905D82100
00605-
254-F
RAFT
CLEAR TECHNICAL REPORT NO. 254-F
FINAL REPORT OF 1981
MAIN LAKE WATER QUALITY CONDITIONS
FOR LAKE ERIE
Edited by
Laura A. Fay
Prepared for
U.S. Environmental Protection Agency
Great Lakes National Program Office
Region V, Chicago, Illinois
Grant No. R005555-02
Project Officer: Clifford Risley Jr.
THE OHIO STATE UNIVERSITY
CENTER FOR LAKE ERIE AREA RESEARCH
COLUMBUS, OHIO
August 1982
U.S. Environmental Protection Agency
GLNPO Library Collection (PL-12J)
77 West Jackson Boulevard,
Chicago, IL 60604-3590
-------
TABLE OF CONTENTS
Page
List of Tab!es 11
List of Figures iii
Acknowledgements vi
Executive Summary (Laura Fay) 1
Summary 1981 1
Trends 1970-1981 2
Means Versus Medi ans 2
Future Sampling Design 3
Introduction and Methods (Laura Fay) 4
Objectives of Sampling Plan 4
Description of Sampling Plan 4
Rationale for Parameter Selection 4
Methods 5
Report Objectives 5
Physical Data (Timothy Bartish and Charles E. Herdendorf) 5
Thermal Distribution 5
Dissolved Oxygen 6
Nutrients (Julie Letterhos) 7
Particulates (Gary Arico) 10
Chlorophyll, Solids, Particulate Organic Carbon,
Turbidity, Secchi 10
Available and NonavaiTable Particulate Phosphorus 12
References Cited 15
Tables 17
Figures 46
-------
LIST OF TABLES
Page
1. Dates for 1981 Western Basin Transects 17
2. Dates for 1981 Lake Erie Main Lake Water Quality Cruise 18
3. Geographic Coordinates of 1981 Lake Erie Water Quality
Monitoring Stations 19
4. Water Quality Parameters for Main Lake Erie Monitoring Program.. 21
5. Analytical Methods Summary for 1981 Lake Erie Water Quality
Determinations 22
6. Lake Erie Western Basin Water Quality Summary 24
7. Lake Erie Central Basin Water Quality Summary 26
8. Lake Erie Water Quality Measurements 1981 Western Basin
Cruise Means Concentrations 28
9. Lake Erie Water Quality Measurements 1981 Central Basin
Cruise Mean Concentrations 31
10. Summary of 1981 Central Basin Hypolimnetic Surveys of
Lake Erie 37
11. Estimated Area of the Anoxic Hypolimnion of the Central
Basin of Lake Erie 1930-1981 38
12. Trends in Net Oxygen Demand of the Central and Eastern Basin
Hypolimnions of Lake Erie 1930-1981 39
13. Comparison of 1981 Available and Non-available Phosphorus
Fractions by Percent to Historic Data 40
14. Lake Erie Transparency Measurements 1973-1981 41
15. Lake Erie Water Quality Measurements 1981 Western Basin
Cruise Mean Concentrations Stations 202 and 401 Excluded 43
-------
LISTS OF FIGURES
Page
1. 1981 Station Pattern 46
2. Limnion horizontal distribution maps, for temperature (°C),
1981 47
3. Distribution maps of Hypolimnion thickness (m), 1981 50
4. Thermal structure of central Lake Erie at Station 37, May to
October, 1981 51
5. Thermal cross-section of central Lake Erie, Cruise 4 (June 24-
July 3) 52
6. Central Basin 1981, Dissolved Oxygen Percent Saturation Cruise
means by limnion 53
7. Limnion horizontal distribution maps for dissolved oxygen
(mg/1) and for the composite anoxic area, 1981 54
8. NO, + N02 Basin Comparison of Epi and Hypolimnion
Concentrations 55
9. Ammonia Basin Comparison of Epi and Hypolimnion Concentrations... 56
10. Soluble Reactive Phosphorus Basin Comparison of Epi and
Hypolimnion Concentrations 57
11. Total Phosphorus Basin Comparison of Epi and Hypolimnion
Concentrations 57
12. Soluble Reactive Silica Basin Comparison of Epi and Hypolimnion
Concentrations 58
13. Limnion horizontal maps for nitrate plus nitrite (ug/1) 1981.... 59
14. Limnion horizontal distribution maps for ammonia (ug/1) 1981 63
15. Limnion horizontal distribution maps for soluble reactive
phosphorus (ug/1), 1981 66
16. Limnion horizontal distribution maps for total phosphorus
(ug/1), 1981 70
17. Limnion horizontal distribution maps for soluble reactive
silica (ug/1), 1981 74
m
-------
Page
18. Corrected Chlorophyll a. Western Basin 1981 77
19. Corrected Chlorophyll a_ Central Basin 1981 • 78
20. Total Suspended Solids Western Basin 1981 79
21. Residual Suspended Solids Western Basin 1981 80
22. Total Suspended Solids Central Basin 1981 81
23. Residual Suspended Solids Central Basin 1981 82
24. Volatile Suspended Solids Western Basin 1981 83
25. Volatile Suspended Solids Central Basin 1981 84
26. % Volatile Suspended Solids Western Basin 1981 85
27. % Volatile Suspended Solids Central Basin 1981 86
28. Turbidity Western Basin 1981 87
29. Turbidity Central Basin 1981 88
30. Particulate Organic Carbon Western Basin 1981 89
31. Particulate Organic Carbon Central Basin 1981 90
32. Station 037, 1981. Surface Concentrations of Total Suspended
Solids, Turbidity and Reciprocal of Secchi 91
33. Station 037, 1981. Surface Concentrations of Volatile
Suspended Solids, Particulate Organic Carbon, and Corrected
Chlorophyl 1 a_ 92
34. Limnion horizontal distribution maps for corrected chlorophyll
a. (ug/1), 1981 93
35. Western Basin Secchi Area weighted cruise values, 1978-1981 95
36. Central Basin Secchi Area weighted cruise values, 1978-1981 96
37. Corrected Chlorophyll a Yearly Means Western Basin Surface
(1970-1981) ~ 97
38. Corrected Chlorophyll a^ June to November mean concentrations
(ug/1) in the surface waters of western Lake Erie, 1970-1981 98
IV
-------
Page
39. Corrected Chlorophyll a Yearly Means Central Basin Surface
(1970-1981) 99
40. Corrected Chlorophyll a^ June to November mean concentrations
(ug/1) in the surface waters of central Lake Erie, 1970-1981 100
41. Total Phosphorus Yearly Means Western Basin (1970-1981) 101
42. Total Phosphorus Yearly Means Central Basin (1970-1981) 102
-------
ACKNOWLEDGEMENTS
We wish to thank the USEPA Great Lakes National Program Office for the
funds to complete the 1981 Lake Erie Field Season (Grant No. R 00 5556-02) and
for their continued support which enables CLEAR to be an integral agency in
obtaining data for the Lake Erie data base.
