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thesis entitled

COMMUNITY METABOLISM.IN THERMALLY
AND ORGANICALLY ENRICHED WATERS
OF WESTERN LAKE ERIE

presented by

Charles C . Warner

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of the requirements for

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COMMUNITY METABOLISM IN THERMALLY
AND ORGANICALLY ENRICHED WATERS
OF WESTERN LAKE ERIE

By

Charles C. warner

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Fisheries and Wildlife

1980

64/6705}.

ABSTRACT
COMMUNITY METABOLISM IN THERMALLY

AND ORGANICALLY ENRICHED WATERS
OF WESTERN LAKE ERIE

3?

Charles C. warner

Cross primary productivity and community respiration were measured
in western Lake Erie in the vicinity of the Monroe Power Plant to assess
the impact of the once-through cooling system waters on the aquatic
ecosystem. Samples were collected from lake and river source waters;
the discharge canal, where water temperature increased 6 to 10 C after
passage through the condensers; and the thermal plume. Data were col-

lected monthly from.May 1970 to June 1971 for preoperational estimates

. and from June 1971 to September 1975 for postoperational estimates.

The entrainment of the water mass through the power plant usually
resulted in a depression of the productivity in the discharge canal
waters. Corresponding community respiration rates almost doubled as
predicted by temperature elevations. Despressed productivity recovered
partially moving through the canal, and a slight stimulation occurred
as ambient temperatures were approached in the thermal plume. Respira-
tion rates decreased with water movement through the canal and into the

lake as ambient temperatures were reached.

ACKNOWLEDGEMENTS

I wish to thank Dr. R. A. Cole for his help throughout this study
and his early criticism and suggestions in preparation of this manuscript.
Appreciation is also expressed to my graduate committee members:

Dr. N. R. Kevern, Dr. T. M. Burton, Dr. C.D. Menabb, and Dr. F. M. D'Itri
for their contributions and prompt review of the manuscript. The
assistance of fellow graduate students, especially B. Adams, D. Lavis,
and S. Kilkus, with the field work will always be pleasantly remembered.
I would also like to thank T. Ecker and C. Annett for the use of their
chemical data and J. ijcik for additional primary productivity data.

I am extremely grateful to my wife, Joanne, for her constant encourage-
ment and patience.

Support for this study was made possible through Detroit Edison
Company and United States Environmental Protection Agency contracts with
the Institute of water Research and Michigan State University, Department

of Fisheries and Wildlife.

ii

TABLE OF

INTRODUCTION ,

DESCRIPTION OF THE STUDY AREA , , ,

Western Basin of Lake Erie

RaisinRiver

The Monroe Power Plant

Sampling Locations . , , , ,
The Detroit Edison Sites
The USEPA Sites

METHODS AND MATERIALS , , , , , , ,
The Detroit Edison Sites
Field Procedures
Nutrient Analysis
The USEPA Sites .
Data Analysis

RESULTS AND DISCUSSION - . - . . . .

Gross Primary Productivity
Depthuvariation
Diurnal variation , .'. .
Annual Variation by Season
Temperature Effects , . .
Suspended Solids Effects .
Nutrient Effects

Respiration . . . . . . . . .
Depth Variation
Diurnal Variation . , .
Annual Variation by Season
Temperature Effects , ,
Gross Primary Productivity

CONTENTS

Effects

Gross Primary Productivity/Respiration

CONCLUSIONS
LITERATURE.CITED

APPENDICES , ,

iii

Page

oooooouunb #

10

10
12
14
14

15

15
15
17
21
26
30
35
41
41
41
41
48
50
SO

55
60

63

Table

10

11

LIST OF TABLES

Daily, seasonal, and annual mean GPP and respiration
in g C/m2 by station for the Detroit Edison sites . .

Relative proportion of Raisin River and additional
Lake Erie water pumped through the discharge canal. .

Mean gross primary productivity at the USEPA sites
for cool (Nbvember-April) and warm (May-October)
months of 1973-75 (mg 0 2[liter/hour) . . . . . . . .

Seasonal and annual mean concentrations of suspended
solids in mg/l by station for the Detroit Edison

Sites 0 O O O O O O O O O O O O O O O O O O O I O O 0

Compensation depth (1% light) measured at the Detroit
Edison stations, 1973 and 1974 . . . . . .-. . . . .

Alkalinity, pH, and free 002 concentrations during
19 71 and 1974 O O O O O O O O I O O O O O O O O O O 0

Mean respiration rate for the USEPA study sites for
cool (NOvember-April) and warm (May-October) months
of 1973-75 (mg 02/liter/hour) . . . . . . . . . . . .

Seasonal and annual mean concentrations of total
organic carbon in mg/l by station for the Detroit
Edison 8 1 tea 0 O O O O O O O Q 0 O O O O O I I O O 0

Seasonal and annual mean oxygen concentrations in
mg/l by station and depth for the Detroit Edison
Sites 0 O O O O O O O O O O O O O I O O O O I O O O 0

Seasonal and annual GPP/R ratios by station for the
Detroit Edison sites . . . . . . . . . . . . . . . .

GPP/R ratios for the USEPA study sites for cool

(November-April) and warm (May-October) months of
1973-75 a o e o o o o o o o o o o o o o o o o o o o 0

iv

Page

24

28

29

31

33

39

44

46

47

52

. 54

Table

12

Comparison of productivity measurements in
western Lake Erie, 1962-1974 . . . . . . . . . . .

APPENDICES

Al

A2

A4

A6

Sampling dates for the Detroit Edison study sites,
19 70 through 19 74 O O O O O O 0 O O O O O O O I O 0

Sampling dates for the USEPA study sites, 1972
through 1 9 7 s O O C O O O I O I O O O O I O O I O 0

Mean gross primary productivity and respiration in
mg 02/l/hr for the Detroit Edison study sites . . .

Mean suspended solids, total nongaseous nitrogen,
total soluble phosphorus, and total organic carbon
concentrations in mg/l by station for the Detroit
Edison study sites . . . . . . . . ... . . . . . .

Mean temperature (C) by station for the Detroit
Edison study sites . . . . . . . . . . . . . . .

Mean gross primary productivity and respiration in
mg 0 /l/hr and temperature (C) by station and date

in t

fig

cooling system for the USEPA study sites . .

Page

58

63

64

65

71

75

80

Figure

LIST OF FIGURES

Page
Map of the study area in relation to western Lake Erie . 7

Map showing the vicinity of the Monroe Power Plant and
sampling locations in the cooling system. Locations of
stations 15 and 16 are from samples obtained in the

thermal plume which. altered position with wind changes . 9

Depth profile of mean annual gross primary productivity
at the river, lake, and discharge canal stations, 1970
through 1974 O O I O O O O O O O C O I O O O I O I O O O 16

Diurnal mean gross primary productivity at the river,

lake, and discharge canal stations on 1 July 1970 (,0).

26 August 1971 (A), 1 June 1972 (D), and 18 June 1974

(.. ) O O O O O O O O O O O O O O O O O O O O O O O O O O 18

Effect of incubation time on gross primary productivity
(.26 June 1974 (.0) and 22 August 1974 (A)) and respir-
ation (_26 June 1974 (O) and 22 August 1974 (A)) at the
lake station . . . . . . . . . . . . . . . . . . . . . . 19

Mean gross primary productivity (:0) and mean respiration
(A) at the river, lake, and discharge canal stations,
1970 through 1974 O O O O O C O O O O O O O O O O O O O 22

Mean surface gross primary productivity compared to
temperature for the combined spring and fall season (0)

and summer season (0) at the river, lake, and discharge
canal stations, 1970 through 1974 . . . . . . . . . . . 27

Mean depth of 12 surface light compared to mean suspended
solids concentrations at the river, lake, and discharge
canal stations, 1973 and 1974 . . . . . . . . . . . . . 34

Mean gross primary productivity at 0.5 m compared to

mean suspended solids concentrations at temperature
intervals 8-13 C (,0), 14-20 C (A), 21-27 C (D),

and 28-35 C (O) at the river, lake, and discharge

canal stations, 1970 through 1974 . . . . . . . . . . . 36

vi

Figure

10

11

12

13

14

15

Page

Total nongaseous nitrogen concentrations compared to

mean surface gross primary productivity for April-May

(O), June-July (A), August-September (D), and
October-November (O) at the river, lake and discharge
canal stations, 1970 through 1974 . . . . . . . . . . . . 37

Total soluble phosphorus concentrations compared to

mean surface gross primary productivity for April-May

(O), June-July (A), August-September (D), and
October-November (, O) at the river, lake and discharge
canal stations, 1970 through 1974 . . . . . . . . . . . . 38

Depth profiles of mean annual respiration at the river,
lake, and discharge canal stations, 1970 through 1974 . . 42

Diurnal mean respiration at the river, lake, and dis-
charge canal stations on 1 July 1970 (A), 26 August
1971 (0), 1 June 1972 (O), and 18 June 1974 (A) . . . 43

Mean respiration compared to mean temperature for

March-May (,0), June-July (A), August-September (O),

and October-November (x) at the river, lake, and

discharge canal stations, 1970 through 1974 . . . . . . . 49

Mean respiration compared to mean gross primary pro-
ductivity at temperature intervals 8-13 C (O) ,

14-20 C (A), 21-27 C (,0), and 28-35 C (D) at the

river, lake, and discharge canal stations, 1970 through

1974 . . . . . . . . . . . . . . . . . . . . . . . . . . 51

vii

INTRODUCTION

The effects of thermal effluent on the aquatic environment are of
great interest as the demand for cooling water may increase as much as
10 fold in coming decades (Denison and Elder, 1976). Because of favor-
able economic considerations, power plant designers prefer to locate
their sites on large bodies of water to take advantage of once-through
cooling. Cole (1973) has estimated that by the year 2001 as much as
352 (120 km3) of Lake Erie's water volume could be used annually for
cooling purposes. As the amount of waste heat into Lake Erie increases,
the potential for changes in the phytoplankton population exists. This
paper describes the impact of the once-through cooling system at the
Monroe Power Plant on the algal community along the western shore of
Lake Erie.

Being the primary producers of the aquatic community, any signi-
ficant changes in the phytoplankton populations could influence the rest
of the food chain. Algal community metabolism include two functions:
gross primary productivity (GPP) and respiration (R). Gross primary
productivity is the fixation of carbon resulting from the metabolic
activity of the primary producers. The phytosynthetic process also
produces oxygen which can be measured to quantify the amount of carbon
fixed. Community respiration measures all of the oxygen used by
respiring organisms to oxidize organic carbon to carbon dioxide. The

ratio of gross primary productivity/respiration (GPP/R) can be used as

an indicator of the movement of organic material through the system.

If the ratio is greater than 1.0 the community will gain biomass, where-
as a ratio less than 1.0 implies a decrease in organic material through
decomposition.

Primary productivity is regulated by a combination of factors
including light, temperature, available nutrients, toxins, and the bio-
mass of the phytoplankton populations. Community respiration is regulated
by the abundance of living organisms and an organic substrate to support
them. The rate of respiration is influenced by biomass, temperature,
nutrient availability, and oxygen concentrations.

The entrainment of phytoplankton populations through the cooling
systems of power plants exposes them to an increase in temperature. °
After passing through the condensers, where they are subjected to mech-
anical damage and thermal shocking, the phytoplankton enter the receiving
waters. Possible stimulation or inhibition of their metabolic rates may
occur, depending on the ambient water temperature (Morgan and Stross,
1969). Power plant operation may also effect rates of respiration and
productivity by changing the light penetration, changing nutrient avail-
ability, both as a result of mixing two different water masses, and
exposing populations to chlorine.

The discharge canal area could be a suitable environment for
high GPP/R values resulting in an export of biomass into Lake Erie
waters. This may have a potentially harmful impact upon the receiving
waters, as the decomposition of phytoplankton may require large amounts

of oxygen, decreasing concentrations available for aerobic organisms.

The purpose of this research, as part of a comprehensive ecological

study, was to measure the community metabolism of the near shore western

basin of Lake Erie and evaluate the possible effects of the Monroe Power
Plant. Gross primary productivity and community respiration of organ-
isms entrained through the cooling system were measured to determine
possible changes in the water quality Of the thermal effluent and its
impact upon the receiving waters. This research also considered changes
in the near shore water quality. The eutrophication of Lake Erie has
been studied extensively in recent years (Davis, 1964; Verduin 1964,
1969, and 1972; Arnold, 1969; and Vbllenweider et‘al., 1974). Recent
improvements in municipal and industrial sewage treatment have provided
higher water quality effluents to the lake resulting in a slowing of the
eutrophication process. The western basin, with a rapid flow through
time of about two months (Verduin, 1964), may recover faster than other
parts of Lake Erie. The evaluation of these changes, along with the
impact of power generating plants, is essential in providing information

on which to base future management decisions.

DESCRIPTION OF THE STUDY AREA
Western Basin of Lake Erie

The western basin of Lake Erie covers about 3100 km2 and has a mean
depth of about 7 m. A.chain of islands separates it from the rest of
the lake which has a mean depth of 19 m.(Beeton, 1971). The shallow
near shore western basin is generally vertically mixed both thermally
and chemically (Marcus, 1971; Kreh, 1972; Ecker, 1976; and Annett, 1977),
but under proper conditions it may stratify (Carr et al., 1965). The
action of seiches, generally less than 1 m but occasionally 2 m, occurs
twice daily. The wind generated water movement results in the thorough
mixing of the water column and high trubidity from the resuspension of
sediments. These suspended solids are largely the result of agricultural
disturbance in the watershed (Cole, 1972).

