had
more solids than others.
The data from the kinetics study were analyzed manually. The
channels summed for analysis of the i~iqCs radiotracer were channels
50-70, which represented the 0.605 Mev photopeak. (The calculated
efficiency of detection over the range of this peak was 5.6 percent.)
These data were then used to obtain a model of the kinetics of ^-^Cs
accumulation by bananas following foliar absorption. A modified
Gauss-Newton, non-linear, least squares computer program was used to
95
obtain a curve of best fit to a first order kinetics function.
Tungsten Separation
The 185W x-ray photopeak was in the low-energy region of the
spectrometer (59 Kev, or channel 6) where it encountered interferences
from: 1) electronic noise and 2) backscatter and Compton continuum
associated with the higher energy photopeaks of the other radioisotopes.
Also, because of the very weak energy of this X-ray, the efficiency of
detection was low.

57
Since the may have been masked by high, count rates or was below
the detectable and/or measurable limits of the whole sample, a chemical
separation procedure was developed to simplify the gamma spectra in order
to positively identify the tungsten, if it were present. The bases of
the procedure, which is outlined in Appendix A, were chemical precipita
tion of tungsten using cinchonine^ (a selective precipitant for tungsten)
and a tungsten carrier combined with acid and alkali solubilities.
The counting geometry for these separated samples was 100 ml in the
standard 800 ml container, which was centered over the 10.16 cm x 10.16 cm
scintillation crystal. The smaller volume in conjunction with the
separation increased the efficiency for the detection of -*-^W by decreasing
the losses of X-rays through the sample containers sides, decreasing the
self-absorption losses, and simplifying the spectrum.
The specific samples separated were chosen because they included
1) edible parts (which were the primary samples of interest), 2) treated
foliage (the plant part to which tungsten had been applied), and 3) parts
to which tungsten might have been translocated untreated foliage,
distal inflorescence bract, and pseudostem.
Compositional Analyses
Stable element analyses for Ca, Mg, Mn, Fe, Cu, and Sr in vegetation
and crops from Panama and Colombia were determined at the Central
Analytical Laboratory, Institute of Food and Agricultural Sciences,
University of Florida (IFAS,UF) so that the mineral composition of fruit
from the bioenvironmental feasibility study area could be compared with
the composition of the plants and fruit in the Florida study. A
Beckman D. U. Flame Emission Spectrophotometer was used for these analyses.

58
Stewart Laboratories, Knoxville, Tennessee, analyzed banana, banana leaf,
coconut meat, coconut-water, and frond samples from Homestead, Florida,
for Sr, Mn, Fe, and Cu using a Bausch and Lomb Spectrograph and for Ca,
Mg, and Zn using a Beckman Atomic Absorption Unit. The Tropical Soils
Laboratory (1FAS,UF) analyzed all the samples for potassium using a
Beckman D. U. Flame Emission Spectrophotometer and for phosphorus using
a Fisher Electrophotometer Colorimeter. The method by which the vegeta
tion samples were prepared for these analyses is given in Appendix B.
Soil, coconut puree (meat and coconut water blended), and banana
samples from Homestead, and soil samples from Panama were analyzed for
stable W, Mo, and Cs by activation analysis at the University of Florida
Nuclear Science Center.
0

CHAPTER V
RESULTS
Introduction
As indicated in the literature review, the process of foliar absorp
tion and translocation of fallout is a complex phenomenon with many
physically and chemically interrelated factors. Botanical characteristics
of the plants as well as environmental factors play major roles in the
ultimate extent of absorption of material from the foliage (or more
generally, by the entire plant). The complex interrelationships are
evident in the results of these two experiments: 1) mixed tracer absorp
tion and distribution and 2) kinetics of ^^Cs accumulation in bananas
following foliar absorption.
Environmental Control
As was described in Chapter IV, plastic sheeting, peat moss, and
fencing were utilized to control the radioisotopes and to prevent contam
ination of the general environment. Samples of vegetation (grass, weeds,
and roots), soil, insects, and small animals (mice, a lizard, and frogs)
were obtained from within and/or around the controlled areas to determine
the extent of spread of radioactivity to the general environment. In
addition, samples from adjacent banana plants (suckers, inflorescences,
and bananas) and coconuts from nearby palms were taken and analyzed to
investigate the possibility of interplant translocation (movement) of
the tracers.
59

60
The positive results of the sample analyses are presented in Table 4
and Table 5, Slight contamination was present in grass and weeds, local
soil, and in fruit from adjacent banana and coconut plants.
Samples of grass and weeds were obtained from all quadrants around
the treated palm in an effort to determine the mechanism of transfer of
material to the plants. The grass and weeds (Spanish nettle and a
succulent weed) have different type root systems; the more deeply rooted
weeds consistently showed higher concentrations of ^Cs than did the
shallow-rooted grass. Of these samples, the highest count rates were
in vegetation growing nearest the palm, even though they were from the
north side of the tree the side opposite the treated fronds. The
activity indicated in these samples is postulated to have traveled to
these plants via root-to-root transfer. This is suggested by the
higher activity in the roots of the treated palm tree. Soil samples
taken in the area were negative except for one sample taken at a point
on the periphery of the plastic sheeting where some rain water had
flowed to the unprotected ground. This contamination was removed in
soil excavated to a depth of about 8 cm in the contaminated area.
In Table 5 the indicated contamination of the soil was again by
root-to-root-to-soil movement and not by direct surface contamination.
The contaminated soil from the base of the test tree was from an area
near the treated plant's rhizome. The other positive soil samples were
taken from points adjacent to the plants, where the concentration of
roots would have been the greatest. In all cases, soil samples taken
directly under the treated foliage of the plants were negative, which
indicated no direct contamination from the experiment.

TABLE 4'
a
COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED PALM POSITIVE SAMPLES
Sample 185W 85Sr 134Cs 59Fe Distance
From Test
cpm/g :
t 2a
cpm/g
+
2a
cpm/g
+
2 a
cpm/g
2a
Tree (Met'
PALM EAST OF TEST TREEb
Mature Fruit
0.002
+
0,01
-0.0002

0.003
0.01
+
0.001
-0.0004
0.002
5
Young Fruit
0.004
+
0.002
0.0001
+
0,003
0.007

0.001
0.002
:
0.003
5
PALM WEST OF TEST TREE0
Mature Fruit
0.005
+
0.002
0.003

0.003
0.02
+
0.002
0.0007
+'
0.003
5
Young Fruit
0.008

0.002
0.003

0.009
0.1
+
0.005
-0.002
1
0.003
0,02d
5
Weeds S.W. Test Tree
-0.011
+
0.015d
1.2

0.10
1.7
+
0,053
0.002

4-5
SOUTH OF TEST TREEC
Spanish Nettle
1.1

0.66
-0.22

2.3d
2.9

0.30
-0.22

2.4
3
Grass
2.1
+
1>4d
-0.28
4-
3.3
3.4

0.43
-0.66

4.9
3
Roots of Treated Palm
NORTH OF TEST TREE
0.04

0.4d
-0.24
+
3.0d
12.

0.38
-0.13

1.6
2
Succulent Weed
-0.04

0.7
0.92

4.2d
10.
+
0.54
-0.17
+;
2.7
0.2
Grass
0.66

0.77
-0.23

3.5
6.6

0.45
-0.22

2.8
1
EAST OF TEST TREE
Spanish Nettle
1.3
+
0.64
-0.11

2 8j
4.7
+
0.36
-0.10
+
2.4
2-3
Grass
0.0
+
0.6
-0.57
J-
1.9d
2.3
+
0.25
-0.08

2.
2-3
WEST OF TEST TREE0
Spanish Nettle
0.28

0.52
0.87

1.9
1.9
+
0.24
-0.13
+
2.0
2-3
Grass
-0.02
+
0.6
-0.20

1.7
1.5

0.21
-0.24

2.1
2-3
Chicken Weed
2.0
+
1.1
-0.02

5.
12.
+
0.69
-0.05
4*
4.
1
a
b
c
d
All samples corrected for decay to November 3, 1967.
Sampled on December 14, 1967.
Sampled on June 5, 1968.
Qaulitative inspection of the gamma scintillation spectrum indicated the .presence of this radioisotope.

TABLE 5a
COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES
Sample
185
cpm/p
w
: 2a
85 Sr
cpm/g

2c
134Cs
cnm/g
2c
59
Fe
cnm/g
2c
Locatii
(Figure
Banana Pulp8
0.019

0.063
0.18
+
0.31
8.2

0.20
-0.052

0.091
B4
Banana Peel8
0.034

0.14
1.5

0.67
12

0.40
1.5

0.22
B4
Soilcd
0.02
+
0.003
0.01
+
0.007
0.03

0.004
0.02
+
0.004
B3
Soilc,e
0.04
+
0.007
0.27

0.036
0,74

0.022
0.16

0.011
B4
Sucker0'^
0.005

0.004
0.032

0,012
0.17
+
0.007
0.005
+
0.007
B4
Banana Pulpc
-0.002

0.006
0.021

0.023
0.18
+
0.013
0.006
JL
0.01
A3
Banana Peelc
0.02
+
0.009
0.006

0.04
0.29

0.018
0.015
+
0.016
A3
Soilc£
0.03
+
0.003
0.01
+
0.008
0.04
+
0.005
0.02

0.004
A3
Banana Pulpc
0.002
+
0.004
0.002
+
0.01
0.02
+
0.006
-0.0006
4-
0.007
C4
Banana Peelc
0.04

0.009
0.017
+
0.021
0.057

0.011
0.036

0.015
C4
Soilc,d
0.03
0.004
0.008

0.008
0.03
+
0.005
0.02

0.006
C4
Distal Inflof. Bract^
0.007

0.004
0.012

0.010
0.04
4-
0.006
0.005
4*
0.006
C4
aAll count data corrected for decay to November 3, 1967.
kSampled on November 21, 1967.
^Sampled on December 14, 1967.
uRadon daughters only as shown by qualitative identification of spectrum.
eFrom location of rhizome of treated plant.
^Sucker developed from part of rhizome remaining from where treated parent wTas removed,
%ncorrected for radon daughters, but spectroscopy indicated tracer peaks of ^sr and us.

63
Translocation to Other Trees
Translocation did occur between the treated trees and other trees
and plants in the areas, as is shown in Table 4 and Table 5. (The coconut
fruit samples were not counted in the standard geometry, since only
qualitative indication of translocation was desired.) The trees from
which the samples were taken are shown in Figure 6 (p. 33). Only the
adjacent palms on either side of the treated tree showed evidence of any
translocation. (Fruit of various ages were taken from each of the palm
trees to determine the extent of the intertree translocation.) The
results show that L~54Cs was the most mobile radiotracer-between trees.
Slight amounts of were translocated to the fruit of the adjacent
palms, and possibly some -*Sr and -^Fe moved to the adjacent plants.
The sites from which the follow-up samples were taken at the banana
grove are shown in Figure 7 (p. 34). The banana samples obtained on
November 21, 1967 (listed in Table 5) were composited from the banana
plants indicated by the asterisks in Figure 7. These samples were
counted in the standard geometry. Only the results of the positive
samples are shown in the table. All the radiotracers used were trans
located to the adjacent banana plants. While "*Sr and were not
detected in the fruit of the treated plant, these isotopes were trans
located to the fruit of the adjacent trees.
185
Generally, the banana peels concentrated the W with possibly
only traces of it in the edible portion of the fruit. Iron-59 was also
translocated to the fruit of these plants. While all radiotracers were
translocated, ^Cs was translocated to other plants by a factor of
10 to 1,000 times greater than the other radiotracers.

64
Data Analyses Mixed Tracer Uptake
The application of the mixed tracers to a banana plant and a coconut
palm provided data on the relative distribution and concentration patterns
of each tracer within these plants. Since this was the major objective
of the study, no attempt was made to quantitate the tracers on the
treated foliage at the time of application. The data reported in Table 6,
Table 7, and Table 8 are the results of qualitative interpretation of the
gamma ray spectra and relative quantification of the data (i.e., not
absolute) using a simultaneous equations method of separating the
known components of the spectra.
The data are composite averages of several sub-samples of each listed
plant part that resulted from bagging, chopping, and homogenizing of the
plant parts. The data for the treated leaves are representative of the
radiotracer concentrations 17 days after treatment, but they were corrected
for decay to the day of tracer application since radiotracers with differ
ent half-lives were used. It must be remembered that the ^Fe an -^^Cs
data represent two major photopeaks each, while the Sr and AO;,W represent
only one photopeak each. This does not affect comparison of various parts,
but it does affect the comparison of count rates within a given sample.
Coconut Palm Results
1 Q/
As is evident in Table 6 and Table 7, only 1'54Cs was translocated
in significant amounts to any part of the palm. The very young fruit
had the greatest amounts of radioactivity, which would be expected since
it was the most rapidly developing plant part sampled. The largest amounts
of 1-^Cs were in the husks and shells of the coconuts, but direct
quantitative comparison of husks and/or shells with other plant parts is

TABLE 6a
TRACER COUNT RATES COCONUT FROND LEAFLETS AND INFLORESCENCES 18 DAYS AFTER TREATMENT
Sample
185W
cpm/g 2a
85 sr
cpm/g :
2a
134Cs
cpm/g
2a
59Fe
cpm/g
2a
Treated Frond
NDb
1,600

45
5,100

29
63
+
8.8C
Untreated Frond
(Above)
0.6 0.4
75
+
3.0
180
+
2.1
ND
Untreated Frond
(N. Side)
-0.07 0.1
5.6
+
0.9
32
+
0.6
-0.15
+
0.16
Inflorescence
ND
120
+
8.4
500
+
5.2
ND
Inflorescence
2. 0.9
230
+
6.3
400
+
3.9
5.6
+
1.2
Inflorescence
-0.13 0.3
62
+
1.9
87
+
1.2
0.6
+
0.4
Inflorescence
0.02 0.2
26

0.9
49
+
0.6
0.5
+
0.2
Inflorescence
-0.02 0.07
7.6

0.4
20
+
0.3
-0.06

0.1
aAll data corrected for decay to November 3, 1967.
^Not detectable when the 2a error term was included with the net count rate the result remained negative
cAnalysis of chemically separated sub-sample indicated that this isotope was present.

TABLE 7a
TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER TREATMENT
Sample
185w
cpm/g 2a
85 sr
cpm/g 2a
134Cs
cpm/g
2a
59Fe
cpm/g 2a
YOUNG FRUITb
NDC
-0.2
6.2
350
+
4.0
0.
1.
IMMATURE FRUITd
Milk and Meat
ND
-0.3
0.3
20
+
0.2
ND
Husks
ND
-0.15
0.20
20
+
0.1
ND
IMMATURE FRUITe
Milk
0.014 0.018
+i
CM
O
O
1
0.1
2.4
+
0.1
CM
O
O
1
0.02
Meat
ND
ND
46
+
0.5
ND
Husks
ND
0.7
0.2
17
+
0.1
ND
MATURE FRUIT
Milk
ND
-0.07
0.1
5.6
+
0.1
ND
Meat
-0.06 0.06
-0.02
0.4
13

0.3
-0.05
0.09
Shell
ND
ND
21
+
0.2
ND
Husks
ND
0.5
0.1
10
+
0.1
ND
aAll data corrected for decay to November 3, 1967.
bFruit about 3 to 6 centimeters in diameter.
cNot detectable when the 2a error term was included with the net count rate the result remained negative.
dShell only a thin layer of tissue with little meat developed.
eShell only a thin layer of tissue which was unseparable from the meat; fruit about 8 to 13 centimeters in
diameter.
*Analysis of a chemically separated sub-sample indicated that this isotope was present.

TABLE 8a
TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER TREATMENT
Sample
185w
cpm/g i 2a
85 Sr
cpm/g i 2g
^cs
cpm/g 2q
59Fe
cpm/g 2a
TREATED PLANT PARTS
Lamina
NDb>c
14,000
+
280
36,000
+
180
6,400
+
69
Midrib
ND
3,500
+
100
9,300
+
66
900
+
23
Axial
ND
2,400
+
42
3,800
+
28
300
+
8
UNTREATED PLANT PARTS
Upper Pseudostem
120 7
3,200
+
47
3,100
+
31
810
+
11
Lower Pseudostem Interior
NDC
90
+
19
1,400
+
13
92
+
4
Lower Pseudostem Exterior
ND
90
+
18
1,100
+
12
27
+
4
Rhizome
ND
ND
960
+
10
ND
Lamina: Youngest
NDC
510
+
20
1,900
+
13
84
+
4
Midrib: Youngest
ND
600
+
27
1,800
+
17
41
+
5
Inflorescence Stem
ND
74
+
51
4,800
+
34
91
+
11
Distal Inflorescence Bract
NDC
ND
15,000
+
65
NDC
Banana Pulp
NDC
ND
3,400
+
22
-6.
,1
7.1c
Banana Peel
-5.2 5.8
ND
3,200
+
26
85
+
9
DAUGHTER PLANT PARTS
Upper Pseudostem
ND
ND
1,800
+
14
ND
Lower Pseudostem
ND
-0.
,34
19
1,700
+
14
-0.
,1
4
Lamina
ND
750
+
36
2,500
+
25
510
+
9
Midrib
-1.4 2.3
140
+
16
1,400
+
11
92
+
4
aAll data corrected for decay to November 3, 1967.
bNot detectable when the 2q error term was Included with the net count rate the result remained negative
cData from chemically separated sub-sample indicated that this isotope was present.
CT\

68
not possible because the former did not lend themselves to counting in
the standard geometry.
Strontium, iron, and tungsten did translocate from the treated fronds
on the south side of the tree to a younger frond on the north side. How
ever, a much greater amount of 5gr moved to an untreated frond directly
above the treated fronds.
The data for some of the inflorescences may be high because of direct
contamination since the rachises (the ribbing that supports the leaflets)
of the three fronds were treated as well as the leaflets. It is possible
that at the time of application some of the tracer solution was channeled
to the inflorescences which were associated with the treated fronds.
Also, the heavy rain (3.8 cm), which occurred within an hour of treatment,
may well have washed additional tracer down the rachises to the bases of
the treated fronds.
Although no attempt was made to relate the inflorescences to the
particular fronds with which they were associated, it is clear that the
^^Cs (150 1 cpm/g fresh x^eight) measured in an inflorescence sampled
on December 14, 1967, as a follow-up sample resulted from translocation
from untreated parts since this inflorescence did not emerge until after
all treated parts were removed on November 21, 1967.
Banana Plant Results
In addition to the four leaves, the axial of the banana plant was
treated with some tracer solution. (The banana leaf is composed of four
distinct parts: 1) the leaf sheath, which helps form the pseudostem,
2) the petiole, the portion extending from the axial to where the "leaf"
tissue begins, 3) the lamina, the "leaf" photosynthetic area, and 4) the

69
midrib, the "channeled" ribbing which separates the lamina halves and is
an extension of the petiole.) In Table 8 the axial is considered to be
from about 5 cm below the pseudostem top to about 8 cm out on each
petiole. The untreated banana leaf was the youngest leaf on the plant,
and it was still in a vertical position well above the four treated
leaves; thus, it could not have been directly contaminated. The lower
pseudostem was a section from about 30 cm above the ground. This part
was separated into interior and exterior portions on the basis of tissue
color. The central, white core was termed the lower pseudostem
(interior), and the exterior part was that which contained some green
pigmentation. The rhizome was the entire subterranean base of the
parent plant. The daughter plant was a new growth with five leaves and
was about 2 m tall. It was to one side and slightly to the rear of the
area below the treated leaves.
Generally, there was greater translocation of all the radionuclides
by the banana plant than by the palm. Cesium-134 was very mobile through
out the banana plant, and it particularly concentrated in the inflores-
cence and the fruit. The 4Cs concentration in the developing distal
inflorescence bract was four times greater than in the fruit.
Strontium-85 translocated to newly developing lamina tissue in the young
leaves of the parent and daughter plants. There is some indication that
59
Fe was translocated to the bananas and that the peels concentrated this
isotope relative to the banana pulp (see Table 8). The chemical separa
tion results did indicate the possible presence of -^Fe in the banana
pulp. However, this could have been slight contamination of the pulp
from the peels while separating the pulp from the peels of the green
bananas (which is quite difficult).

70
Chemical Separation
The chemical separation procedure outlined in Appendix A was used
to simplify the complex gamma ray spectra so that positive identifica
tion could be made of tungsten in representative samples of fruit,
foliage, and other plant parts. Prior to separation, tungsten was
masked by electronic noise interference and Compton continuum from the
other radiotracers as shown in Figure 20. Following separation, the
185
samples spectra were greatly simplified. If w were present, it was
in the NaOH soluble, HC1 insoluble portion of the separated sample,
while strontium and iron were in the NaOH insoluble, HC1 soluble
fraction. Although cesium was primarily in the NaOH soluble, HC1 soluble
portion, it was also present in the other three fractions of the
separated sample since cesium is amphoteric. Table 9 shows the general
results of the separation. Figure 21 through Figure 28 show the typical
spectra of 1) the chemically separated portions of the treated coconut
frond sub-sample (4 portions) and 2) the chemically separated portions
of the treated banana leaf sub-sample (4 portions).
Following the chemical separation, as expected, tungsten was
detectable on the treated foliage. Also, it was evident that W had
translocated to untreated foliage on both test plants and possibly to
the upper pseudostem (interior). For the latter, it is probable that
the activity in this sample originated from direct application, since
the petioles of the test tree were also treated and the radiotracer
solution probably "drained" into the pseudostem's upper section. The
edible parts of the fruit from both test trees and the distal inflores
cence bract of the banana plant did not have any detectable radiotungsten.
The value of the chemical extraction is illustrated in Figure 20 through

Counts per Channel in 15 Minutes (Thousands)
FIGURE 20: SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED

72
Fraction
Supernatant
Precipitant
Supernatant
Precipitant
aIn order of
TABLE 9
RESULTS OF CHEMICAL SEPARATION FOR 185W
Tube
1
1
2
2
NaOH
Insoluble
Insoluble
Soluble
Soluble
HC1
Soluble
Insoluble
Soluble
Insoluble
Radioisotope3
85Sr, 59Fe, 134Cs
134
Cs
134Cs, 85Sr
185W, 134Cs
decreasing abundance.

Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 21: SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 SOLUBLE PORTION
Co

Counts per Channel in 15 Minutes
FIGURE 22: SUB-SAMPLE- TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 INSOLUBLE PORTION

Counts per Channel in 15 Minutes (Thousands)
22

Counts per Channel in 15 Minutes
900
800
Channel Number (10 Kev/Channel)
FIGURE 24: SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1 INSOLUBLE PORTION

Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 25: SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 SOLUBLE PORTION

Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 26: SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 INSOLUBLE PORTION
vj
oo

' Counts per Channel in 15 Minutes (Thousands!
Channel Number (10 Kev/Channel)
FIGURE 27: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 SOLUBLE PORTION

Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
co
FIGURE 28: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 INSOLUBLE PORTION

81
Figure 24, which show the components of the unseparated coconut frond
and the spectra of the separated sample. In Figure 20, the tungsten is
IOC
undetectable, \ihile Figure 24 clearly shows the presence of W.
Stable Element Data
Since this study was conducted in the sub-tropical climate of south
Florida, partial stable element analyses of the soil and vegetation
samples from south Florida and from Panama were made so that the applica
tion of these tracer results might be extrapolated to the Panamanian
conditions. Table 10 shows the partial stable element compositional
analyses of various samples from south Florida and Panama.
The major elements are in reasonable agreement when one considers
what the data represent. The Panamanian samples represent data of the
mean of many samples, while those from Florida are determinations of at
most three samples. (The differences in the minor elements are typical
when comparing interlaboratory results of trace metal analyses as well
as plant tissue.In general, the elemental composition of plants vary
widely with age of tissue and environmental conditions prior to sampling.
Even so, there is generally good agreement among the banana pulp samples
from both locations and also between coconut meat samples. Notable
exceptions are in the 1) Fe, Mn, and Zn concentrations in the banana
leaf and pulp samples and 2) Fe, Mn, Zn, and Cu in the coconut plant
parts other than the coconut meat.
97
According to Gamble e_t al. the soil compositions in south Florida
and Panama have similar tungsten concentrations. The cesium composition
of the soils in the two Homestead, Florida, experiments vary considerably.
The total cesium concentration in the soil at the coconut palm site x^as

TABLE 10a
PARTIAL ELEMENT COMPOSITIONAL ANALYSES
Element; Parts per million (ppm)
Sample
Ca
Sr
Fe
Mg
Mn
Zn Cu
P K
Cs
Mo
W
BANANA LEAF
East Glade
5,200
46
2.6b
2,400
15b
50
27b
780
11,000
NA
NA
NA
Panama Darienc
8,700
23
420
4,200
310
0.8
16
1,900
25,000
NA
NA
NA
BANANA PULP
East Glade
170
1.4
9.1
1,000
0.78
14
4.8
1,800
7,200b
0.014d
1.0
0.015
Panama Darienc
230
1.8
31
1,000
19
0.7
9.0
1,200
11,000
NA
NA
NA
USDA Miami 2e
530
6.9
14
840
0.19
54
3.1
NA
8,800
NA
NA
NA
USDA Miami 3e
190
1.7
0.14
730
0.14
2.3
0.14 NA
10,000
NA
NA
NA
SOIL .
East Glade
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.069
1.8s
0.25
Homestead
NA
NA
NA
NA
NA
NA
NA
NA
NA
2.9f
4.5^
l.ld
COCONUT MEAT
Homestead
620
0.77
22
1,000
12
24
13
2,400
9,000
0.044f
1.0d
0.015d
Panama Darienc
220
1.0
17
1,200
5.8
16
4.0
2,000
5,-7 00
NA
NA
NA
COCONUT FROND
Homestead
5,500
30
24
1,300
7.0
62
30
1,600
6,100
NA
NA
NA
Panama DarienC
3,700
15
130
4,000
68
19
8.0
980 .
7,000
NA
NA
NA
COCONUT HUSK
Homestead
2,300
13
25
690
0.19
40
18
740
11,000
NA
NA
NA
Panama Darienc
1,100
12
45
1,100
10
11
2.5
280
11,000
NA
NA
NA

aExcept where noted, all values are averages of three determinations.
^Values are averages of two determinations.
cMean of all samples from Darien Provence, Panama.
^Activation analysis determination 5%.
eAll values based on one determination only.
^Activation analysis determination 4%.
^Activation analysis determination 2.9%.
^Activation analysis determination 2.5%.
NA -indicates the samples were not analyzed for this element.

