ANALYSIS OF DIURNAL OXYGEN CURVES
FOR THE ESSAY OF REAERATION RATES
AND METABOLISM IN POLLUTED MARINE BAYS
"Waste Disposal in the Marine Environment"
Periamnp Press, 19(l
ANALYSIS OF DIURNAL OXYGEN CURVES
FOR THE ESSAY OF REAERATION RATES
AND METABOLISM IN POLLUTED MARINE BAYS
HOWARD T. ODUM*
Institute of Marine Science, The Uni-
versity of Texas, }'ort Aransas, Texas
Many of the biologic al and chemical events in marine estuaries are sup-
Plit' with energy, through a 'd~aly pulse of pjiC.s. ,ii,.:.ic- and respiratory
1etabohi n. Both of these types of metabolism are inter.ie pe- del nt chemi-
::allU, lnked through physical patterns of circulation. Such systems contain-
nr photOSynthesis, circulation, and community respiration are termed eco-
Ristuarine ecosystems are of an import-export type in which the relative
Atflats of inflow and outgo of organic matter and raw materials control the
Bgtre of metabolism. Imports of organic matter favor respiration whereas
b lBts of regenerated inorganic raw materials stimulate photosynthesis.
When rnan modifies the estuaries by adding substances or c Ea-. iink rates
icirculahtjn, he profLjridl.d; affects the entire metabolism and the relative
etOu,"e of photosynthesis and respiration. Consequently measurements of
t overall phltoi s .',',rii- -' and community respiration are a p rint i .-ial means
"the estimation of overall E..oill:nrn rI'li.i i. Since the mir-t ibohL uptake and
e1aee of particijlar chemical elements bears a definite relation.;.i to the
4'Yallcarbon synthesis and regeneration, metabolic rate measurements
A't al&Q be used to obtain rates of cycling of elements for predicting fates of
a~inacttee pro ll..a te .
This Paper some methods for the assay of total estuarine metabolism
vtiped ii rn-n-p:illul,... waters are extended to some p)Oilluiite estuarine
*. a Ti.e amount of total metabolism in the ecosystem, the relative role
ltt oriv 'th bi and respiration, the role of export and import of organic
bt and the exchange of gases with the a:mosphr.l:- are re a :-.:1 measured
t .- "' t'' a-,, som e Eiluiio,-, types. Several t'; iLt-, types of p Ill,,t....
sm are described.
:1 Li. [i L )S
tiri rmeasurernrents of dissolved .-. L:rL and carbon-dioxide by the pH
reth nade in estuarine waters every three hours with various replica-
other special means for es ti n.atin overall representive of large
Sreaearch assistance of Mr. Gonzalo Garza.
estuarine areas and l- arg water masses. Then hiarlv rate of change gra
are constructed :or oxygen and carb.n- l*oi..*:. From these curves are
estimated rates of gross photosynthesis, total community rcipiration anr
gaseous exchange with the ;at no.phere. The derails of t'-%e methods at,-
tions, variations, and applications to estuarine waters are given in previous
p'uit.ih.at:orns (Odumr, l',t, : CO.ltLn and HEoskin, 1958; Park, Hood, and Odur,
1i.6; and Beyers and Odum, 1959).
Some of the results of pr*. .vi.ius studies may be summarized as folloai
for 'rnpolluted estuaries.
CONCLUSIONS i-P.RO.1 lR E VO11l .S T [UDIE S
1. Gross photosynthesis and total community respiratory metabolism
general range from 1 to 60 gm / .12 / day oKygen.
2, In shallow systems less then 3 meters in depth, bottom respiratory
metabolism is usually greater in magnitude than the metabolism of thi water
with its plankton. In very shallow waters less than 0.5 M in deptl, bottoa
photosynthesis and respiration may exceed mrctbol srmr in th;c water by 100
3, High metabolic rates are associated with hijh circulation rates,
4. The reaeration constant for estuaries and streams is about 1-2 gm
oxvyen / M2 / hr for 0.2 atmosphere o'cv..n gradient between water and air.