The western basin receives about 95% of its water from the inflow
of the Detroit River, about 2.5% from the Maumee River, and less than
0.52 from the Raisin River. The prevailing southwest wind and inflowing
Detroit River water are responsible for the clockwise movement of water
in the southwestern corner of the western basin (Kovacik, 1972). The
western basin receives about 902 of the total water discharged into
Lake Erie, but occupies only about 52 of the total lake volume. The
water quality of the western basin depends almost entirely on that
of the incoming water, because of its rapid flushing rate. The Detroit
River is the largest contributor of nitrogen and phosphorus into the
basin (Barlow, 1966). However, the Maumee River contributed about 252
of the phosphorus in the basin in the 1960's (FWPCA, 1968), which is much

greater than expected from discharge rates.

Raisin River

The Raisin River also had a strong impact on the study site since
much of the power plant intake water came from it, even though the
volume contribution to Lake Erie was extremely small. The lower Raisin
River is dredged annually by the U.S. Army Corps of Engineers to remove
accumulated sediment. It was highly polluted with municipal and
industrial wastes until recently (1972). Anoxia was very common in the
summer throughout the water column, but recent modifications to the
Monroe sewage treatment plant improving the quality of the effluent have
lessened the harmful effects. Two paper companies contributed much of
the biodegradable organics while a chrome plating plant added various

metal ions to the effluent.
The Monroe Power Plant

A 3200 megawatt coal fired steam electric generating station util-
izing once-through cooling is operated by the Detroit Edison Company
at Monroe, Michigan. The first of four units came on line in June 1971.
Subsequent units were added annually with the final unit completed in
the spring of 1974. Following initial start up, there were numerous
operational problems resulting in varying power production levels and
heat discharge into the lake. However, the pumping rate of the cooling
water remained fairly constant, initially about 22 m3/second and increas-
ing with the completion of additional units to 85 m3/second with all
units in operation. There has been considerable variation in the elevation
of the cooling water temperature as it crosses the condensers, having a

maximum increase of 11 C and an average of 7 to 8 C.

The power plant is located on a filled portion of the Raisin River
delta on the western shore of Lake Erie (Figure l). The intake of the
once-through cooling system is located in the river about 1 km from.the
mouth. When the pumping rate of the power plant exceeds the discharge
rate of the Raisin River, additional water from Lake Erie provides the
difference by inflow through the river mouth. The Raisin River discharge
rates varied from a high of 120 m3/second in the spring to a low of
3 m3/second in the late summer. Thus, the river contributes most of the
intake cooling water in the spring and the lake contributes most in the
late summer. Conductivity data indicate the river water tends to override
the incoming lake water during times of high flow and some of this water
may escape to the lake (Cole, 1976).

After passing through the plant cooling condensers, the heated water
is released into a discharge canal. This canal is 2600 m long and
averages 175 m.in width. The upper half has been dredged to a depth of
7 m and the lower half to a depth of 3 m. This canal was not subjected
to operational conditions until the first unit came on line in 1971.
During 1970 it functioned only as an embayment of Lake Erie, with the
water exchange occurring mainly during storms and seiches. This canal
has a fully operational flow through time of approximately four.hours,
where about 14% of the heat is lost to the air. Upon discharge into the
lake, the plume waters return to ambient temperature in 15 to 45 hours
(MSU, 1974).

In addition to chlorine releasedby the sewage treatment plant, the
power plant also chlorinates the cooling water to prevent the growth of
bacterial slimes on the inside walls of the condensers. This treatment

occurs twice a day in the summer and once a day in the winter, with a

 

Huron) Q Detroit
River \a River
hi ".
“h ‘.
Raisin
'iver
LAKE
IERJE
' I
b 0"
Maumee ‘ km
Bay p—-—I
'\ .
- Lake
I Erie
Maumee
lfiiver ‘

 

 

 

Figure 1. Map of the study area in relation to Western Lake Erie.

desired concentration of less than 0.5 mg/l total residual chlorine at

the head of the discharge canal.
Sampling Locations

The Detroit Edison Sites

Gross primary production and community respiration studies were
conducted as part of the Detroit Edison supported environmental impact
assessment of the Monroe Power Plant. Three sites (Figure 2) were
sampled from May 1, 1970 through October 24, 1974 on a biweekly basis,
as weather permitted (Table A1). Winter sampling from Nevember through
early March was very limited because of highly unfavorable lake conditions.
Station 3 was located in the lake, approximately 1.5 km due east of the
Raisin River mouth, and had a depth of about 6 m. Station 9, located
in the Raisin River about 0.5 m upstream.from the power plant intake, had
a dredged depth of 7.5 m. Station 8 was located in the discharge canal,
approximately 1.3 km from its entrance into Lake Erie, and had a depth

of about 7 m.

The U.S.E.P.A. Study Sites

The United States Environmental Protection Agency (USEPA) supported
a three year study to determine the effects of entrainment in the cooling
system of the power plant. Seven stations (Figure 2) were sampled
bimonthly from November 1972 through September 1975 (Table A2). Stations
3, 8, and 9 were the same as the Detroit Edison study sites. Stations
3 and 9 were selected to sample the source waters for the cooling intake.
The discharge canal was sampled at the upstream end, station 12; the

middle, station 8; and the downstream end, station 14. Two stations

      
 

. h Lake
DISC arge Erie
Plum Canal
Creek ,
O ,,
0 1 kn1

| Station 15
0 Station 16

Figure 2. Map showing the vicinity of the Monroe Power Plant
and sampling locations in the cooling system.
Locations of station 15 and 16 are from samples
obtained in the thermal plume which altered position
with wind changes.

10

were located in the lake to follow the water mass as it mixed with the
lake. Station 15 was located along the central axis of the thermal
plume at a point where the temperature was about one-half the difference
between the ambient lake temperature and the lower discharge canal
temperature. Station 16 was located along the central axis near the
plume edge where the temperature was 1 to 2 C above ambient. These

lake stations varied in position, depending on the movement of the lake

currents due to wind direction and the river and discharge canal flow.

METHODS AND MATERIALS
The Detroit Edison Sites

Field Procedures

The Detroit Edison study productivity samples were taken with an
8 liter Van Dorn water bottle from.just below the surface and at
0.5 m, 1.5 m, and 2.5 m depths. Duplicate clear and dark 300 ml Pyrex
borosilicate glass bottles were filled by gravity flow, with an exchange
of at least three volumes. Two water samples were also taken at each
depth to determine the initial oxygen concentration. The dark bottles
‘were double wrapped with black plastic tape and then painted white to
prevent light and heat from entering. The tops were covered with
aluminum foil caps to prevent light from entering through the glass
stopper.

The light and dark bottles were returned in gitg_to the correspond-
ing depth of collection. They were attached to a metal rod with clips,
one rod at each of the four depths. The rods were supported by a

styrofoam float which was anchored at each end to prevent drifting. The

ll

floats were oriented so the bottles were not in the shadow formed by the
styrofoam.as the sun passed overhead.

.Lnusitu_incubations were conducted near midday, usually between
1000 and 1500 hours. Exposure time was approximately four hours in
length. Sample fixation and titration were done using the modified
Winkler dissolved oxygen test, as outlined in Standard Methods (Anon.,
1965). All samples were immediately fixed upon completion of the
incubation. Titrations on most occasions were completed within one hour
of fixation. Gross primary production and respiration values were
determined from dissolved oxygen changes (Strickland, 1960).

Diurnal gross primary productivity was measured on several occasions
during the study period at stations 3, 8, and 9, using two different
methods. The first involved 3 to 4 consecutive incubation periods of
approximately 4 hours during the daylight period. Midpoints of the time
intervals were used to position the data points. The other method
involved sample exposures for various time periods according to the

following idealized schedule when sunrise occurred at 0600 hours:

0600 0100 10|00 1100 1100 1T0 1T0 2000
2 hr

94hr ,- ——_—’
gg!!!
8 h. -!_-_!-

12 hr ———-——————————————

 

 

 

 

The initial starting time corresponds to sunrise. The samples,
two light and two dark bottles, were incubated at 0.25 m. The above

data were used to estimate the percentage of total productivity that

12

occurred during the four hour incubation periods.
Alkalinity and pH measurements were taken once a season from 1600
to 0800 hours the following morning. Alkalinity was determined as

described in Standard Methods (Anon., 1965). All pH measurements were

 

taken with a Porto-matic pH Meter. Secchi disc transparency data were
taken with a 20 cm disc. During 1973-75, light penetration measurements
were taken with a Whitney-Montedoro submarine photometer. Temperature
profiles were taken at all stations using a YSI Model 51A.combination
thermistor meter. Oxygen profiles were made with the same meter, which
was standardized against the modified Winkler method.

Daily solar radiation was measured using a Belfort pyroheliometer
and a Eppley pyroheliometer. A polar planimeter was used to convert
from area to total Langleys per day. Meteorological data were obtained
from the U.S. Department of Commerce records taken at Detroit City

Airport and Toledo Express Airport.

Nutrient Analysis

water samples for chemical analysis were taken at approximately the
same time as those for community metabolism. Samples were obtained with
the same 8 liter van Dorn water bottle from 0.5 m and 2.5 m. A subsample
was preserved in a 4% formaldehyde solution for phytoplankton analysis.
water chemistry samples were preserved with HgCl2 in the field and
processed in the water chemistry laboratory operated by the Institute
of water Research at Michigan State University. Laboratory analyses

were carried out for chloride, total Kjeldahl nitrogen, total soluble

phosphorus, total organic carbon, and suspended solids.

13

Chloride analyses were accomplished with mercuric nitrate titration
of a 25 ml sample to the diphenylcarbazonedmercury complex endpoint. A
mixed indicator containing Xylene cyanol FF was used, as outlined in
Standard Methods (Anon., 1965).

Total Kjeldahl nitrogen was measured by digesting a 50 ml sample
with a mercury catalyst. Ammonia formed in the digestion of nitrogen!
containing organic compounds and nitrogen already present as ammonia
were distilled and determined by Nesslerization. The micro-Kaeldahl

method that was followed was outlined in Standard Methods (Anon., 1965).

 

Nitrate nitrogen was determined as outlined in Standard‘Methods
(Anon., 1965). Samples containing more than the maximum.standard of
0.7 mg/liter had to be diluted to within the standard range. Total
nongaseous nitrogen was assumed to be the sum of nitrate nitrogen and
total Kjeldahl nitrogen.

Total soluble phosphorus concentrations were determined using a
modification of the technique described by wadelin and Mellon (1953)
as described by Annett (1977). The phosphorus atom was reacted with
molybdate ions, extracted with chloroformbutanol, and the absorbance
was measured spectrophotometrically.

Total organic carbon was determined, after adding HCl to a pH
less than 1, on a Beckman single channel carbon analyser as described
by the EPA (Anon., 1971).

Total suspended solids were defined as the dry weight gain of a
millipore filter (0.4511) from.a 100 ml water sample passed through the
filter. The filters were dried in a desicator, weighed, used to collect

the sample, and then dried to a constant weight.

14

USEPA Sites

USEPA study productivity samples were also measured by the change
in oxygen. 'Three, 300 m1 light bottles and three dark bottles were
filled with water collected with an 8 liter Van Dorn water bottle and
suspended in §i£u_at the depth of collection, 0.5 m in 1972 and 1973
and 0.2 m from 1973 through 1975, at all stations. The bottles were
incubated from 0800 to 1230 in the morning period, 1200 to 1800 in the
afternoon, and from 2100 to 0100 in the evening. Incubation times
varied from 2 to 4.5 hours. Temperature and oxygen profiles, solar
radiation, light penetration, pH, and alkalinity measurements were

taken using methods described above in the Detroit Edison study.
Data Analysis

Carbon fixation was obtained from.oxygen values by using the ratio
of 0.312 mg carbon fixed per 1.0 mg oxygen evolved (westlake, 1969).
The data were converted from volumetric units to areal units by morpho-
metric profiles of mean oxygen production. An extrapolation of the GPP
and respiration data were made to calculate total productivity for the
entire water column when the station depth exceeded the sampling depth.
These data were then used to calculate seasonal and annual estimates of
carbon fixation and the corresponding productivity to respiration ratio.
This ratio can be used as an indicator of the change in the eutrophic
condition of the lake, possibly the result of the input of thermal
effluent from.the power plant. Linear regression analyses were run to
determine relationships between gross primary productivity and respir-
ation and various nutrient, temperature, light, and suspended solids

concentrations.

15

RESULTS AND DISCUSSION
Gross Primary Productivity

Depth Variation

Vertical profiles of gross primary productivity (GPP) indicate
a significant decrease in the rate of carbon assimilation at depths
greater than 1.5 m (Figure 3). The river exhibited the lowest product-
ivity rates at all depths over the entire study period. In 1970 the
discharge canal served only as an embayment of the lake. The first
pumping units came on line in May 1971. During those two years the
productivity was highest in the discharge canal, with the lake values
being intermediate. In 1972 the pumping rate was doubled (44 m3/sec)
with subsequent units being added in 1973 and 1974. Upon addition of
the second and succeeding units, the rate of production in the discharge
canal was usually lower than that of the lake.

The waters of the western basin of Lake Erie, because of its extreme
shallowness, are stirred thoroughly from.top to bottom by wave and
seiche action (Verduin, 1964). This results in relatively homogeneous
temperature profiles, nutrient concentrations, and biological populations.
Cody (1972) was unable to determine the existance of a thermocline in
the areas of Niagara Reef and North.Bass Island. Similar results were
also described by Marcus (1971) and Kreh (1972) for the study area.