84
.42 times that in the East Glade soil. However, the stable cesium concen
tration in the coconut meat was only three times that in the banana pulp.
Since the available cesium concentration in each location is unknown,
an explanation of this concentration difference is not possible.
Data Analyses Kinetics Study Miami
Cesium-134 Accumulation
The kinetics of cesium movement from the banana plant's foliar sur-
134
face to the fruit was determined by measuring the rate of Cs accumu
lation in the fruit. The accumulation rate derived in this study can be
characterized by a first order kinetics function of the type__ .
where
dCt
dt
dCt
dt
k
k(Ce Ct)
(1)
134,
= the change in the Cs concentration in
the banana fruit with time;
= the rate constant in units of days
= the equilibrium concentration value of
134,
lCs in the fruit;
134,
Ct = the concentration of Cs in the fruit
at time "t."
The solution to Equation (1) is
n r-\ -kt..
cea e )
(2)
where
= the time after treatment of the foliage.

85
The rate constants (k) which are presented in Table 11 and are
shown on Figure 29 through Figure .31 for the rspective trees, represent
an overall uptake and translocation to the fruit, or rate of accumulation
in the fruit. The data from the three banana plants were also treated
as replicates, and an average rate constant (k) was calculated for the
rate of cesium accumulation in bananas following foliar absorption. The
rate constants for Tree 1 and Tree 3 were essentially the same, even
though the plants were of different varieties and the fruit were in
different stages of development. It is postulated that the slightly
higher rate constant for Tree 2 was a result of the abnormal condition
of the inflorescence of this plant, which caused the fruit to develop
in the axial; thus, the distance over which the translocation had to
take place was significantly shorter than in Tree 1 and Tree 3. (The
tracer was applied to the lamina, leaf, midrib, and petioles of all
three trees and not just to the lamina.) Generally, there is good
agreement among all three trees' rate constants, and the calculated
combined rate constant of -0.133 per day is only approximately 10
percent higher than the individual constants for Tree 1 and Tree 3.
The engineering significance of these results will be discussed in
the next chapter.
Rain Effect on Equilibrium Concentration
The effect of rain wash-off played a significant role in estab
lishing the equilibrium concentration (Ce) level in the fruit. No
rain fell during the process of applying the tracer to Tree 1; a light
rain began while treating Tree 2; and by the time Tree 3 was treated, a
tropical downpour was occurring. While Tree 1 received more tracer than
the other trees, Tree 2 attained a Ce of approximately twice that for

86
TABLE 11
134
SUMMARY OF Cs RATE OF UPTAKE EXPERIMENT
Banana Tree
k
(day-1)
ce
(pCi/g)
Time to
50 % Ce
(days)
Treated
Area
(cm^)
Activity
Applied
(yCi)
Tree
1: Musa walap
-0.123
16,000
5.8
13,900
175
Tree
2: Musa ra.japuri
-0.158
32,000
4.3
10,800
147
Tree
3: Musa kullan
-0.122
5,000
5.8
21,800
150

PERCENTAGE EQUILIBRIUM: (C/C ) x 100
87
FIGURE 29: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa walap
TREE 1

PERCENTAGE EQUILIBRIUM: (C/Ce) x 100
88
Time: Days
FIGURE 30; RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa rajapuri
TREE 2

PERCENTAGE EQUILIBRIUM: (C/C ) x 100
89
Time: Days
FIGURE 31: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa kullan
TREE 3

90
Tree 1 and approximately 6.5 times that for Tree 3, as is shown in
Table 11 and Table 12. Rain wash-off was probably the most significant
factor contributing to the variation in the Ce values; however, plant
morphology and fruit maturity also probably had an influence on the
equilibrium concentrations. These factors will be discussed more fully
in the next chapter. Also shown in Table 12 are the Ce values as a
i n/
percentage of the concentration of XJ4Cs/ml in the solution applied to
the plants.
Three sets of treated leaf lamina punch samples were obtained
during the study to evaluate the change in foliar concentration with
time. The laminas' tracer concentrations, as shown by the punch
samples, are presented in Table 13. As is evident, the activity
remaining on Tree 1 following completion of tracer application was 2.5
times that on Tree 2 and 4 times that for Tree 3, while the tracer
applied varied by less than 16 percent. These differences are attribut
able to the effect of the rain. (The procedure employed was to apply
the tracer to a given tree and then to take the punch samples before
proceeding to the next tree.)
The rain on the first day of the study was 6.83 cm, and 17.35 cm
fell during the first 10 days. Between May 20 and June 5, when the
final sets of punch samples were taken, another 25.40 cm of rain fell.
The heavy rains during the first 10 days of the experiment probably
washed off all the tracer adhering to the surface of the foliage. There
fore, the pool from which the additional loss of tracer came was the
interior of the.leaf. Thus, the differences between the leaf concentra
tions the tenth and twenty-sixth days reflect the influence of foliar
leaching of material from the leaves. The reason for the high loss from

91
TABLE 12
EQUILIBRIUM CONCENTRATION VALUES Ce VERSUS AGE OE ERUIT
Banana
Plant
Ce
(pCi/g)
nS
X 100
Estimated Percentage
Maturitv
Tree 1:
Musa walap
16,000
0.40%
67
Tree 2:
Musa raiapuri
32,000
0.80%
33
Tree 3:
Musa kullan
5,000
0.12%
100
Q
(pCi/g)leaf/(pCi/ml)solution.

92
TABLE 13
COUNT RATE PER UNIT WEIGHT AS INDICATED BY PUNCH SAMPLES3
Date of Sampling Tree 1
Bffi/jg.
Tree 2 Tree 3
PCi/g pCi/g
10 May 1968
985,000
410,000
244,000
20 May 1968
22,300
51,000
15,300
5 June 1968 15,200
8,300
13,500
Q
Adjusted for geometry by applying an average geometry correction factor
since these samples were counted in non-standard geometry.

93
Tree 2 during this period is unclear, but it is suspected that an
untreated portion of the leaves was included in the final leaf sample
(Table 14 treated leaves) from which the terminal punch samples were
obtained.
Other Factors Affecting the Equilibrium Concentrations
The other factors which probably influenced the Ce values were
plant morphology and fruit maturity. As previously discussed, the
inflorescence of Tree 2 had failed to emerge from the axial. Thus, the
relative importance of the tracer applied to the leaf ribbing, petiole,
and axial was greater for Tree 2 since this activity was much nearer to
the base of the fruit's inflorescence.
The effect of fruit maturity is shown in Table 14 and in Figure 32,
which shows that the normalized equilibrium concentration was roughly
inversely proportional to the age of the fruit. In all cases ^^Cs
translocated to other parts of Tree 1 in greater quantities than in
Tree 3 on a percentage basis. This reflects the general slowing of
metabolism of Tree 3 as the fruit reached maturity. The most significant
point here is the concentrations in the distal inflorescence bracts. As
in the fruit, the concentration in the bract of Tree 2 was twice that of
the bract from Tree 1 and ten times that in the bract on Tree 3. In the
latter case, the distal inflorescence bract had withered by the end of
the experiment. The ^-^Cs concentration in the youngest distal bract
(Tree 2) was 48.5 percent of the concentration in the treated leaves
after 26 days. In comparison, the distal bract of Tree 3, whose fruit
began to ripen by the termination of the study, had a concentration only
3 percent of the treated leaves; and the distal bract of Tree 1, whose

94
TABLE 14a
CONCENTRATION OF 13lCs
IN BANANA PLANT
PARTS AND PEAT MOSS
Sample
Count Rate
: pCi/g dry
weight
Tree 1
Tree 2
Tree 3
Treated Leaves
17,700
8,300
13,100
Pseudostem (Center section)
190
250
200
Distal Inflorescence Bract
1,900
4,000
400
Banana Fruit
15,300
27,900
4,900
Untreated Leaf Lamina
560
100
Untreated Leaf Midrib
190
66
Peat Moss^
170
150
60
£
Samples taken on June 5, 1968.
^Grab samples each value an average of three samples.

NORMALIZED EQUILIBRIUM CONCENTRATION
95
MATURITY: PERCENTAGE
FIGURE 32: RELATIVE EQUILIBRIUM CONCENTRATION
AS A FUNCTION OF FRUIT MATURITY

96
fruit was about two-thirds mature, had a concentration 11 percent of
that on the treated leaves 26 days after treatment. These differences
probably reflect the differences in the rate of accumulation of metabolic
sugars. (The values presented for the treated leaves in Table 14 are
from composite, large, treated leaf samples; while those in Table 13 are
from composited punch samples of each leaf which was treated.)
Translocation
Although the primary objective of the kinetics study was to deter
mine the kinetics of -*--^Cs accumulation in the banana following foliar
absorption, additional information was derived concerning the distribu
tion patterns of -^-^^Cs in the plant and translocation to other plants.
As was also shown in the mixed tracer study, J"34Cs exhibited general
mobility throughout the treated plants (as shown in Table 14). (All the
leaves on Tree 2 received tracer solution directly; thus, no untreated
leaves were sampled.) The peat moss samples listed in Table 14 were grab
samples taken from beneath the treated leaves at the end of the study.
Since the peat and plastic were replaced after the tenth day, the radio-
tracer in these samples must have been a result of only foliar leaching
and not direct drippage during tracer application or wash-off immedi
ately after the treatment.
On September 13, 1968, about four months after the experiment began
and three months after the treated plants were removed, samples were
taken of adjacent trees' fruit, distal inflorescence bracts, and grass
from the area. The locations from which these samples were obtained are
shown in Figure 12 (p. 43), and the J4Cs concentrations of the samples
are shown in Table 15. The data are on a wet-weight basis in the standard

97
TABLE 15
RADIOACTIVITY IN ADJACENT FRUIT BEARING PLANTS AND NEARBY GRASS
Sample
Wet-Weight
pCi
pCi/g
grams
Grass 1
71
250
3.5
Grass 2
93
63
0.7
Grass 3
37
27
0.7
Distal Inflorescence Bract
- 4
250
230
0.9
Banana Pulp 4
530
190
0.4
Banana Peel 4
450
220
0.5
Distal Inflorescence Bract
- 5
390
450
1.2
Banana Pulp 5
490
870
1.8
Banana Peel 5
420
1,000
2.4

98
counting geometry (800 ml). Distilled water was added to the grass
samples, and they were homogenized to provide a more reproducible geom
etry in the counting containers. The other samples were counted in their
wet states in the standard geometry.
In the banana parts, the ratio of (^-34cs)peel/(-^^Csjpulp was
approximately 1.3. While approximately 4.5 times more tracer was con
centrated by the fruit of Tree 5 than Tree 4, the concentration of tracer
in the distal bracts differed only by 25 percent. Tree 5 was farther
away from the treated plant (Tree 2), and the fruit of Tree 4 probably -
did not require as much nutrient from the plant because of its maturity;
therefore, in spite of its more distant location, the fruit on the plant
farther away accumulated more ^-^Cs because of its fruiting stage. In
addition to this cause for the higher tracer levels in Tree 5, the
results may indicate a distribution effect of the respective plants'
root systems. The concentration in the fruit of Tree 5 compared with
that of Tree 2 was 0.015 percent. It is believed that this activity
was derived from plant-to-plant (root) transfer.
\

CHAPTER VI
DISCUSSION OF RESULTS
Efficacy of Field Experiments
When properly conducted, field experiments should provide invalu
able data under natural conditions as opposed to the artificial condi
tions present in greenhouse or pot studies. In greenhouse or pot
studies the atmospheric and terrestial environments are artificial and
plant root morphology is affected. For instance, the effects of rain
fall, dew, wind, and temperature changes are eliminated; the moisture,
physiochemical and textural soil conditions may be different; and plant
root system development is altered relative to natural conditions.
Also, since plants in a greenhouse study are protected against the
deleterious effects of rain and wind, the foliage in these plants
would probably not have the physical damage which is characteristic
of field-grown plants.
In the study under discussion, an attempt was made to maintain
as nearly as possible natural conditions which might be representative
of those found in banana and coconut plantations in Panama. The
experiments took place in the sub-tropical climate of south Florida
rather than in the artificial environment of a greenhouse, and the
only alteration of the environment was in placing plastic sheeting
immediately beneath the treated plants to control the spread of the
radiotracers.
99

100
The results obtained from this field study reflect the complex
environmental conditions which occur in the natural sub-tropical climate
while greenhouse or pot studies would not have. As a result of con
ducting this study in the field, valuable knowledge was obtained of 1)
rain effect, 2) plant-to-plant translocation via root systems, and 3)
foliar leaching from banana plants. This type of information is needed
to provide answers to the complex environmental questions which are
required to evaluate environmental effects of man's engineering
endeavors and to plan future studies.
Success of Environmental Protection Procedures
Field experiments, while often preferable to greenhouse studies,
do present several problems. One of these is that of environmental
contamination. Using the techniques employed in this study, however,
it is felt that radiotracer experiments can be conducted in the field
with negligible environmental contamination, as shown by the environ
mental monitoring carried out with this study.
Radioactivity in grass samples collected from areas beneath the
banana trees used in the USDA kinetics experiment shows the limited
amount of contamination that resulted from this study (Table 15). Even
though there was a total of 42.7 cm of rain in the 26-day period, there
was little contamination of the environment. Most, if not all, of this
contamination probably resulted from root leaching of the isotopes into
the surrounding soil and absorption by the neighboring roots or perhaps
by direct root-to-root transfer. Hence, this soil and neighboring
vegetation contamination was an uncontrollable factor. In addition, con
sidering the distances involved, the extent of this translocation was

101
entirely unexpected. The environmental protection provided by the
plastic and peat moss was successful in preventing direct soil contam
ination beneath the treated foliage. The same conclusions are valid
for the mixed tracer study where soil contamination was associated only
with the area adjacent to the rhizomes of the plants which had activity
translocated to them and to the soil around the bases of the treated
trees (see Table 4 and Table 5). It should be emphasized that the
levels of radioactivity in the soil and these plants were such that
they were detectable only through low-level gamma spectroscopy no
contamination was indicated by a Geiger counter survey. Even in the
cases where the soil was slightly contaminated, the contamination could
have been eliminated by removing the soil in the area immediately
adjacent to the "contaminated" plants, if it had been deemed necessary.
The radiotracers in the adjacent banana or coconut plants were probably
a result of transfer of material through root-to-root contact.
Care must continually be exercised over the ingress and egress to
the study area when conducting a field study in order to prevent contam
ination of the environment. The most important key to the successful
completion of an environmental tracer study, such as this, is detailed
consideration prior to entering the field of all possible modes of
losing control of the radioactivity and careful planning to avoid the
hazards envisioned.
The logistic problems of conducting environmental radiotracer
studies are considerable. In particular, the amount of material
requiring disposal is large because of the peat, plastic, and large
volume of the plants. If better statistical designs involving replica
tion were attempted, the volume of waste would be vastly increased;

102
however, by using tracers with shorter half-lives, waste disposal would
be significantly simplified or eliminated.
Besides the contamination and logistics problems, the data from
the field studies are also more difficult to interpret because of the
many variables present in an uncontrolled environment. However, the
benenfits of field studies are worth the additional data analysis
problems.
Significance of Results in Relation to Radioactive Fallout
The ultimate interest in studying the environmental behavior of
radioactive fallout is to determine the critical pathways to mans total
radiation exposure. Probably the most critical pathway of radioactive
fallout to man is through the food he eats. In the area of the proposed
Panama canal, bananas and coconuts comprise a large percentage of that
food. Therefore, the amount of radioactive fallout which would find
its way into the fruits of the banana and coconut plants after a nuclear
excavation is of utmost importance in determining the total radiation
exposure of the native populace.
There are three ways in which bananas and coconuts may become
contaminated by fallout: directly on the surface of the fruit; by
plant root absorption from the soil and translocation to the fruit; and
by foliar contamination and translocation to the fruit. Direct fruit
contamination followed by absorption and transfer into the interior
parts of some fruits is known to occur. While direct contamination of
the fruit of banana and coconut plants may occur, these plants have
extensive leaf areas which provide an umbrella-type protection for
these fruits and which provide extensive surface areas for foliar

103
absorption; thus, as a contributor to the total radionuclide contamina
tion of the fruit, it is unlikely that direct fruit absorption would be
a significant source of contamination except for nuclides which are
not translocated from the foliage or from the soil via the roots. There
is a need for research on the degree of internal fruit contamination
that could result from direct absorption of nuclides which are not
translocated from other absorbing areas of the plants. Surface contam
ination which remains on the surface of the banana peels or coconut
husks should not be an internal health hazard since these outer fruit
layers are discarded. However, in the case of surface contamination,
the fruit should be washed before being consumed since external surface
contamination can be carried to the edible parts of the fruit in the
process of preparing the fruit for consumption.
Much research has been conducted on the behavior of fallout in
various types of soils and the absorption of radionuclides by plant
roots from contaminated soils. Generally, researchers have found that
strontium is the most limiting radionuclide when the soil-to-plant
pathway is considered. This is due to its physical and chemical
properties, its fission yield, and its limiting maximum permissible
concentration (MPC). However, as was indicated in the literature
review, tungsten can also be absorbed from alkaline soil by plants and
is subsequently translocated to the aerial parts of the plant. Addi
tional research is needed to evaluate the extent of contamination of
bananas by strontium and tungsten following root absorption. Iron is
generally rather immobile in soils due to its physical and chemical
properties, and cesium is complexed by the soil organic matter and
undergoes ion exchange on the clay fraction of the soil. Thus, these

104
isotopes are usually not limiting relative to soil-to-plant uptake.
Since direct fruit absorption and root absorption are not likely to be
the primary source of fruit contamination by cesium, deposition of fall
out on the aerial parts of banana and coconut plants will probably be
the critical pathway of contaminating these fruits.
The mixed tracer study at Homestead provided a measure of the
relative distribution patterns of Sr, Fe, W, and Cs in banana and
coconut plants following foliar absorption. Based on the facts that
137
Cs has a long half-life and a high fission yield and on the results
of this research, probably only cesium will cause significant contam
ination (that which might approach limiting values) of edible portions
of bananas and coconuts after foliar deposition of fallout. For this
reason, cesium will be emphasized in subsequent discussions.
Similarly, the banana plant will be stressed in the following
discussion since it is the more probable critical pathway to man com
pared to the coconut plant. This is indicated by 1) the fact that
bananas represent a much greater portion of the diet of the ethnic
groups in Panama than does the coconut (up to 85 percent versus 6 per
cent) and 2) the mixed tracer study results which showed that a higher
percentage of cesium was translocated to the bananas from the foliage
than to the coconuts in the coconut palm. (As is shown in Table 6,
Table 7, and Table 8, the fraction of cesium translocated to the young,
new fruit on the palms was about the same as in the bananas; however,
the edible parts of the coconut had not yet developed. Therefore, the
only valid comparison is between the fractions translocated to the
edible parts of the respective types of fruits; i.e., while the mature
coconut meat and milk had 0.36 percent as much radiocesium as the

105
residual on the coconut fronds, the banana pulp had 9.4 percent as much
cesium as the residual activity on the banana plant lamina.)
Evaluation of Allowable Activity on Plant Foliage
The purposes of the Bioenvironmental and Radiological-Safety
Feasibility Study were to develop guidelines for determining the
allowable concentrations of radionuclides following a Plowshare event
and to evaluate the ecological feasibility of a project such as
construction of an interoceanic sea-level canal by nuclear means.
In order to calculate the maximum allowable concentration of fall
out on the banana foliage (Cl), the following factors must be considered:
1) the radionuclide of interest, 2) the physical half-life of the radio
isotope, 3) the biological half-life of the radionuclide in the body,
4) the period of exposure, 5) the rate of uptake by the critical body
organ, and 6) the relative transmission factor (RTF) from the foliage
to the fruit (derived from this research).
Since no criteria have been established for determining allowable
population exposures following a Plowshare event, the following approach
will be taken as a first step in developing the allowable fruit and leaf
surface concentrations: 1) the allowable annual whole-body dose to a
suitable sample of the critical population group in Darien Provence,
Panama, is assumed to be 0.17 rem; 2) the annual dose is received in
two segments during the ingestion phase and during the elimination
period following the termination of intake; 3) the period of ingestion
is a variable; and 4) the allowable leaf surface concentration (Cl) will
be determined as a function of the duration of ingestion to limit the
total yearly whole-body dose as a result of Cs intake via contaminated
bananas.

106
137
The whole-body dose resulting from intake of Cs through the
consumption of bananas is a function of the rate of intake (R), the
duration of ingestion, and the biological half-life of ^^Cs. Since
the physical half-life is so long (30 years), the biological half-life
determines the rate of decrease of the body burden (B) of AJ/Cs. The
dose received during the period of ingestion is a function of the rate
of ingestion and the biological elimination constant (k), while the
dose received following the termination of ingestion is determined by
the body burden (B) of LJ/Cs accumulated during the ingestion phase
and the biological elimination constant. Equation (3) shows how the
body burden varies with the duration of intake:
= R kB (3)
dt
where
B
R
k
dB
dt
the body burden of Cs in yCi;
the rate of AJ/Cs ingestion in pCi/day;
the biological elimination constant for ^^^Cs in the
body: 0.0099 days-^ assuming a biological half-life of
70 days;
the change in the body burden as a function of time.
The solution to Equation (3) is
B = -|-(1 e~kt) (4)
In addition to the other variables previously mentioned which
determine the dose due to the intake of radiocesium, the dose is inversely
proportional to the mass of the body since the whole body is the critical
no
organ for radiocesium. Thus, the dose rate during the consumption
period can be expressed as:

107
where
dP(I)
dt
(DCF) B
W
(5)
D(I) =
dD(I) =
dt
(DCF) =
W
the whole-body dose received during the ingestion
phase;
the change in D(I) with time;
the Dose Conversion Factor for ^^Cs: -r-a-^~k8 .
yCi-day
= the mass of tissue which is assumed to receive
radiation exposure; i.e., the whole-body weight in
kilograms Kg;
t = the duration of ingestion in days.
Now, substituting for "B" from Equation (4) and solving for D(I),
Equation (5) leads to
D (I)
(DCF) R , e"kt
W k k
-)
(6)
Substituting "t," the duration of the consumption, into Equation (6) and
rearranging slightly, the whole-body dose received during the period of
ingestion can be expressed as:
D(I)
.(DQF). R (tk + ekt 1)
W k"
(7)
The long-term whole-body dose rate following the ingestion period is
a function of the biological removal constant and the body burden B(t)-
and may be expressed as:
dD (E) = (DCF) B (t) (e-k0)
dt W
(8)
where
0 = the duration of the elimination phase in days.