The editor and authors wish most to acknowledge Dr. Karl is Svanks,
without whose help we wound never have been able to leave the dock.
VI
-------
EXECUTIVE SUMMARY
Summary 1981
Stratification existed in the central basin from early June to mid-
September, an observed period of 109 days. The thermal structure was not as
pronounced for the early June cruise as it was in 1980 but the other
stratified cruises resembled a typical stratified year. The maximum anoxic
area was recorded during cruise 5 (early September). The composite of the
anoxic area is shown in Figure 7 ajid represents 29 percent of the total
central basin surface area (4,280 km2).
The nutrient distributions and concentrations were comparable to those
found during other years with two exceptions. Increased western basin
nutrient concentrations can be explained due to flooding in the Toledo Area on
June 13th and 14th. NOAA (1981) reported 8.48 inches of rainfall over the 2-
day period which resulted in increased concentrations of soluble reactive
phosphorus, total phosphorus and soluble reactive silica. A slight increase
in ammonia concentrations was observed (Figure 9). Another unusually heavy
rain storm on September 3rd and 4th in the Toledo area resulted in 6.05 inches
of rain. This storm was more widespread and extended to the Cleveland area
dropping 6.8 inches of rain. Increases in nutrients were recorded for both
the western basin and the central basin. Toledo reported a total annual
rainfall of 38.4 inches which was 7 inches above the average annual Toledo
rainfall of 31.5 and Cleveland reported 4 inches above its average annual
rainfall of 35 inches. The increase in total annual rainfall for these two
areas is not as significant as the magnitude of the rainfall received during
discrete storms.
The heavy precipitation also increased the western basin concentrations
of total solids, residual solids, and turbidity. The 1981 area weighted
secchi data (Table 14, Figure 35) alluded to poorer water quality in the
western basin when compared to the 1978-1980 data, possibly explained by the
June and September storms.
The results of the 1981 apatite phosphorus study were compared to other
Lake Erie investigators' available and non-available phosphorus results for
tributaries (DePinto 1981; Logan 1979) and sediments (Williams 1976). The
percentages of the apatite (nonavaiTable) phosphorus found in the western and
central basins water column were intermediate between data reported for the
tributaries and the sediments (Table 13). Data reported for the organic and
NAIP types indicates fairly uniform percentages of availability of phosphorus
(NAIP) for the western and central basins (22-27 percent) and a higher
percentage of organic phosphorus in the central basin (63 percent) when
compared to the western basin (45 percent). The availability of a portion of
this organic fraction is variable.
-------
Trends 1970-1981
Extensive analysis of Lake Erie trends have been reported by Fay and
Herdendorf (1981) and by the Lake Erie Technical Assessment Team (Rathke
1982). It is not necessary to reiterate the conclusions of these reports,
only to add the 1981 data to them. No trends are evident when utilizing the
surface annual mean concentrations for corrected chlorophyll ji for 1970 to
1981 (Figure 37 and 39). Data for total phosphorus annual mean concentrations
also show no distinct pattern (Figures 41 and 42). The determination of
trends is not a simple matter and cannot be determined by the simplistic
calculation of mean annual concentrations. This technique reflects the
variability enhanced by the changes in the number of stations, location of
stations and the scheduling and number of cruises between the years. When
proper filtering of the data is accomplished there appears to be a slight
decrease in chlorophyll & lake concentrations since 1977 (Figures 38 and 40).
The remaining mild fluctuations between years are explained by fluctuations
in water level. Higher water level years had slightly lower levels of
chlorophylls and lower water level years had higher chlorophyll
concentrations (Fay and Herdendorf 1981).
The addition of station 202 located at the mouth of the Maumee River for
field years 1980 and 1981 make the interpretation of long-term trends
difficult because of the increased magnitude of the nutrient concentrations.
Limnion means for the western basin have been recalculated (Table 15)
excluding the two river mouth stations 202 (Maumee River) and 401 (Detroit
River). There is a 25 percent reduction in the mean annual TP concentration
with the elimination of these two stations from 41.80 ug/1 to 32.16 ug/1.
Before the long-term trends can be finalized, it will be 'necessary to repeat
the western basin volume weighting procedure for both 1980 and 1981 to comply
with the data available for 1973 to 1979.
Means Versus Medians
Statistical analysis of past years of Lake Erie data has demonstrated
that the sample populations for total phosphorus and corrected chlorophyll ^
are not normally distributed about the sample mean. In other words, if all
the data were plotted, one would not end up with the bell-shaped curve of a
normal population. Statistical means and standard deviations are tools for
the characterization of normal populations only. For other populations, non-
parametric statistical tools (medians and quantiles) should be used. To
examine the effect of using mean statistics on a non-Gaussian population we
have presented means, standard deviations, and medians (the 50th percentile)
by limnion, basin and cruise (Tables 8 and 9). The use of limnion mean
concentrations may be justified for the central basin population due to the
similarity in values of means and medians. When large differences did exist,
it was rare and generally encountered for hypolimnion samples. However, the
western basin repeatedly demonstrated means that were 100 percent greater
than medians for total phosphorus, soluble reactive phosphorus, soluble
reactive silica, nitrate plus nitrite, ammonia, turbidity, and solids. This
is partially the result of the inclusion of station 202 at the mouth of the
Maumee River which always has high concentrations biasing the western basin
-2-
-------
mean. Even with the elimination of station 202 data, the range of
concentrations in the western basin is large. It appears that the median may
provide the best characterization statistic for the lake (Table 15).
Future Sampling Design
To insure future reliability of the Lake Erie data base, scientific
statistical analysis must be performed on the already existing data base to
determine critical station locations, number of stations, times of sampling,
and number of cruises. The fluctuations between years for the mean annual
concentrations of TP and corrected chlorophyll a^ are supplied by the spring
and fall data and, for some types of historical trends these data points are
eliminated. The lake must be divided into homogeneous areas or zones using
the clustering technique and the number of stations to be sampled within each
zone should be calculated. The time and money expended to scientifically
select numbers of stations and cruises will be returned in savings during
cruise time and in data analysis. The technical ability to design a new lake
program is available (El-Shaarawi 1982).
-3-
-------
INTRODUCTION
Objectives of Sampling Plan
The 1981 sampling scheme was designed to obtain Lake Erie western and
central basin data as an integral portion of the U.S. plan to study the lower
lakes. The station pattern selected affords us the luxury of monitoring the
extent of anoxia in the central basin, while obtaining data that can be
utilized for trend analysis due to the continued sampling of these stations
since 1973. The U.S. economic situation has presented a great impetus for the
creation of the ultimate Lake Erie sampling design, one which would minimize
use of our resources (time and money) and maximize our annual monitoring
information .on the lake. The resulting sampling program was an attempt at
this design.