Lower values are found in still and partly stratified waters. higher values
are found where currents are large and wave action great.
5. In some environments metabolic estimates from carbon-dioxide data
are Fruch larger tlian estimates from oxygen curves on a strnilacr molar
basis. This discrepancy may be due to nighttime anaerobic nietaboli5r
followed by aerobic daytime recovery.
6. Because of the small partial pressure of carbon-dioxide in the atmno*
here of the order of 0.0003 atmospheres, diffusion ol carbon-dioxide Irin"
air into the water is very slow. On the other hand the diffusion of carbo-b
dioxide out from a supersaturated system may be as rapid as diffusion Of
oxygen. A diurnal fluctuation from siupersaturaei on to undersatluraion 1 ay
pump out carbon-dioxide.
7. Total community respiration closely follows total plotoy-vI.hesi duir
ing the rise and fall of metabolism during a year in stabilized systCems
consumers are regulated so that their life cycles and energy requirement
are in phase with the pulse of energy from the sun or from import.
8. Streams and estuaries receiving large river flow have an excel'
r a spi ration over photosynthesis apparently due to the rateof import olorbb
matter from the land run-off. Loss of photosynthe.is withincreasing tjrbido
of systems receiving runoff is partly compensated for by extra importtalOy
or organic matter associated with turbidity. System with large irmpo$ stn
have higher total respiratory metabolism than fertile photosynthetti Sig
u. Coral reefs and shallow grass flats are among the most fertile marine
10. Because of uncertainties about the r. ,-liti of neasuramenets in bottles
~d because of the large role of current and bottom metabolism in estuaries,
where apF'pLic.uL the diurnal measurements in free water are preferable to
measurements of BOD and bottle metabolism.
11. The diurnal curve methods cannot be easily used in many estuaries
where there are complexities of vertical stratification and c' ar eirnL tidal cur-
rents, which prevent the observer from readily obtaining average v.il.-t-s for
whole water masses. Many estimates of metabolic rate from diurnal curves
tend to be underestimates.
In most of the studies carried out so far, measurements have. been rhade
by observers in the field in small boats at all times of day and night. Some
recent measurements have been taken with a pi lot model of a buoy developed
by Joe Glover and George Creedle which take samples in glass stoppered
'itOles in a refrigerated chamber every 3 hours. The buoy contains a storage
battery, atimer, and solenoid switches for alhin -rji bottles to fill by gravity
'11-rugi valves opened at time intervals. Samples are removed from the buoy
aUthe end of a 24 hour period for Winkler analysis or pH determination.First
prellim~narl, tests r n r.parin measurements in the buoy with those outside the
buoy indicate satisfactory agreement in waters where bottom- metabolism is
4"IMniant. The buoy is manufactured by Texas Scientific Equipment Corpora-
eaOBox 4367, Austin 51, Texas.
DIURNAL OXYGEN CURVES FROM POLLUTED WATERS
In Figures I and 2 are shown two extreme examples of the diurnal oxygen
raphs for some waters known to be highly influenced by pollution. In each
Ares are curves of per cent saturation,-.., iti rate of change, and corre:-
an oxygen rate of change where the gaeos e.....i.arie withthe atmosphere has
*aI U btracted, In the corrected i:rap-. .xALe.:r, believed to be diffusing out is
r'te~ ed and 'j',ten believed to be diffusing in is removed. The corrected
ithe ':' graph is the oxygen rate of change that might have been obtained
ay were covered with a plastic layer.