108
The accumulated whole-body dose D(E) during the period following the
end of the ingestion is given by Equation (9) as follows:
D(E) W k
When Equation (4) is substituted for B(t), Equation (9) can be expressed
as:
D(E) = .(Pgll-R-. (1 e"kt)(l e k6). (10)
W kZ
137
The total dose received due to the ingestion of Cs in bananas
is the sum of the dose received during the ingestion phase and that
resulting during the elimination phase, or
D(T) = D(I) + D (E) (11)
where
D(T) = the total dose received.
When Equation (7) and Equation (9) are substituted for D(I) and D(E) in
Equation (11), the total dose received is given by Equation (12)
D(T)
<££F>A (tk + e-kt 1) + .(PCF) R (1 e-kt)(1 e-fc0j <12)
o i,2 Hr
which, simplifies to
D(T)
[ (tk + e-kt
W kz
1) + (1 e-kt)(1 e"k0)]
Furthermore, since
R = C(f)M
and
C(f)
C(L)
(13)
RTF =

109
where
C(f) = the concentration of in the fruit: yCi/g;
M = the mass of fruit consumed per day g/day;
RTF = the relative transmission factor;
C(L) = the concentration of on the leaf: yCi/g.
Equation (13) can be rearranged and solved for C(L) after substituting
for "R" and "C(f)M as shorn by Equation (14):
C(L) (yCi/g) = D(T) W k2 (14)
(DCF)(M)(RTF)[(tk + e_kt 1) + (i e~kt)(1 -ek0)] -
The data developed in this study have provided a measure of the RTF.
As shown in Table 16, the RTF varied according to the maturity of the
banana plant's fruit and environmental conditions the fruit on Tree 1
and Tree 2 were immature, while the fruit on Tree 3 was mature. The RTF
for Tree 1 through Tree 3 are based on the leaf punch samples taken on the
tenth day of the study, since the later data for Tree 2 probably were
affected by inclusion of untreated foliage which resulted in a lower
calculated residual concentration in the treated leaf at the end of the
study.
Although the RTF is based on the ratio of the -*--^Cs concentration
in the fruit to the residual concentration on the foliage rather than
on the foliar concentration immediately after treatment, the estimates
of allowable leaf concentrations will be conservative since the
(yCi/g leaf)residual is smaller than the (yCi/g leaf)initial; thus, the
RTF based on the residual activity is larger, which results in smaller
allowable leaf surface concentrations as calculated by Equation (14).
Equation (14) can be evaluated for the critical population group
in Darien Provence, Panama, if the following assumptions are made:

TABLE 16
RELATIVE TRANSMISSION FACTORS
Study
Concentration
on Leaf: C(L)
Concentration
in Bananas: C(f)
RTF
Comment
East Glade
36,000 cpm/g
3,400
cpm/ ga
0.10
No rain
Kinetics Study
Tree 1
22,300 pCi/gb
16,000
PCi/g
0.72
Rain after tracer application
Tree 2
51,000 pCi/g
32,000
PCi/g
0.63
Malformed inflorescence and light
rain during the tracer application
Tree 3
15,300 pCi/g
5,000
PCi/g
0.33
Heavy rain during the tracer
application and the fruit was mature
aFruit concentration adjusted since the data in Table 8 (p.67) represent a condition of 87 percent of
^the equilibrium as defined by the kinetics study.
Picocuries per gram.
110

Ill
1) the (DCF) for 137Cs is 0.03 r-~Kg
yCi-day
2) the allowable yearly whole-body dose is 0.17 rem;
3) the mass (M) of bananas consumed per day is 1,700 grams
4) the weight per unit area (mg/cm; of banana leaf is 15.9 as
shown by this study, or 159 g/m2;
92
5) the standard man weighs 70 Kg.
r\ 1
Now, the leaf surface concentration (yCi/nrO of /Cs fallout can be
calculated to provide the allowable fallout densities on the foliage as
a function of the duration of ingestion to give the limiting dose as
shown by Equation (15):
C(L) (pCi/m2) = (M)036 (15)
(RTF)[(tk + e-kt 1) + (1 e-kt)(1 e-k0)]
Figure 33 shows the C(L) as a function of the duration of ingestion
and the RTF to provide a maximum yearly whole-body dose of 0.17 rem. As
is evident by the C(L) for Tree 1 and Tree 2 compared to Tree 3, more Cs
could be allowed on the foliage of trees with mature fruit. The indicated
higher allowable concentrations on the East Glade tree are because the
activity applied to the lamina was not removed by rain; thus, the RTF
was smaller, and the C(L) was larger.
The curves shown on Figure 33 bracket the calculated allowable C(L)
values derived from the data of these experiments. The East Glade data
represent conditions without rain wash-off effects, while the USDA data
include rain wash-off and indicate the effect of fruit maturity also. One
can interpret these curves as indicative of the permissible leaf concen
trations (yCi/m^) which would result in limiting ingestion rates of -^^Cs
as a function of the duration of ingestion of the contaminated fruit.
While the curves are specific to limit annual whole-body doses to 0.17 rem

137
Maximum Allowable Leaf Surface Concentration of Cs: Ci/m
112
Duration of Ingestion Days
FIGURE 33: MAXIMUM ALLOWABLE LEAF SURFACE CONCENTRATION OF 137Cs TO
GIVE A 0.17 REM ANNUAL WHOLE BODY DOSE AS A FUNCTION OF
ASSUMED DURATION OF INGESTION OF CONTAMINATED FRUIT

113
for a critical population group composed of "standard men" who consume
1,700 g of bananas per day, Equation (15) can be used to calculate either
the allowable leaf surface concentration to yield an allowable dose or to
evaluate the projected dose due to an estimated fallout density for any
size man, any rate of intake, or duration of intake.
Two factors add some conservatism to these calculations: 1) the
radiotracers were applied in soluble form, which increased the percentage
of absorption and 2) the RTF for the three kinetics study plants were
conservative since the residual concentrations were significantly reduced
by rain.
However, the limitations of this calculation cannot be stressed too
strongly for the following reasons: 1) the calculations assume that the
entire inventory of the radionuclide which reach the edible plant parts
was derived from foliar-absorption; (it is the belief of the author that
the contribution of axial-absorbed radioactivity in the banana plant will
be as significant as that due to leaf absorption;) 2) the Cl are based on
the assumption that the entire body burden and resulting doses are derived
from the ^37cs in the bananas ingested; and 3) the total exposure of the
population to all fallout in combination must be considered and not just
Kinetics of Cesium Accumulation in the Banana Plant
This is the only study known to the author in which a model was
developed to measure the overall kinetics of accumulation of an element
from the foliage to the fruit of a banana plant, or any other plant.
Historically, only the rate of absorption by the foliage and/or the
distribution patterns have been studied. It is significant that the

114
overall accumulation of 134cs by the banana fruit from the foliage was a
first order function since this type of kinetics is often characteristic
of biological processes.
The literature review yielded only one reference to a mathematical
model of absorption and/or translocation of material from plants' foliar
surfaces. Jyung et al. indicated that foliar absorption characterized
by a first order reaction possibly indicated a passive component of
absorption with the initially rapid uptake being closely related to
environmental conditions. Overall, these authors feel that foliar
absorption by green leaves is characterized by a rapid non-metabolic
(passive) phase followed by a second, slower, metabolically controlled
step which they related to carrier concepts.
1 2
Although Jyung ejt al. were mainly concerned with the absorption
of ions from the leaf's surface and the subsequent translocation from
the absorbing location, it was shown in the literature review that the
processes of absorption and translocation are intimately interrelated.
Therefore, while the rate of accumulation of ''^Cs by bananas was the
12
phenomenon modeled here, the mechanisms suggested by Jyung ert al. may
be applicable to these studies.
Although three varieties of dwarf banana plants were employed for
the study and although they had fruit at different stages of development,
the rate constants were surprisingly similar. The more rapid rate of
accumulation of x Xs in the fruit of Tree 2 is probably related to the
morphology of the plant. The fruit was the youngest (about two months
old) of the three bunches, and it was developing in the axial of the plant
rather than on the inflorescence away from the plant. Therefore, any
radiotracer that reached the axial via external pathways would have

115
circumvented the foliar barriers and the necessity for translocation
from the foliage to the inflorescence and then to the fruit. The axially
deposited fraction of the tracer needed only to be absorbed by the
inflorescence and translocated the short distance to the fruit. Also,
tracer that reached the axial was prevented from being washed from the
plant by the rainfall that occurred during and following the application
of the ^^Cs.
Relative to fallout following a Plowshare event, an important aspect
of these results is that the rate of accumulation in the bananas was
sufficiently rapid to allow *'^Cs to reach equilibrium concentrations
within one month. For comparison, the literature gave only one indication
of the time of accumulation to equilibrium of a nutrient in a fruit and
oo 27
that was concerned with J P in apples. Eggert et al. found that 30 days
after treatment of apple leaves 2 to 3 percent of the phosphorus in the
apples was P, and after only 14 days the tracer in untreated leaves
approached that in the treated leaves. Although the apple and banana are
two entirely different plants, the time to maturation of the respective
fruits is not very different. Therefore, the unit of days with respect
134
to the time of accumulation of Cs by bananas from the foliage is
reasonable.
The one reference to translocation rates from banana leaves after
foliar treatment was in regard to absorption of urea nitrogen. Freiberg
46
and Payne showed that in twelve days 22 percent of nitrogen applied as
urea translocated from the foliage to an untreated leaf 4.6 m away. This
provides a guide to the rates of metabolism and translocation of metabolic
products from the banana foliage since the nitrogen was incorporated into
products of metabolism prior to being translocated. Since urea and cesium

116
are the two most rapidly translocated minerals (see Table 1, p. 12), a 4-
to 6-day time to 50 percent equilibrium for cesium accumulation in the
fruit of the banana plant is reasonable. All the other data in the
literature are concerned with rates of absorption by the foliage and
not translocation rates.
Effect of Rain
Although determining the effects of rain on the fate of fallout on
tropical fruit plants was not an objective of this research, the field -
study provided significant data on these effects which will be very
important in predicting the radiological consequences of a Plowshare
event in the tropics. In the mixed tracer study, for instance, approxi
mately twice as much mixed tracer solution was applied to the three fronds
of the palm as was applied to the banana leaves; yet, at the end of the
experiment the treated banana leaves had roughly ten times the concen
tration of radiotracers on them as did the palm leaflets. (The East Glade
banana plant was treated following a light shower, but no additional rain
fell afterwards until near the end of the experiment; on the other hand,
a 3.8 cm rainfall occurred within an hour of treating the palm fronds.)
While part of the concentration difference was probably related to
botanical variations between the coconut palm and the banana plant, the
rain wash-off effect probably was a major factor.
The kinetics of x'54Cs accumulation experiment provided an even greater
illustration of the importance of rain on the absorption of foliar-deposited
fallout. Tree 1 was treated when no rain was falling, treatment of Tree 2
was during a light rain, and by the time Tree 3 was treated, a regular
downpour was in progress. This had a significant effect on the equilibrium

117
constants which were 16,000 pCi/g, 32,000 pCi/g, and 5,000 pCi/g for
Tree 1 through Tree 3 respectively. The difference in the equilibrium
concentration value of Tree 3 and the other trees was most probably the
amount of tracer that was washed from the leaves, coupled with a lower
rate of metabolism in the maturing fruit. However, despite tracer loss
due to rain, it was conclusive in this study that even following heavy
rains a significant amount of radioactivity will remain on or in the
foliage of the banana and coconut plants. Also, whether the rain occurs
during or following the period of fallout deposition, there will be
sufficient residual activity on the foliage to provide a source of
contamination of the fruit through translocation. This is evidently, in
part, due to rapid absorption by the leaves and translocation from the
foliage to the interior of the plant and then to the fruit. While the
rain did have a significant effect on the absorption and translocation of
the fallout, generally it can be concluded that the environmental conditions
did not affect the rate of -^^Cs accumulation by the fruit since the rates
of accumulation (k) for Tree 1 and Tree 3 were the same, despite the
effect of the rain.
Translocation of Radiotracers in Coconut and Banana Plants
Coconut Palm
Levi^O^ postulated that interflow between the xylem and phloem in
dicotyledons resulted in movement of some of the strontium and iron from
the foliage. Translocation of these elements from the foliage also occurred
in this study. Even though the vascular system of palms (as well as
banana plants) is basically different from that of dicotyledons, similar
phenomena may occur in the palm (or the banana plant). Also, Ambler has

118
reported two-directional movement of ions in the xylem of corn plants,
which are monocotyledons like palms and banana plants. Thus, this phenom
enon may have been influential in establishing the patterns of ion trans
location in the coconut (and banana plants). In addition, several
researchers^-68,69,70 have reported limited movement of iron from plants
foliage to new tissue. The results of the mixed tracer study also indicated
this tendency for coconut palms.
The differences in the amount of tracers translocated to the mature
coconut frond directly above the treated fronds and the younger frond on
the north side of the tree are interesting to consider. The frond above
or
the treated ones had about 15 times more OJSr concentration than the one
above and on the north side of the tree. This is probably related to the
distribution of vascular organs within the foliar tissues and to the
location of the vascular systems of the untreated fronds relative to that
of the treated ones. However, it is surprising to note that the ^^Cs/^Sr
ratio in the frond above is only two, while in the literature cesium is
reported to be much more mobile than strontium. This difference is
probably associated with the location of the fronds at their insertion into
the crown of the palm and the nature of the vascular system of the palm
compared to the other plants which are usually studied.
The frond on the north side of the tree had roughly twice as high
1 q /
4Cs concentration as did the other sampled, untreated frond (from the
south, or the treated side). Cesium is very mobile in plants, and since
this frond was younger, its metabolic activity was greater and foliar
leaching was probably less than on the older frond. The fact that more
59
Fe was translocated to the younger frond is additional evidence that its
IQ/
metabolic activity x^as involved in establishing the higher LJ4Cs levels.

119
Banana Plant
In the banana plant, all the radiotracers were absorbed and trans
located to a considerably greater extent than by the palm tree. One of
the reasons for this was the difference in rainfall already noted. Two
other reasons were the differences in morphology and metabolism between
the two plant species.
The banana leaves in this study were badly torn and hung quite limply
causing more tracer to be lost by drippage during application to the
banana leaves than to the rigid, intact coconut palm leaflets. (The
three plants treated in the kinetics study had minimal lamina tears.)
This loss may have been partially compensated for by the opening provided
for the tracer through the broken cuticular areas. This mode of absorption
would vary with the age of the tear and the degree of tissue repair, or
healing, and may have played an influential role in establishing the amount
of tracer that was initially rapidly absorbed.
The banana plant morphology furnishes a large leaf surface area; a
channel to convey solution into a central point, the axial; and a fairly
direct avenue, provided by the axial, into the interior of the pseudostem.
(Interior here refers to the space between the leaf sheaths which make up
the pseudostem.) Once solution enters the intraleaf space, it is not
capable of being lost as is a surface-deposited material. Therefore, it
provides a source of radioactivity for absorption by the leaf sheaths.
The difference in the life span of the coconut palm and banana plant
may also account for part of the difference in the translocation of radio-
tracers. While the coconut palm is a tree with a very long life span, the
banana plant is a perennial herb, and, as such, its rate of metabolism may
be much higher causing material to move through the plant at higher rates.

120
The concentration of the various isotopes varied considerably in the
banana plant from one plant part to another showing a definite difference
in the translocation of the isotopes. Evidently, the upper pseudostem just
below the axial concentrated the tracers that reached it directly from the
axial, since the amounts of Sr, J7Fe, and JW there were considerably
greater than in the axial (see Table 8, p. 67). (The axial received some
directly applied tracer in addition to that drained to it from the midribs
of the treated leaves and that which translocated from the leaves.) Cesium
was translocated throughout the plant concentrating in equal amounts in the
fruit and lamina, but the distal inflorescence bract had a ^-^Cs concen
tration at least three times that of any other untreated plant part. This
high ^"^Cs concentration was a result of a higher rate of metabolism and
growth in the distal inflorescence bract where the banana "flowers" were
developing. The banana peels contained as much *^Fe as did the untreated
lamina, and -*Sr and **^Fe were translocated from the axial to the growing
plant parts such as the younger lamina of the new leaf and the developing
daughter plant where they were preferentially concentrated in the lamina.
The iron which was translocated from the banana foliage was probably
72
influenced by two factors. First, the iron was chelated; other authors
have shown that a greater fraction of foliar-absorbed iron is translocated
when it is applied as a chelate. Secondly, the morphology and physiology
of the treated banana plant probably played a significant role in deter
mining the amount of radioiron translocated from the foliage.
Interplant Translocation
The mechanism of translocation of the radionuclides from the test
trees to the neighboring plants is postulated to have occurred through

121
direct root-to-root transfer. Tracers absorbed by the roots are translo
cated fairly uniformly to the rest of the plant's vascular system. The
higher levels of radioactivity in the younger fruit can be explained on
the basis of higher growth rates and mitrient requirements. The banana
peels seemed to concentrate translocated (plant-to-plant) ^Sr, ^Fe, and
in addition to ^^Cs. Traces of these isotopes were also evident in
the banana pulp samples.
The differences in the translocation patterns exhibited by Sr, Fe, W,
and Cs can be explained by the work of other investigators even though
they studied different plants. While Sr, Fe, and Mo (and probably W) are
absorbed fairly rapidly initially, the rate of absorption decreases sharply
10 33 34
within a few hours. This absorption pattern has been attributed
to. saturation of leaf tissue at the point of absorption combined with an
inability to translocate the minerals from the leaf 36 Moorby^
concluded that translocation through leaf tissue to veins is a metaboli-
cally controlled process and element discrimination occurs at this point.
Biddulph^ suggested that chemical precipitation of elements in the veins
of the leaf is the inhibiting mechanism for non-mobile elements.
Inorganic compounds generally translocate upwards through the xylem,
and organic compounds move through the phloem.^ Cesium is generally
considered phloem mobile, and its translocation has been related to the
37
movement of sugars in the plant. Conversely, strontium and iron are
xylem mobile.-*-0>21s48 Since inorganic ions are generally xylem mobile, it
is possible that cesium is translocated in both vascular tissues, as has
been reported in corn. Thus, it is distributed throughout the plant.
Divalent cations will not translocate through the phloem,10,21,48
which carries nutrients and products of photosynthesis from the foliage

122
/* rt r ft
to the roots. However, researchers0 ,0 have shown that divalent ions
such as Fe, Zn, and Mn are absorbed and translocated as natural chelates,
which are organic compounds. Therefore, it is possible that the Sr, Fe,
and W were translocated down the plants to the roots and then to adjacent
plants via the phloem as organic chelates since they were applied chelated
with EDTA.
It is likely that the tracers, chelated with EDTA, exhibited greater
mobility than has been indicated in the literature for purely ionic
elements. Another possibility is that the tracers which entered the
plants via the axial and the pseudostem may have been absorbed by the
phloem in the pseudostem and were translocated to the roots, while the
tracers absorbed by the lamina were immobilized. The use of EDTA chelate
provided an artificial condition which would not be expected to exist
relative to radioactive fallout after a Plowshare event. However, since
the mobility of the ions was possibly enhanced by the chelate, the results
of the study were biased on the conservative side in relation to radiolog
ical considerations.
Long-Term Effects of Foliar Contamination
The Plowshare detonations may be viewed as a single series of events
spaced over a relatively short time span compared to the physical half-
life of Cs. During the excavation phase of the project, many of the
local people would be temporarily relocated. Thus, bananas growing in the
cleared sectors during the periods of actual fallout deposition (i.e.,
those which would have received the highest concentrations of fallout)
would not enter the diets of the people. However, because of the methods
of cultivating banana plants, fallout deposited on the banana plants could
have a long-term effect on the fruit of subsequent harvests.

123
The banana plant is propagated vegetatively; that is, new plants
develop from the same "root," or rhizome, as the "parent." The rhizome
also serves as a nutrient source for the new plants. In addition, after
a bunch of bananas has been harvested from a plant, the remaining
vegetation is allowed to decay on the ground; thus, the nutrients stored
in the plant are recycled.
137
Therefore, not only will new plants have Cs available for contam
inating their fruit from the rhizomes, but also, cesium obtained from
the decaying foliage may be more biologically available for absorption
by the roots than that originally deposited directly on the soil.
Similarly, while Sr, Fe, and W will not be a problem relative to direct
fruit contamination following foliar-absorption, when recycled via
decaying vegetation, they (and other fission and activation products)
may contribute significantly to the total fission product inventory
absorbed by the roots of the new plants and translocated to the developing
fruit. This pattern of recycling could result in fruit contamination by
many of the other intermediate-lived and long-lived radionuclides for many
years following detonation of Plowshare devices.
Therefore, it is expected that foliar-deposited fallout will result
137
in contamination of the existing crop of bananas by Cs and contamination
of future generations of bananas by ^^Cs and by other radioisotopes due
to recycling of the plant nutrients from decaying plant parts. The extent
of this recycling should be studied to evaluate the total significance of
this potentially serious problem.

SUMMARY
This study has demonstrated that 1) environmental radiotracer exper
iments can be safely conducted using the techniques employed and 2) valu
able knowledge regarding rain effects and interplant translocation can
be obtained by performing the experiments in the field. These experiments
were conducted in south Florida fields using the following techniques:
1) the area beneath the foliage to be treated was cleared of all vegeta
tion, 2) plastic sheeting was spread over the cleared area, 3) peat moss
was spread over the plastic to absorb all drippage and wash-off, and
4) the areas around each treated plant were secured by fencing.
Four banana leaves and three coconut fronds were treated with a
carrier-free solution of mixed radiotracers: ^Sr, 185^ and 134cs.
The study showed that ^4qs was 1) rapidly translocated from the banana
leaves, 2) more uniformly distributed than the other radionuclides used
in the study, and 3) accumulated in the fruit, while Fe, Sr, and W were
not. Cesium nd iron also accumulated in the other actively growing
plant parts new leaves and daughter plants.
Strontium-85, tungsten-185, and iron-59 were absorbed by the
banana leaves, but their mobility was much less than that of cesium.
Strontium translocated in small amounts to newly developing leaves and
young leaves where its congener, calcium, is used in cell wall formation.
The which translocated in the treated plant, was detected in the
youngest banana leaf and the lower pseudostem; and ~^Fe accumulated in
the actively grox^ing plant parts the young lamina, banana peels
inflorescence, and the daughter plant.
124

125
1 <)/
In a replicated study, accumulation of 4Cs by bananas after foliar
treatment was characterized by a first order kinetics function of the
form C = Cgil-e-^) where "C" is the concentration of cesium in the fruit
at the time"t," "Ce" is the equilibrium concentration of cesium in the
fruit, and "k" is the rate constant of cesium accumulation in the bananas.
The results of the replicated study yielded the following accumulation
coefficients, or constants (k), for the three plants: -0.123, -0.158, and
-0.122 per day; the best fit value of the replicates was -0.133. The
respective equilibrium concentration values expressed as a percentage of
the concentration of the solution applied were: 0.40 percent, 0.80 percent,
and 0.12 percent. (An estimated Ce for cesium in the mixed tracer banana
plant study was 0.48 percent as a percentage of the tracer concentration
applied.) The rates of accumulation were independent of the environmental
conditions; while the equilibrium concentration values were significantly
affected by the amount of radioactivity remaining on the foliar surface
(rain wash-off effect), plant morphology, and stage of fruit development.
All the radionuclides were translocated from the treated banana
plant in detectable amounts to adjacent banana plants (not of a common
clone). The rapid rate at which this interplant translocation occurred
indicates direct root-to-root transfer. Cesium-134 was the dominant
radionuclide in the fruit parts (peel and pulp) from these trees. But
IOC
JW also accumulated in these banana peels as did slight amounts of
-*Sr and ^^Fe, traces of which also were found in the pulp. (However,
all these isotopes translocated in very minute quantities to the adjacent
plants.)
The morphology and physiology of the banana plant (a monocotyledon)
and the chelated condition of the tracers possibly enabled greater

126
movement of these isotopes through the banana plant than is reported in
the literature for the more commonly studied dicotyledons. The axial of
the banana plant serves as an excellent trap for retention and absorption
of fallout, and it may be very significant in the total above-ground
absorption phenomenon.
In the coconut palm, while all the radiotracers used were absorbed,
only cesium was translocated to the fruit. Slight amounts of strontium,
iron, and tungsten did translocate from the fronds to other younger,
growing plant parts (fronds and inflorescences). In comparison with the
translocation of these radiotracers by the banana plant, the transloca
tion in the coconut palm was small.
Translocation of -*-~^Cs in trace quantities also occurred from the
treated coconut palm to the nearest adjacent palm trees. This movement
is postulated to have occurred through direct root-to-root transfer.
Because of the heavy rains which occurred during these studies, it
is evident that even though rain may tend to wash foliar-deposited
radioactivity from plants, a significant amount of fallout will be retained
by the foliage and axial to provide a reservoir of contamination for the
fruit. Also, as shown by the foliar leaching which occurred between the
tenth and twenty-sixth days of the kinetics study, repeated rain following
deposition of fallout will tend to slowly leach additional small fractions
of fallout from within the foliage.
The results of the studies undertaken were used in developing a model
to predict the radiological dose to an individual who consumes bananas
contaminated with Cs. The whole body dose is related to the concentra
tion of fallout on the leaf surface (pCi/m^) so that the yearly whole-
body dose or the "allowable leaf surface concentration" may be calculated

127
as a function of the rate of ingestion and duration of ingestion of
contaminated fruit, once an allowable dose is determined or a concentra
tion of fallout has been predicted.
This research has laid the ground-work for future studies of behav
ior of fission products in these tropical plants. Some additional studies
which would add important data on the characteristics of fallout contam
ination of coconut palms and banana plants are:
1) determination of the magnitude of fallout absorption by the
fruit itself;
2) determination of the magnitude of banana fruit contamination
due to axial-pseudostem trapping and absorption of fallout com
pared to that resulting from only leaf and only root absorption;
3) determination of the relationship between molybdenum and
tungsten in biological systems;
4) plant root uptake studies from tropical soils by the coconut
palm and the banana plant;
5) the degree of contamination of future generations of bananas
, through nutrient recycling due to decay of contaminated
vegetation.