Description of Sampling Pattern
The 1981 station pattern (Figure 1) is a reduced version of the 1973 main
lake plan with two exceptions. Stations have been added at the mouths of the
Maumee (202) and Detroit (401) Rivers to define the loading sources and a
twelve station transect from Locust Point, Ohio to Leamington, Ontario was
added to characterize the mixing of the Detroit and Maumee River water masses.
This transect was sampled monthly during March, April, May, November and
December and on a bimonthly basis from June to October. The analysis of the
western basin transect is not presented here, but the data corresponding to
the 9 main lake cruises has been included in the western basin cruise means
and contours (Table 1). A reduced station plan (n = 13) was followed for the
central basin spring and fall cruises (1-3 and 7-9) while the full basin
coverage plan (n = 31) was implemented during the stratified cruises. The
original schedule required three cruises following the establishment of
stratification and prior to turnover on a 3-4 week interval basis. However,
due to boat mechanical failure no cruises could be made for the months of July
and August. The geographic coordinates of all stations are presented in Table 3.
Parameter Selection
The rationale for measuring the selected parameters is based on the
knowledge desired to answer standard limnological questions. Many of the
parameters have been selected so that continuing records of data may be
available for historical trend analyses. Anyone who has attempted historical
data analysis knows of problems resulting from changing parameters or
technology for valuable parameters. The value of the consistency of the
following parameters to limnology and to historical data analysis is great;
temperature, dissolved oxygen, pH, conductivity, secchi depth, turbidity and
suspended solids. Other parameters are more valuable in determining the
degree of the eutrophication and for estimating the benefit of many of the
improvements made to sewage treatment plants, industrial effluents and
agricultural runoff around the Lake Erie basin (total phosphorus, soluble
-4-
-------
reactive phosphorus, total filtered phosphorus, nitrate plus nitrite, ammonia
and soluble reactive silica). Chlorophyll analysis has been carried out
continually since 1970 and provides historical data for trophic status
analysis and for estimation of the phytoplankton production. Other
biological parameters (particulate organic carbon, particulate organic
nitrogen, phytoplankton and zooplankton) are useful, but expensive and very
time-consuming. Select stations and cruises were chosen for analysis of
biological parameters to maximize knowledge gained. An explanation of the
parameter monitoring program is presented in Table 4.
Methods
A summary of the methods employed for the 1981 season is presented in
Table 5. A detailed description of the methods is presented in Letterhos
(1982).
Report Objectives
The main objective of this technical report is to update the Lake Erie
data base for total phosphorus, corrected chlorophyll ji and dissolved oxygen
for lake managers. The second thrust of this report is to pass on new
information regarding Lake Erie, i.e., seasonality of nutrients other than
total phosphorus, and the availability of phosphorus forms.
The volume weighted data presented in this report was produced by the
Survey 8 program (Hanson et al. 1978). Tonnage and volume-weighted limnion
mean concentrations were produced for total phosphorus, soluble reactive
phosphorus, corrected chlorophyll ^, nitrate plus nitrite, ammonia, and
soluble reactive silica (Tables 6 and 7). Arithmetic limnion means were
calculated for all parameters by basin (Tables 8 and 9) and for those persons
wishing volume weights of other paramters, reasonable estimates may be
obtained by multiplying the limnion concentrations (Tables 8 and 9) by the
limnion volumes presented in Tables 6 and 7.
PHYSICAL DATA
Thermal Distributions
The main lake horizontal distribution of temperatures follows the
pattern described by Zapotosky (1980); essentially, the lake warms in the
spring and cools in the fall in a west-to-east gradient. Vertical temperature
profiles during non-stratified periods in 1981 indicate differences from
surface to bottom never exceeding 2.4 C in either basin (Figure 2).
In 1981, thermal stratification was first observed during cruise 3 (June
3) remaining, although only at select stations, during cruise 6 (September
20), covering a span of at least 109 days. The thickest hypolimnion was found
-5-
-------
in the mid portion of the central basin, between Cleveland and Eireau (Figure
3). The thickest hypolimnion encountered was 9.7 m during cruise 3 (early
June), decreasing steadily throughout the season. Initial hypolimnion
temperatures were about 9°C. The minimum bottom temperature, 7.3 C, was found
in the eastern portion of the central basin at (station 26) during cruise 4
(late June), which may be the result of intrusion of eastern basin mesolimnion
water.
Temperature profiles for station 037 (Figure 4) located in the middle
portion of the central basin, are presented for cruises 2-7 (May through
October). Stratification began in early June; however, the thermocline at
this time was not as pronounced as it was in June of 1980. The development of
the limnions progressed according to the classic description (Hutchinson
1957). The location of the mesolimnion fluctuated between 14-16 meters
throughout the stratified season while the slope of the rate of change of
temperature per meter increased from 2°C/m in early June to 4.8°C/m in early
September.
Due to the prevailing south-west winds and the Coriolis effect,
downwelling occurs along the south shore and upwelling on the north shore of
the central basin, giving a predominant tilt to the thermocline. However,
during our sampling cruises of 1981, this condition was not as noticeable as
during other years (Zapotosky and Herdendorf 1980). This may be a result of
different wind and hydrodynamic forces encountered during 1981, but it more
likely reflects conditions only during sampling cruises (Figure 5).
Although stable thermal stratification does not occur in the western
basin, occasionally conditions are favorable for a temporary, ephemeral
thermocline to develop. These conditions were encountered during only one
cruise in 1981 (cruise 3). As is generally the case, the thermocline was
within 1 m of the bottom, and the temperature difference above and below the
thermocline was slight, usually only 2-4C. This stratification has been
regarded as having little importance; however, due to the high oxygen demand
of western basin sediments, the high temperatures to which the sediments are
subjected, and the small volume of the hypolimnion, severe oxygen depletion
leading to anoxia will probably accompany each occurence of thermal
stratification in the western basin (Bartish 1983).
Although it is possible that western basin stratification may be an
extension of the central basin meso- or hypolimnion, this condition is assumed
not to exist for the purposes of this report, and western basin mesolimnion
and hypolimnion data are not reported.
