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UNITED STATES DEPARTMENT OF THE INTERIOR
FLORIDA DEPARTMENT OF NATURAL RESOURCES
MAP SERIES NO. 35, 1969 published by BUREAU OF GEOLOGY
I I I I
COLOR OF WATER IN FLORIDA STREAMS
Matthew I. Kaufman
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
A knowledge of the occurrence and distribution of color in surface waters,
from natural as well as man-influenced sources, is important to the understanding
and management of the quality aspects of Florida's water resources. The color of
water is significant for both domestic and industrial uses and is also related to
productivity and trace metal concentration in aqueous environments. Regional
differences of color in surface waters exist which can be related in part to natural
decomposition of organic material and in part to industrial and agricultural
influences. The occurrence and distribution of color in Florida streams and canals
is described herein, including sources, significance, regional distributions and
chemical associations, seasonal variations, and the relations of color to
SOURCES, NATURE, AND SIGNIFICANCE OF COLOR
Natural waters exhibiting a yellow to brown color are common throughout
many parts of the world. Waters of this type are often referred to as swamp,
humus, or colored water (Christman and Ghassemi, 1966). The color may be of
organic or mineral origin. Organic sources include humic materials (decaying
vegetation, tannins, peat), aquatic plants, etc. Inorganic sources are metallic
substances such as iron and manganese compounds, chemicals, and dyes.
Numerous industries discharge materials that contribute to the color of water,
including pulp and paper, textile, and refineries. Agricultural drainage and
returned irrigation water also contribute to color of water (FWPCA, 1968; McKee
and Wolf, 1963).
According to the Research Committee Report (1966), the effectiveness of
decomposition of organic in contributing to water color depends on the quantity
of material undergoing decomposition and the rate of decomposition. In tropical
and subtropical regions, the quantity of vegetation is abundant and the rate of
decomposition is high; thus rivers in the southeastern U.S., Central America, and
northern South America are highly colored. Black and Christman (1963a) noted a
linear relation between total organic matter and color value of water. The organic
macromolecules are similar to soil organic and the aqueous extractives of wood,
soil, and vegetation at various stages of growth and decay (Res. Comm. Rept,
1966; Christman and Ghassemi, 1966).
Most of the organic matter in naturally colored surface waters consists of
simple to complex mixtures of nonvolatile polymeric hydroxy carboxylic acids
(Lamar and Goerlitz, 1966; Lamar, 1968). Many of these acids color the water
yellow to brown, influence the pH of some stream waters, and account for the
acidic properties of organic color. These organic acids exist in water as negatively
charged colloidal sols which exert a holding action for a number of metallic ions
such as iron and manganese. This holding action has been referred to as
adsorption, bonding, complexion, and chelation. The negative charge has been
attributed by Black and Christman (1963b) to ionization of the carboxyl and
aromatic hydroxyl groups.
Color values are determined by the comparison method (Rainwater and
Thatcher, 1960). One standard color unit is produced by a solution containing I
mg/l (milligram per liter) platinum and 0.25 mg/1 cobalt. The color of a water
sample is compared with that of glass discs calibrated to correspond with colors
on the platinum-cobalt scale.
Both soil and water humics are capable of stimulating the growth of algae. Thus
water color plays a significant role in maintaining high primary productivity in
aqueous environments. The relation between water color and productivity
involves trace metal stabilization by the humics. In some instances, however,
where humics are highly concentrated they may severely limit organic
productivity because of absorption and reduction of photosynthetically active
light (Res. Comm. Rept, 1966). According to FWPCA (1968), color in excess of
50 units may limit photosynthesis and have a deleterious effect upon aquatic life,
particularly phytoplankton and the benthos. Slack and Feltz (1968) noted that
organic loading of a stream (due to natural leaching and decomposition)
contributed to dissolved oxygen depletion and that water color was inversely
related to dissolved oxygen and directly related to iron and manganese
concentrations. Low dissolved oxygen or anaerobic conditions resulting from
decaying vegetation are favorable for the reduction of iron to the soluble ferrous
species (Lamnar, 1968).
Color is aesthetically undesirable in waters used for domestic purposes and may
dull clothes and stain fixtures. The 1962 USPHS Drinking Water Standards limit
the color of acceptable water to 15 units. Most Florida streams exceed these limits
most of the time and would require treatment for removal of the color. Color is
undesirable in water for a number of industrial uses, with limits ranging from
0-100 units (McKee and Wolf, 1963). Humic derived color is also significant in
other aspects of hydrology. There is a possible role of humics in corrosion (lead in
particular is rendered soluble by water humics) and they may interfere with
coagulation of other constituents of natural waters, particularly with procedures
involving colorimetric analyses (Res. Comm. Rept., 1966).