APPENDIX A

CHEMICAL SEPARATION PROCEDURE FOR TUNGSTEN ANALYSIS
1) Dry a few grams of the sample.
2) Ash 2-3 grams at 550 C to whiteness (overnight).
3) Dissolve the ash in 5 ml of 6N NaOH and bring to gentle boil for
15 minutes.
4) Wash sample into centrifuge tube with distilled water and centrifuge
the tube.
5) Pour supernatant into another centrifuge tube (Tube 2); (Tube 1
contains the NaOH insoluble precipitate, and Tube 2 contains the
NaOH soluble supernatant).
6) Add 16 mg tungstate carrier and 8 mg cinchonine to Tube 2 and mix
well.
7) Add 5 ml concentrated HC1 (8N) to both centrifuge tubes and mix well
check pH; if not acidic, add more HC1.
8) Centrifuge both portions Tube 1 and Tube 2.
9) Pour supernatants into separate 800 ml counting containers and add
distilled water to 100 ml volume.
10) Wash precipitates into separate 800 ml counting containers and add
distilled water to 100 ml.
11) Count all four sample portions using the Packard gamma scintillation
spectrometer.
12) Sum activities in all four samples over each photopeak region; solve
by method of simultaneous equations to quantitate.
129

APPENDIX B

DRY ASHING PROCEDURE PLANT TISSUE101
1) Dry the samples at 100 C.
2) Ash about 2 grams at 550 C until ash becomes gray (overnight).
3) Cool, add excess concentrated HC1 (reagent grade), evaporate excess
acid carefully.
4) Reheat to 550 C for 1-2 hours to whiteness.
5) If ash is not white, cool, add 25 percent HNO^, re-evaporate
carefully to dryness.
6) Heat to 550 C and cool.
7) Add a few drops of concentrated HC1, dilute with demineralized water
to 50 ml.
131

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70. Doney, R. C., R. L. Smith, and H. H. Wiebe, "Effects of Various
, Levels of Bicarbonate, Phosphorus and pH on the Translocation
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71. Simmons, J. N., R. Swidler, and H. M. Benedict, "Absorption of
Chelated Iron by Soybean Roots in Nutrient Solutions," Plant
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Ee~> by Intact Leaves and Enzymatically Isolated Leaf Cells of
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73. Davis, J. J., "Cesium and Its Relationship to Potassium in Ecology,"
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709-712 (1956). (Translated from Russian, USAEC Report
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76. Gulyakin, I. V. and E. V. Yudintseva, "Uptake of Strontium, Caesium,
and Some Other Fission Products by Plants and Their Accumulation
in Crops," Proceedings of the Second International Conference
on the Peaceful Uses of Atomic Energy, September 1-13, 1958.
Vol. 18: Waste Treatment and Environmental Aspects of Atomic
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77. Klechkovsky, V. M. and G. N. Tslihckeva. On the Behavior of Fission
Products in Soil, Their Absorption by Plants and Their Accumu
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78. Rediske, J. H. and F. P. Hungate, "The Absorption of Fission Products
by Plants," Proceedings of the International Conference on the
Peaceful Uses of Atomic Energy. Vol. 12: Radioactive Isotopes
and Ionizing Radiations in Agriculture, Physiology, and
Biochemistry. Geneva, August 8-20, 1955. New York: United
Nations, 1956.
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Hideo Nishita, and Kermit H. Larson, "Soil-Plant Interrelation
ships with Respect to the Uptake of Fission Products 1. The
Uptake of Sr^O, Csl37} Ru^06} Cel^4 f Y^l," Oak Ridge, Tennessee:
Technical Information Services, USAEC Report UCLA-247 (1953).
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Caesium by Plants from Foliar Sprays," Nature, 181: 1300-1303
(1958).
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and Its Uptake by Plants," Radioecology. Edited by Vincent
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by Two Insect Species," Health Physics, 14: 162-165 (1968).
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84. Wilson, D. 0. and J. F. Cline, "Removal of Plutonium-239, Tungsten-185,
and Lead-210 from Soils," Nature, 209: 941-942 (1966).
85. Essington, E. H., H. Nishita, and A. J. Steen, "Release and Movement
of Radionuclides in Soils Contaminated with Fallout Material
from an Underground Thermonuclear Detonation," Health Physics,
11: 689-698 (1965).
86. Romney, E. M. and W. A. Rhoads, "Neutron Activation Products from
Project Sedan in Plants and Soils," Proceedings of the Soil
Science Society of America, 30: 770-773 (1966).
87. Romney, E. M., A. J. Steen, R. A. Woods, and W. A. Rhoads,
"Concentration of Radionuclides by Plants Grown on Ejecta from
the Sedan Thermonuclear Cratering Detonation," Proceedings of
the International Symposium on Radioecological Concentration
Processes, Stockholm, Sweden, April 25-29, 1966. Oxford:
Pergamon Press, 1966.
88. Norton, K. R., "Boron Deficiency in Bananas," Tropical Agriculture,
42: 361-367 (1965).
89. Martin-Prevel, P., J. Godefroy, G. Montagut, and J. Lacoeville,
"Soil-Plant Studies on Bananas One Method of Studying the
Fertility," Fruits d1Outre Mer, 20: 157-170 (1965).
90. Buchanan, David W., "Coconut Nutrition," Temperate to Tropical Fruit
Nutrition. Edited by Norman F. Childers. Horticultural
Publications, Rutgers University. Somerville, New Jersey:
Somerset Press, 1966.
91. Friedlander, Gerhart and Joseph W. Kennedy. Nuclear and
Radiochemistry. New York: John Wyley and Sons, 1962.
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Cratering," A Memorandum, University of California Lawrence
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Florida (1968).

BIOGRAPHICAL SKETCH
Walter Nelli Thomasson was born on April 15, 1940, in Owensboro,
Kentucky. He attended elementary schools in Arlington, Virginia, and Oak
Ridge, Tennessee. His high school education was obtained at Oak Ridge
High School. He received his Bachelor of Engineering degree in civil
engineering from Vanderbilt University, Nashville, Tennessee, in 1962.
He attended graduate school at the University of Illinois on United
States Public Health Service Traineeships from September, 1962, to June,
1964, where he earned his Master of Science in sanitary engineering in
October, 1963. From June, 1964, to June, 1966, he served as a commis
sioned officer in the United States Public Health Service (USPHS) and was
stationed at the Southwestern Radiological Health Laboratory, Las Vegas,
Nevada.
In June, 1966, he returned to graduate school at the University of
Florida under a United States Public Health Service Traineeship to pursue
his doctorate in environmental engineering. From January, 1969, until
October, 1971, he was employed as an environmental engineer with the
United States Atomic Energy Commission, Division of Reactor Licensing,
Washington, D. C. He is currently employed by the Environmental
Protection Agency, Office of Radiation Programs in Rockville, Maryland.
He is a reserve officer in the USPHS, is a member of the Health
Physics Society, and is certified as an Engineer-in-Training in Tennessee.
He is married to the former Clarissa (Lissie) Camfield of Miami, Florida,
and they have two daughters: Lane and Amie.
141

I certify that I have read this study and that in ray opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
William 'Emmett Bolcff, Chaifman
Associate Professor of Environmental
Engineering
I certify that I have read this study and that in my opinion it
conforms, to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy. .
/Q.
Herbert A. Bevis
Associate Professor of Environmental
Engineering
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
Charles E. Roessler *
Assistant Professor of Radiation
Biophysics
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a.dissertation for the degree of
Doctor ofPhilosophy.
H) SjJL. M
Billy G. Durbant
Professor or Nuclear Sciences

This dissertation was submitted to the Dean of the College of Engineering
and to the Graduate Council, and was accepted as partial fulfillment for
the requirements for the degree of Doctor of Philosophy.
March, 1972
Dean, Graduate School

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TITLE: Uptake and translocation of & ,& p Sr Q pQ Fe 'G ,SG pW and '3Q 'Cs by banana plants
and coconut plants following foliar application, (record number: 580537)
PUBLICATION DATE: 1972
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Counts per Channel in 15 Minutes (Thousands)
22


PERCENTAGE EQUILIBRIUM: (C/Ce) x 100
88
Time: Days
FIGURE 30; RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa rajapuri
TREE 2


119
Banana Plant
In the banana plant, all the radiotracers were absorbed and trans
located to a considerably greater extent than by the palm tree. One of
the reasons for this was the difference in rainfall already noted. Two
other reasons were the differences in morphology and metabolism between
the two plant species.
The banana leaves in this study were badly torn and hung quite limply
causing more tracer to be lost by drippage during application to the
banana leaves than to the rigid, intact coconut palm leaflets. (The
three plants treated in the kinetics study had minimal lamina tears.)
This loss may have been partially compensated for by the opening provided
for the tracer through the broken cuticular areas. This mode of absorption
would vary with the age of the tear and the degree of tissue repair, or
healing, and may have played an influential role in establishing the amount
of tracer that was initially rapidly absorbed.
The banana plant morphology furnishes a large leaf surface area; a
channel to convey solution into a central point, the axial; and a fairly
direct avenue, provided by the axial, into the interior of the pseudostem.
(Interior here refers to the space between the leaf sheaths which make up
the pseudostem.) Once solution enters the intraleaf space, it is not
capable of being lost as is a surface-deposited material. Therefore, it
provides a source of radioactivity for absorption by the leaf sheaths.
The difference in the life span of the coconut palm and banana plant
may also account for part of the difference in the translocation of radio-
tracers. While the coconut palm is a tree with a very long life span, the
banana plant is a perennial herb, and, as such, its rate of metabolism may
be much higher causing material to move through the plant at higher rates.


137
Maximum Allowable Leaf Surface Concentration of Cs: Ci/m
112
Duration of Ingestion Days
FIGURE 33: MAXIMUM ALLOWABLE LEAF SURFACE CONCENTRATION OF 137Cs TO
GIVE A 0.17 REM ANNUAL WHOLE BODY DOSE AS A FUNCTION OF
ASSUMED DURATION OF INGESTION OF CONTAMINATED FRUIT


11
37
Moorby related cesium absorption to sugar metabolism by the plant.
38
ThorneJ indirectly agreed with Moorby in suggesting that the negative
effect of shade on foliar absorption may be related to reduced carbohy
drate concentrations during periods of low light intensity or darkness.
The most rapid absorption results when a mineral is in solution,H
and cations are absorbed more rapidly than anions.^9 Absorption from
dilute acidic solutions (pH 4 to 5) is roughly linear with time until
evaporation and crystallization of the salts on the surface become
limiting.The hydrogen ion concentration plays a significant role in
the absorption of Sr, Fe, and W. At pH 4.5, four times as much strontium
is absorbed as at pH 2.5, and 40 times as much absorption occurs at pH
4.5 as at pH 8.2.^ iron absorption is higher at acid pH since iron
hydroxides precipitate, under alkaline conditions. Conversely, tungsten
will precipitate at neutral or acid pH. Lipid or oil solubility, in
particular, seems to play a major role in the uptake of minerals from
the foliage.^
20
Wittwer et_ al. have summarized and ranked various foliar nutrients
according to their relative rates of absorption, their degree of mobility
in the plant, and their leachability. Their own data and data of others
39
are shown in Table 1. Wittwer has also compiled data from various
o or q£
researchers'5 ~5 on rates of absorption of various elements. These
results and some from other authors are shown in Table 2 where the times
are the extremes from various studies when a time interval is indefinite.
It must be emphasized that these data only represent absorption and do
not indicate translocation rates nor rates of accumulation in edible
plant parts.


121
direct root-to-root transfer. Tracers absorbed by the roots are translo
cated fairly uniformly to the rest of the plant's vascular system. The
higher levels of radioactivity in the younger fruit can be explained on
the basis of higher growth rates and mitrient requirements. The banana
peels seemed to concentrate translocated (plant-to-plant) ^Sr, ^Fe, and
in addition to ^^Cs. Traces of these isotopes were also evident in
the banana pulp samples.
The differences in the translocation patterns exhibited by Sr, Fe, W,
and Cs can be explained by the work of other investigators even though
they studied different plants. While Sr, Fe, and Mo (and probably W) are
absorbed fairly rapidly initially, the rate of absorption decreases sharply
10 33 34
within a few hours. This absorption pattern has been attributed
to. saturation of leaf tissue at the point of absorption combined with an
inability to translocate the minerals from the leaf 36 Moorby^
concluded that translocation through leaf tissue to veins is a metaboli-
cally controlled process and element discrimination occurs at this point.
Biddulph^ suggested that chemical precipitation of elements in the veins
of the leaf is the inhibiting mechanism for non-mobile elements.
Inorganic compounds generally translocate upwards through the xylem,
and organic compounds move through the phloem.^ Cesium is generally
considered phloem mobile, and its translocation has been related to the
37
movement of sugars in the plant. Conversely, strontium and iron are
xylem mobile.-*-0>21s48 Since inorganic ions are generally xylem mobile, it
is possible that cesium is translocated in both vascular tissues, as has
been reported in corn. Thus, it is distributed throughout the plant.
Divalent cations will not translocate through the phloem,10,21,48
which carries nutrients and products of photosynthesis from the foliage


84
.42 times that in the East Glade soil. However, the stable cesium concen
tration in the coconut meat was only three times that in the banana pulp.
Since the available cesium concentration in each location is unknown,
an explanation of this concentration difference is not possible.
Data Analyses Kinetics Study Miami
Cesium-134 Accumulation
The kinetics of cesium movement from the banana plant's foliar sur-
134
face to the fruit was determined by measuring the rate of Cs accumu
lation in the fruit. The accumulation rate derived in this study can be
characterized by a first order kinetics function of the type__ .
where
dCt
dt
dCt
dt
k
k(Ce Ct)
(1)
134,
= the change in the Cs concentration in
the banana fruit with time;
= the rate constant in units of days
= the equilibrium concentration value of
134,
lCs in the fruit;
134,
Ct = the concentration of Cs in the fruit
at time "t."
The solution to Equation (1) is
n r-\ -kt..
cea e )
(2)
where
= the time after treatment of the foliage.


70
Chemical Separation
The chemical separation procedure outlined in Appendix A was used
to simplify the complex gamma ray spectra so that positive identifica
tion could be made of tungsten in representative samples of fruit,
foliage, and other plant parts. Prior to separation, tungsten was
masked by electronic noise interference and Compton continuum from the
other radiotracers as shown in Figure 20. Following separation, the
185
samples spectra were greatly simplified. If w were present, it was
in the NaOH soluble, HC1 insoluble portion of the separated sample,
while strontium and iron were in the NaOH insoluble, HC1 soluble
fraction. Although cesium was primarily in the NaOH soluble, HC1 soluble
portion, it was also present in the other three fractions of the
separated sample since cesium is amphoteric. Table 9 shows the general
results of the separation. Figure 21 through Figure 28 show the typical
spectra of 1) the chemically separated portions of the treated coconut
frond sub-sample (4 portions) and 2) the chemically separated portions
of the treated banana leaf sub-sample (4 portions).
Following the chemical separation, as expected, tungsten was
detectable on the treated foliage. Also, it was evident that W had
translocated to untreated foliage on both test plants and possibly to
the upper pseudostem (interior). For the latter, it is probable that
the activity in this sample originated from direct application, since
the petioles of the test tree were also treated and the radiotracer
solution probably "drained" into the pseudostem's upper section. The
edible parts of the fruit from both test trees and the distal inflores
cence bract of the banana plant did not have any detectable radiotungsten.
The value of the chemical extraction is illustrated in Figure 20 through


Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 21: SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 SOLUBLE PORTION
Co


139
84. Wilson, D. 0. and J. F. Cline, "Removal of Plutonium-239, Tungsten-185,
and Lead-210 from Soils," Nature, 209: 941-942 (1966).
85. Essington, E. H., H. Nishita, and A. J. Steen, "Release and Movement
of Radionuclides in Soils Contaminated with Fallout Material
from an Underground Thermonuclear Detonation," Health Physics,
11: 689-698 (1965).
86. Romney, E. M. and W. A. Rhoads, "Neutron Activation Products from
Project Sedan in Plants and Soils," Proceedings of the Soil
Science Society of America, 30: 770-773 (1966).
87. Romney, E. M., A. J. Steen, R. A. Woods, and W. A. Rhoads,
"Concentration of Radionuclides by Plants Grown on Ejecta from
the Sedan Thermonuclear Cratering Detonation," Proceedings of
the International Symposium on Radioecological Concentration
Processes, Stockholm, Sweden, April 25-29, 1966. Oxford:
Pergamon Press, 1966.
88. Norton, K. R., "Boron Deficiency in Bananas," Tropical Agriculture,
42: 361-367 (1965).
89. Martin-Prevel, P., J. Godefroy, G. Montagut, and J. Lacoeville,
"Soil-Plant Studies on Bananas One Method of Studying the
Fertility," Fruits d1Outre Mer, 20: 157-170 (1965).
90. Buchanan, David W., "Coconut Nutrition," Temperate to Tropical Fruit
Nutrition. Edited by Norman F. Childers. Horticultural
Publications, Rutgers University. Somerville, New Jersey:
Somerset Press, 1966.
91. Friedlander, Gerhart and Joseph W. Kennedy. Nuclear and
Radiochemistry. New York: John Wyley and Sons, 1962.
92. Warner, Dean H., "Statement on Release of Radioactivity during
Cratering," A Memorandum, University of California Lawrence
Radiation Laboratory, Livermore, California, June 29, 1967.
93. Blotcky, Alan J., Barney T. Watson, and Richard E. Ogborn, "Computer
Applications in Neutron Activation Analysis," Applications
of Computers to Nuclear and Radiochemistry. Edited by G. D.
O'Kelley. National Academy of Sciences National Research
Council Nuclear Sciences Series NAS-NS 3107. (Proceedings
of a Symposium, Gatlinburg, Tennessee, October 17-19, 1962.)
Office of Technical Services, Department of Commerce, Washington,
D. C.
94. U. S. Public Health Service. Radiological Health Handbook.
U. S. Department of Commerce. Government Printing Office, 1960.
95. Dixon, W. J., "Biomedical Computer Programs, X-Series Supplement,
BMD X85, Nonlinear Least Squares," University of California.
Publications in Automatic Computation, No. _3. University of
California Press, Berkeley and Los Angeles, 1969.


102
however, by using tracers with shorter half-lives, waste disposal would
be significantly simplified or eliminated.
Besides the contamination and logistics problems, the data from
the field studies are also more difficult to interpret because of the
many variables present in an uncontrolled environment. However, the
benenfits of field studies are worth the additional data analysis
problems.
Significance of Results in Relation to Radioactive Fallout
The ultimate interest in studying the environmental behavior of
radioactive fallout is to determine the critical pathways to mans total
radiation exposure. Probably the most critical pathway of radioactive
fallout to man is through the food he eats. In the area of the proposed
Panama canal, bananas and coconuts comprise a large percentage of that
food. Therefore, the amount of radioactive fallout which would find
its way into the fruits of the banana and coconut plants after a nuclear
excavation is of utmost importance in determining the total radiation
exposure of the native populace.
There are three ways in which bananas and coconuts may become
contaminated by fallout: directly on the surface of the fruit; by
plant root absorption from the soil and translocation to the fruit; and
by foliar contamination and translocation to the fruit. Direct fruit
contamination followed by absorption and transfer into the interior
parts of some fruits is known to occur. While direct contamination of
the fruit of banana and coconut plants may occur, these plants have
extensive leaf areas which provide an umbrella-type protection for
these fruits and which provide extensive surface areas for foliar


136
48. Biddulph, 0., "Translocation of Inorganic Solutes," Plant Physiology,
11: 553-603 (1959).
49. van Overbeek, J., "Absorption and Translocation of Plant Growth
Regulators," Annual Review of Plant Physiology, 7: 355-372
(1956).
50. Biddulph, 0., "Translocation of Radioactive Mineral Nutrients in
Plants," Conference on the Use of Isotopes in Plant and Animal
Research, Kansas State College, June 12-14, 1952, USAEC Report
TID 5098.
51. Williams, R. F., "Redistribution of Mineral Elements during
Development," Annual Review of Plant Physiology, 6: 25-42
(1955).
52. Linck, A. J. and C. A. Swanson, "A Study of Several Factors Affecting
the Distribution of Phosphorus-32 from the Leaves of Pism
sativum," Plant Soil, 12: 57-68 (1960).
53. McCollum, J. P. and J. Skok, "Radiocarbon Studies on the Translocation
of Organic Constituents into Ripening Tomato Fruits," Proceedings
of the American Society of Horticultural Science, 75: 611-616
(1960).
54. Koontz, Harold and Orlin Biddulph, "Factors Affecting Absorption and
Translocation of Foliar Applied Phosphorus," Plant Physiology,
32: 463-470 (1957).
55. Barrier, G. E. and W. E. Loomis, "Absorption and Translocation of
2,4-DiChlor-phenoxyacetic Acid and P^2 by Leaves," Plant
Physiology, 32: 225-231 (1957).
56. Milbourn, G. M., F. B. Ellis, and R. S. Russell, "The Absorption of
Radioactive Strontium by Plants under Field Conditions in the
United Kingdom," Journal of Nuclear Energy, 10: 116-132 (1959).
57. Wallace, T., "Trace Elements in Plant Nutrition," World Crops,
9: 289-292 (1967).
58. Boyer, T. C. and P. R. Stout, "The Macronutrient Elements," Annual
Review of Plant Physiology, 10: 277-300 (1959).
59. Wittwer, S. H. and H. B. Tukey, "Isotopic Tracers in Plant Nutrition,"
Mineral Nutrition of Fruit Crops. Horticultural Publications,
New Brunswick, New Jersey, 1954. '
60. Stout, P. R. and W. R. Meagher, "Studies of the Molybdenum Nutrition
of Plants with Radioactive Molybdenum," Science, 108: 471-473
(1948).
61. Gerloff, G. C., "Comparative Mineral Nutrition of Plants," Annual
Review of Plant Physiology, 14: 107-124 (1963).


TABLE 10a
PARTIAL ELEMENT COMPOSITIONAL ANALYSES
Element; Parts per million (ppm)
Sample
Ca
Sr
Fe
Mg
Mn
Zn Cu
P K
Cs
Mo
W
BANANA LEAF
East Glade
5,200
46
2.6b
2,400
15b
50
27b
780
11,000
NA
NA
NA
Panama Darienc
8,700
23
420
4,200
310
0.8
16
1,900
25,000
NA
NA
NA
BANANA PULP
East Glade
170
1.4
9.1
1,000
0.78
14
4.8
1,800
7,200b
0.014d
1.0
0.015
Panama Darienc
230
1.8
31
1,000
19
0.7
9.0
1,200
11,000
NA
NA
NA
USDA Miami 2e
530
6.9
14
840
0.19
54
3.1
NA
8,800
NA
NA
NA
USDA Miami 3e
190
1.7
0.14
730
0.14
2.3
0.14 NA
10,000
NA
NA
NA
SOIL .
East Glade
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.069
1.8s
0.25
Homestead
NA
NA
NA
NA
NA
NA
NA
NA
NA
2.9f
4.5^
l.ld
COCONUT MEAT
Homestead
620
0.77
22
1,000
12
24
13
2,400
9,000
0.044f
1.0d
0.015d
Panama Darienc
220
1.0
17
1,200
5.8
16
4.0
2,000
5,-7 00
NA
NA
NA
COCONUT FROND
Homestead
5,500
30
24
1,300
7.0
62
30
1,600
6,100
NA
NA
NA
Panama DarienC
3,700
15
130
4,000
68
19
8.0
980 .
7,000
NA
NA
NA
COCONUT HUSK
Homestead
2,300
13
25
690
0.19
40
18
740
11,000
NA
NA
NA
Panama Darienc
1,100
12
45
1,100
10
11
2.5
280
11,000
NA
NA
NA


TABLE 5a
COUNT RATES IN BANANAS, DISTAL INFLORESCENCE BRACT, AND SOIL OF ADJACENT BANANA TREES POSITIVE SAMPLES
Sample
185
cpm/p
w
: 2a
85 Sr
cpm/g

2c
134Cs
cnm/g
2c
59
Fe
cnm/g
2c
Locatii
(Figure
Banana Pulp8
0.019

0.063
0.18
+
0.31
8.2

0.20
-0.052

0.091
B4
Banana Peel8
0.034

0.14
1.5

0.67
12

0.40
1.5

0.22
B4
Soilcd
0.02
+
0.003
0.01
+
0.007
0.03

0.004
0.02
+
0.004
B3
Soilc,e
0.04
+
0.007
0.27

0.036
0,74

0.022
0.16

0.011
B4
Sucker0'^
0.005

0.004
0.032

0,012
0.17
+
0.007
0.005
+
0.007
B4
Banana Pulpc
-0.002

0.006
0.021

0.023
0.18
+
0.013
0.006
JL
0.01
A3
Banana Peelc
0.02
+
0.009
0.006

0.04
0.29

0.018
0.015
+
0.016
A3
Soilc£
0.03
+
0.003
0.01
+
0.008
0.04
+
0.005
0.02

0.004
A3
Banana Pulpc
0.002
+
0.004
0.002
+
0.01
0.02
+
0.006
-0.0006
4-
0.007
C4
Banana Peelc
0.04

0.009
0.017
+
0.021
0.057

0.011
0.036

0.015
C4
Soilc,d
0.03
0.004
0.008

0.008
0.03
+
0.005
0.02

0.006
C4
Distal Inflof. Bract^
0.007

0.004
0.012

0.010
0.04
4-
0.006
0.005
4*
0.006
C4
aAll count data corrected for decay to November 3, 1967.
kSampled on November 21, 1967.
^Sampled on December 14, 1967.
uRadon daughters only as shown by qualitative identification of spectrum.
eFrom location of rhizome of treated plant.
^Sucker developed from part of rhizome remaining from where treated parent wTas removed,
%ncorrected for radon daughters, but spectroscopy indicated tracer peaks of ^sr and us.