Dissolved Oxygen
The seasonality of dissolved oxygen concentrations in the central basin
has been studied intensely since 1970. The decrease in oxygen concentrations
throughout the summer is anticipated as a result of the climatic warming of
the water, which causes decreased solubility. In spite of this, the DO
saturation of the water column should remain near 100 percent. The central
basin epilimnion waters remained above the 90 percent saturation level
-6-
-------
throughout the summer months and reached a minima of 89 percent during late
October. The hypolimnion portion of the central basin has a continuously
decreasing saturation during the stratified period (Figure 6) reaching a
minimum of 14.5 percent during early September (cruise 5). A slight increase
in hypolimnion percent saturation is seen between the early and mid-September
cruises (Numbers 5 and 6) due to destratification of the shore stations and to
reaeration of the hypolimnion due to mixing. Contours of dissolved oxygen
hypolimnion concentrations (Figure 7) verify that the mid-September cruise
(5) exhibited the largest area of anoxia (less than 0.5 mg/1). The composite
area of anoxia found during the entire 1981 field season was 4,280 knr or 29
percent of the entire central basin area (Table 10). The summary of the
central basin hypolimnetic cruises is provided in Table 11. Similar summaries
have been provided in CLEAR Technical Reports for 1973 through 1980.
The central basin hypolimnion DO concentration dropped from 9.42 mg/1 in
early June to 1.54 mg/1 in early September, a total of 7.88 mg/1 in three
months time. The oxygen depletion rate calculated from these data is 0.47 g
Op m day . Oxygen demand rates from 1930 to 1981 are also presented on an
area! and volumetric basis (Table 12).
The net effect of the oxygen depletion in the central basin depends on
the rate of depletion, the duration of anoxia and the area! extent of anoxia.
The duration of anoxia is variable due to meteorological conditions making
predictions difficult. The Sandusky sub-basin stations are the first to
become anoxic as a result of the shallow depth and the high oxygen demand rate
due to the heavy sedimentation that occurs here. As the western basin water
passes over the Sandusky ridge, it slows down due to the increased depth.
This area is reported to have the highest sedimentation rate in the central
basin. The Sandusky sub-basin is also the first area to destratify. It would
be impossible to determine with any certainty the maximum area of anoxia. The
data in Table 12 represents estimates of the composite anoxic areas on the
stratified cruises by year back to 1930 (Taken from Herdendorf 1980) when data
was available.
NUTRIENTS
Nutrients monitored in 1981 included soluble reactive phosphorus (SRP),
total phosphorus (TP), total filtered phosphorus (TFP), ammonia (NH?),
nitrate plus nitrite (NO., + N0?) and soluble reactive silica (SRS). Water
samples for SRP, NH3, NO^T + NOp and SRS were run on board the R/V Hydra while
TP and TFP were sent to Columbus for analysis after each cruise.
Since the central basin was not sampled in July and August, data in
Figures 8 to 12 show the change in nutrient concentrations from the beginning
of July to the beginning of September rather than actual nutrient levels
during this time period. In reality, soluble nutrient concentrations would
probably have been at a minimum during the summer months due to reduced
-7-
-------
loading, little agitation by winds and waves, and high algal demand (Burns
1976; Rathke 1979; Herdendorf et al. 1980; Fay and Herdendorf 1981). It was
possible to sample the western basin transect during the ship's down time
(July and August) using a small boat so the graphs for the western basin
represent the transect data only.
Vertical seasonal distribution patterns are presented in Figures 8 to 12
for both epilimnion and hypolimnion of the four central basin stratified
cruises. Since stratification did not exist in the western basin means of
surface and bottom concentrations are plotted to obtain basin seasonal
distribution patterns.
Western basin concentrations exceeded those of the central basin
epilimnion at all times. During periods of summer stratification and anoxia,
central basin hypolimnion values surpassed the average western basin
concentrations for SRP, NH, and SRS suggesting an appreciable amount of
regeneration.
Nitrate plus nitrite concentrations in the western basin were highest in
June, averaging 1168 ug/1, decreasing rapidly to 430 ug/1 by early July.
Values remained fairly constant through September and then rose to a peak of
630 ug/1 in November. Central basin concentrations show a different and less
dramatic seasonal distribution as seen in Figure 8. Highest values were
measured in late March (369 ug/1) and steadily declined through September (143
ug/1) with slight pulses in early July, late October and early December.
Central basin hypolimnion values showed a decrease throughout the period of
stratification with concentrations becoming lower as the length of anoxic
period increased.
Ammonia in the western basin was high in the spring (80.4 ug/1), falling
to 22.2 ug/1 by May. Following a slight rise in late June, levels fell to a
low of 10.5 ug/1 in mid-August and then rose steadily throughout autumn (48.2
ug/1). Concentrations increased rapidly in November (160.4 ug/1) and then
returned to early fall levels by the beginning of December. Concentrations in
the central basin epilimnion were much less variable than the western basin,
ranging from 5.0 to 39.1 ug/1. Pulses occurred in early June and September.
Hypolimnion ammonia values were higher than epilimnion values ranging from
26.1 to 58.5 ug/1 (Figure 9).
Soluble reactive phosphorus and total phosphorus showed the same
distribution pattern throughout the year for both the western and central
basins (Figures 10 and 11). Western basin phosphorus levels were highest in
late June and early September with values of approximately 10 ug/1 for SRP and
56 ug/1 for TP. Phosphorus concentrations in the central basin showed little
variation throughout the year with SRP ranging from 1.3 to 5.7 ug/1 and TP
from 9.9 to 22.3 ug/1. Hypolimnion values in both cases were higher than
epilimnion values, but still fell within the same ranges.
Soluble reactive silica was the most variable of all the nutrients
measured. Western basin concentrations ranged from a low of 372 ug/1 in early
June to a high of 1521 ug/1 in late September. Changes during cruise
-8-
-------
intervals were always abrupt as seen in Figure 12. Central basin distribution
showed highest concentrations present from April to May, then steadily
increased through September, at which time values began a gradual decline.
Silica in the hypolimnion exhibited the widest range, beginning with 279 ug/1
in early June, 488 ug/1 by the first part of July, rising to 1730 ug/1 by the
beginning of September and then declining throughout the rest of the
stratified period (mid-September).
Horizontal distribution patterns of all the above nutrients (Figures 13
to 17) tended to decrease from west to east and south to north. Highest
concentrations appeared at the mouth of the Maumee River, being rapidly
diminshed as river water mixed with higher quality lake water and Detroit
River water. Concentrations continued to decrease with the increasing water
volume moving east. Occasional high points were noted along the southern
shore at the inflow of the Cuyahoga and Grand Rivers. Epilimnion and
hypolimnion isopleths are presented for all stratified cruises and wherever
any significant differences occurred between surface and bottom. Cruise 1 was
not contoured for lack of sufficient data, and the same applies to ammonia for
cruise 3.
The horizontal distribution of nutrients is controlled by a variety of
factors: currents, extent of loading and location of point sources, wind
direction, depth, and thermal structure. The Detroit River has the greatest
influence on western basin concentrations due to the large volume of water
being discharged. Highest nutrient levels are found along the southwest shore
from the River Raisin to the eastern end of Maumee Bay. Anoxia in the central
basin accounts for areas of high concentrations in the hypolimnion during
stratified cruises.