The productivity of the water column varied greatly. 0n numerous
occasions, particularly at the lake station, the GPP was higher at the
0.5 m depth than at the surface. This is in agreement with other
investigators' results working in similar conditions (Vbllenweider and

Nauwerck, 1961; Cody, 1972; and Glooschenko et a1., 1974). This below

16

 

 

 

 

 

 

 

River
1970-0
1971- A
1972- U
1973-0
1974- a
l l l L
0.0
A Lake
2 0 5
o
’6
E
5
n,
13 1.5-
2 5 v w I l I l l l I 4L
Discharge
Canal
5—. l 1 l 1 1 l L 1 I _
' .10 .20 .30 .40 .50 .60 .70 .80 90
mg 02/I/hr
Figure 3. Depth profile of mean annual gross primary productivity

at the river, lake, and discharge canal stations,
1970 through 1974.

17

surface inhibition has been attributed to sensitization to high light
levels and photoautoxidation, causing irreversible destruction to
some parts of the photosynthetic apparatus (Vollenweider and Nauwerck,
1961).

Yearly averages for the lake (station 3) for 1971 and 1972 exhibited
photoautoxidation. This surface depression of GPP did not appear to be
seasonal in nature, as it was measured throughout the year. However,
this trend was rarely exhibited in the river (station 9) and discharge
canal (station 8). Yearly averages of GPP remained almost constant in
their rate of decrease with depth in the river and discharge canal. GPP
at 2.5 m was nearly 0.00 mg 02/1/hr in the river at all times. The values
at the same depth were similar (< 0.02 mg 02/1/hr) in the discharge canal
during operation, except 1971 and 1972 when the flow of cooling water
was slight. The lake station exhibited production at 2.5 m.(0.5-1.0 mg
02/1/hr) on most occasions because of greater light penetration in the
water. The discharge canal showed similar results in 1970 and 1971 when

it operated as an embayment to the lake.

Diurnal Variation

 

Diurnal gross primary productivity was measured on four occasions
(Figure 4) using a four hour incubation period and on two occasions
using incubation periods of 2, 4, 6, 8, and 12 hours (Figure 5). Diurnal
GPP rates calculated from the four hour incubation periods resulted in
a maximum rate of photosynthesis occurring at midday, seven to eight
hours after sunrise in the summer. This corresponds closely With the
peak.height of the sun in the sky. All three stations showed similar

patterns of maximum productivity.

18

...l

 

 

 

4CD

 

 

2!“)
Discharge

Canal

mg C/m3/hr

244)
2¢IO
160-
12¢)-

ICIP

l A l

3 s 7 9 11 13 Is {7 19 21
Time

A

 

 

Figure 4. Diurnal mean gross primary productivity at the river,
lake, and discharge canal stations on 1 July 1970 (C)),
26 August 1971 (A), 1 June 1972 (D), and 18 June 1974 (O).

24v :3 33%;» NN new AOV Ema mesh 03 hunt/3960.3 manning mmowm no mafia coaumnooaw mo uoowwm

v— «—

W4

.aoaunuw 33H onu um AA‘V «RH unswam NN mam ADV 3.3 0:3. 03 cowumufiamou pom

'— N— O—

o— V—N— O— 0
u q d u a

 

4

tea.

\

/

E o.

a #4

0

Eu

0— 0— V— N— O— O
u 1 q d a 1

Ala)

£0

0— o- v- N. O—
1 q u u a

m m_m_m_m_fi_m so
.or
.o«.
.On.
.oc.
can gen.

 

.n shaman

|/3 6m

:11

20

Lake station diurnal rates remained almost constant over the
four sampled dates. The rates were also more equal over the photoperiod,
remaining so for an eight to ten hour period. The discharge canal values
showed a much higher peak in production in 1970 and 1971 during the
midday period, while the values determined in 1972 more closely resembled
the lake data. River station values also exhibited the midday peak,
although lower than in the lake station.

The results of the mixed incubation times showed the photosynthetic
maximum.occurring four to five hours after sunrise and then decreasing
as the sun approached its maximum height in the sky at midday (Figure 5).
The rate of production was not constant over the photoperiod as other
data showed, but dropped off much more rapidly once the maximum.rate
was reached. Other investigations concur with this trend. Vbllenweider
and Nauwerck (1961) and Munawar et a1. (1972) measured maximum rates
of photosynthesis occurring in mid to late morning, with a decline in
the afternoon and evening. Verduin (1957) reported maximum rates bet-
ween 0700 and 1000 hours in the morning, a reduced rate between 1000 and
1600, and a negative rate between 1600 and 1900 hours while working in
western Lake Erie. This suggests another parameter, besides solar
radiation, as the limiting factor of GPP.

One explanation for the maximum productivity rate occurring at
midday for the four hour incubations may be a consequence of the chosen
time frames for the exposure of the samples. It is possible that the
maximum rate of GPP was spread over two sampling periods, thereby
causing a decrease in the first value and an increase in the second,

skewing the diurnal curves to the right.

21

Gross primary productivity was measured during the midday time
interval (0900-1600 hours) on most occasions. The in sign rate of
carbon assimilation was lowest in the river on 35 of the 48 dates
sampled (Figure 6). The river had the highest production rate on only
3 of 48 occasions. The lake station had the highest GPP levels on 28
of the sampling dates and the discharge canal had the highest rates on
17 dates, 15 of which were in 1970 and 1971 when the canal had no or
very low flow through rates. After two units of the power plant came
on line, there were only two occasions where GPP rates were the highest.
The lake station had the lowest level of production on five dates, four
of which were in the 1970 and 1971 period. The discharge canal had the

lowest rate of carbon fixation on nine dates, all in 1972 to 1974.

Summary of the GPP data (48 dates sampled)

River Lake Discharge Canal
Highest 3 28 17
Lowest 35 4.5 8.5

The lake station had a maximum.GPP of 563jmg C/mzlhr on 30 August
1972. Maximum.rate for the discharge canal was 498 mg C/mzlhr on
16 July 1971. The river station also had a maximum rate on 30 August

1972 of 294 mg C/mzlhr.

Annual variatiOn by Season

Daily estimates of gross primary productivity were based upon the
proportion of carbon fixation that occurred during the exposure period.
The diurnal data were combined to give a proportional estimate of

production during the whole photoperiod. This proportion was then used

22

.q~mH swaounu chaa .mGOfiumum Hanna omumnomfiu

 

 

 

can .oxMH .um>Hu onu um A49 coaumuwmmmu :moa pan AOV >ua>fiuo=coua humafiua mmoum can: .0 anomfim
QNO— Gho- Nho— —NO— 050—
zo... < 3 <2 _z.o.m.<.:_..z.<1 6.953221 _z.o.m.<.:_.._2.<_ 6.959322}
“ I“ H” ”K“ rm
10—
.ncao
cotacum_0 un—
rnvu n.
I! nu
/
{Kin 4?. <_ a ...
Tn nf
e
axon A
lu—
& In
lu—
co>_m
.m-

 

23

to determine the percentage of production that occurred during the
exposure period and the daily estimate was then calculated. The
incubation times were chosen to correspond to periods of maximum pro-
duction in order to minimize the variability occurring in the diurnal
cycle.

Primary productivity was highly variable from one sampling period
to the next, even during the same season (Figure 6). This was due
mainly to changes in available light, suspended solids in the water
effecting the light penetration, algal biomass, and water temperature.
Seasonal GPP was also variable (Table l). The lake station had the
highest level of productivity in the summer season during the study
period, with the exception of 1971 when the spring season was most
productive. Discharge canal productivity maxima also occurred in the
summer except for the fall of 1974. The maximum.productivity of the
river was more variable with the summers of 1970, 1972, and 1974; fall
of 1971; and spring of 1973 having highest rates.

Yearly productivity values were more consistant. The lake had the
highest GPP for all seasons except in 1970 where the discharge canal
values were higher during the time it was not receiving the flow of
cooling water. In 1971 the lake and discharge canal values were almost
equal. The river had the lowest annual productivity in all years except
1974, when high summer values greatly increased the annual productivity.

Productivity values varied greatly from.ane year to the next with-
no apparent relationship. Annual productivity estimates for the lake
ranged from 300 g C/m? (1970) to 852 g C/mé (1972). The discharge canal

ranged from a low of 227 g C/m2 (1974) to a high of 786 g C/m2 (1971).

24

Table 1. Daily, seasonal, and annual mean GPP and respiration in
g C/m2 by station for the Detroit Edison sites.

 

 

(Discharge
9 (River) 3 (Lake) 8 Canal)

Spring 1970 GPP R GPP R GPP R

Daily 0.8 8.4 0.9 2.0 2.0 7.1

Seasonal 71.0 756.3 78 3 181.1 185.8 647.9
Summer 1970

Daily 1.5 4.3 1.7 2.4 2.7 4.4

Seasonal 141.2 392.2 159.2 214.8 250.7 404.0
Fall 1970

Daily 0.7 3.2 0.7 0.3 2.2 10.7

Seasonal 63.7 286.7 62.9 24.6 100.1 933.7
1970 Mean 275.9 1444.2 300.4 420.4 536.5 1985.6

274 days
-Spring 1971

Daily 0.8 8.4 4.0 4.1 2.3 3.7

Seasonal 68.7 764.4 361.0 370.4 212.3 340.3
Summer 1971

Daily 1.0 7.3 2.9 4.0 3.6 6.7

Seasonal 94.4 668.0 261.6 361.3 323.1 611.5
Fall 1971

Daily 1.4 4.0 1.5 1.2 2.6 5.2

Seasonal 124.7 362.2 135.7 106.5 239.2 476.8
Winter 1971 '

Daily --- --- 0.3 1.3 -0.1 0.7

Seasonal --- --- 30.0 118.3 -6.8 64.6
1971 Mean 287.8 1794.5 788.3 956.4 767.8 1493.3

365 days
Spring 1972

Daily 0.6 6.3 3.1 1.6 1.2 2.5

Seasonal 50.1 574.2 282.1 149.2 112.2 231.1
Summer 1972

Daily 1.5 8.0 3.7 2.4 1.9 2.9

Seasonal 139.0 723.5 331.7 220.2 176.1 261.2
Fall 1972

Daily 0.6 3.6 2.6 2.5 0.9 2.3

Seasonal 54.2 325.8 238.9 225.7 83.7 207.5
1972 Mean 243.2 1623.4 852.7 595.1 372.0 699.8

 

273 days

25

Table 1 (Con't.)

 

 

 

Discharge
(9) River (3) Lake (8) Canal
GPP ‘ R GPP R GPP R

Spring 1973

Daily 0.8 1.5 1.6 2.8 1.0 2.4

Seasonal 70.4 134.7 146.2 258.4 89.2 217.5
Summer 1973

Daily 0.6 1.7 3.2 2.0 1.1 3.5

Seasonal 56.6 155.6 287.7 184.7 101.8 316.7
Fall 1973

Daily 0.5 1.7 1.3 0.7 0.4 1.2

Seasonal 47.0 156. 119. 59.2 36.9 111.0
1973 Mean 174.0 446.8 553.1 502.3 227.8 645.2

273 days
Spring 1974

Daily 0.4 0.4 0.8 1.2 0.2 0.8

Seasonal 34.3 36.4 69.8 112.0 19.1 76.4
Summer 1974

Daily 2.3 5.0 2.8 2.4 1.1 3.8

Seasonal 207.9 458.6 253.6 219.3 100.7 348.5
Fall 1974

Daily 1.0 7.1 2.2 2.2 1.2 4.2

Seasonal 91.9 649.7 151.7 198.4 107.1 385.0
1974 Mean 334.1 1144.8 475.0 529.6 226.9 810.0

 

 

 

26

River values were more constant, from 174 g C/m2 (1973) to 334 g C/m2

(1974).

Temperature Effects

 

Linear regression analysis yields a significant (p< 0.05) relation-
ship between gross primary productivity and temperature in the spring
and fall of the year at temperatures less than 20 C at stations 3, 8, and
9 (Figure 7). When all stations were combined the relationship was
highly significant (p<=0.01). This trend was not evident during the
summer periods when temperatures exceeded 20 C. This variability
apparently is related to factors other than temperature alone. The lake
and discharge canal showed approximately the same variability for the
summer season while the river was highly erratic. This may be due to
the presence of other factors which have a greater effect on production
than temperature.

The mean annual gross primary productivity was usually less in the
upper discharge (station 12) than predicted from.the mixing of river and
lake cooling waters (Table 2 and 3). The productivity of the water at
station 12 more closely resembled that of the river (station 9) than of
the lake (station 3), even.when the lake water was the major contributing
component. Mean afternoon productivities averaged 332 less than.morn-
ing samples. Evening samples showed negligible production, as expected
for the dark hours. The inhibition of gross primary production in the
upper discharge canal could have resulted from four possible factors, or
a combination of them; mechanical damage from passage through the con-
densers, thermal shocking as a result of a rapid temperature increase
during passage, inhibiting factors in the river water from.apstream

sources, or exposure to chlorine as a result of daily application to keep

27

 

 

  

 

1 6- River
Spring+fall
"2‘ r=o.74
go
o... o
D 0 Summer
n 0 °_ El r=o.01
0.4 O D an ...
0 00 0000
00 0 ° . B r . .
‘6. Lake
Summer
1.2‘ ”0.18
a pgjno
b o. d
f Fall
:0. r=o.es
‘.
0 0-
O
C)
E 0.0 I I I v r v v I v
Spring+fall
1.6- Discharge Canal 0 o ”0.63

 

 

o D a
4 a 1'2 1'6 2'0 2'4 as 32 36
Temperature (C)

 

0.0 v .