9
Temperature and humidity are the primary factors that determine the
rate of drying of solutions on foliage, and the rate of absorption is
quite dependent on these parameters.^^3 High relative humidity, dew,
and general dampness act contrary to rain and increase, rather than
decrease, foliar absorption by maintaining the material in solution
O C
longer. Ambler and Menzel J ranked relative humidity as the single most
important variable controlling retention of 85gr by foliage. But
according to the same authors, species variation, under identical environ
mental conditions, may cause retention of fallout to vary from 10 to 90
percent. The species variation is a function of the surface wettability
of the foliage. As the relative humidity increases, the degree of hydra
tion and cuticle permeability increase causing greater absorption.^5^
Similarly, Bukovac eh al.^6 reported that rewetting of the leaves
greatly increases absorption of fallout.
Although the most rapid absorption occurs under wet conditions, dry
27
state absorption does occur over extended time periods. Dry absorption
can be explained by the fact that although the surface appears dry, there
is a thin aqueous film of moisture created by the plant's transpiration.
28
This solvent may be more important than the nutrient-carrier solution.
Mechanisms of Ion Absorption
There is some disagreement about the way in which ions deposited on
foliage pass into the plant's interior. Yamada^ has described the
passage of ions across the cuticle in a manner analogous to the classical
po pn
diffusion equation. Others have described continuous pathways
through the cuticle via surface imperfections. Generally, ion absorption
is a combination of passive and active processes. Initial penetration of


90
Tree 1 and approximately 6.5 times that for Tree 3, as is shown in
Table 11 and Table 12. Rain wash-off was probably the most significant
factor contributing to the variation in the Ce values; however, plant
morphology and fruit maturity also probably had an influence on the
equilibrium concentrations. These factors will be discussed more fully
in the next chapter. Also shown in Table 12 are the Ce values as a
i n/
percentage of the concentration of XJ4Cs/ml in the solution applied to
the plants.
Three sets of treated leaf lamina punch samples were obtained
during the study to evaluate the change in foliar concentration with
time. The laminas' tracer concentrations, as shown by the punch
samples, are presented in Table 13. As is evident, the activity
remaining on Tree 1 following completion of tracer application was 2.5
times that on Tree 2 and 4 times that for Tree 3, while the tracer
applied varied by less than 16 percent. These differences are attribut
able to the effect of the rain. (The procedure employed was to apply
the tracer to a given tree and then to take the punch samples before
proceeding to the next tree.)
The rain on the first day of the study was 6.83 cm, and 17.35 cm
fell during the first 10 days. Between May 20 and June 5, when the
final sets of punch samples were taken, another 25.40 cm of rain fell.
The heavy rains during the first 10 days of the experiment probably
washed off all the tracer adhering to the surface of the foliage. There
fore, the pool from which the additional loss of tracer came was the
interior of the.leaf. Thus, the differences between the leaf concentra
tions the tenth and twenty-sixth days reflect the influence of foliar
leaching of material from the leaves. The reason for the high loss from


94
TABLE 14a
CONCENTRATION OF 13lCs
IN BANANA PLANT
PARTS AND PEAT MOSS
Sample
Count Rate
: pCi/g dry
weight
Tree 1
Tree 2
Tree 3
Treated Leaves
17,700
8,300
13,100
Pseudostem (Center section)
190
250
200
Distal Inflorescence Bract
1,900
4,000
400
Banana Fruit
15,300
27,900
4,900
Untreated Leaf Lamina
560
100
Untreated Leaf Midrib
190
66
Peat Moss^
170
150
60
£
Samples taken on June 5, 1968.
^Grab samples each value an average of three samples.


108
The accumulated whole-body dose D(E) during the period following the
end of the ingestion is given by Equation (9) as follows:
D(E) W k
When Equation (4) is substituted for B(t), Equation (9) can be expressed
as:
D(E) = .(Pgll-R-. (1 e"kt)(l e k6). (10)
W kZ
137
The total dose received due to the ingestion of Cs in bananas
is the sum of the dose received during the ingestion phase and that
resulting during the elimination phase, or
D(T) = D(I) + D (E) (11)
where
D(T) = the total dose received.
When Equation (7) and Equation (9) are substituted for D(I) and D(E) in
Equation (11), the total dose received is given by Equation (12)
D(T)
<££F>A (tk + e-kt 1) + .(PCF) R (1 e-kt)(1 e-fc0j <12)
o i,2 Hr
which, simplifies to
D(T)
[ (tk + e-kt
W kz
1) + (1 e-kt)(1 e"k0)]
Furthermore, since
R = C(f)M
and
C(f)
C(L)
(13)
RTF =


46
activity, concrete semi-vault with 60 cm of concrete on all sides.
Figure 13 shows the large NaI(Tl) crystal inside the lead shield with
the standard 800 ml sample container in place.
The zoological samples were placed in plastic vials and analyzed
with a lead-shielded, 4.4 cm diameter x 5.08 cm thick Nal(Tl) well-
crystal with a 1.91 cm diameter x 3.8 cm deep well coupled to a photo
multiplier tube. A 512-channel Nuclear Data pulse-height analyzer
(Model ND 180M) received the output from the photomultiplier.
Gamma Spectroscopy System Calibration
The low-level counting system was energy calibrated using a combina
tion ^^Cs and ^Co button-type check source, so that each of the 200
channels in a memory-half represented 10 Kev and full scale was 2.0 Mev.
The energy calibration and background were checked at the start and end
of each day or after counting any samples with high count rates.
Figure 14 through Figure 18 show the gamma scintillation spectra of
the energy calibration standards of each nuclide considered in this study.
The was considered in the analyses since it is present in all biolog
ical material, and the data must be corrected for its presence. Figure 19
shows the combined spectra of the tracers in a composite energy stand
ard which contains roughly equal quantities of each radiotracer used.
The low-level counting system was calibrated for differences in
geometry with each of the four nuclides employed in this study. Starting
with a fixed amount of radiotracer and 10 ml of distilled water in the
800 ml container, the same amount of tracer was counted as successive
increments of distilled water were added to the container. All counting
was done on a relative basis in analyzing the results of the mixed tracer


CHAPTER II
CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION
Introduction
Foliar absorption is a complex phenomenon which is often utilized
to supply some of the minor, required nutrients to plants. Any substance
that can be absorbed by plant roots can be absorbed by the foliage more
efficientlyFoliar absorption, leaching, and root absorption are
closely related, and all play significant roles in radioactive contamina
tion of crops. For instance, 1) foliar absorption can influence root
uptake of minerals by stimulating the plants metabolism,^ 2) leaching
of nutrients from the foliage also stimulates the rate of root absorption
and translocation of minerals through plants, and 3) once a mineral has
been absorbed by the plant, it is subject to foliar leaching by atmos-
pherxc moisture.
Contamination of fruit by above-ground deposition, other than direct
fruit deposition, involves two stages: 1) absorption by the foliage and
2) translocation from the absorption site to the fruit.Each element
is absorbed and translocated at rates specific to the element and plant
in question.^ The rates of absorption and translocation are closely
related; for example, tissue saturation at the site(s) of absorption may
occur if the absorbed material is slowly translocated, or remains
stationary.The distribution pattern in the plant is also character
istic of the plant and the material.^
5


6
Plant Factors Affecting Foliar Absorption
The major work on foliar absorption has been conducted in temperate
climates with crops such as beans, corn, and apples. While these are
not the tropical banana plants nor coconut palms under consideration,
the studies on them have provided a very generalized concept of the
variables that affect foliar absorption.
Foliar Characteristics
As one would expect, the foliar characteristics of a plant play a
primary role in the rate of foliar absorption and the degree of absorp
tion. Some factors which may affect absorption are leaf size, leaf
surface, the number and size of stomata (organs of respiration), and
the vascular system (xylem and phloem) of the leaf.
The leaf size is important because a large leaf provides more sur
face area for foliar deposition and absorption and, therefore, will
increase absorption by the plant. The leaf surface is important because
it must be penetrated in order for a substance to be absorbed by the
foliage. Surface characteristics which may retard absorption are waxy
surfaces (cuticles), thick surfaces, and the occurrence of ion binding on
surfaces opposite the site of entry.^ Non-waxy cuticles, thin surfaces,
leaf wetness, and various leaf imperfections, such as hairs, injuries, or
protuberances, may aid, or encourage, absorption. The size, concentration,
and location of the stomata may also play a role in foliar absorption due
1 2
to 1) the surface area effect, 2) thinner cuticles which line the
12
stomata, and 3) the location of the stomata relative to the venal
13
system. The vascular system (venal system), consisting of the xylem
and phloem, can also affect absorption. Plants with well-developed


122
/* rt r ft
to the roots. However, researchers0 ,0 have shown that divalent ions
such as Fe, Zn, and Mn are absorbed and translocated as natural chelates,
which are organic compounds. Therefore, it is possible that the Sr, Fe,
and W were translocated down the plants to the roots and then to adjacent
plants via the phloem as organic chelates since they were applied chelated
with EDTA.
It is likely that the tracers, chelated with EDTA, exhibited greater
mobility than has been indicated in the literature for purely ionic
elements. Another possibility is that the tracers which entered the
plants via the axial and the pseudostem may have been absorbed by the
phloem in the pseudostem and were translocated to the roots, while the
tracers absorbed by the lamina were immobilized. The use of EDTA chelate
provided an artificial condition which would not be expected to exist
relative to radioactive fallout after a Plowshare event. However, since
the mobility of the ions was possibly enhanced by the chelate, the results
of the study were biased on the conservative side in relation to radiolog
ical considerations.
Long-Term Effects of Foliar Contamination
The Plowshare detonations may be viewed as a single series of events
spaced over a relatively short time span compared to the physical half-
life of Cs. During the excavation phase of the project, many of the
local people would be temporarily relocated. Thus, bananas growing in the
cleared sectors during the periods of actual fallout deposition (i.e.,
those which would have received the highest concentrations of fallout)
would not enter the diets of the people. However, because of the methods
of cultivating banana plants, fallout deposited on the banana plants could
have a long-term effect on the fruit of subsequent harvests.


aExcept where noted, all values are averages of three determinations.
^Values are averages of two determinations.
cMean of all samples from Darien Provence, Panama.
^Activation analysis determination 5%.
eAll values based on one determination only.
^Activation analysis determination 4%.
^Activation analysis determination 2.9%.
^Activation analysis determination 2.5%.
NA -indicates the samples were not analyzed for this element.


19
Cesium
Cesium's physical and chemical properties enable it to enter readily
the food chains to man. There is an abundance of literature on the
cycling of radiocesium in the environment. Cesium is the most electro
positive and active of all metals, and it forms strong bases and salts.^
Cesium is usually water soluble and is similar to potassium in its chem
ical, physical, and physiological properties.^(However, the cesium
to potassium congener relationship is not a good one in environmental or
biological studies.) Cesium is important in fallout because 1) it has
a high fission yield, 2) it has a long-lived radioisotope ('37cs)> and
3) it is very soluble.
Radiocesium is more rapidly translocated than any other fission
product.75,76,77 The final distribution pattern of cesium in plants
varies with the plant species; however, when it is available during the
vegetative growth phase, it is mainly concentrated by the leaves and
flowers or fruit. ^>^9 Other authors^ >30 80 jjave reported that
following foliar absorption, cesium moved freely throughout the plant
with the greatest accumulation in the stems. Moorby^ studied the
influence of light on the absorption and translocation of cesium, and he
concluded that absorption and translocation of cesium are related to the
plant's sugar metabolism. He stated that active metabolism and a
source of sugars in the treated foliage are a prerequisite for transloca-
37
tion of cesium. Moorby also found that a higher percentage of foliar-
applied cesium moved upward than toward the plant's base.


107
where
dP(I)
dt
(DCF) B
W
(5)
D(I) =
dD(I) =
dt
(DCF) =
W
the whole-body dose received during the ingestion
phase;
the change in D(I) with time;
the Dose Conversion Factor for ^^Cs: -r-a-^~k8 .
yCi-day
= the mass of tissue which is assumed to receive
radiation exposure; i.e., the whole-body weight in
kilograms Kg;
t = the duration of ingestion in days.
Now, substituting for "B" from Equation (4) and solving for D(I),
Equation (5) leads to
D (I)
(DCF) R , e"kt
W k k
-)
(6)
Substituting "t," the duration of the consumption, into Equation (6) and
rearranging slightly, the whole-body dose received during the period of
ingestion can be expressed as:
D(I)
.(DQF). R (tk + ekt 1)
W k"
(7)
The long-term whole-body dose rate following the ingestion period is
a function of the biological removal constant and the body burden B(t)-
and may be expressed as:
dD (E) = (DCF) B (t) (e-k0)
dt W
(8)
where
0 = the duration of the elimination phase in days.


28
concern in environmental radiation problems. It has a very penetrating
gamma ray and a beta particle; it is deposited throughout the body in
muscle tissue; and it has a long effective half-life. Both of these
radioisotopes are produced with high fission yields in nuclear devices.
Nothing is known of the distribution patterns, kinetics of absorption,
and assimilation of these isotopes by banana plants or coconut palms.
Iron (Fe-59) was chosen because 1) it is a required plant nutrient
and 2) considerable research has been devoted to iron utilization by
plants; therefore, this isotope would provide a means of judging these
results qualitatively with prior work.
Tungsten, while not a fission product, is expected to be the most
no
common activation product from the nuclear devices, as was indicated
in the Sedan Project. Although the half-lives of and are not
long (145 days and 74 days respectively), they are longer than the other
major activation products, and the quantities that are expected from
nuclear cratering devices make tungsten one of the most significant
radioelements.^2 Little is known of its ecological relationships to
plants, and nothing is known of it with respect to banana or coconut
plants.
Field Procedures Mixed Tracer Expriment
Site Preparation
The coconut and banana sites were prepared in similar manners on
November 3, 1967. The area beneath each tree was cleared of all under
brush, and the ground was covered with plastic sheeting (0.012 centimeter
cm) out to a sufficient distance from the plant's stem to intercept all
drippage. Finally, the plastic was covered with approximately 7 cm of


Counts per Channel in 60 Minutes
190
FIGURE 15: STRONTIUM-85 STANDARD
VO


FIGURE 4: APPLICATION OF MIXED TRACERS TO COCONUT PALM


TABLE 16
RELATIVE TRANSMISSION FACTORS
Study
Concentration
on Leaf: C(L)
Concentration
in Bananas: C(f)
RTF
Comment
East Glade
36,000 cpm/g
3,400
cpm/ ga
0.10
No rain
Kinetics Study
Tree 1
22,300 pCi/gb
16,000
PCi/g
0.72
Rain after tracer application
Tree 2
51,000 pCi/g
32,000
PCi/g
0.63
Malformed inflorescence and light
rain during the tracer application
Tree 3
15,300 pCi/g
5,000
PCi/g
0.33
Heavy rain during the tracer
application and the fruit was mature
aFruit concentration adjusted since the data in Table 8 (p.67) represent a condition of 87 percent of
^the equilibrium as defined by the kinetics study.
Picocuries per gram.
110


Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
co
FIGURE 28: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 INSOLUBLE PORTION


13
TABLE 2
RATES OF ABSORPTION
Element
Time for
Absorption
Percentage
Absorbed
Reference
Cs
24 Hours
45
26
142 Hours
80
26
Sr
24 Hours
10
26
142 Hours
40
26
Mg
10-24 Hours
50
39
Ca
10-94 Hours
50
39
Mn
1-2 Bays
50
39
Fe
5-15 Days
50
7
Zn
1-2 Days
50
39
K
10-24 Hours
50
39
Mo
10-20 Days
50
39
5-15 Days
50
7
Cl
1-4 Days
50
39
I
10-20 Days
50
39
S
5-15 Days
50
7
5-10 Days
50
39
P
5-15 Days
50
7
5-10 Days
50
39
Urea N
0.5-2 Hours
50
39
(Banana)
25 Minutes
65
46
(Banana)
30 Hours
100
47


60
The positive results of the sample analyses are presented in Table 4
and Table 5, Slight contamination was present in grass and weeds, local
soil, and in fruit from adjacent banana and coconut plants.
Samples of grass and weeds were obtained from all quadrants around
the treated palm in an effort to determine the mechanism of transfer of
material to the plants. The grass and weeds (Spanish nettle and a
succulent weed) have different type root systems; the more deeply rooted
weeds consistently showed higher concentrations of ^Cs than did the
shallow-rooted grass. Of these samples, the highest count rates were
in vegetation growing nearest the palm, even though they were from the
north side of the tree the side opposite the treated fronds. The
activity indicated in these samples is postulated to have traveled to
these plants via root-to-root transfer. This is suggested by the
higher activity in the roots of the treated palm tree. Soil samples
taken in the area were negative except for one sample taken at a point
on the periphery of the plastic sheeting where some rain water had
flowed to the unprotected ground. This contamination was removed in
soil excavated to a depth of about 8 cm in the contaminated area.
In Table 5 the indicated contamination of the soil was again by
root-to-root-to-soil movement and not by direct surface contamination.
The contaminated soil from the base of the test tree was from an area
near the treated plant's rhizome. The other positive soil samples were
taken from points adjacent to the plants, where the concentration of
roots would have been the greatest. In all cases, soil samples taken
directly under the treated foliage of the plants were negative, which
indicated no direct contamination from the experiment.


LIST OF FIGURES
Figure Page
1. FRUIT OF TREATED COCONUT PALM 24
2. FAST GLADE BANANA GROVE 25
3. TREATED BANANA PLANT AT EAST GLADE 26
4. APPLICATION OF MIXED TRACERS TO COCONUT PALM 30
5. REMOVAI. OF PEAT AND PLASTIC BENEATH PALM PRIOR TO SAMPLING .. 32
6. HOMESTEAD COCONUT GROVE 33
7. EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS 34
8. USDA BANANA EXPERIMENT SITE 36
9. TREE 1 USDA BANANA SITE .' 37
10. PREPARED SITE USDA PLANT INTRODUCTION STATION TREE 2 AND
TREE 3 39
11. EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER, AND
COUNTING CONTAINER AND SOLUTION APPLICATOR 40
12. 134Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS .. 43
13. COUNTING CONTAINER IN POSITION OVER Nal(Tl) CRYSTAL PACKARD
LOW-BACKGROUND SYSTEM 47
14. TUNGSTEN-185 STANDARD 48
15. STRONTIUM-85 STANDARD 49
16. CESIUM-134 STANDARD 50
17. IRON-59 STANDARD 51
18. POTASSIUM-40 STANDARD 52
19. STANDARD CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr,
134Cs, AND 59Fe 53
vii


TABLE 7a
TRACER COUNT RATES COCONUT FRUIT PARTS 18 DAYS AFTER TREATMENT
Sample
185w
cpm/g 2a
85 sr
cpm/g 2a
134Cs
cpm/g
2a
59Fe
cpm/g 2a
YOUNG FRUITb
NDC
-0.2
6.2
350
+
4.0
0.
1.
IMMATURE FRUITd
Milk and Meat
ND
-0.3
0.3
20
+
0.2
ND
Husks
ND
-0.15
0.20
20
+
0.1
ND
IMMATURE FRUITe
Milk
0.014 0.018
+i
CM
O
O
1
0.1
2.4
+
0.1
CM
O
O
1
0.02
Meat
ND
ND
46
+
0.5
ND
Husks
ND
0.7
0.2
17
+
0.1
ND
MATURE FRUIT
Milk
ND
-0.07
0.1
5.6
+
0.1
ND
Meat
-0.06 0.06
-0.02
0.4
13

0.3
-0.05
0.09
Shell
ND
ND
21
+
0.2
ND
Husks
ND
0.5
0.1
10
+
0.1
ND
aAll data corrected for decay to November 3, 1967.
bFruit about 3 to 6 centimeters in diameter.
cNot detectable when the 2a error term was included with the net count rate the result remained negative.
dShell only a thin layer of tissue with little meat developed.
eShell only a thin layer of tissue which was unseparable from the meat; fruit about 8 to 13 centimeters in
diameter.
*Analysis of a chemically separated sub-sample indicated that this isotope was present.


25
FIGURE 2: EAST GLADE BANANA GROVE


ACKNOWLEDGEMENTS
The author wishes to thank Dr. Herbert A. Bevis and Dr. Emmett
Bolch, who alternately served as chairman of his supervisory committee,
for their direction, encouragement, and assistance. He also acknowl
edges the help and encouragement of Drs. Charles E. Roessler and Billy
G. Dunavant who served on his committee. Particular thanks are extended
to Dr. John F. Gamble who spent many hours helping the author in the
field as well as providing invaluable guidance in the laboratory.
Mrs. Scott Zimmerman was indispensable in helping with the
radiological analyses. Mrs. Jo Anne Selin was helpful in performing
laboratory analyses, and Mrs. Effie Galbraith was of great: help in
obtaining necessary laboratory equipment.
The author wishes to thank Mr. Laurin Wheeler, Dr. Sam Snedaker,
Mr. Harvey Norton, and Mr. Gordon Renshaw who provided help in the
field operations. Appreciation and thanks are also extended to the
personnel at the University of Floridas Sub-Tropical Experiment
Station at Homestead, Florida, particularly to Dr. Paul Orth, for their
assistance and for making their facilities available for the research.
Much thanks is due Mr. Wallace Manis, his personnel, and the United
States Department of Agriculture for the fine cooperation and the use
of the Plant Introduction Station, Miami, Florida.
The author also wants to recognize the general support and assist
ance he received from the secretarial staff of the Soils Department of
the College of Agriculture and the Institute of Food and Agricultural
ii


8
Other Plant Characteristics
Other plant characteristics which help determine the extent of fruit
contamination are the root structure morphological and physiological -
and the morphology of the foliage. Pseudostems may play a major role in
the absorption of fallout in the banana plant. Material collecting in the
axial (where the leaves come together forming the pseudostem) would not
he subject to washing or leaching and could be absorbed and held in the
hollow pseudostem, or between its leaf sheath layers. Banana (and also
coconut) plants have a central rib down each leaf which supports the
foliage this is termed the midrib. These are generally "U" shaped, and
in the banana plant they serve to channel runoff material to the axial.
21 a
Middleton^ and Handley et_ al have noted the importance of the axial in
contamination of fruit by fallout.
Environmental Factors Affecting Foliar Absorption
Environmental conditions at the time of fallout formation and deposi
tion strongly influence the amount of radioactivity available for absorp
tion by plants. Wind velocity in conjunction with fractionization of fall
out with respect to radionuclides and particle size will determine which
radioisotopes will be deposited in a given location. Rain during and
following fallout deposition decreases the fraction of fallout retained
22
by foliage. According to Tukey ert al., up to 85 percent of foliar
contamination may be removed by a normal rain, and the amount retained is
23
decreased as the rain intensity increases. However, Russell and
24
Possingham concluded that rain, after the deposition period, had no
effect on retention of fallout by herbage,


' Counts per Channel in 15 Minutes (Thousands!
Channel Number (10 Kev/Channel)
FIGURE 27: SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1 SOLUBLE PORTION


17
Strontium
Generally, strontium is not translocated from the site of foliar
absorption.However, Ambler^ reported that strontium translocated
from bean and corn leaves in both upward and downward directions, gener
ally to other leaves. He concluded that this was reverse movement
through the xylem to the transpiring leaves since no strontium was
detected in the fruit or roots, as would have been the case if phloem
movement had occurred. In other studies slight, but measurable amounts
of strontium translocated to cherries and tomatoes from the plants'
foliage.^ Handley et al.^ have reported that 9 percent of the strontium
applied to the foliage translocated from the leaves to new tissue.
The small degree of strontium translocation from the foliage is in
contrast to its general translocation after absorption by the root
system. The uptake of strontium by plants from soil is related to the
following factors: 1) percentage organic matter in the soil; 2) calcium
content of the soil; 3) soil pH; 4) soil exchangeable cations; 5) soil
exchange capacity; 6) soil moisture; 7) soil nutrient status; 8) depth
of roots in the soil; and 9) cultivation techniques. Strontium absorbed
by the foliage is largely immobile,^but strontium absorbed by the
18
roots is translocated to all the above-ground plant parts. However,
if contaminated foliage is allowed to accumulate on the ground beneath
the plants, significantly greater strontium contamination may occur than
if the fallout had directly contaminated the ground. For example,
3
Russell and Milbourn found that 25 percent more strontium was accumu
lated by crops when contaminated stubble was fallowed under than when
land clear of stubble was cultivated. Thus, foliar-absorbed and immo
bilized strontium in fallout became available to edible plant parts if
the vegetation was plowed under recycling the plant's nutrients.