Nutrients were volume-weighted utilizing the Survey 8 program (Hanson et
al. 1978) to obtain estimates of the quantities (metric tons) of nutrients
present in each basin. This data appears in Tables 6 and 7. Although
concentrations in the western basin consistently surpass those in the central
basin, the actual quantities available in the central basin exceed those in
the western basin due to the greater volume of water in the basin.
For the most part, all nutrients followed the seasonal pattern shown to
be characteristic of Lake Erie in previous studies, that is, higher
concentrations in spring and fall and lower concentrations in the summer.
High nutrient values are measured in the spring due mostly to increased
loading from runoff of melting snow and ice, and rainfall. In addition,
nutrient levels increase as a result of resuspension of sediments due to high
wind velocities. In late spring and early summer, when the winds subside,
sediment particles resettle, removing much of the available nutrients to the
bottom. As loading diminishes, algal demand consumes a large percentage of
the dissolved nutrients, further reducing concentrations. Once
stratification is established, a thermal barrier inhibits mixing of
epilimnion and hypolimnion waters, resulting in a decrease in epilimnion
values while hypolimnion values increase. In the fall, when surface
temperatures are low enough to cause turnover, nutrient-rich bottom waters
are mixed throughout the water column and surface concentrations again rise.
-9-
-------
If anoxia has been particularly extensive, nutrient levels could rise even
higher than spring runoff values.
The western basin showed a different nutrient distribution than normal
in 1981. Due to the shallowness of the basin, it is especially susceptible to
even slight increases in loading and changes in the weather. In -June of 1981,
the Maumee River drainage basin, which has a major influence on western basin
water quality, experienced a record rainfall of more than eight inches (NOAA
1981). Nitrate plus nitrite and silica concentrations were most notably
affected by the increased runoff caused by the extensive flooding. Phosphorus
concentrations also rose. Nutrient concentrations rapidly returned to
"normal" levels, except for silica. Since diatoms, which are the major
consumers of silica, are not dominant in the summer, the extreme amount of
silica deposited by the June flood had no major sink and remained abnormally
high through the rest of the year. Ammonia values in November (cruise 8), as
seen in . Figure 9), indicated a large increase, however, this reflects
concentrations of over 1000 ug/1 measured at the mouth of the Maumee River
averaged with the western basin stations which averaged only about 25 ug/1.
The difference in cruise 8 means with (160.4 ug/1) and without (25.9 ug/1)
station 202 at the mouth of the Maumee River is 84 percent. The apparent
increase in ammonia for the entire basin seen in Figure 9 is not valid.
PARTICULATES
Chlorophyll, Solids, Particulate Organic Carbon and Turbidity
Corrected chlorophyll ^ concentrations during the 1981 field season
decreased from a spring pulse, reaching a minimum in early June, and then
increased to a maximum in the late summer or early fall (Figures 18 and 19),
which is about the time of turnover. These general trends occurred in each
basin of the lake, although the central basin concentrations were lower than
the western basin. Surface values generally showed greater fluctuation than
the bottom values but the seasonal patterns were similar.
Total suspended solids (TSS), residual suspended solids (RSS), and
volatile suspended solids (VSS) concentrations in the western basin were much
higher than those in the central basin. The shallowness of the western basin
explains for the most part the higher concentration of solids. The graphs of
the western basin seasonal concentrations for TSS and RSS are mirror images
(Figure 20 and 21) with a slight difference in concentration. The same holds
true for the relationship in the central basin (Figures 22 and 23). Residual
solids were about 75 to 85 percent of the total suspended solids (TSS) in the
western basin and represented 45 to 55 percent of the TSS in the central
basin. Although the western basin VSS concentrations were double those of the
central basin (Figures 24 and 25), the percentage of VSS in the western basin
ranged from 15 to 25 percent while the central basin was nearly triple that
(45-55 percent) (Figures 26 and 27). The bottom values were slightly higher
-10-
-------
than the surface values for all three forms of solids, but followed the same
pattern as the surface values.
Turbidity cruise means in Lake Erie were highly correlated with total
suspended solids cruise means for the 1981 field season in both the western
and central basins (Figures 28 and 29) (r = .95 western basin, r = .98 central
basin). The western basin concentrations are approximately eight times
higher than the central basin. As with solids, the turbidity surface values
were usually slightly lower than bottom waters for both basins.
Particulate Organic Carbon (POC) is another parameter that has similar
characteristics to TSS, RSS, VSS, turbidity and corrected chlorophyll ^. POC
concentrations were higher in the western basin than in the central basin
(Figures 30 and 31), and correlated well with corrected chlorophyll a (r = .95
western basin, r = .76 central basin) and VSS (r = .83 western basin, r = .86
central basin). Corrected chlorophyll a and VSS also correlated well in the
central basin surface waters (r = .91"), showing a three-way relationship
between corrected chlorophyll a, VSS and POC.
To demonstrate the relationship between the particulate parameters,
surface data has been graphed seasonally for a station from the mid-lake
portion of the central basin (no. 37). TSS, turbidity and the reciprocal of
the secchi depth showed exceptional similarity in behavior (Figure 32).
The relationship between POC and VSS (Figure 33) is also similar
throughout the season. Uncorrected chlorophyll ^ data which was thought to be
more closely correlated with the organic parameters of VSS and POC did not
display the same behavior. Corrected chlorophyll a^ which represents only the
actively photosynthesizing algae was much more in harmony with the
fluctuations in concentrations of POC and VSS. The one anamoly in the similar
behavior of these three parameters occurred during the December cruise when
both chlorophyll a corrected and uncorrected, were observed to increase
compared to the prior cruise while POC and VSS decreased. During all the
other cruises, there was a positive correlation between the three parameters.
The isopleths for corrected chlorophyll ai (Figure 34) show the highest
concentrations in the southwestern end of the western basin and the lowest
concentrations in the northeastern portion of the central basin. The
distributional patterns for chlorophyll ^ for the spring and summer months
were very similar to those of total phosphorus with the maximum concentrations
along the Michigan and Ohio shores of the western basin and the United States
shore of the central basin.
Future measurement of these "particulate" parameters (corrected
chlorophyll a^, VSS, turbidity and POC) may lead to formulation for prediction
of concentrations of all these parameters by using only one measurement.
Secchi
Since the invention of the Secchi disk in 1865, it has been used as an
oceanographic and limnological tool to estimate water clarity. Although the
-11-
-------
determination of secchi depth is a simple measurement, there are many sources
of variability, for example, the patchiness of particulates and plankton in
the water, the whiteness of the disc, the altitude of the sun, the reflection
from the water surface, the height of the waves and the height of the observer
above the water. However, compared to other parameters, secchi probably
provides the longest continuously recorded data base with the fewest
methodology changes and problems. For this reason, and for its usefulness in
determining water clarity/quality, secchi depth data has been selected as a
trophic status indicator (Gregor and Rast 1979; Dobson 1976).