A CASE rF LA-PGC EXCESS OF PHOTOSYNTHESIS OVER RESPIRATION
In :., Oso Bay near Corpus Christi, Texas (Figure 1), treated effluent
*y. estic .*s,. provides a rich nutrient medium to a shall encrn~oed
t~ahle a algal growths develop along the lateral mud flats causing a local
'"l of th Odors in residential districts nearby. The summer diurnal
traiio Yget analyzed in Figure I is distinctive. The oxygen remained ow0r
P lor, the entire day and night indicating great excess of photosynthesis
nuhe iesPiration (R). Such ratios of P and R do accur in nature in non-
Wlante ar in northern waters in the spring of the year, but such great
a o P and R has not often been found in non-polluted Texas waters.
S Ie,,,1' e condition of the estuary is similar to that in alal cultures
SWhere cells are maintained in rapid gro-th and high P FP. ratio by
55 OSO BAY JulIE 30, 19'9
0.6 M 22 %.
02 0- 0
0 6 12 1 oo00
P= 6.8GM/Ma / \ K;I OGM./M/HP.
FhE + DAY/ \ AT 0% SAT.
04. Nk2ATE OF CHANGE -
R= 24 GM/Mt DAY t^
Diurnal Curves of Oxygen, per cent oxygen saturation and
rate of change of oxygen in a bay receiving treated sewage
effluent (03i Bay near Corpus Christi,Texas). The dashed
curve is the diffusion corrected curve as calculated --'th
an aeration coefficient corn-pulte with the formula
K 100 where Q in the rate of change
at a time at night and S is the satu ration deficit in per cent
at the same time of night. The amount of dotted area is
orniptEc as the total gross photosynthesis of the system.
The excess of photosynthesis over respiration and the re-
sulting aJ];;J problem are a pollution resulting from over
lt rli Il .',Lion.
COC. JS CH-'?"I 0 JULY13, i'S1
4- TU:-, '0.- e- iN r o
3- 35 %\
00 6 0
oi c Fig. 2.
etal rveaBs of olygen, per cent oxygen saturation, and rate of change of
tmt a bay rec ei ing multiple organic effluents. The dashed curve has
~ Cle It ated from the rate of oxygen change curve using an aeration co-
e4t b eeved to be maxmrn- possible (from other data). The residual
pivat tfAed) indicates the corse of ntght respiration. Morning and evening
at to Lrave "tecr :connected with a straight line to outhne the h vpothetical
a t t~L t et day-trne community respiration usLed in computations. The
el.tGs re'ip ratfon over photosynthesis and the resLiltrig anaerobic
e a pollution resulting from excess organic import.
----; _I ..
frequent renewal and turnover of medium (Ludwig,OOswald,Gotaas andLy
1951). Equally high values of photosynthesis are found in many non-pollutea
Texas bays, in tropical grass flats and reefs in Puerto Rico. and in othe
naturally fertile waters.
In the Oso there is little water exchanges with other bays and there ate
changeable temperature and salinity conditions which interfere with colori
tion by ordinary marine consumers. Thus the production by algae is not ca.
surned as readily as normally but remains to be deposited on the mud flataia
a nuisance. Respiration did not balance photosynthesis in the central watD
area. If such conditions persist one might recommend measures for allow
re-entry of normal consumer food chains with more fishing as abeneficialb.
product and less odoriferous, microbiological consumption on the margin,
Considerable insight as well as quantitative estimation of rates are thus pro*
vided by the diurnal analysis of such a pollution situation.
Application of the formula for reaeration constant derived from sinnltan.