40
FIGURE 11: EQUIPMENT USED IN PROCESSING SAMPLES BLENDER, CUTTER,
AND COUNTING CONTAINER AND SOLUTION APPLICATOR


22
Fallout and Plant Nutrition
While considerable research has been conducted on foliar nutrition
using required trace elements, which are potential activation products
(e.g., Mg, Mn, and Fe) little research was conducted on uptake and
80
translocation of fission products by foliage prior to 1960. Then in
n /
1963 Bukovac et_ al. 0 concluded that aerial parts of plants are important
pathways for fission product absorption. Since then, substantial research
has been devoted to this topic.
No reference could be found in the literature concerning fission or"
activation product absorption by banana plants or coconut palms. The
only references to mineral usage by these plants were concerned with
eliciting growth responses to a particular mineral element or to cure a
disease. No mention was made of rates of absorption or translocation by
these plants except for foliar nutrition of banana plants with urea.^s47
However, even these studies only developed rates of translocation to
other foliage and not to the fruit.


123
The banana plant is propagated vegetatively; that is, new plants
develop from the same "root," or rhizome, as the "parent." The rhizome
also serves as a nutrient source for the new plants. In addition, after
a bunch of bananas has been harvested from a plant, the remaining
vegetation is allowed to decay on the ground; thus, the nutrients stored
in the plant are recycled.
137
Therefore, not only will new plants have Cs available for contam
inating their fruit from the rhizomes, but also, cesium obtained from
the decaying foliage may be more biologically available for absorption
by the roots than that originally deposited directly on the soil.
Similarly, while Sr, Fe, and W will not be a problem relative to direct
fruit contamination following foliar-absorption, when recycled via
decaying vegetation, they (and other fission and activation products)
may contribute significantly to the total fission product inventory
absorbed by the roots of the new plants and translocated to the developing
fruit. This pattern of recycling could result in fruit contamination by
many of the other intermediate-lived and long-lived radionuclides for many
years following detonation of Plowshare devices.
Therefore, it is expected that foliar-deposited fallout will result
137
in contamination of the existing crop of bananas by Cs and contamination
of future generations of bananas by ^^Cs and by other radioisotopes due
to recycling of the plant nutrients from decaying plant parts. The extent
of this recycling should be studied to evaluate the total significance of
this potentially serious problem.


TABLE 4'
a
COCONUT SITE TRANSLOCATION OF RADIOTRACERS FROM TREATED PALM POSITIVE SAMPLES
Sample 185W 85Sr 134Cs 59Fe Distance
From Test
cpm/g :
t 2a
cpm/g
+
2a
cpm/g
+
2 a
cpm/g
2a
Tree (Met'
PALM EAST OF TEST TREEb
Mature Fruit
0.002
+
0,01
-0.0002

0.003
0.01
+
0.001
-0.0004
0.002
5
Young Fruit
0.004
+
0.002
0.0001
+
0,003
0.007

0.001
0.002
:
0.003
5
PALM WEST OF TEST TREE0
Mature Fruit
0.005
+
0.002
0.003

0.003
0.02
+
0.002
0.0007
+'
0.003
5
Young Fruit
0.008

0.002
0.003

0.009
0.1
+
0.005
-0.002
1
0.003
0,02d
5
Weeds S.W. Test Tree
-0.011
+
0.015d
1.2

0.10
1.7
+
0,053
0.002

4-5
SOUTH OF TEST TREEC
Spanish Nettle
1.1

0.66
-0.22

2.3d
2.9

0.30
-0.22

2.4
3
Grass
2.1
+
1>4d
-0.28
4-
3.3
3.4

0.43
-0.66

4.9
3
Roots of Treated Palm
NORTH OF TEST TREE
0.04

0.4d
-0.24
+
3.0d
12.

0.38
-0.13

1.6
2
Succulent Weed
-0.04

0.7
0.92

4.2d
10.
+
0.54
-0.17
+;
2.7
0.2
Grass
0.66

0.77
-0.23

3.5
6.6

0.45
-0.22

2.8
1
EAST OF TEST TREE
Spanish Nettle
1.3
+
0.64
-0.11

2 8j
4.7
+
0.36
-0.10
+
2.4
2-3
Grass
0.0
+
0.6
-0.57
J-
1.9d
2.3
+
0.25
-0.08

2.
2-3
WEST OF TEST TREE0
Spanish Nettle
0.28

0.52
0.87

1.9
1.9
+
0.24
-0.13
+
2.0
2-3
Grass
-0.02
+
0.6
-0.20

1.7
1.5

0.21
-0.24

2.1
2-3
Chicken Weed
2.0
+
1.1
-0.02

5.
12.
+
0.69
-0.05
4*
4.
1
a
b
c
d
All samples corrected for decay to November 3, 1967.
Sampled on December 14, 1967.
Sampled on June 5, 1968.
Qaulitative inspection of the gamma scintillation spectrum indicated the .presence of this radioisotope.


100
The results obtained from this field study reflect the complex
environmental conditions which occur in the natural sub-tropical climate
while greenhouse or pot studies would not have. As a result of con
ducting this study in the field, valuable knowledge was obtained of 1)
rain effect, 2) plant-to-plant translocation via root systems, and 3)
foliar leaching from banana plants. This type of information is needed
to provide answers to the complex environmental questions which are
required to evaluate environmental effects of man's engineering
endeavors and to plan future studies.
Success of Environmental Protection Procedures
Field experiments, while often preferable to greenhouse studies,
do present several problems. One of these is that of environmental
contamination. Using the techniques employed in this study, however,
it is felt that radiotracer experiments can be conducted in the field
with negligible environmental contamination, as shown by the environ
mental monitoring carried out with this study.
Radioactivity in grass samples collected from areas beneath the
banana trees used in the USDA kinetics experiment shows the limited
amount of contamination that resulted from this study (Table 15). Even
though there was a total of 42.7 cm of rain in the 26-day period, there
was little contamination of the environment. Most, if not all, of this
contamination probably resulted from root leaching of the isotopes into
the surrounding soil and absorption by the neighboring roots or perhaps
by direct root-to-root transfer. Hence, this soil and neighboring
vegetation contamination was an uncontrollable factor. In addition, con
sidering the distances involved, the extent of this translocation was


400
300
200
100
0
FIGURE 18: POTASSIUM-40 STANDARD
(75 Grams KC1 in 750 ml water in standard 800 ml container over 10.08 cm x 10.08 cm Nal(Tl) crystal)
Ul
to


38
Site Preparation
The site was prepared in a manner similar to that employed in the
previous experiment. One modification was that a slight mound of earth
was placed beneath the plastic sheeting around the periphery of each
tree, forming a bowl to help retain runoff in the event of a heavy rain.
A 1.8 m high, chain-link fence with a gate was constructed across the
front opening of the test enclosure providing permanent security. Radi
ation warning signs were posted, and the area was surveyed for back
ground radiation levels. Figure 10 shows the area beneath Tree 2 and
Tree 3 as it was prepared for the experiment.
Tracer Application
The solution applied to these banana plants contained 4 yCi/ml,
carrier-free ^^Cs in a NaEDTA solution. In the laboratory, 50 ml of
the tracer solution was placed into each of three continuous-feeding,
plastic squeeze bottles with sponge applicators (5 cm x 1.3 cm). One
applicator was used on each tree. Figure 11 shows the plastic applica
tor and the equipment used to process the samples in the laboratory.
Sampling
Immediately after the tracer solution was applied to each leaf, a
series of ten punch samples was taken with a hand paper punch in order
to quantitate the radioactivity per unit surface area. Similar samples
were obtained on the tenth and twenty-sixth days of the experiment. In
relation to this procedure, Freiberg and Payne^ had stated that, since
the banana leaf has such a large area, leaf samples could be taken with
out significantly altering the total leaf photosynthetic activity.


64
Data Analyses Mixed Tracer Uptake
The application of the mixed tracers to a banana plant and a coconut
palm provided data on the relative distribution and concentration patterns
of each tracer within these plants. Since this was the major objective
of the study, no attempt was made to quantitate the tracers on the
treated foliage at the time of application. The data reported in Table 6,
Table 7, and Table 8 are the results of qualitative interpretation of the
gamma ray spectra and relative quantification of the data (i.e., not
absolute) using a simultaneous equations method of separating the
known components of the spectra.
The data are composite averages of several sub-samples of each listed
plant part that resulted from bagging, chopping, and homogenizing of the
plant parts. The data for the treated leaves are representative of the
radiotracer concentrations 17 days after treatment, but they were corrected
for decay to the day of tracer application since radiotracers with differ
ent half-lives were used. It must be remembered that the ^Fe an -^^Cs
data represent two major photopeaks each, while the Sr and AO;,W represent
only one photopeak each. This does not affect comparison of various parts,
but it does affect the comparison of count rates within a given sample.
Coconut Palm Results
1 Q/
As is evident in Table 6 and Table 7, only 1'54Cs was translocated
in significant amounts to any part of the palm. The very young fruit
had the greatest amounts of radioactivity, which would be expected since
it was the most rapidly developing plant part sampled. The largest amounts
of 1-^Cs were in the husks and shells of the coconuts, but direct
quantitative comparison of husks and/or shells with other plant parts is


18
Iron
Iron is a transition element with variable valence states, is easily
oxidized and reduced, and has a strong tendency to form organic
complexes.Plants require only small quantities of iron and use it in
the reduced state.^^
Classically, iron has been considered to be slowly absorbed by
28 1 8
foliage and immobile after absorption. But recent research by
several investigators^->68,69,70 indicated that it may have limited
mobility from the foliage of plants, being translocated to young leaves
13
and meristem regions. Eddings and Brown attributed differences in
mobility of iron in three species of plants to variations in stomata and
venal organs. Biddulph determined that iron is immobilized through
precipitation as iron phosphate in veins at high pH and high phosphate
concentrations; while with low pH and low phosphate, iron is evenly
distributed in the plant. If iron is translocated, it probably enters
the leaf via the stomata and is then translocated across the mesophyl
to the phloem. Thus, the more cells through which it must pass before
reaching the phloem, the less it will be translocated. Simmons et al.,^
using nutrient solutions void of iron to grow bean plants, detected
foliar-to-root-to-solution translocation of iron, applied to the leaves
as iron sulfate, within a few days.
72
De 1L have shown that iron, chelated with ethylenediamine-
tetraacetic acid (EDTA), will penetrate the cuticle to a greater degree
than free ionic iron; however, chelated iron does not improve cellular
uptake by isolated cells. While the total iron absorbed is not increased
by chelation, the percentage translocated is improved.


26
FIGURE 3: TREATED BANANA PLANT AT EAST GLADE


56
the spectra hecause it is less sensitive than other methods to changes in
energy calibration of the spectrometer, and it can be used in conjunction
with manual methods of solving a set of simultaneous equations. The
computer output provided the net counts per minute (cpm) of -*Sr,
i^Cs, 59Fe, and 40K in each sample and also the two-sigma standard
error for each isotope in each sample.
Since the samples from the various segments of the Homestead coconut
and banana experiments were separated into sub-samples for analysis, the
final results of the individual sample components were summed to present
the composite average count rates in the given plant part. It was not
possible to treat these separate portions as replicates, since some had
more solids than others.
The data from the kinetics study were analyzed manually. The
channels summed for analysis of the i~iqCs radiotracer were channels
50-70, which represented the 0.605 Mev photopeak. (The calculated
efficiency of detection over the range of this peak was 5.6 percent.)
These data were then used to obtain a model of the kinetics of ^-^Cs
accumulation by bananas following foliar absorption. A modified
Gauss-Newton, non-linear, least squares computer program was used to
95
obtain a curve of best fit to a first order kinetics function.
Tungsten Separation
The 185W x-ray photopeak was in the low-energy region of the
spectrometer (59 Kev, or channel 6) where it encountered interferences
from: 1) electronic noise and 2) backscatter and Compton continuum
associated with the higher energy photopeaks of the other radioisotopes.
Also, because of the very weak energy of this X-ray, the efficiency of
detection was low.


Counts per Channel in 60 Minutes
Channel Number (10 Kev/Channel)
FIGURE 14: TUNGSTEN-185 STANDARD
-CN
CO


127
as a function of the rate of ingestion and duration of ingestion of
contaminated fruit, once an allowable dose is determined or a concentra
tion of fallout has been predicted.
This research has laid the ground-work for future studies of behav
ior of fission products in these tropical plants. Some additional studies
which would add important data on the characteristics of fallout contam
ination of coconut palms and banana plants are:
1) determination of the magnitude of fallout absorption by the
fruit itself;
2) determination of the magnitude of banana fruit contamination
due to axial-pseudostem trapping and absorption of fallout com
pared to that resulting from only leaf and only root absorption;
3) determination of the relationship between molybdenum and
tungsten in biological systems;
4) plant root uptake studies from tropical soils by the coconut
palm and the banana plant;
5) the degree of contamination of future generations of bananas
, through nutrient recycling due to decay of contaminated
vegetation.


138
74. Schultz, R. K., "Soil Chemistry of Radionuclides," Health Physics,
11: 1317-1324 (1965).
75. Gulyakin, I. V. and E. V. Yudintseva, "Entry of Radioactive Isotopes
into Plants through the Leaves," Doklady Acad Nauk SSSR, 111:
709-712 (1956). (Translated from Russian, USAEC Report
NP-tr-4.)
76. Gulyakin, I. V. and E. V. Yudintseva, "Uptake of Strontium, Caesium,
and Some Other Fission Products by Plants and Their Accumulation
in Crops," Proceedings of the Second International Conference
on the Peaceful Uses of Atomic Energy, September 1-13, 1958.
Vol. 18: Waste Treatment and Environmental Aspects of Atomic
Energy. Geneva: United Nations, 1958.
77. Klechkovsky, V. M. and G. N. Tslihckeva. On the Behavior of Fission
Products in Soil, Their Absorption by Plants and Their Accumu
lation in Crops. USAEC Report tr-2867 (1957).
78. Rediske, J. H. and F. P. Hungate, "The Absorption of Fission Products
by Plants," Proceedings of the International Conference on the
Peaceful Uses of Atomic Energy. Vol. 12: Radioactive Isotopes
and Ionizing Radiations in Agriculture, Physiology, and
Biochemistry. Geneva, August 8-20, 1955. New York: United
Nations, 1956.
79. Neel, James W., Jon H. Olafsen, Allen J. Steen, Barbara E. Gillooly,
Hideo Nishita, and Kermit H. Larson, "Soil-Plant Interrelation
ships with Respect to the Uptake of Fission Products 1. The
Uptake of Sr^O, Csl37} Ru^06} Cel^4 f Y^l," Oak Ridge, Tennessee:
Technical Information Services, USAEC Report UCLA-247 (1953).
80. Middleton, L. J., "Absorption and Translocation of Strontium and
Caesium by Plants from Foliar Sprays," Nature, 181: 1300-1303
(1958).
81. Romney, E. M. and J. D. Childress, "Reactions of Tungsten in Soils
and Its Uptake by Plants," Radioecology. Edited by Vincent
Schultz and Alfred W. Element, Jr. (Proceedings of the First
National Symposium on Radioecology, Colorado State University,
Fort Collins, Colorado, September 10-15, 1961). New York:
Reinhold Publishing Corporation, 1963.
82. Kaye, Stephen V. and D. A. Crossley, Jr., "Radiotungsten Retention
by Two Insect Species," Health Physics, 14: 162-165 (1968).
83. Wittwer, S. H., "Nutrient Uptake with Special Reference to Foliar
Absorption," Atomic Energy and Agriculture. Edited by C. L.
Comar. (American Association for the Advancement of Science
Publication No. 49). Baltimore: Horn-Shafer, 1957.


125
1 <)/
In a replicated study, accumulation of 4Cs by bananas after foliar
treatment was characterized by a first order kinetics function of the
form C = Cgil-e-^) where "C" is the concentration of cesium in the fruit
at the time"t," "Ce" is the equilibrium concentration of cesium in the
fruit, and "k" is the rate constant of cesium accumulation in the bananas.
The results of the replicated study yielded the following accumulation
coefficients, or constants (k), for the three plants: -0.123, -0.158, and
-0.122 per day; the best fit value of the replicates was -0.133. The
respective equilibrium concentration values expressed as a percentage of
the concentration of the solution applied were: 0.40 percent, 0.80 percent,
and 0.12 percent. (An estimated Ce for cesium in the mixed tracer banana
plant study was 0.48 percent as a percentage of the tracer concentration
applied.) The rates of accumulation were independent of the environmental
conditions; while the equilibrium concentration values were significantly
affected by the amount of radioactivity remaining on the foliar surface
(rain wash-off effect), plant morphology, and stage of fruit development.
All the radionuclides were translocated from the treated banana
plant in detectable amounts to adjacent banana plants (not of a common
clone). The rapid rate at which this interplant translocation occurred
indicates direct root-to-root transfer. Cesium-134 was the dominant
radionuclide in the fruit parts (peel and pulp) from these trees. But
IOC
JW also accumulated in these banana peels as did slight amounts of
-*Sr and ^^Fe, traces of which also were found in the pulp. (However,
all these isotopes translocated in very minute quantities to the adjacent
plants.)
The morphology and physiology of the banana plant (a monocotyledon)
and the chelated condition of the tracers possibly enabled greater


140
96. Welcher, F. J., Editor. Standard Methods of Chemical Analysis.
Vol. 2 Part A: Industrial and Natural Products and Non-
Instrumental Methods. Sixth Edition. Princeton, New Jersey:
D. van Nostrand Company, 1963.
97. Gamble, John F., Samuel C. Snedaker, and Associates. Final Report
Agricultural Ecology Volume 1_ Results. University of
Florida, Institute of Food and Agricultural Sciences,
University of Florida, Gainesville, Florida. (Prepared for
Battelle Memorial Institute, Columbus, Laboratories,
December, 1968.)
98. International Commission on Radiological Protection. Report of
Committee II on Permissible Dose for Internal Radiation
(1959). Pergamon Press: London, 1959.
99. Federal Radiation Council. Background Material for the Development
of Radiation Protection Standards. Report No. _7: Protective
Action Guides for Strontium-89, Strontium-90, and Cesium-137,
May, 1965.
100. Levi, E., "The Distribution of Mineral Elements Following Leaf and
Root Uptake," Physiologia Plantarum, 21: 213-226 (1968).
101. Breland, H. L., Class Laboratory Handout on Ashing Techniques,
Soils Department, University of Florida, Gainesville,
Florida (1968).


118
reported two-directional movement of ions in the xylem of corn plants,
which are monocotyledons like palms and banana plants. Thus, this phenom
enon may have been influential in establishing the patterns of ion trans
location in the coconut (and banana plants). In addition, several
researchers^-68,69,70 have reported limited movement of iron from plants
foliage to new tissue. The results of the mixed tracer study also indicated
this tendency for coconut palms.
The differences in the amount of tracers translocated to the mature
coconut frond directly above the treated fronds and the younger frond on
the north side of the tree are interesting to consider. The frond above
or
the treated ones had about 15 times more OJSr concentration than the one
above and on the north side of the tree. This is probably related to the
distribution of vascular organs within the foliar tissues and to the
location of the vascular systems of the untreated fronds relative to that
of the treated ones. However, it is surprising to note that the ^^Cs/^Sr
ratio in the frond above is only two, while in the literature cesium is
reported to be much more mobile than strontium. This difference is
probably associated with the location of the fronds at their insertion into
the crown of the palm and the nature of the vascular system of the palm
compared to the other plants which are usually studied.
The frond on the north side of the tree had roughly twice as high
1 q /
4Cs concentration as did the other sampled, untreated frond (from the
south, or the treated side). Cesium is very mobile in plants, and since
this frond was younger, its metabolic activity was greater and foliar
leaching was probably less than on the older frond. The fact that more
59
Fe was translocated to the younger frond is additional evidence that its
IQ/
metabolic activity x^as involved in establishing the higher LJ4Cs levels.


126
movement of these isotopes through the banana plant than is reported in
the literature for the more commonly studied dicotyledons. The axial of
the banana plant serves as an excellent trap for retention and absorption
of fallout, and it may be very significant in the total above-ground
absorption phenomenon.
In the coconut palm, while all the radiotracers used were absorbed,
only cesium was translocated to the fruit. Slight amounts of strontium,
iron, and tungsten did translocate from the fronds to other younger,
growing plant parts (fronds and inflorescences). In comparison with the
translocation of these radiotracers by the banana plant, the transloca
tion in the coconut palm was small.
Translocation of -*-~^Cs in trace quantities also occurred from the
treated coconut palm to the nearest adjacent palm trees. This movement
is postulated to have occurred through direct root-to-root transfer.
Because of the heavy rains which occurred during these studies, it
is evident that even though rain may tend to wash foliar-deposited
radioactivity from plants, a significant amount of fallout will be retained
by the foliage and axial to provide a reservoir of contamination for the
fruit. Also, as shown by the foliar leaching which occurred between the
tenth and twenty-sixth days of the kinetics study, repeated rain following
deposition of fallout will tend to slowly leach additional small fractions
of fallout from within the foliage.
The results of the studies undertaken were used in developing a model
to predict the radiological dose to an individual who consumes bananas
contaminated with Cs. The whole body dose is related to the concentra
tion of fallout on the leaf surface (pCi/m^) so that the yearly whole-
body dose or the "allowable leaf surface concentration" may be calculated


27
' Selection of Tracers
In miclear fission by thermal neutrons, fission products range from
mass numbers of 72 to 161. ^ The most common fission products occur
around mass numbers 95 and 138. Of over 275 possible fission products,
only 13 significant isotopes are present singly or in combination
(e.g., Sr-Y) three months after a detonation.^ In addition, many other
nuclides may be produced through neutron activation of stable elements
in the nuclear device's components and in the surrounding soil. The
Relative Significance Index (RSI), developed by the Lawrence Radiation
Laboratory, University of California (the laboratory responsible for
designing and fabricating the nuclear devices to be employed in cratering
activities), ranked isotopes of 1) strontium and cesium (fission, products)
and 2) iron and tungsten (activation products) among those which should
be considered in the environmental radiation hazards evaluation connected
with the Panama Canal feasibility study.
Generally, the selection of the isotopes was based on the desire to
have a mixture of gamma emitting radionuclides with minimum interference
among the respective photopeaks. The radionuclides of ^Sr and ^^Cs were
chosen because they have much shorter half-lives (65 days and 2.1 years
respectively) than their longer-lived sisters (^Sr: 27 years; ^^Cs:
30 years), which are the major long-lived fission products of concern.
(The shorter half-lives make these isotopes less hazardous to use in
tracer studies.) Strontium-90 is generali.y considered to be the most
hazardous and limiting fission product as far as man is concerned since
1) it accumulates in bone; 2) it has a fairly energetic beta particle;
and 3) its effective half-life in the body is long. Cesium-137 is the
other long-lived fission product that is generally considered to be of


72
Fraction
Supernatant
Precipitant
Supernatant
Precipitant
aIn order of
TABLE 9
RESULTS OF CHEMICAL SEPARATION FOR 185W
Tube
1
1
2
2
NaOH
Insoluble
Insoluble
Soluble
Soluble
HC1
Soluble
Insoluble
Soluble
Insoluble
Radioisotope3
85Sr, 59Fe, 134Cs
134
Cs
134Cs, 85Sr
185W, 134Cs
decreasing abundance.