As in past studies, individual station secchi values were area-weighted
utilizing the grid pattern established for the 1973-1975 Lake Erie study
(Zapotosky 1980). Theoretically, each of the 50 grids represents a
homogeneous water quality area. The basin area weighted cruise mean has been
calculated for only the three intensive stratified cruises because these were
the only times when every grid was sampled. For a listing of the stations and
their respective grid numbers, see Table 3. Data for area weighted secchi
depth are presented for 1973-1981 (Table 14). As expected, the water clarity
in the western basin is less than that for the central basin, with the yearly
mean secchi depth only 20 percent of that for the central basin.
It is not possible to discuss the seasonality of secchi depth data based
on only three data points for 1981. Graphs of area weighted cruise means from
1978 to 1981 have been plotted to verify the seasonal cycle (Figures 35 and
36). The western basin data is much more variable within one month over the
four years than is the central basin data. The range of western basin values
throughout the year (0.6-3.0 m) is lower than for the central basin (1.25-7.02
m). The data for 1981 appears to indicate lower water quality in general
throughout the summer period when compared to 1978-1980. This may be the
result of the Maumee River flooding that was discussed in the nutrient
section. The central basin cycle is more easily discerned, the lowest secchi
depths are found in the spring; the highest secchi depths occur in July and
early August (6-7 m) which then decrease until after turnover. Secchi depths
increased again after turnover in October and November to the level of those
found in May and June.
Using the simplistic trophic classification system established by Dobson
et al., 1974 for yearly mean secchi data, the western basin would be
classified as eutrophic (0-3 m) and the central basin as mesotrophic (3-6 m).
Available and NonavaiTable Particulate Phosphorus
The availability of phosphorus has been a widely researched and debated
topic for some time. Since the Water Quality Agreement between Canada and the
United States, along with their efforts to limit wastewater effluents of
phosphorus to 1 mg/1 along with the inception of phosphrus detergent bans in
the early 1970's, the focus of Great Lakes researchers has switched from the
total quantity of phosphorus entering the Great Lakes to the quality (or
availability) of phosphorus entering the Great Lakes. Historically,
phosphorus loading to Lake Erie has been based on total phosphorus input, but
not all of this phosphorus is available for biological growth. There exists a
-12-
-------
need to better quantify the biological availability of total phosphorus
within the lake itself for more accurate phosphorus loading values.
The objective of the study undertaken in 1981 was to determine the
availability of particulate phosphorus within the water column of Lake Erie by
a chemical fractionation procedure. This procedure has been used by other
investigators to determine the biological availability of particulate
phosphorus in tributaries around the Lake Erie drainage basin and in lake
bottom sediments.
Once a particulate sample has been collected the phosphorus is separated
into five basic fractions:
Non-apatite inorganic
1. Reactive Sodium Hydroxide Extractable Phosphorus.
This phosphorus is mostly absorbed on inorganic material and is
considered available for biological growth.
2. Citrate-Dithionite-Bicarbonate (CDB) Extractable Phosphorus.
This phosphorus is chemically bound or sorbed on inorganic material
and becomes available only under reducing conditions.
Organic
3. Nonreactive Sodium Hydroxide Extractable Phosphorus.
Ths fraction is mostly organically bound phosphorus and its
availability is variable.
4. Residual Phosphorus.
This fraction comprises any phosphorus that is highly refractory
organic or strongly bound with inorganic material and is not
available for biological growth.
Apatite
5. Acid Extractable Phosphorus.
This fraction is more commonly called apatite and is not available
for biological growth. This phosphorus is basically in the form of
complexes with calcium.
In summary, there are three types of particulate phosphorus: non-apatite
inorganic, organic, and apatite phosphorus. Non-apatite inorganic phosphorus
(NAIP) is considered to be an addition of Reactive Sodium Hydroxide
Extractable Phosphorus and the CDB Extractable Phosphorus. Organic
phosphorus is considered to be the sum of Nonreactive Extractable Phosphorus
and the Residual Phosphorus fraction.
Table 13 shows the comparison of percentages of the three phosphorus
types from 1981 data to that of area tributaries (DePinto 1981 and Logan 1979)
and lake sediments (Williams 1976). NAIP is a high percentage of the total
-13-
-------
participate phosphorus in the tributaries and bottom sediments studies
(approx. 45%). This can be explained by the greater amount of clays and silts
(inorganic material) in these areas. Only 22 percent and 27 percent NAIP was
found in the water columns samples of the central and western basins
respectively. The settling of sediments out of the water column can explain
this lower percentage.
The apatite fraction of the lake bottom sediments contributed over 30
percent to the particulate phosphorus content (Williams 1976). This is
attributed to the high inorganic content of insoluble material on the bottom.
The percent of apatite P in tributaries samples is relatively low (7-10%). A
majority of the particulate phosphorus in these tributaries is from
agricultural runoff and point source input which is usually not in the apatite
form. The open lake shows an intermediate percentage (17%) between the
tributaries and bottom sediments. A combination of low apatite percentages
coming into the lake from tributaries (7-10%) and resuspension of high apatite
sediments (35-38) from the lake bottom can explain these percentages. Note
the nearly double percentage of apatite phosphorus in the western basin (23%)
to that of the central basin (11%). With the western basin being generally
less than one-half as deep as the central basin, significantly more
resuspension will occur, thus giving a higher percentage of apatite
phosphorus.
The organic phosphorus fraction of the tributaries and bottom sediments
show basically the same percentages (approximately 25%). This is low in
comparison to the 45 percent and 63 percent of the water columns of the
western and central basins respectively. The open lake (water column) portion
is considerably higher in plankton concentrations compared to the tributaries
due to slower flows, and lower turbidities and thus result in a much higher
percentage of organic particulate phosphorus. Note the higher organic
percentage in the central basin. There will be less resuspension of inorganic
material in the central basin and this gives the increase in organic
particulate phosphorus, percentage-wise.
Since this is the first year that available particulate phosphorus data
on the open lake has been collected, no trends or direct comparisons can be
made, but with continuous yearly research, total phosphorus loading values
can be corrected by knowing the amount of nonavaiTable phosphorus within the
water column.
-14-
-------
REFERENCES CITED
Burns, N.M. (Spec. Ed.) 1976. Lake Erie in the early seventies. J. Fish.
Res. Bd. of Can. 33(3):349-643.
DePinto, J.V., T.C. Young and S.C. Martin. 1981. Algal-available phosphorus
in suspended sediments from lower Great Lakes tributaries. J. Great
Lakes Res. 7(3):311-325.
Dobson, H.F.H. 1976. Eutrophication status of the Great Lakes. CCCIW, in-
house unpubl. document. 124 p.