Figure 7. Mean surface gross primary productivity compared to
temperature for the combined spring and fall season (K3)
and summer season (E!) at the river, lake, and discharge
canal stations, 1970 through 1974.

28

Table 2. Relative preportion of Raisin River and additional Lake Erie
water pumped through the discharge canal.

 

 

Season Mean River Lake Input Canal
Discharge m3/sec m3/sec (Z of Discharge m3/sec
(Z of canal flow) canal flow)
Spring 1970 15.7 0.0
Summer 1970 11.3 0.0
Fall 1970 6.0 _ 0.0
Spring 1971 8.8 (42) 12.2 (58) 21.0.
Summer 1971 1.6 ( 8) 19.4 (92) 21.0
Fall 1971 2.6 (12) 18.4 (88) 21.0
Winter 1971 9.1 (43) 11.9 (57) 21.0
Spring 1972 12.4 (34) 24.4 (66) 36.8
Summer 1972 4.1 (12) ’ 29.2 (88) 33.3
Fall 1972 33.0 (100) 0.0 ( 0) 31.5
Spring 1973 36.8 (78) 10.5 (22) 47.3
Summer 1973 11.6 (20) 46.2 (80) 57.8
Fall 1973 5.2 ( 8) 59.6 (92) 64.8
Spring 1974 33.7 (69) 15.3 (31) 49.0
Summer 1974 4.5 ( 6) 74.3 (94) 78.8

Fall 1974 4.4 ( 8) 49.9 (92) 54.3

29

Table 3. Mean gross primary productivity at the USEPA sites for cool
(November-April) and warm (May-October) months of 1973-75

(mg Oz/liter/hour).

 

 

 

 

Station
Upper Middle Lower
Period Lake River Canal Canal Canal Thermal plume
Year-season 3 9 12 8 14 15 16
Morning
1973-cool 0.03 0.06 0.03 0.00 0.03 0.05 0.01
-warm 0.76 0.39 0.34 0.36 0.42 0.62 0.79
1974-cool 0.04 0.06 0.04 0.01 0.03 0.05 0.00
-warm 0.52 0.22 0.33 0.48 0.50 0.61 0.73
1975-cool 0.08 -0.02 0.08 0.07 0.02 -0.05 0.12
-warm 0.54 0.56 0.58 0.54 0.74 0.64 0.64
Grand mean-cool 0.05 0.03 0.05 0.03 0.03 0.02 0.04
Grand mean-warm 0.61 0.39 0.47 0.46 0.55 0.62 0.72
Grand mean-3 year 0.33 0.21 0.24 0.24 0.29 0.32 0.44
Afternoon
1973-cool -0.04 0.01 0.01 0.03 0.05 0.07 0.00
swarm 0.26 0.13 0.21 0.12 0.16 0.31 0.30
1974-cool 0.04 -0.01 0.04 -0.02 0.00 0.00 0.01
-warm 0.43 0.33 0.41 0.40 0.43 0.58 0.43
1975-cool -- -- -- -- —- -- --
~warm 0.70 0.34 0.33 0.41 0.41 0.95 0.88
Grand meanvcool 0.00 0.00 0.02 0.00 0.02 0.02 0.00
Grand meandwarm 0.46 0.27 0.32 0.31 0.33 0.61 0.54
Grand mean-3 year 0.23 0.13 0.18 0.16 0.18 0.22 0.27
Evening
1973-cool 0.02 -0.02 0.00 0.00 0.00 0.01 0.00
-warm 0.02 0.02 -0.03 0.00 0.01 -0.06 —0.01
1974-cool -0.05 0.01 -0.01 0.03 0.01 -0.01 -0.03
-warm -0.01 0.02 -0.02 -0.08 -0.01 0.00 -0.01
l975-cool -0.04 -0.04 -0.03 -0.02 -0.04 0.00 -0.01
-warm 0.04 -0.04 -0.05 -0.10 0.07 0.04 0.03
Grand mean-cool -0.02 -0.02 -0.01 -0.00 -0.01 0.00 -0.01
Grand mean-warm 0.02 0.00 -0.03 -0.06 0.02 -0.01 0.00
Grand mean-3 year 0.00 -0.01 -0.02 -0.03 0.00 0.00 0.00

 

30

the condensers free of slime accumulation. However, no chlorination
occurred during the afternoon sampling periods so the depression
of productivity must have resulted also from other factors.

As water passed through the discharge canal, there was a recovery
of the depressed productivity. The three year grand mean for the
morning sampling period showed a 21% increase in productivity, almost
reaching the predicted values for the system based on the mixing of
the water masses (Table 3). The afternoon productivity remained almost
constant, slightly below predicted values.

The productivity of the thermal effluent continued to increase as
the water moved into the lake. Mid-plume productivities at station 15
usually exceeded those of the lake (station 3) prior to intake. Station
16 values averaged 332 above lake productivities, even though tempera-

tures were only 1 to 2 C above ambient.

.Suspended Solids Effects

Suspended solids and algal density are the major factors that
influence light penetration into the aquatic system. Due to the heavy
“agricultural disturbance in the Lake Erie watershed, the levels of
suspended solids were high. Concentrations were quite variable over
the study period and no apparent annual trends were revealed (Table 4).
Levels were generally highest in the spring, corresponding to high run-
off rates and flow rates of the river, and lowest in the late summer.
The near shore of the western basin of Lake Erie, being very shallow, is
subject to remixing of settled bottom.materials during periods of high

turbulence. The increasing proportion of lake water being taken for

31

Table 4. Seasonal and annual mean concentrations of suspended solids
in mg/l by station for the Detroit Edison sites.

 

 

 

 

 

 

 

 

Season . Station
9 (River) 3 (Lake) 9 (Discharge Canal)

Spring 1970 42.0 41.6 66.4
Summer 1970 53.0 26.2 43.8
Fall 1970 37.0 17.5 20.7
1970 Mean 45.9 28.9 45.4
Spring 1971 67.5 35.1 61.1
, Summer 1971 29.6 21.1 33.2
Fall 1971 45,9 16.0 41.1
1971 Mean 45.9 23.1 43.7
Spring 1972 24.4 16.0 33.0
Summer 1972 23.7 8.8 19.3
Fall 1972 55.7 17.2 27.0
1972 Mean 31.0 13.3 26.3
Spring 1973 24.1 15.9 25.4
Summer 1973 43.1‘ 22.2 46.3
Fall 1973 21.2 17.8 28.9
1973 Mean 33.7 19.8 37.7
Spring 1974 56.8 37.9 73.5
Summer 1974 25.5 13.3 25.0
Fall 1974 66.3 16.5 29.3
1974 Mean 52.6 23.7 44.8

 

 

32

cooling after plant operation began, has resulted in a decrease in the
annual concentrations of suspended solids in the discharge canal.

The compensation point, where 1 percent of the surface light is
available for photosynthesis, is generally accepted as the maximum depth
where net primary production occurs. The compensation point in the
river (station 3) averaged 1.7 m and the lake 3.1 m.(Table 5). The
discharge canal average, during the first two years of the study, was
similar to the lake. This occurred before the canal received the flow
of cooling water. As pumping units came on line, the discharge canal
received the input of river water, resulting in the decreased photic
zone.

Upon operation of all pumping units, the volume of intake water
usually exceeded the total river flow and resulted in additional lake
water being mixed with the river water.. This should have resulted in
the discharge canal light penetration values being intermediate between
the river and lake values, proportionally related to the percentage each
contributed to the discharge waters. During 1973 and l974.the compen-
sation depth of the river and discharge canal were the same (1.7 m).
This implies the additional input of material causing a decrease in the
light penetration, possibly the erosion of bottom sediments from the‘
discharge canal.

A significant relationship exists between the depth of the compen-
sation point (1% light) and the suspended solids concentration in the
river (p< 0.05), lake (p<0.05), and the discharge canal (p<0.01)
(Figure 8). Because of the relatively high suspended solids levels and

a corresponding shallow depth of the euphotic zone, less than 3 m ,

33

Table 5. Compensation depth (11 light) measured at the Detroit Edison
stations, 1973 and 1974.

 

 

 

 

 

 

Date River Lake Discharge Canal
Depth (m) 2 of lake Depth (m) Depth (m) 2 of lake
1! light 12 light 12 light 11 light 12 light
depth depth
1973
6-21 1.00 36 2.80 1.40 63
7-7 0.88 54 1.62 0.90 56
8-16 2.00 68 2.92 1.72 59
9-10 1.78 75 2.38 -- -
10-9 1.91 59 3.22 1.72 53
1974
7-16 2.00 48 4.18 2.21 53
7-31 - -- 3.45 -- -
9-27 1.27 43 2.93 -- --
10-24 2.92 71 4.12 2.05 50
11-7 2.58 60 4.30 2.00 47
Mean 1.72 55 3.13 1.72 57

34

 

 

 

 

:6
'3
120— 0 River
0 A Lake
no 0' 0 Discharge Canal
ICNO
90 «‘8.
.o‘.
’0
813--
7¢I"
t-
3
2 60 -
\
2’ ' -
50i- o
a a
4° .. reek. o
A
30 -
20 - o ,. :.°
A A . A
a, 4A
1¢)- .A
1 1 1 1
1.0 2.0 3.0 4.0 11.0
Depth (m)

Figure 8. Mean depth of 1% surface light compared to mean suspended
solids concentrations at the river, lake, and discharge
canal stations, 1973 and 1974.

35

large portion of the near shore area does not contribute to the
productivity of the system. I

Suspended solids and GPP were inversely related but highly
variable, with no significant (p<0.05) relationship for all stations
(Figure 9). The lowest productivity rates and highest suspended
solids levels were found in the river, while the inverse was true in
the lake. The discharge canal showed a decrease in productivity over
the study period, while the suspended solids concentrations increased

and then slightly decreased.

Nutrient Effects

Productivity does not appear to be related directly to either total
nongaseous nitrogen or total soluble phosphorus (Figures 10 and 11). At
particular times they may exhibit a dominant role but no positive trends
were observed.

Free CO2 concentrations decreased from maximum spring levels to
minimum.values in late summer and a gradual increase in the fall
(Table 6). River values were consistantly highest, resulting from high
respiration rates. On most occasions the concentration of free CO2 in

the river water was above atmospheric saturation (0.70 mg/l), resulting

in an export of CO from the water due to supersaturated conditions.

2

Lake values were the lowest, with unsaturated conditions existing,

resulting in an import of atmospheric CO into the lake system. Dis-

2
charge canal values were usually intermediate.
CO2 concentrations indicate levels low enough to limit productivity

occasionally occurred in the lake and discharge canal. Summer and early

fall values approaChed or fell below the 0.31 mg/l concentration that favors

36

 

 

 

 

 

0.0« River
0 r=OJO
t!
0.64 D A r=0.16
D r=0.08
0.4- D
.A
4A
. ӎ
o m DDAD A 1:)
C¥FEP E!
0.0 . . emu—MA .‘L. . 9..
(J
1.2-4 A
ake
1.0' D L
D o 1': 0.20
0.8. o D A r=o.oo
r; o o o A c1 r=o.o7
g 0.6. on
2 A
7‘ 0°“ 95A A on
0 3"? a :1
'3 or A
E A A
a 0.0 I t I I I U I f 1 I r j
0
1.2- .
1.04 0 Discharge Canal
A r=0.17
0‘” D r: 0.15
D O r=0.29
0.6.. U .. O D
C1
Cl C!
O.4~ O D ‘0
.,DH3
A.
0.2- A A A . o a A A
{I
00 O E . a A
° 1'0 2? 3'0 410 5‘0 6‘0 7'0 8'0 9‘0 160 1101 o
Suspended Solids (mg/I)
Figure 9. Mean gross primary productivity at 0.5 m compared to mean

suspended solids concentrations at temperature intervals
8-13 0 (0). 14-20 c (A), 21—27 c (:1), and 28-35 c (e)
at the river, lake, and discharge canal stations, 1970
through 1974.

37

 

 

 

 

 

LGOJ River
0 r=0.2 I
A |'=0.6 8
”9‘ o r=o.1 a
. '20.:
AA A 61::
0.80“ . A
D
A D 2 0A a
0.4 0" % ..A A o A
D n A &
D &. D o . A
0.00 . . .' . 9 Ar . . . .
I32.8
1.608 Lake
A 0 r=°e°‘
" A r=o.44
g d
2 1.20 A D 720.0.
‘N A e r=o.e 3
o 0.804 o A '
A
s o -
v d D A
a. 0.40 O“ A
11 A00
0 0.00 .1 I I I I I l l I
1.60- 8 Discharge Canal
0 no.4 7
A 720.2 0
1.204 f: .30
D a E O I: ”3.1 6
.9 O A
0.8 0‘ 0 Do
A A
. oAA o g
0.4 0.. A A0 O
0 a A A n
A ,- , :—
°'° ° to 210 310 4.0 5.0 do 7Fo do 9.0
Total Nongaseous Nitrogen (mg/I)
Figure 10. Total nongaseous nitrogen concentrations compared to mean

surface gross primary productivity forApril-May (O),
June-July (A), August-September (D), and October-November (0)
at the river, lake, and discharge canal stations, 1970

through 1974.