Figure Page
20. SUB-SAMPLE TREATED PALM LEAFLETS UNSEPARATED 71
21. SUB-SAMPLE TREATED PALM LEAFLETS NaOIl INSOLUBLE, HC1
SOLUBLE PORTION 73
22. SUB-SAMPLE TREATED PALM LEAFLETS NaOH INSOLUBLE, EC1
INSOLUBLE PORTION 74
23. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1
SOLUBLE PORTION 75
24. SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, IICl
INSOLUBLE PORTION 76
25. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
SOLUBLE PORTION 77
26. SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1
INSOLUBLE PORTION 78
27. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
SOLUBLE PORTION 79
28. SUB-SAMPLE TREATED BANANA LAMINA NaOH SOLUBLE, HC1
INSOLUBLE PORTION 80
29. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa walap TREE 1 87
30. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa ra;japuri Tree 2 88
31. RATE OF ACCUMULATION OF 134Cs BY BANANAS FOLLOWING FOLIAR
APPLICATION Musa kullan TREE 3 89
32. RELATIVE EQUILIBRIUM CONCENTRATION AS A FUNCTION OF FRUIT
MATURITY 95
33. MAXIMUM ALLOWABLE LEAF SURFACE CONCENTRATION OF 137Cs TO GIVE
A 0.17 REM ANNUAL WHOLE BODY DOSE AS A FUNCTION OF ASSUMED
DURATION OF INGESTION OF CONTAMINATED FRUIT 112
viii


85
The rate constants (k) which are presented in Table 11 and are
shown on Figure 29 through Figure .31 for the rspective trees, represent
an overall uptake and translocation to the fruit, or rate of accumulation
in the fruit. The data from the three banana plants were also treated
as replicates, and an average rate constant (k) was calculated for the
rate of cesium accumulation in bananas following foliar absorption. The
rate constants for Tree 1 and Tree 3 were essentially the same, even
though the plants were of different varieties and the fruit were in
different stages of development. It is postulated that the slightly
higher rate constant for Tree 2 was a result of the abnormal condition
of the inflorescence of this plant, which caused the fruit to develop
in the axial; thus, the distance over which the translocation had to
take place was significantly shorter than in Tree 1 and Tree 3. (The
tracer was applied to the lamina, leaf, midrib, and petioles of all
three trees and not just to the lamina.) Generally, there is good
agreement among all three trees' rate constants, and the calculated
combined rate constant of -0.133 per day is only approximately 10
percent higher than the individual constants for Tree 1 and Tree 3.
The engineering significance of these results will be discussed in
the next chapter.
Rain Effect on Equilibrium Concentration
The effect of rain wash-off played a significant role in estab
lishing the equilibrium concentration (Ce) level in the fruit. No
rain fell during the process of applying the tracer to Tree 1; a light
rain began while treating Tree 2; and by the time Tree 3 was treated, a
tropical downpour was occurring. While Tree 1 received more tracer than
the other trees, Tree 2 attained a Ce of approximately twice that for


UPTAKE AND IRANHLOCATION OF
85Sr, 59Fe> 1H5W AND 134Cs BY BANANA PLANTS
AND COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION
BY
WALTER NEILL THOMASSON
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1972


CHAPTER III
PLANT NUTRITION
Introduction
In this study the only required mineral nutrient employed as a
radiotracer was iron, which enters the plant's cytochrome respiratory
system.57 The other radiotracers used in the study have congeners
which are required mineral nutrients: strontium and calcium, tungsten
and molybdenum, and cesium and potassium. (The latter relationships are
CO
not as definite and consistent as the strontium-calcium relationship. )
cn
Calcium is mainly utilized by plants in meristematic parts, such as
new leaves,^ and may be used to form calcium-pectate which provides cell
CO
walls with their rigidity. Molybdenum acts as an electron-carrier in
the nitrate-reductase system,and potassium is associated with carbo-
c O
hydrate utilization.
Mineral requirements of all plants differ quantitatively, and plants
under unusual environmental conditions may exhibit specific requirements
for trace elements not ordinarily used.Differences exist even among
CO
strains and varieties of a species because of their genetic composition.
Mineral nutrients, except potassium and sodium, are most likely
f\ 9
absorbed and translocated as natural chelates. Chelates are regularly
employed to supply Fe, Zn, and Mn to valuable crops, such as fruit and
ornamentals.63
16


35
Field Procedures Kinetics Study Miami
General
A second field experiment was conducted between May 10, 1968, and
June 5, 1968, at the United States Department of Agricultures Plant
Introduction Station, Miami, Florida, to obtain data on the rate of
accumulation of ^^Cs in the banana fruit after foliar absorption. The
experimental site was one of several 7.6 m square enclosures in a
structure originally designed for plant preservation and propagation.
Figure 8 shows the test area.
The banana plant was selected because 1) it is very important in the
diets of the ethnic groups in the canal study areas and 2) the transloca
tion of cesium is fairly rapid in the banana plant. The banana plants
chosen for the study x^ere of the species Musa and varieties walap
CTree 1), rajapuri (Tree 2), and kullan (Tree 3). All three trees were
dwarf varieties. The fruit on Tree 1 was approximately two-thirds
mature; Tree 2 had fruit that was very young on an inflorescence which
had failed to emerge from the plants axial causing the bananas to
develop in the axial; and fruit on Tree 3 was nearly mature (it ripened
after cutting). Figure 8 and Figure 9 show the general study area and
plants. Only ^^Cs was selected for this study since 1) it was rapidly
and freely translocated through the banana plant in the mixed tracer
study, 2) in the previous study Sr, Fe, and W were generally rather
immobile after foliar absorption, and 3) cesium had been shown to be the
most critical fission product or activation product of concern in this
study.


This dissertation was submitted to the Dean of the College of Engineering
and to the Graduate Council, and was accepted as partial fulfillment for
the requirements for the degree of Doctor of Philosophy.
March, 1972
Dean, Graduate School


Page
V. RESULTS 59
Introduction 59
Environmental Control 59
Data Analyses Mixed Tracer Uptake 64
Data Analyses Kinetics Study Miami 84
VI. DISCUSSION OF RESULTS 99
Efficacy of Field Experiments 99
Success of Environmental Protection Procedures 100
Significance of Results in Relation to Radioactive
Fallout 102
Evaluation of Allowable Activity on Plant Foliage 105
Kinetics of Cesium Accumulation in the Banana Plant ..... 113
Effect of Rain 116
Translocation of Radiotracers in Coconut and Banana
Plants 117
Long-Term Effects of Foliar Contamination 122
SUMMARY 124
APPENDIX A: CHEMICAL SEPARATION PROCEDURE FOR TUNGSTEN ANALYSIS ... 128
APPENDIX B: DRY ASHING PROCEDURE PLANT TISSUE 130
LIST OF REFERENCES 132
BIOGRAPHICAL SKETCH 141
v


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AUTHOR: Thomasson, Walter
TITLE: Uptake and translocation of & ,& p Sr Q pQ Fe 'G ,SG pW and '3Q 'Cs by banana plants
and coconut plants following foliar application, (record number: 580537)
PUBLICATION DATE: 1972
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TABLE 8a
TRACER COUNT RATES BANANA TREE PARTS 18 DAYS AFTER TREATMENT
Sample
185w
cpm/g i 2a
85 Sr
cpm/g i 2g
^cs
cpm/g 2q
59Fe
cpm/g 2a
TREATED PLANT PARTS
Lamina
NDb>c
14,000
+
280
36,000
+
180
6,400
+
69
Midrib
ND
3,500
+
100
9,300
+
66
900
+
23
Axial
ND
2,400
+
42
3,800
+
28
300
+
8
UNTREATED PLANT PARTS
Upper Pseudostem
120 7
3,200
+
47
3,100
+
31
810
+
11
Lower Pseudostem Interior
NDC
90
+
19
1,400
+
13
92
+
4
Lower Pseudostem Exterior
ND
90
+
18
1,100
+
12
27
+
4
Rhizome
ND
ND
960
+
10
ND
Lamina: Youngest
NDC
510
+
20
1,900
+
13
84
+
4
Midrib: Youngest
ND
600
+
27
1,800
+
17
41
+
5
Inflorescence Stem
ND
74
+
51
4,800
+
34
91
+
11
Distal Inflorescence Bract
NDC
ND
15,000
+
65
NDC
Banana Pulp
NDC
ND
3,400
+
22
-6.
,1
7.1c
Banana Peel
-5.2 5.8
ND
3,200
+
26
85
+
9
DAUGHTER PLANT PARTS
Upper Pseudostem
ND
ND
1,800
+
14
ND
Lower Pseudostem
ND
-0.
,34
19
1,700
+
14
-0.
,1
4
Lamina
ND
750
+
36
2,500
+
25
510
+
9
Midrib
-1.4 2.3
140
+
16
1,400
+
11
92
+
4
aAll data corrected for decay to November 3, 1967.
bNot detectable when the 2q error term was Included with the net count rate the result remained negative
cData from chemically separated sub-sample indicated that this isotope was present.
CT\


47
FIGURE 13: COUNTING CONTAINER IN POSITION OVER Nal(Tl) CRYSTAL
PACKARD LOW-BACKGROUND SYSTEM


91
TABLE 12
EQUILIBRIUM CONCENTRATION VALUES Ce VERSUS AGE OE ERUIT
Banana
Plant
Ce
(pCi/g)
nS
X 100
Estimated Percentage
Maturitv
Tree 1:
Musa walap
16,000
0.40%
67
Tree 2:
Musa raiapuri
32,000
0.80%
33
Tree 3:
Musa kullan
5,000
0.12%
100
Q
(pCi/g)leaf/(pCi/ml)solution.


Counts per Channel in 60 Minutes
Channel Number (10 Kev/Channel)
FIGURE 16: CESIUM-134 STANDARD
Ul
o


I certify that I have read this study and that in ray opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
William 'Emmett Bolcff, Chaifman
Associate Professor of Environmental
Engineering
I certify that I have read this study and that in my opinion it
conforms, to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy. .
/Q.
Herbert A. Bevis
Associate Professor of Environmental
Engineering
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
Charles E. Roessler *
Assistant Professor of Radiation
Biophysics
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a.dissertation for the degree of
Doctor ofPhilosophy.
H) SjJL. M
Billy G. Durbant
Professor or Nuclear Sciences


20
Tungsten
Essentially all cationic salts of tungsten are insoluble in water.
Some anionic salts of tungsten are quite soluble in water, and it is in
this form that tungsten usually enters into environmental chemical
o-i
processes. This element has been studied biologically least of any of
the Group VI B transition elements, and there is no available ecological
82
cycling information on it, nor could any botanical kinetics studies
related to it be found.
If it is assumed that tungsten will behave in a manner similar to
molybdenum, then the limited information about molybdenum may be useful
as a guide to the behavior of tungsten. Molybdenum has been reported to
be somewhat mobile following foliar treatment.One author^
suggested that it is translocated through the transpiration system
(xylem) to adjacent leaves in a manner similar to the way manganese is
moved. The only studies reported concerning tungsten and plants have
81 84
been involved with root absorption.
While no information relative to foliar absorption of tungsten could
be found, various authors have shown that it is utilized by plants
84
following root uptake. Wilson and Cline found that potassium tungstate
provided tungsten in an easily available form as an anion in basic soil.
In acidic soil, tungsten was absorbed very little; therefore, these
authors concluded that tungsten must be in the form of tungstate, an anion,
before it can be absorbed by roots. They also concluded that tungsten
could be absorbed in biologically significant quantities from the soil,
but the uptake is very dependent on soil pH. Finally, Kaye and Crossley^
suggested that the movement of tungsten through food chains would
approximate the movement of cesium.


CHAPTER VI
DISCUSSION OF RESULTS
Efficacy of Field Experiments
When properly conducted, field experiments should provide invalu
able data under natural conditions as opposed to the artificial condi
tions present in greenhouse or pot studies. In greenhouse or pot
studies the atmospheric and terrestial environments are artificial and
plant root morphology is affected. For instance, the effects of rain
fall, dew, wind, and temperature changes are eliminated; the moisture,
physiochemical and textural soil conditions may be different; and plant
root system development is altered relative to natural conditions.
Also, since plants in a greenhouse study are protected against the
deleterious effects of rain and wind, the foliage in these plants
would probably not have the physical damage which is characteristic
of field-grown plants.
In the study under discussion, an attempt was made to maintain
as nearly as possible natural conditions which might be representative
of those found in banana and coconut plantations in Panama. The
experiments took place in the sub-tropical climate of south Florida
rather than in the artificial environment of a greenhouse, and the
only alteration of the environment was in placing plastic sheeting
immediately beneath the treated plants to control the spread of the
radiotracers.
99


103
absorption; thus, as a contributor to the total radionuclide contamina
tion of the fruit, it is unlikely that direct fruit absorption would be
a significant source of contamination except for nuclides which are
not translocated from the foliage or from the soil via the roots. There
is a need for research on the degree of internal fruit contamination
that could result from direct absorption of nuclides which are not
translocated from other absorbing areas of the plants. Surface contam
ination which remains on the surface of the banana peels or coconut
husks should not be an internal health hazard since these outer fruit
layers are discarded. However, in the case of surface contamination,
the fruit should be washed before being consumed since external surface
contamination can be carried to the edible parts of the fruit in the
process of preparing the fruit for consumption.
Much research has been conducted on the behavior of fallout in
various types of soils and the absorption of radionuclides by plant
roots from contaminated soils. Generally, researchers have found that
strontium is the most limiting radionuclide when the soil-to-plant
pathway is considered. This is due to its physical and chemical
properties, its fission yield, and its limiting maximum permissible
concentration (MPC). However, as was indicated in the literature
review, tungsten can also be absorbed from alkaline soil by plants and
is subsequently translocated to the aerial parts of the plant. Addi
tional research is needed to evaluate the extent of contamination of
bananas by strontium and tungsten following root absorption. Iron is
generally rather immobile in soils due to its physical and chemical
properties, and cesium is complexed by the soil organic matter and
undergoes ion exchange on the clay fraction of the soil. Thus, these


Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of Doctor of Philosophy
UPTAKE AND TRANSLOCATION OF
85Sr, 5^Fe, 185W AND 184cs BY BANANA PLANTS
AND COCONUT PLANTS FOLLOWING
FOLIAR APPLICATION
By
Walter Neill Thomasson
March, 1972
Chairman: William Emmett Bolch, PhD.
Major Department: Environmental Engineering
Bananas or plantains (cooking bananas) and coconuts comprise a
significant part of the diets of the people residing in the areas of
Panama and Colombia under consideration for a sea-level interoceanic
canal. The coconut is also a major export commodity. Because of their
importance in the area diet and economy, a mixed radiotracer experiment
on a banana plant and a coconut palm was designed as part of the eval
uation of the radiological effects of a Plowshare project, such as the
one proposed for construction of a sea-level interoceanic canal. In
conjunction with the experiment, field and laboratory procedures were
also developed. A second replicated field study was conducted to meas
ure the rate of accumulation of -*-8^Cs in bananas following foliar
application of the isotope.
ix


37
FIGURE 9: TREE 1 USDA BANANA SITE


values (Ce) expressed as a percentage of the concentration applied to
the foliage were 0.40 percent, 0.80 percent, and 0.12 percent. The Ce
varied as a function of the maturity of the fruit and the atmospheric
conditions during and following tracer application. However, the rate
constants were independent of the atmospheric conditions.
As a result of these field experiments, it is evident that even
with heavy rain during and following the period of fallout deposition
radiologically significant amounts of radioactivity will be absorbed
and retained by the foliage of banana and coconut plants.
Using the results of this study, a model was developed to predict
the yearly whole body dose to an individual who eats contaminated
bananas. This model evaluates the dose as a function of 1) the
concentration (yCi/m^) of fallout on the plant foliage; 2) the rate of
consumption of contaminated bananas; and 3) the duration of consumption
of the bananas.
xi


15
metal group move freely from the foliage to other plant parts via the
phloem, while the alkaline earths divalent cations move only upwards
and will not translocate via the phloem.10*21,48
Translocation from the foliage may be related to the metabolism and
movement of carbohydrates.^ Moorby*^ concluded that translocation
through leaf tissues to veins is a metabolically controlled step, and
discrimination against phloem mobile elements probably occurs at this
point in the translocation process. Biddulph^ has suggested that
chemical precipitation of elements in the extremities of the leaf's
veins may be the inhibiting mechanism of utilization and transport of
some elements.
During the active plant growth phase, nutrients translocated from
the leaf probably move via the phloem as opposed to movement via the
xylem (transpiration system) following root absorption. Leaf maturity
and metabolically active plant parts may be the primary factors that
SI S2 S3
determine the direction of translocation. 5 5 While there is
. r ^ ^
greater absorption by younger leaves, the greatest translocation
54
is from the older leaves. The distribution of radionuclides is
proportional to the metabolic activity of the tissue,^ and the rate of
movement and final direction of translocation of ions are controlled by
C C C/f
internal mechanisms. Generally, mineral nutrients (or fallout) will
move towards the actively growing parts and nutrient storage organs such
as meristems, apical growth points, and fruit. Therefore, the distribu
tion patterns depend on the relative rates of growth and the position of
t 2
the treated foliage and storage organs with respect to each other.
Although there is more translocation when the fruit is young, the
increased movement is not necessarily to the fruit.^


CHAPTER I
INTRODUCTION
The United States Atomic Energy Commission (AEC) has developed a
program, Plowshare, to investigate potential uses of nuclear devices
for peaceful purposes. These devices have been proposed for use in
excavating harbors, cutting railroad passes, developing water resources,
and excavating canals the most widely publicized use. Nuclear cratering
tests have been conducted at the Nevada Test Site in a program to develop
the technology and engineering design criteria required to utilize this
means of excavation. Lawrence Radiation Laboratory's Plowshare Division
has the primary responsibility for developing special nuclear devices for
engineering application.^
Sea-Level Canal Bioenvironmental and Radiological-Safety
Feasibility Study
The need for a new interoceanic sea-level canal has been well
demonstrated. Nuclear excavation is being considered for two of the
proposed new canal routes: 1) Route 17 in Panama's Darien Provence,
approximately 100 miles east of the existing canal, and 2) Route 25 in
northwestern Colombia, along the Panamanian-Colombian border.
The United States Congress passed Public Law 88-609 which authorized
the President to appoint a commission to investigate and to determine
the site and the best means of constructing a sea-level canal connecting
the Atlantic and Pacific Oceans. Nuclear excavation was proposed as a
1


APPENDIX A


114
overall accumulation of 134cs by the banana fruit from the foliage was a
first order function since this type of kinetics is often characteristic
of biological processes.
The literature review yielded only one reference to a mathematical
model of absorption and/or translocation of material from plants' foliar
surfaces. Jyung et al. indicated that foliar absorption characterized
by a first order reaction possibly indicated a passive component of
absorption with the initially rapid uptake being closely related to
environmental conditions. Overall, these authors feel that foliar
absorption by green leaves is characterized by a rapid non-metabolic
(passive) phase followed by a second, slower, metabolically controlled
step which they related to carrier concepts.
1 2
Although Jyung ejt al. were mainly concerned with the absorption
of ions from the leaf's surface and the subsequent translocation from
the absorbing location, it was shown in the literature review that the
processes of absorption and translocation are intimately interrelated.
Therefore, while the rate of accumulation of ''^Cs by bananas was the
12
phenomenon modeled here, the mechanisms suggested by Jyung ert al. may
be applicable to these studies.
Although three varieties of dwarf banana plants were employed for
the study and although they had fruit at different stages of development,
the rate constants were surprisingly similar. The more rapid rate of
accumulation of x Xs in the fruit of Tree 2 is probably related to the
morphology of the plant. The fruit was the youngest (about two months
old) of the three bunches, and it was developing in the axial of the plant
rather than on the inflorescence away from the plant. Therefore, any
radiotracer that reached the axial via external pathways would have


104
isotopes are usually not limiting relative to soil-to-plant uptake.
Since direct fruit absorption and root absorption are not likely to be
the primary source of fruit contamination by cesium, deposition of fall
out on the aerial parts of banana and coconut plants will probably be
the critical pathway of contaminating these fruits.
The mixed tracer study at Homestead provided a measure of the
relative distribution patterns of Sr, Fe, W, and Cs in banana and
coconut plants following foliar absorption. Based on the facts that
137
Cs has a long half-life and a high fission yield and on the results
of this research, probably only cesium will cause significant contam
ination (that which might approach limiting values) of edible portions
of bananas and coconuts after foliar deposition of fallout. For this
reason, cesium will be emphasized in subsequent discussions.
Similarly, the banana plant will be stressed in the following
discussion since it is the more probable critical pathway to man com
pared to the coconut plant. This is indicated by 1) the fact that
bananas represent a much greater portion of the diet of the ethnic
groups in Panama than does the coconut (up to 85 percent versus 6 per
cent) and 2) the mixed tracer study results which showed that a higher
percentage of cesium was translocated to the bananas from the foliage
than to the coconuts in the coconut palm. (As is shown in Table 6,
Table 7, and Table 8, the fraction of cesium translocated to the young,
new fruit on the palms was about the same as in the bananas; however,
the edible parts of the coconut had not yet developed. Therefore, the
only valid comparison is between the fractions translocated to the
edible parts of the respective types of fruits; i.e., while the mature
coconut meat and milk had 0.36 percent as much radiocesium as the


117
constants which were 16,000 pCi/g, 32,000 pCi/g, and 5,000 pCi/g for
Tree 1 through Tree 3 respectively. The difference in the equilibrium
concentration value of Tree 3 and the other trees was most probably the
amount of tracer that was washed from the leaves, coupled with a lower
rate of metabolism in the maturing fruit. However, despite tracer loss
due to rain, it was conclusive in this study that even following heavy
rains a significant amount of radioactivity will remain on or in the
foliage of the banana and coconut plants. Also, whether the rain occurs
during or following the period of fallout deposition, there will be
sufficient residual activity on the foliage to provide a source of
contamination of the fruit through translocation. This is evidently, in
part, due to rapid absorption by the leaves and translocation from the
foliage to the interior of the plant and then to the fruit. While the
rain did have a significant effect on the absorption and translocation of
the fallout, generally it can be concluded that the environmental conditions
did not affect the rate of -^^Cs accumulation by the fruit since the rates
of accumulation (k) for Tree 1 and Tree 3 were the same, despite the
effect of the rain.
Translocation of Radiotracers in Coconut and Banana Plants
Coconut Palm
Levi^O^ postulated that interflow between the xylem and phloem in
dicotyledons resulted in movement of some of the strontium and iron from
the foliage. Translocation of these elements from the foliage also occurred
in this study. Even though the vascular system of palms (as well as
banana plants) is basically different from that of dicotyledons, similar
phenomena may occur in the palm (or the banana plant). Also, Ambler has


CHAPTER V
RESULTS
Introduction
As indicated in the literature review, the process of foliar absorp
tion and translocation of fallout is a complex phenomenon with many
physically and chemically interrelated factors. Botanical characteristics
of the plants as well as environmental factors play major roles in the
ultimate extent of absorption of material from the foliage (or more
generally, by the entire plant). The complex interrelationships are
evident in the results of these two experiments: 1) mixed tracer absorp
tion and distribution and 2) kinetics of ^^Cs accumulation in bananas
following foliar absorption.
Environmental Control
As was described in Chapter IV, plastic sheeting, peat moss, and
fencing were utilized to control the radioisotopes and to prevent contam
ination of the general environment. Samples of vegetation (grass, weeds,
and roots), soil, insects, and small animals (mice, a lizard, and frogs)
were obtained from within and/or around the controlled areas to determine
the extent of spread of radioactivity to the general environment. In
addition, samples from adjacent banana plants (suckers, inflorescences,
and bananas) and coconuts from nearby palms were taken and analyzed to
investigate the possibility of interplant translocation (movement) of
the tracers.
59


PERCENTAGE EQUILIBRIUM: (C/C ) x 100
87
FIGURE 29: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa walap
TREE 1


21
85
Essington et al. reported that radioisotopes of tungsten were the
most abundant radionuclides in fallout 167 days after the Sedan Plowshare
thermonuclear test. Studies by Romney and Rhoads^ and Romney et al.^
of tungsten accumulation by plants following the Sedan test showed that
radiotungsten was by far the dominant radioelement in plants grovro on the
Sedan ejecta after three years of cropping. These investigators found
that the greatest concentration of radiotungsten occurred in the leaves
of these desert plants. Although this was root-absorbed tungsten, it
clearly showed the utilization of this element by one species of plant.
Nutrition of Banana Plants and Coconut Palms
O Q
According to Norton, little is known of the nutrition of bananas,
particularly the mineral nutrition. Generally, this plant exhibits
great flexibility in its cationic composition;^ this characteristic is
reflected in the fact that the mineral element concentration of banana
plant parts varies greatly during the plant's twelve-month growth cycle.
The most prominent compositional characteristic of the banana plant is
its high potassium content.
Most of the research on coconut palms has centered around the major
nutrients, of which potassium has been found to be the dominant cation
in the edible part of the coconut.^ According to Buchanan,there has
been a lack of interest in microelements in the past, and the literature
on coconut nutrition is relatively limited considering the importance of
this crop to human livelihood.


Counts per Channel in 15 Minutes
FIGURE 22: SUB-SAMPLE- TREATED PALM LEAFLETS NaOH INSOLUBLE, HC1 INSOLUBLE PORTION


Counts per Channel in 15 Minutes
900
800
Channel Number (10 Kev/Channel)
FIGURE 24: SUB-SAMPLE TREATED PALM LEAFLETS NaOH SOLUBLE, HC1 INSOLUBLE PORTION


45
radionuclide translocation to other trees, and 3) leaf punch samples from
the kinetics study.
The whole coconuts, coconut shells, and husks were counted in plastic
hags laid over the large crystal detector of the low-background analyzer
system. This geometry was used for two reasons: 1) reducing these samples
to a small enough volume to be counted in the standard geometry would
have necessitated ashing with possible loss of cesium through volatiliza
tion and 2) the identification, or presence, of the radioisotopes in
these samples was more important than relative quantification of the
tracers. Identification was of primary interest because 1) the prelim
inary analysis indicated that low levels (trace amounts) of isotopes
were involved; 2) the samples from the adjacent trees were analyzed only
to obtain translocation data for planning future studies; and 3) the fact
that interplant translocation occurred is of greater significance than
the amount, since so little radioactivity was involved.
Gamma Spectroscopy Systems
Except for the zoological samples, gamma ray spectroscopic analyses
were made using a 10.16 cm x 10.16 cm right-cylinder, Nal(Tl) scintilla
tion crystal coupled to a photomultiplier tube. The base of the stand
ard geometry 800 ml container was the same diameter as the scintillation
crystal. (A plastic centering ring was used to hold the containers in
constant position over the detector.) The photomultiplier was connected
to a Pckard (Model 116) 400-channel multi-channel pulse-height analyzer.
The crystal was located inside a 51 cm x 51 cm x 61 cm high, tri-component
shield (5 cm thick lead sides, floor, and cover with graded cadmium and
copper lining). The entire analyzer system was housed in a large, low-level


105
residual on the coconut fronds, the banana pulp had 9.4 percent as much
cesium as the residual activity on the banana plant lamina.)
Evaluation of Allowable Activity on Plant Foliage
The purposes of the Bioenvironmental and Radiological-Safety
Feasibility Study were to develop guidelines for determining the
allowable concentrations of radionuclides following a Plowshare event
and to evaluate the ecological feasibility of a project such as
construction of an interoceanic sea-level canal by nuclear means.
In order to calculate the maximum allowable concentration of fall
out on the banana foliage (Cl), the following factors must be considered:
1) the radionuclide of interest, 2) the physical half-life of the radio
isotope, 3) the biological half-life of the radionuclide in the body,
4) the period of exposure, 5) the rate of uptake by the critical body
organ, and 6) the relative transmission factor (RTF) from the foliage
to the fruit (derived from this research).
Since no criteria have been established for determining allowable
population exposures following a Plowshare event, the following approach
will be taken as a first step in developing the allowable fruit and leaf
surface concentrations: 1) the allowable annual whole-body dose to a
suitable sample of the critical population group in Darien Provence,
Panama, is assumed to be 0.17 rem; 2) the annual dose is received in
two segments during the ingestion phase and during the elimination
period following the termination of intake; 3) the period of ingestion
is a variable; and 4) the allowable leaf surface concentration (Cl) will
be determined as a function of the duration of ingestion to limit the
total yearly whole-body dose as a result of Cs intake via contaminated
bananas.