Dobson, H.F.H., M. Gilbertson and P.G. Sly. 1974. A summary and comparison
of nutrients and related water quality in Lakes Erie, Ontario, Huron and
Superior. J. Fish. Res. Bd. Can. 31:731-738.
El-Shaarawi, A. 1982. Personal communication. Canada Centre for Inland
Waters.
Fay, L.A. and C.E. Herdendorf. 1981. Lake Erie water quality: Assessment of
1980 open lake conditions and trends for the preceding decade. CLEAR
Tech. Rept. No. 219. The Ohio State University. 162 p.
Gregor, D.J. and W. Rast. 1979. Trophic characterization of the U.S. and
Canadian nearshore zones of the Great Lakes. IJC. 38 p.
Hanson, B., F. Rosa and N. Burns. 1978. Survey 8, a budget calculation
program for Lake Erie. CCIW, in-house document, unpubl. mimeo. 54 p.
Herdendorf, C.E. 1980. Lake Erie nutrient control assessment: An overview of
the study, pages 1-63 j[n C.E. Herdendorf (ed.) Lake Erie nutrient control
program, an assessment of its effectiveness in controlling lake
eutrophication. EPA report 600/3-80-062.
Herdendorf, C.E., K. Svanks, J. Zapotosky, R. Lorenz, and J. Mizera. 1979.
Lake Erie water quality: Main lake status for 1977 final report. CLEAR
Tech. Rept. No. 129. The Ohio State University. 85 p.
Hutchinson, G.E. 1957. A Treatise on Limnology: Volume 1, Part 1, Geography
and Physics of Lakes. Wiley & Sons, New York. p. 540.
Letterhos, J. 1982. CLEAR analytical methods manual. CLEAR Tech. Rept. No.
205. The Ohio State University.
Logan, T.J., T.O. Oloya, and S.M. Yaksich. 1979. Phosphate characteristics
and bioavailability of suspended sediments from streams draining into
Lake Erie. J. Great Lakes Res. 5(2):112-123.
-15-
-------
National Oceanic and Atmospheric Administration. 1981. Toledo, Ohio local
climatological data. Annual summary with comparative data. Asheville,
North Carolina. 4 p.
Rathke, D.E. 1979. Plankton and nutrient distributions and relationships in
the central basin of Lake Erie during 1975. CLEAR Tech. Rept. No. 119.
The Ohio State University. 169 p.
Rathke, D.E. (Ed.). 1982. Final report for the Lake Erie intensive study.
(In press).
Williams, J.D.H., J.-M. Jaquet and R.L. Thomas. 1976. Forms of phosphorus in
the surficial sediments of Lake Erie. J. Fish. Res. Bd. Can. Vol. 33.
Zapotosky, J.E. and C.E. Herdendorf. 1980. Oxygen depletion and anoxia in
the central and western basins of Lake Erie, 1973-1975. Pages 71-102 _in
C.E. Herdendorf (ed.) Lake Erie nutrient control program, an assessment
of its effectiveness in controlling lake eutrophication. USEPA Report
600/3-80-062.
-16-
-------
^partial
TABLE 1
DATES FOR 1981 WESTERN BASIN TRANSECTS
Cruise No.
1
2
3
4
5
6
7
8*
9
10
11
12
13
14
15
16
Calendar Date
March 26
May 5
May 15
June 3
June 12
June 24
July 12
July 21
August 12
September 11
September 23
September 29
October 23
October 31
November 14
December 5
Julian Date
085
125
135
154
163
175
193
202
224
254
266
272
296
304
318
340
-17-
-------
TABLE 2
DATES FOR 1981 LAKE ERIE MAIN LAKE WATER QUALITY CRUISE
Cruise No. Calendar Date
1 March 24 - March 29
2 May 2 - May 6
3 June 2 - June 7
4 June 24 - July 3
5 September 1 - September 11
6 September 12 - September 24
7 October 23 - October 30
8 November 12 - November 19
9* December 3 - December 6
Julian Date
083-087
122-126
153-158
175-184
244-254
255-267
296-303
316-323
337-340
Julian
Mid Point
085
124
155
179
249
261
299
319
338
*0nly western basin and Sandusky sub basin
-18-
-------
oo
i— Z
CO O
o oo
oo cu
Q t-i
C£ Z
o o
o 2:
o
O I—
o o:
UJ LU
CJ (—
CO
UJ
_ I
CQ
to o
3 Z
cr
•o
'
fa
CQ
3 a.
O)
-o
3
+J
•r~*
CT>
O
O)
-a
3
C 1-
o ai
•i- JD
-M E
03 3
4-> Z
OO
i— CM
-o
a>
3
O
o
OOCJOOOCJOOCJOOOOCJOOOOOOOOOOOO
cr>i— oivoiocjOi— i— r^cviCMoor— oovooojcMojr^cncot^i— coo
r-CMr— r— i— i— OJCMOJr— i— CVJCVJCVJi— i— CMCMCJr-i— i— i—r— r— i— i—
r— e\ji—
CMOOOO^-O.— i— OOLncjcvjoo«i-«s-if)OOir)«s-ir)Oi— OJOOCMOO
ooooooooooooooooooooooooooo
OOOOr— OOi— i— Or— r— r— r— i— i— CMOr— r-i— CMCMCMCMCSJCM
COCOCOCOCOOOOOCOCOCOCOCOOOCOCOCOCOCOOOCOCOCOCXDCOCOCOCO