38

 

 

 

 

‘ River
"6 o O no.6: m r: 0.03
A 7:0.07 0 7:0...
1,204
A
t! ‘A
o.ao« A .
.. 3 ° 0
0.4 o- ' A A 8 0 o
A g 0'80 an an“ A
0.00 I I I I I 4r I I I I
l32‘]
1.60- Lake
0 r=0.05
A A 7:054
E'o’O" Or:°.75
\ A 0 7:0.26
\ 0.8 o. D” AA
0! a o
C) 1K3 .1 .A
E 0.4 0-1 A.A DA
A04 §
Q . .
o. 0 6
o 0.00 j g I I I I I T r I
0
1.6 0-1 A
Discharge Canal
0 r=0.74
1201 Ar=005
e a D .
OA :1 o r=o.oe
A Q 40 e -
o a o- 0 e no.7:
° :1 C1 C]
All
one (D
1 8 2A0 A
8““ C! .A
0.00 . r T 9‘ ° .9 . . u . .
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
Total Soluble Phosphorus(mgll)
Figure 11. Total soluble phosphorus concentrations compared to mean

surface gross primary productivity for April-May (o),
June-July (A), August-September (D). and October-November (0)
at the river, lake, and discharge canal stations, 1970

through 1974.

39

 

 

 

 

 

aa.a ma.a aa.c ~a.~ ma.c me.~ am.m Ill nm.a o¢.n oe.o No.o ac.c n~.o ~a.~
N.» a.» n.» m.» m.~ a.m o.~ us: a.» a.“ h.m n.» a.» o.m «.w
oua oaa «HM «ma oma una oma JHw wNa oma coa oaa moa woa oaa
mama oooo mama coaN coca cmma ammo coco. cmau mmoa mama mama moco maau naoa
Na.¢ ~m.o ~m.a «.mm m.aa 0a.: 35.» me.o eo.m sw.m mo.o mm.c eo.o am.c am.o
m.n m.~ m.» a.c «.5 m.s n.n o.s s.~ o.“ o.m e.w o.w a.» o.»
«ma «ma «ma oNa Nua oNa ~aa waa.l,o~a oaa aaa qoapl,~aa mo om
caua mmwo once coaN oaea coma memo oomo cmau .ouea mmua ammo mace maau mama
mc.m «.ma m.aa m.ma we.a we.~ o~.m mo.¢ mm.e mq.a am.o nm.a ~¢.o ”5.0 mm.o
w.n «.5 m.~ «.5 N.@ a.» a.“ N.“ e.h N.» o.w a.m m.m e.w w.m
oaa oNa waa «Na waa oaa eoa «ca Noa eaa ca O¢ ca «a we
moma ammo memo mmow oeea oqaa mace mace moam ooua coma came nceo cmcu anea
om.o om.o om.o wc.c om.o an.a om.a ms.~ om.a om.o mm.c mn.o mm.o on.o mm.o
~.m ~.m ~.m a.» s.m a.» ~.w m.s N.» c.w a.» m.m mum s.m o.m
«ma oma ona oNa «ma MHH Naa Naa eoa eaa «a Nca emu «a mca
caoa oaso comm mmsa coma mmaa mmso ma- omsa ocna oaaa ammo oqmm mafia Nana
Auo>amv m Aamaou owuosomanv Adamav

.chaa can anaa unauav mcowumuucoocou

N

aa\mev
ovum «co
ma
aa\mevxa<
OEfiH

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ma
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animalaa
amINaIaa

annealoa
animaloa

anlmlm
annalm

ahloalh
animals

mum:

on menu new .mn .auaaaamxa¢ .o magma

40

aaawsv

 

 

 

 

 

 

 

 

mo.o mo.N ww.o mm.o cw.a mn.c n~.o mm.c mm.o. a~.o a~.o en.o c~.o na.o mn.c ovum Nov
o.w N.@ m.» w.m m.m m.m m.m w.» w.w o.m o.a w.w c.¢ a.m o.m ma
mNa ona cma. moa msa caa eaa .Ibaa OHa eaa om Noa Na mm woa Aa\wvaa<
ooaa cone coca occm coca coaa Gena ooam oocm coca ocaa coho coca ooou coca mafia

aa\wavu
~a.o we.c mm.a me.~ em.o cm.o no.0 mm.o ea.c <~.o ae.o ac.a ms.o a~.c an.o ovum cu
a.» w.w N.m o.w c.m o.» n.w e.m m.m <.m a.» m.m e.m w.m n.@ no
maa mea eaa oNa oaa ooa Naa moa mm ma moa Noa om om cm Aa\wavxa<
coca coco ooem scam occa coca coco ccem ooc~ coca coca oooc ooew ooo~ coca usak

aa\mav
ma. 0 cm.m mu.e we. a ma. e ma.~ me.a om.~ oh.a «a. m cm. a «e. o ma. a am. a Ne.a menu «00
w. w o.» o.w c. s o. m a.m N.m o.w ~.w m. n a. w a. m m. m c. w ~.w no
mqa ona maa «ma uoa oma ama cea oea wmwl oaa oaa oaa «Ca «Ca Aa\wavxa<
omoa coco coca coca ccca omca oooc poem ocom coca cmoa coca coqu oooN coca weak

aaawee
ea.m we.~ oc.n mo.n ca.s ma.e on.~ Nm.~ ca.~ ow. N mc.m we. a ¢o.a No. N ma.a menu «on
o.w m.w m.u a.m m.n c.m N.m ~.m a.w a. w o.w m. m ~.m o. m a.m me
can «ma «ma cow NMa .www moa «ma aha coa oua caa moa Noa mm Aa\wsvxa<
coma ocmc coon coca coca ocua ocmo coon coca coca co~a oomc ooem coou coca uses

Auo>auv m Aaocmo owuoSouanv m Auxoav m

a.u.:oov

ehlhwla
eulomlm

enlwmlw
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«Banana
«steal:
mum:

.c macaw

41

blue-green algal production (King, 1970). Diurnal curves revealed the
expected increase in 002 during the dark hours. Levels decreased in the
morning hours but did not peak before maximum productivity occurred,

indicating that CO was not limiting.

2

Respiration

Depth Variation

Vertical profiles indicated a decrease in the rate of respiration
with increasing depth (Figure 12). All three stations; lake (3),
discharge canal (8), and river (9), exhibited approximately a 40%
decrease in respiration at 2.5 m relative to surface values. This
decline is attributed primarily to the decreasing rate of photosynthesis,

discussed below.

Diurnal Variation

Diurnal respiration rates generally paralleled the diurnal curves
for productivity, although the changes were not as pronounced (Figures
5 and 13). Maximum rates corresponded very closely to the midday peaks
in GPP. Lowest respiration occurred in the evening hours when agal
productivity ceased (Table 7). The evening rates of respiration were
found to be about 40% below the daytime rates. All stations exhibited
similar trends. The decrease in respiration was slightly greater during

water temperatures less than 10 C.

Annual variation by Season
Daily respiration rates were variable over the study period for
all stations (Figure 6). Mean seasonal values were generally highest in

the summer (Table 1). Spring and fall values were similarly lower.

42

0.0-

0.5q

1.5‘

 

 

 

0.0-1
Lake
0.5-

'5-
C

Depth (m)

2.5

 

0.0‘
0.5-

Discharge
Canal

 

15"
e

1"

 

2.5

 

I U

0.2 0.4 0.6 o. no 1T2 I'.4 1:6 133 2.0 212
mg Ozlllhr

Figure 12. Depth profiles of mean annual respiration at the river,
lake and discharge canal stations, 1970 through 1974.

#3

.30. River

 

 

 

 

.30. Lake

 

 

mg 02/llhr

 

 

    

Discharge Canal

 

 

 

'o
o

 

Time
Figure 13. Diurnal mean respiration at the river, lake, and discharge

canal stations on 1 July 1970 (A), 26 August 1971 (.0),
1 June 1972 (O), and 18 June 1974 (A).

44

 

 

 

Table 7. Mean respiration rate for the USEPA study sites for cool
(NovembervApril) and warm (May-October) months of l973v75
(mg 02/11ter/hour).
Station
Upper Middle Lower
Period Lake River Canal Canal Canal Thermal plume
Year—season 3 9 12 8 14 15 16
Morning
1973-cool 0.00 0.05 0.01 0.02 0.05 0.02 —0.01
—warm 0.08 0.07 0.05 0.08 0.08 0.09 0.10
1974-cool 0.04 0.03 0.05 0.03 0.03 0.02 0.02
~warm 0.10 0.05 0.08 0.08 0.09 0.09 0.09
1975-cool 0.00 0.06 0.10 0.12 0.06 0.02 0.00
—warm 0.10 0.06 0.14 0.13 0.10 0.03 0.05
Grand meanvcool 0.01 0.05 0.05 0.06 0.05 0.02 0.01
Grand mean-warm 0.09 0.06 0.09 0.10 0.09 0.07 0.09
Grand meanv3 year 0.05 0.05 0.07 0.08 0.06 0.05 0.05
Afternoon
1973-cool 0.10 0.05 0.07 0.11 0.12 -0.02 0.00
—warm 0.09 0.16 0.12 0.05 0.08 0.11 0.08
1974-cool 0.02 —0.01 0.05 0.03 0.02 —0.02 0.00
~warm 0.03 0.04 0.13 0.14 0.13 0.13 0.12
1975-cool -- -- —- -— —- —- —-
—warm 0.09 -0.02 0.10 0.13 0.11 0.12 0.17
Grand mean-cool 0.06 0.02 0.06 0.07 0.07 -0.02 0.00
Grand mean-warm 0.07 0.06 0.12 0.11 0.11 0.12 0.12
Grand mean-3 year 0.06 0.04 0.09 0.09 0.09 0.05 0.06
Evening
1973-cool ~0.02 -0.05 0.03 0.03 0.06 0.02 0.00
-warm 0.03 0.09 0.09 0,07 0.04 0.04 -0.04
1974-cool -0.01 -0.04 0.05 0.05 0.09 -0.02 -0.04
-warm 0.06 0.04 0.07 0.11 0.05 0.09 0.04
l975~cool -0.06 0.00 0.08 0.06 0.05 0.01 0.04
-warm 0.02 0.05 0.09 -0.05 0.09 0.08 0.09
Grand mean-cool -0.03 -0.03 0.05 0.05 0.07 0.00 0.00
Grand mean-warm 0.04 0.06 0.08 0.04 0.06 0.07 0.03
Grand mean-3 year 0.01 0.02 0.07 0.04 0.06 0.04 0.01

 

45

However, the maximum respiration rates during the study period occurred
in the spring and fall at stations 3, 8, and 9: lake, spring 1971,

370 g C/mz; discharge canal, fall 1970, 933 g C/mz; and the river,
spring 1971, 764 g C/mz, respectively. Winter data from.the Monroe
demonstration sites were limited, but the USEPA entrainment data
indicated winter respiration rates were the lowest of all seasons
(Table 7).

Mean annual river respiration remained constant from 1970 through
1972 and then significantly decreased in 1973 and 1974. These lower
values coincided with improvements to the Monroe Sewage Treatment Plant
and subsequent decrease in industrial and municipal sewage entering the
Raisin River. Mean annual concentrations of organic carbon followed .
similar decreases during the same period (Table 8). Mean annual GPP
values over the study period remained constant from 1970 through 1972,
decreased in 1973, and reached their maximum in 1974 (Table 1).

Mean annual oxygen values for the river more than doubled in 1973 and
1974 from the three preceding years (Table 9). The decrease in respir-
ation, due to decreased organic loading, along with relatively constant
GPP rates, has resulted in significantly higher oxygen concentrations
in the Raisin River during the last two years of the study period.

Mean annual respiration for the lake station (3) remained almost
constant, except 1971, which was almost double the average rate. The
discharge canal exhibited its highest respiration rate during 1970,
before it received thermal effluent from the power plant. The rate
of carbon release greatly decreased as additional cooling water was
pumped through the discharge canal. This led to the greater incorpor-

ation of lake water into the canal as water demands exceeded the volume

46 '

Table 8. Seasonal and annual mean concentrations of total organic
carbon in mg/l by station for the Detroit Edison sites.

 

 

 

 

 

 

 

 

Season Station
9 (River) 3 (Lake) 9 (Discharge Canal)
Spring 1970 21.3 13.4 14.0
Summer 1970 13.9 6.5 16.4
Fall 1970 16.3 7.4 10.5
1970 Mean 16.7 9.0 14.6
Spring 1971 16.3 6.5 15.3
Summer 1971 13.7 9.6 13.2
Fall 1971 22.4 12.1 17.4
1971 Mean 17.1 9.7 15.3
Spring 1972 12.2 4.9 9.8
Summer 1972 10.7 4.0 6.3
Fall 1972 9.9 5.4 7.1
1972 Mean 10.9 4.6 7.7
Spring 1973 10.8 5.9 9.3
Summer 1973 9.8 6.4 7.2
Fall 1973 7.5 4.8 5.7
1973 Mean 9.4 5.9 7.2
Spring 1974 10.4 5.5 10.0
Summer 1974 10.7 5.0 5.5
Fall 1974 9.2 5.3 8.2
1974 Mean 10.0 5.3 8.2

 

 

Table 9. Seasonal and annual mean oxygen concentrations in mg/l by

47

station and depth for the Detroit Edison sites.