eous equations as described earlier (Odumn and 4Hoakin, 1958) yieldedK-0.90
gm/M2/H for 05 saturation. The formula may be used wherever it may be
assumed that respiration is fa rly constant,
A CASE OF LARGE EXCESS OF- RESPIRATION OVER PHOTOSYNTHESIS
In the boat harbor of Corpus Christi, Texas, there are a great many
sources of organic matter entering the water from municipal and industrial
sources. Imports also include nutrients capable of stimulating photosynthe-
sis. In Figure 2 is shown the diurnal oxygen curve in the surface waters of
a portion of the upper end of the harbor,
In the ship harbor, in contrast to the curve from the Oeo Bay. oxygenis
undersaturated throughout the day and night indicating a great excess 0a H
over P. In this case oxygen is entering the water at all times, but more
rapidly at night. There is a strong pulse of photosyrithesas during the day
which is as large as that in most ordinary bays. Unlike most nearby bayls
however, there is a very great total respiration (35 gm/M2/day). The
analysis provides an estimate of the actual in. situ metabolism wilthut the
complexities of bottles, dilutions, and assumptions. In waters of Corpu
Christi Bay outside of the polluted basin, metabolic values were much sll
(about 3 grm/M2/day) as estimated with a similar diurnal curve analysis.
DIURNAL VARIATION OF rESPIRATION
In the analysis of Figure 2, the usual procedure of determiing the re*0
aeration coefficient from the diurnal using computations with simultatmne
equations was not carried out, because it was obvious that there was able
great change of respiration rate during the night Instead, a reason
value for reaeration in an enclosed harbor was assumed from previously-
lished studies as 0.8 gm oxygen/M /hr at 100?, saturation deficit. Bec'e<
gthe relatively deep water (2.7 M) the diffusion correction was relatively
all, A dashed line was drawn sunrise and sunset points to indicate the
.ioible daytime course of respiration rate.
Although it is fully realized that respiration of plants, microorganisms
d anrmalj varies markedly with the time of day, data are not yet adequate
I generalize for ordinary bays as to the relative magnitudes at different
jisa of day. Thus in previous publications constant night respiration was
ihunmed as a first approximation in order to pe rnit computation of reaera-
itorates. In curves of carbon-dioxide where diffusion is minor, consider-
Ile variation of carbon-dioxide metabolism was noted during the course of
the night (Park, Hood,and Odurn, 1959). In Silver Springs (Odur, 1957)
oime increased respiration was observed in late evening in comparison to
that at dawn.
in environments low in oxygen like that in Figure 2 the variation of com-
minity respiration can be recognized readily as the oxygen concentration
drops below one mg/liter~ Many srudies have shown that when oxygen falls
below one rg/liter, metabolism of consumers is diminished. For a whole
after it is obvious that oxygen metabolism must cease when the system runs
antof oxygen. In Figure 2 it is clear that oxygen has become limiting after
dark and respiration diminished. Anaerobic respiration undoubtedly proceeds
i ught to be partially equilibrated in the following day. Accelerated oxygen
respiration in the morning thus may counteract ph-otos nTtheesi.
&Sch oscillatory systems cannot support consumers but only specialized
piles capable of alternating aerobic and anaerobic metabolism,
The overall effect of pliltcosynthesis coincident with the great respiration
iltchange the form of organic matter. Organic pollutants are replaced
fgst as fast as they are oxidized. The curve in Fiiure 2 is not unlike some
i4 eWage lagoons. The diurnal curve provides an hourly picture.
hi neither Figure 1 nor Fiiur 2 was photosynthesis or respiration
lashed by a pollution situation although the two were less in balance than
Sn nearby non-polluted waters. Where a pollution is directly toxic to
cit may be expected that :hF. re will be little appreciable diurnal oxygen
b Thus if light, nutrient, and organic matter levels are high but meta-
iTs ot sorne toxic type pollution may be recognized. So far this toxic
tPot tion has not been encountered in our studies of the estuarine waters
DIURNAL CURVE ANALYSES AT OT I R POLLUTION SITES
.rrnL8urves brought to us by Mr. Bill tRernrow of the Texas Game and Fish
F .',, oat a marine bay,Clear Lake on Galveston Day when analyzed had
'" 19"'l values not dissimilar to those in Figure 2. At Seabrook on August
S. 5i at 28-32 deg. C, and salinity 14.6 PPT gross photosynthesis was
/day and total respiration 8. 2 gm/M /day. In water 1 M deep the
reaeration coefficient was 0. 2 grn/M /hr/O 2 atmosphere saturation deficit.