81
Figure 24, which show the components of the unseparated coconut frond
and the spectra of the separated sample. In Figure 20, the tungsten is
IOC
undetectable, \ihile Figure 24 clearly shows the presence of W.
Stable Element Data
Since this study was conducted in the sub-tropical climate of south
Florida, partial stable element analyses of the soil and vegetation
samples from south Florida and from Panama were made so that the applica
tion of these tracer results might be extrapolated to the Panamanian
conditions. Table 10 shows the partial stable element compositional
analyses of various samples from south Florida and Panama.
The major elements are in reasonable agreement when one considers
what the data represent. The Panamanian samples represent data of the
mean of many samples, while those from Florida are determinations of at
most three samples. (The differences in the minor elements are typical
when comparing interlaboratory results of trace metal analyses as well
as plant tissue.In general, the elemental composition of plants vary
widely with age of tissue and environmental conditions prior to sampling.
Even so, there is generally good agreement among the banana pulp samples
from both locations and also between coconut meat samples. Notable
exceptions are in the 1) Fe, Mn, and Zn concentrations in the banana
leaf and pulp samples and 2) Fe, Mn, Zn, and Cu in the coconut plant
parts other than the coconut meat.
97
According to Gamble e_t al. the soil compositions in south Florida
and Panama have similar tungsten concentrations. The cesium composition
of the soils in the two Homestead, Florida, experiments vary considerably.
The total cesium concentration in the soil at the coconut palm site x^as


TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ii
LIST OF TABLES vi
LIST OF FIGURES vii
ABSTRACT ix
CHAPTER
I. INTRODUCTION 1
Sea-Level Canal Bioenvironmental and Radiological-
Safety Feasibility Study 1
Research Objectives 2
II. CHARACTERISTICS OF FOLIAR ABSORPTION AND TRANSLOCATION .. 5
Introduction 5
Plant Factors Affecting Foliar Absorption 6
Environmental Factors Affecting Foliar Absorption 8
Mechanisms of Ion Absorption 9
Rates of Absorption of Specific Ions 10
Plant Characteristics Affecting Translocation 14
III. PLANT NUTRITION 16
Introduction 16
Strontium 17
Iron 18
Cesium 19
Tungsten 20
Nutrition of Banana Plants and Coconut Palms 21
Fallout and Plant Nutrition 22
IV. METHODOLOGY 23
Site Selection 23
Selection of Tracers .' 27
Field Procedures Mixed Tracer Experiment 28
Field Procedures Kinetics Study Miami 35
Laboratory Analyses 42
iv


7
vascular systems will absorb more, generally, than those with poorly
developed systems.
Plant Age
Foliar absorption is strongly associated with the age of the plant
and the phase of its growth cycle. As the leaf matures, its absorptive
capacity is reduced. Two events are responsible for this change: 1) the
permeability of the cuticle decreases and 2) the rate of metabolism
14
increases to a maximum, then diminishes. There is some disagreement
as to the effect of leaf age on uptake, but this may be associated more
with the variation of nutrients and materials studied than with the
leaf itself. The cuticular development and concentration of stomata
change as the leaf matures, and this possibly accounts for some variation
1 s
in absorption. Generally, researchers have agreed that because of
thinner cuticles, young leaves absorb more foliar-applied nutrients than
mature leaves. This process is mainly irreversible in immature
leaves.^
Another important age-related factor is the time of contamination
with respect to the growth stage of the plant, since the greatest foliar
absorption of elements occurs during the flowering, or fruiting, stage
(when root absorption is negligible) If fallout occurs prior to
the flowering stage, the fruit will not be directly contaminated, and it
can only receive radioactivity from other plant parts via translocation.
On the other hand, if the fruit has begun to develop prior to the
deposition of fallout, direct surface contamination will result (the
19 20
fruit is capable of absorbing fallout).


96
fruit was about two-thirds mature, had a concentration 11 percent of
that on the treated leaves 26 days after treatment. These differences
probably reflect the differences in the rate of accumulation of metabolic
sugars. (The values presented for the treated leaves in Table 14 are
from composite, large, treated leaf samples; while those in Table 13 are
from composited punch samples of each leaf which was treated.)
Translocation
Although the primary objective of the kinetics study was to deter
mine the kinetics of -*--^Cs accumulation in the banana following foliar
absorption, additional information was derived concerning the distribu
tion patterns of -^-^^Cs in the plant and translocation to other plants.
As was also shown in the mixed tracer study, J"34Cs exhibited general
mobility throughout the treated plants (as shown in Table 14). (All the
leaves on Tree 2 received tracer solution directly; thus, no untreated
leaves were sampled.) The peat moss samples listed in Table 14 were grab
samples taken from beneath the treated leaves at the end of the study.
Since the peat and plastic were replaced after the tenth day, the radio-
tracer in these samples must have been a result of only foliar leaching
and not direct drippage during tracer application or wash-off immedi
ately after the treatment.
On September 13, 1968, about four months after the experiment began
and three months after the treated plants were removed, samples were
taken of adjacent trees' fruit, distal inflorescence bracts, and grass
from the area. The locations from which these samples were obtained are
shown in Figure 12 (p. 43), and the J4Cs concentrations of the samples
are shown in Table 15. The data are on a wet-weight basis in the standard


42
The plants were then cut off at a point approximately 30 cm above the
soil so that transfer of the tracer from the rhizome storage organ (the
"root") to other developing fruit and new sword suckers (young plants
that originate from the rhizome) could be studied.
On September 13, 1968, samples of bananas, distal inflorescence
bracts, and grass were obtained from adjacent plants to determine the
extent of translocation to new daughter plants and to adjacent plants
from the rhizomes of the treated plants. The location of the test trees
and subsequent sampling points are shown in Figure 12.
Laboratory Analyses
Mixed Tracer Experiment Sample Preparation
All samples from the first experiment, except the shells and husks
of the coconuts, were processed to a homogeneous state. The banana pulp
and peels were individually prepared, and the coconut husks, shells, and
meat and water were analyzed separately. A heavy-duty paper cutter was
used to chop the samples, which were then blended in a 4.25 liter (L),
stainless-steel, food blender. The paper cutter, blender, and all
utensils were thoroughly washed after each set of samples was prepared in
order to prevent cross-contamination. The samples were prepared and
analyzed in the anticipated order of the lowest count rate to the highest.
Distilled water was added, as required, to the samples to facilitate
blending, and a few milliliters (ml) of formaldehyde were added as a
preservative. After blending, the samples were poured into 800 ml plastic
containers and weighed prior to low-level gamma scintillation counting.
The dry weights of all samples except the shells and husks were
obtained by drying three portions of each sample at 65-70 C and


A third objective of the study was to investigate the kinetics of
translocation of radiocesium by banana plants (as measured by the rate
of accumulation in the fruit). The banana plant was selected for this
study because 1) the banana comprises the bulk of the diet of the
populations in the study areas, 2) translocation of the radiotracers in
the initial phase of the field study was more rapid in the banana, and
3) the results of the initial study indicated that radiocesium would be
the more limiting radioisotope of the ones studied.


135
35. Martin, D. C., "The Absorption and Translocation of Radiostrontium
by the Leaves, Fruits and Roots of Certain Vegetable Plants,"
PhD Thesis, Michigan State University (1954).
36. Biddulph, 0., "The Distribution of P, S, Ca, and Fe in Bean Plants
as Revealed by Use of Radioactive Isotopes," Plant Analysis and
Fertilizer Problems, Paris: Eighth International Congress of
Botany, 1954.
37. Moorby, J., "The Foliar Uptake and Translocation of Caesium,"
Journal of Experimental Botany, 15: 457-469 (1964).
38. Thorne, Gillian H., "Factors Affecting Uptake of Radioactive
Phosphorus by Leaves and Its Translocation to Other Parts of
the Plant," Annals of Botany, N. S. 22: 381-398 (1958).
39. Wittwer, S. H., "Foliar Absorption of Plant Nutrients," Advancing
Frontiers of Plant Science, 8: 161-182 (1964).
40. Sudia, T. W. and A. J. Linck, "The Effect of pH on the Absorption of
Sr89j p32 an(j pe59 ions by Leaves of Zea mays," Ohio Journal of
Science, 61: 107-112 (1952).
41. Okuda, Azuma and Yasuykuki Yamada, "Foliar Absorption of Nutrients
IV: The Effect of Some Organic Compounds on the Absorption of
Foliar Applied Phosphoric Acid," Soil Science and Plant
Nutrition, 8: 147-149 (1962).
42. Wittwer, S. H. and F. G. Teubner, "Foliar Absorption of Mineral
Nutrients," Annual Review of Plant Physiology, 10: 13-32
(1959).
43. Tukey, H. B., Jr., H. B. Tukey, and S. H. Wittwer, "Loss of Nutrients
by Foliar Leaching as Determined by Radioisotopes," Proceedings
' f. the American Society of Horticultural Science, 71: 496-506
(1958).
44. Stenlid, G. Encyclopedia of Plant Physiology. Berlin, Germany:
Springer-Verlag, 4: 615-637 (1958).
45. Olsen, J. S. and W. C. Cate. "Forest Studies," Annual Progress
Report Health Physics Division, Period Ending July 31, 1960,
Oak Ridge National Laboratory, USAEC Report 0RNL 2994 (I960).
46. Freiberg, S. R. and P. Payne, "Foliar Absorption of Urea and Urease
Activity in Banana Plants," Proceedings of the American Society
for Horticultural Science, 69: 226-234 (1957).
47. Cain, John C., "Absorption and Metabolism of Urea by Leaves of
Coffee, Cacao and Banana," Proceedings of the American Society
for Horticultural Science, 67: 279-286 (1956).


BIOGRAPHICAL SKETCH
Walter Nelli Thomasson was born on April 15, 1940, in Owensboro,
Kentucky. He attended elementary schools in Arlington, Virginia, and Oak
Ridge, Tennessee. His high school education was obtained at Oak Ridge
High School. He received his Bachelor of Engineering degree in civil
engineering from Vanderbilt University, Nashville, Tennessee, in 1962.
He attended graduate school at the University of Illinois on United
States Public Health Service Traineeships from September, 1962, to June,
1964, where he earned his Master of Science in sanitary engineering in
October, 1963. From June, 1964, to June, 1966, he served as a commis
sioned officer in the United States Public Health Service (USPHS) and was
stationed at the Southwestern Radiological Health Laboratory, Las Vegas,
Nevada.
In June, 1966, he returned to graduate school at the University of
Florida under a United States Public Health Service Traineeship to pursue
his doctorate in environmental engineering. From January, 1969, until
October, 1971, he was employed as an environmental engineer with the
United States Atomic Energy Commission, Division of Reactor Licensing,
Washington, D. C. He is currently employed by the Environmental
Protection Agency, Office of Radiation Programs in Rockville, Maryland.
He is a reserve officer in the USPHS, is a member of the Health
Physics Society, and is certified as an Engineer-in-Training in Tennessee.
He is married to the former Clarissa (Lissie) Camfield of Miami, Florida,
and they have two daughters: Lane and Amie.
141


34
D6
D5
D4
D3
D2
D1


V

V

C6
C5
C4
C3
C2
Cl
V
V
O
V


B6
B5
B4
B3
B2
B1

V
X- 0
*o
V

A6
A5
A4
A3
A2
A1
V
V
V
O

V
Negative Samples Obtained
LEGEND: ^3) 12/14/67 41 days after
the study began
V Other Banana Trees Not
Sampled
( pj Test Tree Location
Positive Interplant
y Translocation Samples
^ Obtained 11/21/67 18
days after the study
began
Other Positive Inter-
O plant Translocation
Samples Obtained
12/14/67 41 days after
the study began
FIGURE 7: EAST GLADE BANANA GROVE: BANANA TREE CLUSTER LOCATIONS


Ill
1) the (DCF) for 137Cs is 0.03 r-~Kg
yCi-day
2) the allowable yearly whole-body dose is 0.17 rem;
3) the mass (M) of bananas consumed per day is 1,700 grams
4) the weight per unit area (mg/cm; of banana leaf is 15.9 as
shown by this study, or 159 g/m2;
92
5) the standard man weighs 70 Kg.
r\ 1
Now, the leaf surface concentration (yCi/nrO of /Cs fallout can be
calculated to provide the allowable fallout densities on the foliage as
a function of the duration of ingestion to give the limiting dose as
shown by Equation (15):
C(L) (pCi/m2) = (M)036 (15)
(RTF)[(tk + e-kt 1) + (1 e-kt)(1 e-k0)]
Figure 33 shows the C(L) as a function of the duration of ingestion
and the RTF to provide a maximum yearly whole-body dose of 0.17 rem. As
is evident by the C(L) for Tree 1 and Tree 2 compared to Tree 3, more Cs
could be allowed on the foliage of trees with mature fruit. The indicated
higher allowable concentrations on the East Glade tree are because the
activity applied to the lamina was not removed by rain; thus, the RTF
was smaller, and the C(L) was larger.
The curves shown on Figure 33 bracket the calculated allowable C(L)
values derived from the data of these experiments. The East Glade data
represent conditions without rain wash-off effects, while the USDA data
include rain wash-off and indicate the effect of fruit maturity also. One
can interpret these curves as indicative of the permissible leaf concen
trations (yCi/m^) which would result in limiting ingestion rates of -^^Cs
as a function of the duration of ingestion of the contaminated fruit.
While the curves are specific to limit annual whole-body doses to 0.17 rem


NORMALIZED EQUILIBRIUM CONCENTRATION
95
MATURITY: PERCENTAGE
FIGURE 32: RELATIVE EQUILIBRIUM CONCENTRATION
AS A FUNCTION OF FRUIT MATURITY


3
pot studies the roots of the plants developed abnormal distribution
patterns. Handley et al.^ found that the amount of strontium absorbed
and the translocation patterns differed from greenhouse to the field.
Consequently, a field experiment was selected for this study because,
in the opinion of the investigator, actual field-environmental conditions
would provide more applicable data than would a greenhouse experiment,
particularly in view of the complex relationships involved in foliar
absorption.
The second objective of the study was to determine the distribution
patterns of radionuclides applied to aerial parts of banana and coconut
plants. The banana plant was selected for the study because up to 85
percent of the diet of people in the study areas is composed of bananas
or plantains. In fact, Dr. Torres de Arauz^ reported that as much as
approximately 12 kilograms (Kg) of bananas are consumed weekly per
individual. The coconut was selected because it is an important export
commodity in the economy of one of the local ethnic groups. Also,
coconuts provide a major portion of the fats in much of the populations'
diets. Overall, this fruit constitutes approximately 6 percent of the
total diet in Darien Provence.^
Although much research has been conducted on uptake, translocation,
and concentration of strontium and cesium in the food chain, little work
has been done xjith the other radionuclides, particularly activation
products. In addition, there is no information concerning uptake,
translocation, and concentration patterns of fallout radionuclides by
either the banana or coconut plant. The field study undertaken here was
the first designed to produce data in this area.


LIST OF REFERENCES
1. Todd, David K., "Nuclear Craters for Water Resources Development
and Management," Civil Engineering, 35: 64-67 (1965).
2. Magnuson, Warren G., "A Sea-Level Canal to Link the Atlantic and
the Pacific," Civil Engineering, 34: 70-72 (1964).
3. Russell, R. Scott and G. M. Milbourn, "Rate of Entry of Radioactive
Strontium into Plants from Soil," Nature, 180: 322-324 (1957).
4. Handley, R., R. K. Schultz, H. Marshner, and R. Overstreet,
"Translocation of Carrier-Free 85gr Applied to the Foliage of
Woody Plants," Radiation Botany, 7: 91-97 (1967).
5. Torres de Arauz, Reina, "Human Ecology of Eastern Panama," Presented
at Symposium on Sea-Level Canal Bioenvironmental Studies, Ohio
State University, September 3-5, 1968.
6. Wittwer, S. H., "La Alimentacin Foliar en el Major Amiento da las
Cosechas," Seielo Tico, 12: 90-93 (1960).
7. Matskov, F. F.. and T. K. Ikonenko, "The Correlation between Foliage
Feeding, Photosynthesis and Root Feeding of Plants," Doklady
Akad Nauk SSSR, 118: 601-603 (1958).
8. Tukey, H. B., Jr. and H. J. Amling, "Leaching of Foliage by Rain and
Dew as an Explanation of Differences in Nutrient Composition of
Greenhouse and Field Grown Plants," Michigan Agricultural
Experiment Station Quarterly Bulletin, 40: 876-881 (1958).
9. Mecklenburg, Roy Albert, "The Influence of Foliar Leaching upon
Plant Nutrition with Special Reference to Root Uptake, Trans
location and Loss of Calcium," Thesis, Cornell University,
Ithaca, New York, USAEC Report TID 19810 (UC 48) (1964).
10. Bukovac, M. J. and S. H. Wittwer, "Absorption and Mobility of Foliar
Applied Nutrients," Plant Physiology, 32: 428-435 (1957).
11. Wittwer, S. H., Y. Yamada, W. H. Jyung, and M. J. Bukovac,
"Mechanisms of Ion Uptake by Leaves of Higher Plants as
Revealed by Radioisotopes," Michigan State University, East
Lansing, Michigan, USAEC TID 20184 (1964).
132


97
TABLE 15
RADIOACTIVITY IN ADJACENT FRUIT BEARING PLANTS AND NEARBY GRASS
Sample
Wet-Weight
pCi
pCi/g
grams
Grass 1
71
250
3.5
Grass 2
93
63
0.7
Grass 3
37
27
0.7
Distal Inflorescence Bract
- 4
250
230
0.9
Banana Pulp 4
530
190
0.4
Banana Peel 4
450
220
0.5
Distal Inflorescence Bract
- 5
390
450
1.2
Banana Pulp 5
490
870
1.8
Banana Peel 5
420
1,000
2.4


29
peat moss. The plastic served as an impermeable barrier to percolation
to the ground, and the peat served as an absorbent. Background samples
of the fruit, vegetation, and soil were taken in the area of each test
tree.
Tracer Application
85
A mixture of four microcuries per milliliter (yCi/ml) each of JSr,
^Fe, and and approximately 4 yCi/ml of in a carrier-free,
soluble solution of NaEDTA was applied with a 5 cm wide paint brush. The
soluble, carrier-free tracers provided conservative results, since the
cratering fallout will not be entirely soluble nor carrier-free.
(Although the tracers were applied in soluble forms in order to be
conservative, the general conclusion found in the literature is that
fallout, other than that close-in, is in fairly soluble forms.) The
chelate prevented losses of the tracers on the sides of the container
and possibly made the ^Sr an 59pe more available to the plant; thus,
conservatism was again maintained. A total of approximately 100 ml of
solution was applied to three fronds of the palm tree, and a total of
60 ml was applied to four leaves of the banana tree. A security fence
was constructed around each test tree, radiation warning signs were
posted, and the areas were surveyed with a Geiger counter. Figure 4
shows the application of the nuclides to the coconut palm. The treated
fronds can be seen in Figure 1; they are the three fronds in the fore
ground above the withering frond.
Sampling
OnNovember 21, 1967, 18 days after treatment, the peat and plastic
were removed. The areas were then surveyed and decontaminated to a level


98
counting geometry (800 ml). Distilled water was added to the grass
samples, and they were homogenized to provide a more reproducible geom
etry in the counting containers. The other samples were counted in their
wet states in the standard geometry.
In the banana parts, the ratio of (^-34cs)peel/(-^^Csjpulp was
approximately 1.3. While approximately 4.5 times more tracer was con
centrated by the fruit of Tree 5 than Tree 4, the concentration of tracer
in the distal bracts differed only by 25 percent. Tree 5 was farther
away from the treated plant (Tree 2), and the fruit of Tree 4 probably -
did not require as much nutrient from the plant because of its maturity;
therefore, in spite of its more distant location, the fruit on the plant
farther away accumulated more ^-^Cs because of its fruiting stage. In
addition to this cause for the higher tracer levels in Tree 5, the
results may indicate a distribution effect of the respective plants'
root systems. The concentration in the fruit of Tree 5 compared with
that of Tree 2 was 0.015 percent. It is believed that this activity
was derived from plant-to-plant (root) transfer.
\


PERCENTAGE EQUILIBRIUM: (C/C ) x 100
89
Time: Days
FIGURE 31: RATE OF ACCUMULATION OF 134Cs BY BANANAS
FOLLOWING FOLIAR APPLICATION Musa kullan
TREE 3


115
circumvented the foliar barriers and the necessity for translocation
from the foliage to the inflorescence and then to the fruit. The axially
deposited fraction of the tracer needed only to be absorbed by the
inflorescence and translocated the short distance to the fruit. Also,
tracer that reached the axial was prevented from being washed from the
plant by the rainfall that occurred during and following the application
of the ^^Cs.
Relative to fallout following a Plowshare event, an important aspect
of these results is that the rate of accumulation in the bananas was
sufficiently rapid to allow *'^Cs to reach equilibrium concentrations
within one month. For comparison, the literature gave only one indication
of the time of accumulation to equilibrium of a nutrient in a fruit and
oo 27
that was concerned with J P in apples. Eggert et al. found that 30 days
after treatment of apple leaves 2 to 3 percent of the phosphorus in the
apples was P, and after only 14 days the tracer in untreated leaves
approached that in the treated leaves. Although the apple and banana are
two entirely different plants, the time to maturation of the respective
fruits is not very different. Therefore, the unit of days with respect
134
to the time of accumulation of Cs by bananas from the foliage is
reasonable.
The one reference to translocation rates from banana leaves after
foliar treatment was in regard to absorption of urea nitrogen. Freiberg
46
and Payne showed that in twelve days 22 percent of nitrogen applied as
urea translocated from the foliage to an untreated leaf 4.6 m away. This
provides a guide to the rates of metabolism and translocation of metabolic
products from the banana foliage since the nitrogen was incorporated into
products of metabolism prior to being translocated. Since urea and cesium


Counts per Channel in 15 Minutes
Channel Number (10 Kev/Channel)
FIGURE 26: SUB-SAMPLE TREATED BANANA LAMINA NaOH INSOLUBLE, HC1 INSOLUBLE PORTION
vj
oo


Counts per Channel in 60 Minutes (Thousands)
Channel Number (10 Kev/Channel)
FIGURE 19: STANDARD CONTAINING ROUGHLY EQUAL AMOUNTS OF 185W, 85Sr, 13tCs, AND 59Fe
Ui


43
LEGEND:
O: Denotes the location of banana plants.
D: Denotes the location of daughter plants.
X: Denotes a dead parent plant.
Notes: 1. Numerals are the numbers used to identify the banana plants
in the text.
2. Plants 1, 2, and 3 were the ones treated and sampled to study
the kinetics of -^^Cs movement to the fruit from the foliage.
Plant 4 and Plant 5 were sampled once at the end of the study
(126 days).
134
FIGURE 12:
Cs BANANA KINETICS EXPERIMENT SITE AND SAMPLE LOCATIONS


69
midrib, the "channeled" ribbing which separates the lamina halves and is
an extension of the petiole.) In Table 8 the axial is considered to be
from about 5 cm below the pseudostem top to about 8 cm out on each
petiole. The untreated banana leaf was the youngest leaf on the plant,
and it was still in a vertical position well above the four treated
leaves; thus, it could not have been directly contaminated. The lower
pseudostem was a section from about 30 cm above the ground. This part
was separated into interior and exterior portions on the basis of tissue
color. The central, white core was termed the lower pseudostem
(interior), and the exterior part was that which contained some green
pigmentation. The rhizome was the entire subterranean base of the
parent plant. The daughter plant was a new growth with five leaves and
was about 2 m tall. It was to one side and slightly to the rear of the
area below the treated leaves.
Generally, there was greater translocation of all the radionuclides
by the banana plant than by the palm. Cesium-134 was very mobile through
out the banana plant, and it particularly concentrated in the inflores-
cence and the fruit. The 4Cs concentration in the developing distal
inflorescence bract was four times greater than in the fruit.
Strontium-85 translocated to newly developing lamina tissue in the young
leaves of the parent and daughter plants. There is some indication that
59
Fe was translocated to the bananas and that the peels concentrated this
isotope relative to the banana pulp (see Table 8). The chemical separa
tion results did indicate the possible presence of -^Fe in the banana
pulp. However, this could have been slight contamination of the pulp
from the peels while separating the pulp from the peels of the green
bananas (which is quite difficult).