 

 

 

 

 

 

 

Station 3 (Lake) 8 (Discharge Canal) 9 (River)
0.5m 2.5m 0.5m 2.5m 0.5m 2.5m

Spring 1970 9.6 8.5 9.5 8.1 4.5 4.4
Summer 1970 7.8 7.3 7.8 6.0 2.3 2.3
Fa11.1970 8.8 8.4 9.7 9.2 4.2 4.2

1970 Mean 8.7 8.0 9.0 7.8 3.7 3.6
Spring 1971 11.6 10.5 5.8 5.0 3.8 4.1
Summer 1971 9.8 8.1 4.8 4.1 0.3 0.1

1971 Mean 10.9 9.8 5.0 4.6 2.3 2.1
Spring 1972 11.3 10.3 8.1 8.1 2.0 0.8
Summer 1972 12.0 10.6 7.9 6.7 4.9 3.5
Fall 1972 14.1 13.9 7.5 6.7 3.0 2.1

1972 Mean 12.5 11.6 7.8 7.2 3.3 2.1
Spring 1973 11.2 11.0 8.8 8.7 7.5 7.5
Summer 1973 8.4 8.0 6.2 6.0 5.8 5.6
Fall 1973 10.2 10.2 10.2 0.2 8.1 8.0

1973 Mean 10.0 9.7 8.4 8.3 7.1 7.0
Spring 1974 11.4 11.4 9.6 9.8 10.0 10.0
Summer 1974 8.2 8.1 6.8 6.7 6.0 5.3
Fall 1974 9.9 9.8 8.7 8.3 8.2 7.6

1974 Mean 9.8 9.8 8.4 8.3 8.1 7.6

48

supplied by the river. Respiration rates of the canal fell predictably,
resulting from the combined effects of the lower respiratory demand of
the lake water and the decreasing organic carbon concentration of the

river water.

Tegperature Effects

 

Respiration.was related to temperature seasonally, with significant
(p<0.05) relationships occurring only in the river during August and
September and in the discharge canal during June and July (Figure 14).
Temperatures appeared to contribute more strongly during the cool
seasons, than in the warm summer months. The lake showed the least
variability when all seasons were combined and the discharge canal the
greatest.

The entrainment of the water mass through the power plant resulted
in an elevation of the rate of respiration (Table 7). Mean annual water
temperature elevation across the condensers averaged 7 to 8 C while the
mean annual respiration rate in the upper discharge canal (station 12)
almost doubled. This is in close agreement with the Q10 temperature
increase. The stimulation of respiration was greatest, although variable,
during the cool months, November through April. Mean annual rates for
May through October increased about 50%. Diurnal comparisons indicated
the greatest increase in respiration after entrainment occurred during
the evening hours. Lesser increases were observed for the morning and
afternoon sampling periods.

A 12% summertime and a 16% wintertime heat loss were accompanied
by a 25% decrease in mean annual respiration, regardless of season, as

the water moved through the discharge canal. The respiration of the

49

 

 

 

 

4 r River
. O l'=0.469
3 _ o o A A 7:0.041
' . A o r=0.700 a.
2 _ A A A ,. r=0.119
A ' A ,0 combined r=0.217
O 0 2A 0
.1 . g“ A ,8
x a x 00
0.0 . l 1 x‘ X L l l l 04 l 1 1
.4 - Lake
0 r=0.265
.31. A A f=0.036
g A o r=0.083
.2 .2. 0 x r=0.180
E . 0 2 o combinedr=0.296
'5 .1 - ‘ 9
N O ‘ ... a 4A: a
O o ’l 3 0 use
a ‘ x . ‘ ‘ A
E 0.0 1 11 1 1 1 44 1 1 L
r:
o
3 6 . ‘ Discharge
é o r=0.356
.2 5 . A r=0.565 ..
o f=0.160
4 1- X 7:0.359
combined r=0.120
.3 P o
2 x 0 1|: (P<0.05)
. r- o‘ A A
‘ 2° 2 A
.1 l- 0 0A 0 o
. ‘ ,0 202
. 0 x g A e ‘ A
0 0 . 1 1 1 1 .L A L ‘ 1 1 1
' 4 8 12 18 20 24 28 32 36
Temperature(°C)
Figure 14. Mean respiration compared to mean temperature for

March-May (e), June-July (A), August-September (O),
and October-November (x) at the river, lake, and
discharge canal stations, 1970 through 1974.

50

thermal plume, upon entering the lake, continued to decline as the
temperature of the water decreased. Upon reaching station 16 (1-2 C
over ambient) the mean respiration rate had recoveredtx>its initial
rate before thermal stiumulation. This recovery was independent of
seasonal temperature variation or diurnal changes in the productivity

of the system.

Cress Primary Productivity Effects

 

Respiration rates were clearly related to gross primary productivity
(Figure 15). Highly significant (p<0.01) relationships existed in the
lake and discharge canal at temperatures above 20 C. Neither station
exhibited a positive relationship at temeperatures less than 20 C, but
with temperatures combined, a highly significant (p<0.01) relationship
existed. In the river just the opposite was true, respiration being
related to GPP at temperatures below 20 C (p<0.01) and unrelated above
20 C. The decomposition of allochthonous organic material may have been
a major contributor to respiration at the higher temperatures, thereby
confounding the relationship, but at lower temperatures its impact may
have been minimal. Gross primary productivity emerged as the main

contributor.
Gross Primary Productivity/Respiration

Season GPP/R ratios were based on mean seasonal averages of daily
GPP and respiration (Table 10). Highest river ratios occurred in the
springs of 1973 and 1974, the result of greatly reduced respiration due
to decreased sewage input. In three of the five years, highest ratios

for the lake occurred in the fall. Autotrophic conditions (GPP/R>l).

51

0,6- River

0 r:0.9 9*
O.4< A ”0.63:”:
‘ . A o r:0.00

 

 

A
0.4 Lake
0 r:0.05
06‘ ar:0.40
0 r :0.6 9:1: :1:
0.4‘ . e

. ‘—
r:0,44**

 

 

Respiration (mg 02 l l Ihr)

  

O.8« Discharge Canal
0r:1.00
o.e« A ' Arzo,2e
0 r:0.35
04- D r:0.7 1 :1: :1:
e a '
02-1 ° . n r:0-55 **
o.o-
=1! (p<0.01)
*Ilt (P<0.05)

 

 

fl

ofo oh of: oi: 014 035 03 of 7 ofs 0.9
GPPUflgOz/l/hr)

Figure 15. Mean respiration compared to mean gross primary productivity
at temperature intervals 8-13 C (0), 14—20 C (A),
21-27 C (e ), and 28-35 C (a) at the river, lake, and
discharge canal stations, 1970 through 1974.

52

Table 10. Seasonal and annual GPP/R ratios by station for the
Detroit Edison sites.

 

 

 

 

 

(Discharge
9 (River) 3 (Lake) 8 Canal)
Spring 1970 0.09 0.43 0.29
Summer 1970 0.36 0.74 0.62
Fall 1970 0.22 2.56 0.11
1970 Mean 0.19 0.71 0.27
Spring 1971 0.09 0.97 0.62
Summer 1971 0.14 0.72 0.53
Fall 1971 0.34 1.27 0.50
Winter 1971 -- 0.25 --
1971 Mean 0.16 0.82 0.51
Spring 1972 0.09 1.89 0.49
Summer 1972 0.19 1.51 0.67
Fall 1972 0.17 1.06 0.40
1972 Mean 0.15 1.43 0.53
Spring 1973 0.52 0.57 0.41
Summer 1973 0.36 1.56 0.32
Fall 1973 0.30 2.02 0.33
1973 Mean 0.39 1.10 0.35
Spring 1974 0.94 0.62 0.25
Summer 1974 0.45 1.16 0.29
Fall 1974 0.14 0.76 0.28
1974 Mean 0.29 0.90 0.28

 

 

53

occurring in eight of the sixteen seasons sampled, were found only in
the lake. Discharge canal values were intermediate but more closely
resembled those of the river. Maximum ratios occurred in the spring
and summer.

Annual GPP/R, calculated from mean annual GPP and respiration
values, indicate heterotrophic (GPP/RS1) conditions existed for all
stations except the lake in 1972 and 1973. Due to very limited winter
data, annual ratios may have overestimated actual conditions. River
values remained almost constant from 1970 through 1972, more than
doubled in 1973 following increased sewage treatment, and slightly
decreased in 1974. Lake and discharge canal ratios followed similar
trends, although peaking in 1972 and decreasing the last two years.

As successive generating units came on line and approached normal
operating conditions in 1973 and 1974, discharge canal ratios fell
below those of the river due to higher temperatures elevating respir—
ation while algal productivity decreased.

GPP/R ratios were calculated for the discharge canal and thermal
plume stations using hourly GPP and respiration data from the upper
photic zone. While greatly overestimating daily ratios, comparative
analysis can be made as the water moved through the discharge system.
Ratios in the upper discharge were usually less than expected from the
mixing of the water masses, again the result of temperature elevated
respiration and depressed algal production (Table 11). Ratios slightly
increased with movement through the discharge canal and, near ambient
temperatures, recovered to approach those of the original lake water

as the respiration rates fell and productivity recovered.

Table 11.

54

April) and warm (May-October) months of 1973.75.

GPP/R ratios for the USEPA study sites for cool (November-

 

 

 

 

Station
Upper Middle Lower
Period Lake River Canal Canal Canal Thermal Plume
Year-season 3 9 12 8 14 —-13r-_' 16
Morning
1973-cool 1.20 3.00 0.00 0.60 2.50 -1.00
-warm 9.50 5.57 6.80 4.50 5.25 6.89 7.90
1974-cool 1.00 2.00 0.80 0.33 1.00 2.50 0.00
-warm 5.20 4.40 4.12 6.00 5.56 6.78 8.11
1975-cool -0.33 0.80 0.58 0.33 -2.50
-warm 5.40 9.33 4.14 4.15 7.40 21.33 8.00
Grand mean-cool 5.00 0.60 1.00 0.50 0.60 1.00
Grand mean-warm 6.78 6.50 4.67 4.60 6.11 8.86 8.00
Grand mean—3 year 6.66 4.20 3.43 3.00 4.83 6.40 8.80
Afternoon
1973-cool -0.40 0.20 0.14 0.27 0.42 -3.50 0.00
-warm 2.89 0.81 1.75 2.40 2.00 2.82 3.75
1974-cool 2.00 1.00 0.80 -0.67 0.00 -0.00
-warm 14.33 8.25 3.15 2.86 3.31 19.33 3.58
1975-cool -- -- -— -- -- -- —-
-warm 7.78-JJ.00 3.30 3.15 9.09 7.92 5.18
Grand mean-cool 0.00 0.00 0.50 0.00 0.29 ~2.00 0.00
Grand mean-warm 6.57 4.50 2.67 2.82 3.00 6.78 4.50
Grand mean—3 year 3.83 4.00 1.85 1.78 2.00 5.50 4.50

 

55

CONCLUSIONS

Primary production in the lake was highly variable over the study
period. High levels of suspended solids, contributed by the Raisin
River and resuspended by turbulence in the shallow depths, usually
limited productivity to a depth less than 2.5 m.in the nearshore areas.
Maximum production usually occurred in the summer months, with spring
and fall values equally lower. Temperature was significantly related
to productivity only in the spring and fall. Concentrations of total
soluble phosphorus and total nongaseous nitrogen showed no individual
relationship to productivity. Peak daily production occurred in the
late morning hours, before maximum levels of solar radiation were
encountered. Highest annual rates of production occurred in 1971 and
1972, returning to preoperational levels in 1973 and 1974, probably
resulting from sewage clean up of Raisin River water.

The Raisin River usually exhibited the lowest productivity rates
of all stations measured. Annual variability was also lowest and showed
no trends over the study period. Highest levels of suspended solids
usually limited production to a depth less than 1.5 m. Maximum seasonal
rates occurred in the summer, corresponding to trends exhibited by the
lake. The river water was subjected to high levels of industrial and
municipal sewage, along with.nutrient rich.runoff. Productivity rates
were not noticeably effected by the completion of improvements to an

upstream sewage treatment plant in 1972. As power generation increased,

56

larger amounts of river water were diverted through the discharge
canal, thereby moving the river's flow southward into the lake, except
during times of high discharge.

Respiration was clearly related to gross primary production, with
maximum daily rates occurring at nearly the same time as maximum pro-
ductivity. Seasonal maximums of respiration and production occurred
during the summer. Rates of respiration decreased about 402 at depths
below the compensation point. Nighttime respiration showed a similar
decrease from daytime values, implying that the rate of respiration
remained almost constant for that portion of the aquatic community
not engaged in photosynthesis. Respiration rates in the lake remained
fairly constant over the study period. However, with the completion
of the sewage treatment plant, and the corresponding decrease in organic
carbon, the river respiration rates fell. Respiration was related to
gross primary productivity at temperatures greater than 20 C in the
lake but not in the river. At cooler temperatures (less than 20 C),
there is a relationship to temperature in the river, possibly resulting
from decreased decomposition of allochthonous material, which may have
confounded the relationship in warm temperatures.

The entrainment of the water mass through the power plant usually
resulted in a depression of the productivity in the upper discharge
canal waters. The resulting productivity rates of the water closely
resembled those of the river water. This inhibition of productivity
could have resulted from mechanical damage due to condenser passage,
thermal shocking resulting from increased temperature, or the presence
of inhibitors, possibly in the river water. As the water mass moved

through the discharge canal, the depressed productivity recovered

57

partially. Movement of the thermal plume into the lake resulted in
the stimulation of productivity, exceeding the lake values slightly.

Respiration rates in the upper discharge canal almost doubled
after passing through the power plant, as predicted by temperature
elevations. The respiration rates decreased as water moved through
the canal, until a recovery to pre-exposure rates was observed near
the end of the thermal plume, as ambient temperatures were approached.
The increase in respiration, along with a corresponding decrease in
productivity, indicated the existance of a decomposing environment in
the discharge canal waters. This precludes the possibility of photo-
synthetic carbon biomass export into the receiving waters under existing
conditions, a major concern of power plant designers utilizing once-
through.cooling.