REGIONAL DISTRIBUTION AND CHEMICAL ASSOCIATIONS
The distribution of maximum color values in Florida streams and canals is
shown on the large map. The values are time as well as space related and tend to
coincide with periods of high flow. The regional distributions and interpretations
are generalized (based on data from the early 1940's through 1966) and local
variations may be expected to exist Waters exhibiting considerable color include
those in northcentral and northeast Florida (associated in part with drainage from
Okefenokee Swamp in southeast Georgia), coastal areas east of the St. Johns
River, parts of central and eastcentral peninsular Florida, and those waters in the
environs of Lake Okeechobee. Frequency curves of color in selected Florida
waters in figure I show the range of values from regions of low color to regions of
high color. Table I summarizes regional differences of color in Florida streams,
utilizing streams and periods of record considered representative of the region.
Excluding streams affected by industrial and agricultural influences, most of
the highly colored streams in Florida have low specific conductance, are soft,
acidic (low pH) and contain appreciable iron. They are weakly buffered and thus
potentially corrosive. The color in these waters is in general derived from the
Chemical Characteristics Typical of Representative Waters with High C
Cow Cr. nr.
nr. St. Augustine
New R. nr.
lndian Prairie Canal
West Palm Beach
Canal at Canal Pt.
Date Pt-Co Units
pH Iron (Fe) asCaCO 3pmr
4.4 0.60 8
5/3/56 500 4.4 1.5 15
9/2/65 800 4.6 0.55 12
8/11-20/57 560 6.2 0.45 28
7/15-20/57 460 6.2 0.60 38
7/18/55 520 6.0 1.7 91
6/23/54 480 7.2 0.30 519 1
5/16/66 1400 8.2 0.23 96 2
natural decomposition of organic matter. The low pH relates to carbon dioxide
and organic acids produced during decomposition. The low conductance relates in
part to dilution coincident with periods of increased streamflow and in part to
many of the substances in solution being non-conductors. An inverse relation
between color and specific conductance is exhibited by some streams (figure 2).
Although no consistent statewide relation between color intensity and iron
concentration exists, some individual streams exhilit a direct relation (figure 3).
Lamar (1968) reported that filtration of natural surface waters through 0.1 pi and
0.01 u millipore filters removed progressively greater amounts of iron and organic
color. He concluded that a relationship existed between iron concentration, pH,
and the particle size of the organic colloidal sols.
Waters with high color in the environs of Lake Okeechobee have high specific
conductance, are hard, generally alkaline and contain considerable sulfate, nitrate,
chloride, and at times iron. The color is derived from the leaching of organic soils
that accompanies drainage and irrigation of agricultural lands. Color in the
Okeechobee area tends to increase with increasing mineralization (Hillsboro
Canal, figure 2), in contrast to many of Florida's streams. The pumpage of
drainage and irrigation waters into the canal at titr.e results in reversal of flow
direction from the normal situation in which water drains from Lake Okeechobee
toward the Atlantic Ocean.
Several streams in the state receive paper mill wastes and the receiving waters
then become highly colored, soft, alkaline, and highly mineralized. Selected
chemical characteristics of waters with high color are given in Table 2, noting
regional differences and environmental controls and emphasizing that properties
of a given colored water depend on its source.
VARIATIONS WITH DISCHARGE AND TIME
Streams, particularly those subject to large fluctuations in runoff, show
considerable variation in color. In general, increased color is observed immediately
following rainfall due to the initial flush of decayed organic matter into the
stream, with high color tending to coincide with periods of high flow (figure 4).
The effects of dilution with increased discharge following the initial flush, as well
as seasonal variations, contribute to the observed scatter.
Seasonal variations of color and pertinent correlations and interrelations are
portrayed in figures 5 and 6. Fluctuations in colo; values are concomitant with
fluctuations in discharge, irrespective of time of year, and are associated with
variations in iron concentration, specific conductance, and pH. These relations are
typical of those occurring in many of Florida's streams. In southeast Florida, as a
result of the leaching of organic soils that accompanies drainage of water from
agricultural lands, increased color values relate Sirectly to increased specific
conductance and at times to nitrate concentration (figure 7). The latter relation is
especially evident during October and late June to early July when peaks of
nitrate concentration are associated with rapidly increasing color values.
Seasonal variations of color in a number of Florida streams and canals are
summarized in table 3. Maximum color values prelominate during July through
October, coincident with the period of active decomposition and leaching of
organic matter and the flushing action of high mraifall and runoff. Minimum
values tend to occur in May and June(associated wth the period of plant growth,
little rainfall, and low flow) and also in December and January (associated with
the period when vegetation is dormant).
Black, A. P., and Christman, R. F.,
1963a Characteristics of Colored Surfice Waters: Journ. AWWA, v.
55, p. 753-770.
1963b Chemical Characteristics of FLevic Acids: Journ. AWWA,,v.