The oxygen was below saturation all day indicating the excess of respiration
over photosynthesis over a day spar-. On June 26-27, T, in salinity 7 0
10 PPT photosynthesis was 7.9 gm/M /day and respiration was in excess a
16.1 gm/MZ/day. Reaeration was calculated at 1.4 gmr/M2/hr/,0. atmos.
here saturation deficit.
In the Mission River at its estuarine end on Copano Bay there is a dig-
charge of a saline river water much affected by underground brines released
by oil wells (bleedwater). The stream at times is rich in algae as might be
expected where waters are stimulated with nutrient influx. The situation is
complicated by municipal waste effluents and small runoff in dry years. A
diurnal curve analysis by Mr. Charles Hoskin at two stations August 8-9,
1957 resulted in metabolic values from 8 to 16 gm/M /day with respiration
in excess of photosy;.the si and all curves undersaturated throughout the day.
Such patterns are not unusual where there are land drainages. Man's role
in contributing to the moderately high metabolism is hkely to be complex
in this river system.
One of the most drtailc apphclirtons of the diurnal oxygen studiestopar-
tially polluted waters was made by Mr. Charles Hoskin in his masters thesis
(Hoskin, 1959) on the Neuse River in North Carolina. Hoskin found all sta-
tions with an excess of respiration over photosynthesis. Some of his statioal
were unaffected by myan, draining forest lands. Others were heavily pollursa
with very large metabolic rates. The runoff of organic matter from a'ri-
cultural fields and deforested lands increases respiratory metabolism of maa
streams. Such runoff is a type of pollution due to man's activity.
It is thus not easy to -spara'e mTietabolic effects of pollution from 6soc
kinds of natural irfluxes, for natural metabolic systems exist of the tyPe*
found in polltion. For example, diurnal curves made in the swamp wat*
of North Carolina such as in Srngletary Lake,Bladen County, North Carolin
(C. M. Hoskin, March 15-16, 1957) have only respiration and diffusion d1"
out photosynthetic pulse. The source of organic matter is the brown gswam
substances which color the lake waters. Respiration of Z. 2 gm/M2/day i
due to a natural organic matter import. Nutrients are very low and photOs'Y
thesis was not measurable.
Thus measurements of bay metabolism indicate that the types of mnes-
bolism which result from organic pollution fall within the range of extreir
metabolic conditions known in nature. The range of metabolic value i"
estuaries is similar to tl.ose in streams.
Beyers, R.F. and H.T. Odum n1959). The use of CO2 titrations to cai bra
pH curves for estimation of primary production; Limnal and Oceanog'
Vol. 4, pp. 499-502.
icn, G. M. (195~7), Oxygen Metabolism in North Carolina Waters
ubl, Inst. Mar. Sci. Texas, Vol. 6 (in press).
udlg, ,HF., W.J. Oswald, H.B, Gotaas and V. Lynch (1Q51),
Mgse iribiosis in oxidation ponds. L. Growth Characteristics
of Eugla gacili cultured in sewage. Sewage and Industrial
wantl, Vol 23, pp. 1371-1355.
Odum, H.T. (1'56}. Primary production in flowing waters.
Iinology and Oceanrography, Vol. 1, pp. 102-117.
(1957) Trophic structure and productivity of Silver Springs,, Florida.
ecol. Monogr., Vol. 27, pp. 55-112.
Jdtm, H.T. and C.M. Hoskin (1958). Comparative Studies on the
Metaboliam of marine waters. Publications Institute of Marine
Science Texas, Vol. 5, pp. 16-46.
P't, K., D.W. Hood and H. T. Odurn (1',5i),. Diurnal pH variation
iW Texas Bays, and its aFiilication to primary pr- .du, [ion estimation.
Publications Institute of Marine Science Texas, Vol. 5, ipp. 47-64.