Measurements of photosynthesis in western Lake Erie, first performed
by Verduin (1962) and Saunders (1964), were limited to single stations
and covered only certain seasons. Recent studies by Cody (1972) in the
vicinity of the Bass Islands and the Canadian Centre for Inland waters
(Glooschenko, 1974) lake wide have shown a general increase in the rate
of productivity occurring in the western basin (Table 12).

Preoperational productivity in the near shore vicinity of the
power plant was approximately double that found in the open lake by
Glooschenko. Nutrient enrichment from the Raisin River could have been
responsible for this increased productivity, as the completion of new
sewage treatment facilities was followed by declining productivity of
the near shore area. Total soluble phosphorus concentrations were
similar, 0.1-0.2 mg/l (Gachter et al., 1974 and Annett, 1977), for the

near shore and open lake. However, inorganic nitrogen concentrations

58

Table 12. Comparison of productivity measurements in western Lake Erie,

 

1962-1974.

Method g C/m2/day g C/mZIyear Data source
pH—COZ-Oz 0.51 --- Verduin (1962)
14c 0.008-0.031 --- Saunders (1964)
14c 0.83 304 Cody (1972)
02 0.54 197 Cody (1972)
14C 1.13 310 (274 days) Glooschenko (1974)
O 2.20 594 (274 days) warner

2

59

for the study area, 0.7-2.3 mg/l (Ecker, 1976) were significantly
higher than in the open lake, 0.2-0.4 mg/l (Gachter et al., 1974).

Much has been said about the advance of eutrophication in Lake
Erie in recent years. Gross primary productivity/respiration
ratios of 1.0 (Verduin, 1962) and 1.8 (Cody, 1972) indicate that the
rate of production is increasing faster than respiration, a sign of
increased lake enrichment. GPP/R ratios for the study area were almost
1.0 in the lake stations, reflecting a possible return to less eutrophic
conditions or increased respiration from allochthonous inputs.

As demand for cooling water increases in Lake Erie, the possibility
exists for a negative impact from the thermal effluent upon the apparent
recovery of the western basin. The Detroit Edison Power Plant, located
near the mouth of the Raisin River, had little if any measurable impact
upon the productivity of the receiving waters. The depressed produc-
tivity and increased respiration of the light limited system have
resulted in water of slighlty higher quality being released back into
the lake. Hawever, continued monitoring of the productivity should be
maintained at all power plants using once-through cooling to measure
changing conditions that may lead to the thermal stimulation of algal
production. Any changes resulting in the export of organic biomass
into the aquatic system may adversely effect the present recovery of

Lake Erie as a viable natural resource.

LITERATURE CITED

60

LITERATURE CITED

Annett, C.S. 1977. Phosphorus concentrations along the western shore
of Lake Erie. M.S. thesis. Michigan State Univ., East Lansing,
Mich. 82 pp.

Anon. 1965. Standard methods for the examination of water and waste-
water. 12th Edition. American Public Health Association, New
York, New York. 769 pp.

Anon., 1968. Lake Erie environmental summary, 1963-64. U.S. Dept.
of the Interior, Great Lakes Region. Federal water Pollution
Control Administration. Cleveland, Ohio. 170 pp.

Anon. 1971. Methods of chemical analysis of water and wastes. U.S.
Environmental Protection Agency, washington, D.C. 312 pp.

Arnold, E.E. 1969. The ecological decline of Lake Erie. New York
Fish and Game J. 16(1):27-45.

Beeton, A.M. 1971. Chemical characteristics of the Laurentian Great
Lakes, I3; Proceedings of the conference on changes in the chemistry
of Lakes Erie and Ontario. Bull. Buffalo Soc. Nat. Sci. 25(2):l-21.

Carr, J.F., V.C. Applegate, and M. Keller. 1965. A recent occurrence
of thermal stratification and low dissolved oxygen in western Lake
Erie. Ohio J. Sci. 65(6):319-327. '

Carr, J.F. and J.K. Hiltunen. 1965. Changes in the bottom fauna of
western Lake Erie from 1930-1961. Limnol. Oceanogr., 10:551-569.

Cody, T.E. 1972. Primary productivity in the western basin of Lake
Erie. Ph.D. thesis. Ohio State University, Columbus, Ohio. 113 pp.

Cole, R.A. 1972. Physical and chemical limnology along the western shore
of Lake Erie. Tech. Rep. 13. Institute of Water Res., Michigan
State Univ., East Lansing, Mich. 120 pp.

Cole, R.A. 1973. Environmental changes in Lake Erie and their future
impact on lake resources. Techn. Rep. 32.3. Institute of water
Res., Michigan State Univ., East Lansing, Mich. 98 pp.

61

Cole, R.A. 1976. The impact of thermal discharge from the Monroe
Power Plant on the aquatic community in western Lake Erie.
Tech. Rep. 32.6. Institute of water Res., Michigan State
Univ., East Lansing, Mich. 571 pp.

Davis, C.C. 1964. Evidence for the eutrophication of Lake Erie
from phytoplankton records. Limnol. Oceanogr. 9:275-283.

Denison, P.J. and F.C. Elder. 1970. Thermal inputs to the Great
Lakes 1968-2000. Internat. Assoc. Great Lakes Res. Proc.
13th Conf. Great Lakes Res. p. 811-828.

Ecker, T.J. and R.A. Cole. 1976. Chloride and nitrogen concentra-
tions along the west shore of Lake Erie. Tech. Rep. 32.8.
Institute of Water Res., Michigan State Univ., East Lansing,
Mich. 132 pp.

Gachter, R., R.A. Vollenweider, and W.A. Glooschenko. 1974. Seasonal
variations of temperature and nutrients in the surface waters of
Lakes Ontario and Erie. J. Fish. Res. Board Can. 31:275-290.

. Glooschenko, WkA., J.E. Moore,.and R.A. Vollenweider. 1974. Spatial
and temporal distribution of chlorophyll a and pheopigments in
surface waters of Lake Erie. J. Fish Res. Board Can. 31:265-274.

Harlow, G.L. 1966. Major sources of nutrients for algal growth in
western Lake Erie. Univ. Michigan. Great Lakes Res. Div.
Proc. 9th Conf. on Great Lakes Res. Pub. no. 15. pp. 389-394.

King, D.L. 1970. The role of carbon in eutrophication. J. water
Pollut. Contr. Fed. 42:2035-2051. -

Kovacik, T.L. 1972. Information on the velocity and flow pattern of
Detroit River water in western Lake Erie revealed by an accidental
salt spill. Ohio J. Sci., 72(3):81-86.

Kreh, T.V. 1973. An ecological evaluation of a thermal discharge,
Part VII: Postoperational effects of a power plant on phytoplankton
and community metabolism in western Lake Erie. Tech. Rep. 32.1.
Institute of water Res., Michigan State Univ., East Lansing, Mich.
92 pp.

Marcus, M.D. 1972. The distribution of phytoplankton and primary
productivity near the western shore of Lake Erie. Tech. Rep.
14. Institute Water Res., Michigan State Univ., East Lansing,
Mich. 96 pp.

Michigan State university. 1974. Mass transport of biological
materials through a once-through cooling system on Lake Erie,
November 1972-August 1974. Institute of water Res. and Michigan
State Uhiv., East Lansing, Mich. 106 pp.

62

Morgan, R.P. and R.G. Stross. 1969. Destruction of phytoplankton in

the cooling water supply of a stream electric station. Chesapeake
Sci. 10:165-176.

Munawar, M., J. Verduin, and I. Fatima. 1972. Primary production
studies in shallow aquatic environments of Southern Illinois.
Verh. Internat. Verein. Limnol. 18:113-120.

Saunders, G.W. 1964. Studies of primary productivity in the Great
Lakes. Proc. 7th Conf. Great Lakes Res., Inter. Assoc. Great
Lakes Res., Ann Arbor, Mich. p. 122-129.

Strickland, C.D. 1960. Measuring the production of marine phytoplankton.
Bull. Fish. Res. Bd. Can. 122. 172 pp.

Verduin, J. 1957. Daytime variation in phytoplankton photosynthesis.
Limnol. Oceanogr. 2(4):333-336.

Verduin, J. 1962. Energy flow through biotic systems of western Lake
Erie. “Ig_Great Lakes basin, Amer. Assoc. Advance. Sci. Pub.

Verduin, J. 1964. Changes in western Lake Erie during the period
1948-1963. Verb. Internat. Verein. Limnol. 15:639-644.

Verduin, J. 1969. Man's influence on Lake Erie. Ohio J. Sci.
69(2):65-70.

Verduin, J. 1972. Metabolism of the dominant autotrophs of the North
American Great Lakes. Verh. Internat. Verein. Limnol. 18:105-112.

Vellenweider, R.A., M. Munawar, and P. Stadelmann. 1974. A comparative
review of phytoplankton and primary production in the Laurentian
Great Lakes. J. Fish. Res. Board Can. 31:739-762.

Vollenweider, R.A. and A. Nauwerck. 1961. Some observations on the
C 14 method for'measuring primary production. Verh. Internat.
Verein. Limnol. 14:134-139.

wadelin, D. and M.G. Mellon. 1953. Extraction of heteropOly acids with
application to determination of phosphorus. Anal. Chem. 25:1668-
1673.

Westlake, D.F. 1969. Interpretation of results: units and comparability,
pp. 113-117. .32; R.A. Vollenweider (ed.). A.manual on methods for
measuring primary production in aquatic environments. Blackwell
Sci. Pub., Oxford and Edinburgh, England.

APPENDICES

63

Table A1. Sampling dates for the Detroit Edison study sites, 1970
through 1974.

 

 

 

Seasons
Year Spring Summer Fall
1970 5-1 6-23 9-29
5-15 7-7 10-27
5-27 7-21
6-10 8-4
8-24
9-1
1971 4-15 6-30 10-2
5-21 7-16 10-16
6-3 7-29 10-30
6-18 9-15 11-13
1972 5-12 6-28 9-13
6-1 7-12 10-13
6-14 7-25
8-30
1973 4-27 6-21 9-10
5-11 7-7 10-9
5-23 7-17 11-13
8-1
8-16
8-29
1974 3-15 7-16 9-27
4-17 7-31 10-7
5-22 8-27 10-24

64

Table A2. Sampling dates for the USEPA Study sites, 1972
through 1975.

 

 

Date Morning Afternoon Evening
November 1972 11-9 11-10 11-9
January 1973 1-26 1-25 1-18
March/April 1973 4-6 4-5 3-30
June 1973 6-13 6-12 6-11
August 1973 8-10 8-9 8-8
September/October 1973 10-1 9-29 9-28
December 1973 12-14 12-13 12-12
January/February 1974 2-2 2-1 1-31
April 1974 4-12 4-11 4-10
June 1974 6-13 6-12 6-11
August 1974 8-16 8-15 8-14
October 1974 ‘10-21 10-20 10-19
January 1975 1-25 1-25 1-24
March 1975 3-17 3-16 3-15
May 1975 5-18 5-17 5-16
July 1975 7-29 7-28 7-27

September 1975 9-17 9-16 9-15

Mean Gross Primary productivity and respiration in mg 0

Detroit Edison study sites.

Table A3.

2/1/hr by station and date for the

 

2.5m.

1.5m

0.5m

Station Surface (0.0m)

Date

 

 

 

 

GPP

GPP

GPP

GPP

 

0.13 0.05 0.05 0.04 0.34 -0.10 0.04

0.33

5-1-1970

‘83

00
CO

0.30
0.39

5-15-1970

O
O

O
O

0.12

5-27-70

65

0.16 -0.08 0.09

0.01

6-10-1970

0.1
0.2

0.23
0.2

0.10
0.4
0.1

0.39
1.02
0.23

0.06

0.0

6-23-1970

0.15
-0.29

0.08
-0.01

0.08
-0.01

0.03
0.05
-0.04

7-7-1970

0.01
0.1

0.02
0.14
0.03

0.10
0.03

7-21-1970

0.0

0.23
0.00
0.10
0.14
0.09
0.53
0.05

0.93
0.15
0.27
0.96
0.55
2.75
0.96

8-4-1970

8-24-1970

0.07 0.05 0.14 0.04 0.12

0.48

66

 

 

 

 

 

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a9.9 oa.o No.9 oa.o 99.9 9a.9 99.9 9
oa.o 99.9 9a.o 99.9 99.9 99.9 99.9 9
in in :1 in .1 in in 9 oe9ana9ue
99.9 99.9 «9.9 99.9 9a.9 oa.9 99.9 9
99.9 eo.9 9a.9 oa.o 99.9 9a.9 99.9 9
99.9 «a.o 99.9 a9.9 99.9 99.9 99.9 9 999auoale
eeu 9 eeu e eeu 9 eeu
99.9 am.a 29.9 aao.oo ouaoeem coauuum «999

a.o.eouo 99 eaoee

71

Table A4. Mean suspended solids, total nongaseous nitrogen, total
soluble phorphorus, and total organic carbon concentrations
in mg/l by station for the Detroit Edison study sites.