55, p. 897-912.
Christman, R. F., and Ghassemi, M.,
1966 Chemical Nature of Organic Color in Water: Journ. AWWA,
V. 58, p. 723-741.
1968 Water Quality Criteria Report of the National Technical
Advisory Committee to the Secretary of the Interior, 234 p.
Lamar, W. L.,
1968 Evaluation of Organic Color and Iron in Natural Surface
Waters: U. S. Geol. Surv. Prof. raper 600-D, p. 24-29.
Lamar, W. L., and Goeriitz, D. F.,
1966 Organic Acids in Naturally Colored Surface Waters: U. S.
Geol. Surv. WSP 1817-A, 17 p.
McKee, J. E., and Wolf, H. W.,
1963 Water Quality Criteria: State Water Quality Control Board,
pub. 3A, Sacramento, Calif., 548 p.
Rainwater, F. H., and Thatcher. L. L.,
1960 Methods for Collection and Aralysis of Water Samples: U. S.
GeoL Sure. WSP 1454, 301 p.
Research Committee on Color Problems
1967 1966 Report, Journ. AWWA,v. 59 p. 1023-1035.
Slack, K. V., and Feltz, H. R.,
1968 Tree Leaf Control on Low Flow Water Quality in a Small
Virginia Stream: Env. Sci. and Tech., v. 2, p. 126-131.
U. S. Geological Survey,
Quality of Surface Waters of tie U. S. 1940-63: U. S. Geol.
Surv. WSP 942, 950, 970, 1022, 1030, 1050, 1132, 1162,
1186, 1197, 1250, 1290, 1330, 1400, 1450, 1520, 1571,
Water Resources Data for Forida, Part 2, Water Quality
Records 1964,1965, 1966.
ec. Cond., Chemical
Occurrenets of Maximum and Minimum Color Values
in Selected Florida Streams and Canals by Months
Number of Occurrences
hos at 25C Type Remarks Month Maximum Color Minimum C
48 Ca,Mg,Na-Cl Swamp drainage January 0 8
February 2 5
72 Ca,Mg,Na-CI Swamp drainage March 8 4
April 7 4
66 Na-Cl Swamp drainage May 3 28 17
100 Ca,Mg,Na-Cl Swamp drainage + July [23 1
ground water inflow August 87 21 0
97 Ca,Mg-HCO3 Agric drainage + September 24 1
ground water inflow October 19 1
235 Ca-S04 Agric. drainage November 5 3
December 1 10
320 Ca-HCO3 Agric. drainage + 36 stations or, 32 different streams and canals during the
organic soil leach- period 1950-67. Maximum and minimum values occurred
ing; high SO4 more than oneo in the year at many stations.
400 Na-CI,HCO3 Receives paper mill
ST I I I I
PERCENT OF tIME COLOR EOU.LED OR EXCEEDED GIVEn vfLuE
Figure 1. Frequency curves ot color in
selected Florida streams.
sp-c,, ccoucr-nce o--os IT-c
Figure 2. Relation of color values to specific conductance in
selected Florida streams and canals.
0 PE95 R0Ve) NeAr A a.
Figure 4. Relation of color values to discharge in three
streams in N. Central and W. Central Florida.
I I I 00
0 J L] L L'
Figure 5. Seasonal variations of color,
discharge, and iron concen-
tration in two Florida streams.
No. Cent. Florida
No. East Florida
East Cent. Florida
West Cent. Florida
So. East Florida
Regional Comparisons of Color in
Selected Florida Streams and Canals
Streams/Canals Color, Pt-Co Units
Utilized Mean Range
A A '
DISSOLVED IRON (F ), MILLIGRAS PER L0TER
Figure 3. Relation of color values to the dissolved iron
concentration in three streams in N. Central and NE Florida.
Figure 7. Seasonal variations of specific conductance,
color, and nitrate concentration, Hillsboro Canal at
Shawano. SE Florida, 1950-51.
Figure 6. Seasonal variations of discharge, color, ron
concentration, pH, and specific conductance, Manatee
River near Bradenton, W. Central Florida, 1964-65.
MAXIMUM COLOR OF WATER IN FLORIDA STREAMS
(COLOR UNITS, PLATINUM COBALT SCALE)
WATER QUALITY DATA STATIONS, FLORIDA STREAMS
U. S. GEOLOGICAL SURVEY 1940 66
Minimum of 4 yrs. bimonthly, or at least 20 complete
analyses, all flow conditions.
Minimum of 2 yrs. semi-annual, or at least 5 complete
analyses, all flow conditions.
Annual, 1 to 4 complete analyses, generally represents
low flow conditions.
A Daily specific conductance station, minimum record
1 yr. IV)
FLORIDA GEOLOGIC SURVEY MAP SERIES
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