 

 

Total Total
Suspended Nongaseous Soluble Total
Date Station Solids Nitrogen Phosphorus Organic Carbon
5-1-1970 3 54.7 3.73 0.19 11.0
8 63.3 3.71 0.15 12.7
9 38.3 3.74 0.26 18.7
5-15-1970 3 50.3 1.63 0.15 15.3
8 84.7 2.37 0.15 13.7
9 49.7 2.44 0.18 29.7
5-27-1970 3 “33.7 0.89 0.06 16.0
8 75.7 3.47 0.08 19.3
9 51.0 5.95 0.16 22.8
6-10-1970 3 27.7 2.25 0.07 11.5
8 42.0 2.34 0.09 10.3
9 29.0 2.08 0.22 14.0
6-23-1970 3 21.0 1.93 0.05 6.2
8 35.7 3.28 0.07 9.7
9 51.8 6.08 0.11 13.0
7-7-1970 3 25.7 0.88 0.07 5.5
8 62.8 1.77 0.12 15.5
p 9 66.7 1.89 0.24 5.8
7-21-1970 3 25.0 0.71 0.09 5.3
8 45.3 1.46 0.15 16.0
9 38.0 2.24 0.22 13.0
8-4-1970 3 33.7 0.75 0.08 6.2
8 52.0 1.83 0.12 17.3
9 68.3 1.91 . 0.24 17.2
8-24-1970 3 26.7 0.58 0.15 6.2
8 34.7 1.45 0.13 20.2
9 49.0 1.52 0.29 17.5
9-1-1970 3 25.0 0.71 0.10 9.8
8 32.3 1.39 0.17 19.7
9 44.0 1.27 0.35 16.7
9-29-1970 3 20.0 0.55 0.07 8.2
8 24.7 1.51 0.06 10.7
9 37.0 1.33 0.26 16.5
10-27-1970 3 16.3 0.99 0.08 6.5
8 18.7 1.61 0.12 10.3
9 37.0 1.69 0.20 16.0
5-21-1971 3 45.7 1.46 0.10 8.0
8 61.2 2.30 0.16 17.2
9 77.7 2.50 0.24 18.2
6-3-1971 3 31.7 0.74 -- 6.7
8 71.5 3.90 -- 18.3
9 73.5 4.74 -- 20.2

Organic Carbon

Total

Total
Phosphorus

72
Nitrogen

Suspended Total

Solids

Station

Table A4 (Con't)

Date

 

835285238ass-37885035055272
4mm8258m9.0228632947215684
11 11111121112112.1

231 451946076981 8861086
123. - .123023123024 1201202
coo-.-eeeeeeeeeeeeeeeeeeee
000 00000000000000000000

87375720737735305882333702

70123058928749.080030468265
25524432212213?- 2213525615

0.06
0.23

1.40
2.89

533850572072353

“32549067144148?-

1. 1. 1.

0.06
0.18
0.19
0.11
0.16
0.24
0.08
0.13
0.22
0.05
0.10
0.21
0.07
0.14
0.28

010 830304600149
604 20067670138

eeeeeeeeeeeee
098223324027111

32~Io255530o91928~d32

.0 0

143241122 11122

389389389389389389389389389389389389389389389

6-18-1971
6-30-1971
7-16-1971
7-29-1971
9-15-1971
10-2-1971
10-16-1971
10-30-1971
11-13-1971

2-29-1972

6-28-1972
7-12-1972

5-12-1972
6-14-1972

6-1-1972

Organic Carbon

Total

Total
Phosphorus

73

Nitrogen

Suspended Total

Solids

Station

 

Table A4 (Con't.)

Date

837877205523285570053300285830322530008235372
2454735505996045778815008696705704386504561465

111 1
01201201b011012011112122012012012012012012011
0.0000000000000000.0.0000000000000000...so...
oooooooooooooooo0000000oooooooooooooooooooooo

o o o o o o o o
011127123245134122234377 22124113011013012012

8.380148785828300582838777702507058325000720757
O C O O. ...
“53328667773276932282941547344953218637171565

389389389389389389389389389389389389389389389

7-25-1972
9-13-1972
10-13-1972
4-27-1973
5-11-1973
6-21-1973
7-17-1973
8-16-1973
11-13-1973

3-30-1972
7-7-1973
8-1—1973
8-29—1973
9-10-1973
10-9-1973

74

Table A4 (Con't.)

Total

Total

Suspended Total

Solids

Organic Carbon

Phosphorus

Nitrogen

Station

Date

 

332008382503500207328330

128512866999681932690504
121122011000002014002011
oooooooooooooooooooooooo
oooooooooooooooooooooooo
954765245178953667242
coco-0000000000000...

852228785307303005538055
coco-00000900000000.0000
166610523518192273477338

27679615413211223n126121

389389389389389389389389

3-15-1974
4-17-1974
5-22-1974
7-16-1974
7-31-1974
9-27-1974
10-7-1974
10—24-1974

75

Mean temperature (C) by station for the Detroit Edison

study sites.

Table A5.

 

DEPTH
0.5m

2.5m

1.5n

 

0.0m

Station

Date

 

13.9 13.9

13.8

13.8

5-1-1970

15.0
18.0
18.0

15.0
18.0
18.0

389

5-15-1970

389

7-7-1970

389

7-21-1970

8-4—1970

8-24-1970

26.0 23.5
23.0 23.
25.0 24.

24.0
23.
25.

9-1-1970

10-27-1970

4-15-1971

17.5
21.5
20.0

5-21-1971

6-3-1971

76

Table A5 (Con't.)

DEPTH

1.5m 2.5m

0.5m

 

0.0m

Station

Date

 

22.
31.
24.0

23.5
32.5
24.0

6-18-1971

26.5 26.0 25.0
34.0 34.0 33.0
27.5 27.0 26.5

26.5
34.0
27.5

6-30-1971

7-16-1971

7-29-1971

'9-15-1971

21.5 20.5 20.0
26.0 26.0 25.0
22.5 22.0 21.5

21.5
26.0
23.0

10-2-1971

10-16-1971

10-30-1971

005
.0.
746

000
o o o
747

000
o o o
747

000
so.

ll-l3-l97l

05
11

00
12

nus.
1.9.

00
13

2-29-1972

17.0

17.0

17.0

17.0

5-12-1972

6-1-1972

77

Table A5 (Con't.)

DEPTH

0.5m

2.5m

1.5m

0.0m

 

Station

Date

 

389

6-14-1972

18.0 18.0 18.0
18.5 18.5 18.5
22.0 21.0 20.0

18.0
18.5
23.0

6-28-1972

21.5
26.
21.

22.0
26.0
22.0

7-12-1972

23.0 23.0 23.0
30.0 30.0 30.0
25.0 24.5 24.0

23.0
30.0
25.0

389

7-25-1972

23.0 23.0 23.0
31.0 31.0 31.0
26.0 25.5 25.0

23.5
31.0
26.0

8-30—1972

20.5
28.5
22.0

20.5
31.0
23.0

9-13-1972

10-13-1972

4-27-1973

16.0 16.0 16.0
24.0 24.0 24.
18.5 18.5 18.

16.0
24.0
18.5

5-11-1973

15.
25.
16.

15.
25.
16.5

5-23-1973

23.0 23.0 22.5
30.0 30.0 30.0
25.5 25.0 24.0

23.0
30.0
26.0

6-21-1973

7-7-1973

78

Table A5 (Con't.)

DEPTH

1.5m 2.5m

0.5a

 

0.0m

Station

Date

 

7-17-1973

389

8-1-1973

8-16-1973

8-29-1973

23.5 23.5 23.5

23.5

9-10-1973

19.0 19.0 19.0
26.0 26.0 26.0
22.5 22.0 21.0

19.0
25.0
22.5

10-9-1973

500
o o o
679

..uAunu
O O O

770
11..

050
so.

761
11..

050
o o o
761
11

11-13-1973

000
.00

3-15-1974

050
so.

11

055
so.

11

000
.00

893
1.1

005
so.

893
11

4-17-1974

16.5 16.
26.0 26.
19.0 18.5

16.
26.
19.0

5-22-1974

24.5 24.5 24.5
30.0 30.0 30.0
27.5 27.0 27.0

24.5
31.0
28.0

7-16-1974

25.0 24.5 24.5
30.5 30.5 30.5

25.0
30.5

7-31-1974

79

Table A5 (Con't.)

DEPTH

1.53 2.5m

0.5m

 

0.00

Station

Date

 

27.0 27.0 27.0
36.0 36.0 36.0
29.0 29.0 27.0

27.
36.
29.0

8-27-1974

17.0 17.0 17.0
22.5 22.5 22.5
18.5 18.5 18.5

17.0
23.0
19.0

9-27-1974

14.0 14.0 14.0
230 2305 230
16. 16.0 15.

14.0
23.0
16.5

10-7-1974

11.0 11.0 11.0
20.5 20.5 20.
15.0 14.5 13.

11.0
20.0
14.5

389

10-24-1974

GPP

Evening

 

Temp.

R

lllhr and temperature (C)

2
GPP

by station and date in the cooling system for the USEPA study sites.
Afternoon

 

Temp.

GPP

Morning;

 

Temp.

3

Mean gross primary productivity and respiration in mg 0
Station

25/1973

 

 

Table A6.
Date
11/9-10/1972
1/18-19 &

80

°N°°°
o o o o o
”“0“”

28888

.000.
066°C

”COCO
006°C
0 O O O.
OOOOO

00°C
.0...

Qflwfi’fi

12

8.0 0.00 0.00 10.0 -

4/5/1973

3130 5

0.02

0.03

0.0
0.0
0.0

0.00
0.03
0.09

16.0
13.0
11.5

14
15
16

0.03

0.03
0.03
0.03
-0.06

Evening
GPP

 

Temp.
27.0

0.06

GPP
0.15
0.06

Afternoon

 

Temp.
26.0
26.0

0.09
0.06
0.03

GPP
0.36
0.45
0.09

Morning

 

Temp.
22.0
24.5
25.0

Station
3
12

 

6/11-13/1973

Table A6 (Con't.)
Date

0.03
0.09
0.18

27.0
26.5
24.0

0.03

26.0
25.
22.

0.00
0.1
0.0

0.03

21.0
18.5

0.03
0.06

0.18
0.36

21.5
26.5
18.5

0.09
50.75
1.86
1.86
0.06

0.72
1.62
0.7
1.3
0.12

21.5
26.0
28.0
26.0
18.0

16
3
15
16
3

8/8-10/1973
9/29—10/1/1973

«one
COO
06.9
MOM
GOO
GOO.
comm
I O O
InI-iO
NNN

14
15
16

OflOMOOI-fi

.0 0.. O.

«newsman
Flt-0H

m0‘Nthfi‘O
I-I HHH

M

h

0‘

H

\

Q

...1

t

N

H

\

N

H

GPP

Evening;

Temp.

 

Afternoon
GPP

 

Temp.

0.03
-0.0
0.0
0.0
0.03

GPP
0.00
-0.03
0.03
-0.03
0.03

Morning?»

COGNU‘
@HQNH
Fit-0H

 

Temp.

3
14
15
16

Station
12

 

1/31-2/2/1974

Table A6 (Con't.)
Date

82

0.03
-0.03
0.06
0.06
0.04

0.03
-0.03
0.06
-0.06
0.12
0.03
0.03

nnnn
C‘Owo

0.00
-0.01
0.06
0.06
-0.03

0.00
-0.03
0.06
0.06
-0.03

11.0
11.6
14.3
14.0

0.03
0.03
0.06
-0. 03

0.03
0.03
0.06
-0003

4/10—13/1974

15.0

14.5

14.0

14

-0003
-0003

FIG
H'

-00 03
-00 03

-00 03
-0003

HQ
H

0.06
0.00

0.06
.00

GO
coo
H

15
16

0.03 21.5

0.33

23.0 '
29.3
29.5

0.03
0.06

0.3
0.0
0.36

21.5
28.7

6/11-13/1974
8/14-16/1974

0.03
-0.01
0.08
-0.03
0.07
-0.04

GPP
0.01
-0.06
-0. 27
-0002
0.02
-0.02

Evening

 

Temp.
12.0
12.5
21.2
20.2
19.5
15.5
13.0

0.00
0.07

GPP
0.12

Afternoon

 

Temp.
10.2

GPP
0.13

0.40

Morning:

 

Temp.

12.0

Station
3

 

10/19-21/1974

Table A6 (Con't.)
Date

83

 

OHHQMOQ NOV‘MONM OOHOQOI‘
HOP-060°C OOOOOOO OOOHOHH
0000000 0000000 00000..
O GOOD OOOOOOO OOOOOOH
00000.. 0000000 0000000
OOOOOOO OOOOOOO OOOOOOO
I I I I I I I I I I I
NOMNIflNh MNONWNC O I-INONO
0.00000 000000. s so...
HHMMNO‘Q NQOQNHI‘ WIG‘OMHI‘
I-IO-Iv-Iv-I v-INI-Iv-II-I I-I NNNNl—I
:gln~or~l~~o<=
::::::: ::::::: °°°°°~
o o o o o o 0
0606600
{GOONQO
::::::: ::::::: *""~~“*
o o o o o o o
OOOOOOO
lflONOONO NIhNONNO OOOOOOO
ooooooo ooooooo ooooooo
VONIH~¢MQQ NN‘OQWI‘l-fi NOQNNNO
HI-IHI-I I-Iv-Iv-I HNNNNNN
COOMN M I-INOQONN \DOO‘MGQ‘O
OOHOOIO OOHHHOO I-IOv-Io-IOOv-I
coo-0|. 0.00000 00.0000
NNHNN In NMQQNIHC HOMQ'gQ'I-I
HOHOOIO COO—ICON acne #0
00000.. 0000000 0000000
Ciolvsh~oav\h- ooh-C>U\h-C>c> our-oaoan-«561
000000. 0000000 0000.00
@MQNNNM Nlfla\h@v-IP~ ”Oflh‘DNO
FIF'Io-II-I HHI-II-II-I HNNNNNN

8
14
15
16

1/24-25/1975
3/15-17/1975
5/15-18/1975

 

84

 

 

 

 

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