* CM in i
Or— CMOOOOCOCMi— OLO-^l-LOOi— CMr— OL
oooooooooooooooooo
CMCMCMCMCMCMCMCMCMi — i — r— CM CM CM CM CM i
i — VDOOCMCOOOLO
oo
CM r
ooooo
OOOOOOOOOOOOOOOOOOOOOOOOOOO
-19-
-------
•— o
(C ZT
3
CTT3
S- &I
OJ CD
+->
co«a-
-------
TABLE 4
WATER QUALITY PARAMETERS FOR MAIN
LAKE ERIE MONITORING PROGRAM 1981
PARAMETER
1 . Temperature
2. Dissolved Oxygen
3. pH
4. Conductivity
5. Transparency
6. Alkalinity
7. Total Phosphorus
8. Sol. React. Phosphorus
9. Total Filtered Phosphorus
10. Particulate Phosphorus
11. Non-Apatite Phosphorus
12. Nitrate + Nitrite
13. Ammonia
14. Sol . React. Silica
15. Suspended Solids
16. Volatile Solids
17. POC
18. PON
19. Chi. a^ - corrected
20. Phytoplankton/Zooplankton
21. Turbidity
22. Meteorology
23. Chloride
STORET
CODE
00010
00300
00400
00094
00078
00410
00665
00671
00666
00630
00610
00955
70318
70322
80102
32211
00076
CENTRAL
BASIN
(DO)
X(P)
X
X
X
X
X
X
X
X
037M-S+B
037M-S+B
X
X
X
X
X
Spj S+B
Sp]_ S+B
X
Sp2 S+B
X
X
CENTRAL
BASIN
X(P)
X
X
X
X
X
X
X
037M-S+B
037M-S+B
X
X
X
X
X
Spi S+B
Spi S+B
X
Sp2 S+B
X
X
WESTERN
BASIN
X(P)
X
X
X
X
X
X
X
X
X
X
X
X
R S+B
X
X
X
WESTERN
BASIN
(TRANSECT)
X(P)
X
X
X
X
X*A
X
X
X
323+328 M-S
323+328 M-S
X
X
X
X
X
X* A-S
X* A-S
X
X* A-S
X
X
X
P - Profile measurements A - Alternate Cruises
M - Monthly R - River stations 202 + 401
S - Surface X - all stations - all depths
B - Bottom Sp! - 051, 042, 037, 031, 026
* - 6 of 12 Stations Sp? - 044 + Spi
-21-
-------
CO
CM
i— C/)
e; o
o t->
>- z
a: HH
OO UJ
o
oo
Q >-
O I—
LU «=C
2: ra
cr
^ a:
u LU
I-H H-
a
LU
ca
c>£
E
315
C
O T-
(0 4->
J- U
3 CU
0 4J
U CU
<^ ^^
•!-
•r- 2
CO
"O
C CU
°"~ IJI
C CU -r-
(O r™ T3
a; T- o
0 M- E
0 0
i- S- CU
CU Q. -O
4J °r—
C N
I-H <
O O
0 E
0 0
i— O
o oo
0 0
o o
c
CU
en
X
CU O
s_
3 -0
4-> CU
S_ r—
CU O
0. CO
E co
CU *i"~
1— Q
LO
o
CO
3
o
c
c
4->
CO
I-H
I-H
5 CU
•o
C 'I-
o s-
0 O
E -C
-C U
0
CU
1—
en
3
LO
vo
VO
o
0
^~
rt3
-f^
0
I—
•H
CO
3
i.
o
a.
CO
o
.c
Q_
LO
o
CO
3
o
c
c
re
+->
(/)
h— 1
HH
3
^»
CO
O
o
O)
•r-
^«>
O
(O
O)
a:
CU
r— •
r^
3
O
00
LO
O
CO
3
O
c
c
CO
4-3
CO
I-H
I-H
O 0
O 3
•r- -a
C CU
-C 1-
u
CU
I—
en
3
O
oo
VO
o
o
O)
•1—
S-
4_>
•r—
•zz
(/)
3
r_
Q_
(U
fO
•J— *
*r~
z
,
-a
o
4J
CU
p:
CU
(O
c
CU
_c
a.
HH
I-H
^
CT
o
o
•r-
c
^
o
CU
H-
en
3
o
r*"
10
0
(O
E
o
0
oo
1
CU
t3
0
•r-
r-~
•r—
CO ^
O •!-
T3 0
-Q re
^^
r— U
O •!-
Sr-
(O
•-H X
I-H O
Si
c ^
O S-
0 O
•i- O
C CO
f^ (O
o
CU
h-
en
3
LO
LO
ai
o
o
(O
u
•r*
r-<
•r—
OO
CU
• r-
4-1
O
to
O)
cc
T3
CU
>
^^
O
CO
CO
• r-
Q
°^
CD
CU
-a
•i—
c
to
>^
5_)
•r~
£_
&-
O
(f_
HH
h-l
^
c™
O
(J
•r—
C
r*
o
CU
1—
en
o
^.
en
o
o
CU
•r-
s-
o
p—
e~
O
CM
O
"U
£
CO
ai
C"
•1—
>k
S-
T3
A
CO
T3
(0
a.
S.
CU C
4-* O
i— 'r-
•i- 4->
<4— *f—
c
co en
CO •!-
to
r—
CU
en
o
oo
LD
o
o
*~~.
-a cu
cu •—
^o vtn
E (O
CU S-
a. cu
00 4->
3 i —
00 •!-
^~
tO "
4-> CU
O 3
1— T3
« CO
oo CU
-a s.
f^
0
oo
CNJ
0
-a
c
(0
en
c
•f—
>^
s-
•a
A
CO
-a
(O
a.
s-
cu c
4J 0
r^ *^
•r- 4->
M- -I-
c~
CO CD
CO •!—
(O
r—
cs
E
O
OJ
LO
O
o
A
CU
3
•o
•r-
CO
0)— .
S- CU
•1— •
a; -M
i — 03
•r* ^~
4-> O
(0 >
"o «
> S-
QJ
A 4_)
CO i —
"O "^
•r- H-
^«
O
oo
•o
cu
3
c
^
o
o
^— ^
-22-
-------
•a
cu
3
C
O
O
UJ
_J
CO
<£.
S- 4J
O -i-
iP
c
>> o
o i-
i- 0
3 OJ
0 4J
U O)
eC Q
(U
s_
3
-o
OJ
0
o
S-
CL
S-
o
-a
o
.E
40
o
^"
+•»
c
ZD
-M i.
4) <1J
S- -Q
0 E
4-> 3
co =r
s_
O)
+J
0)
E
2
fO
o.
(•_
•
o
S-
O)
4_)
^
F
o
'aj
ex
O)
c
.c
o
to
HZ
^^
«>
^
VQ
p*s.
o
o
o
>n
+->
•r—
-0
•r-
J3
S-
3
1—
p—
•
O
V
•r—
•a
•^
^
o
o
a>
00
V)
s_
0)
0)
E
CO
o
o
o
o
c
a>
S-
(O
a.
to
C"
fO
S.
t-
co
•
0 .
+-> X
u a>
a;
Q.
co
•—
en
3
f—
i—
CM
CM
CO
T3
^
JZ
Q.
o
s-
o
pv-
JC
CJ
^J-
•
in CM
r^~
T3
O)
-U
(0
3
O (O
0 4-»
C
«% QJ C)
ME -Q
-a > > E S-
c/> .a •=£ aj
i— E
CD »•-<
E
u
^•s^
(/)
i— 0
^•^ c*
^* 0
tO C E
r— O cj -a CM
S- C
(O O
a. cj
CM
O LO
• •
o o
+
0)
JD
0 E
S- O
Q. -i-
4-)
3 (O
-U S-
•i- 4->
tO •!-
t >
E
•i- 4J
E
(O O
(U CX
o
i. CI
O) O)
4-)
E 3Z
i— i CX
CO
to O
(O CJ
i— CJ
E cn
3 E
O O
O r—
O O
0 0
>y
4J
*r-
C"
•r—
,— —
fO
N^
rc r-
Q.
-------
CO
O
CU
1_
O
o
CU
o
(O
o
CU
0
=
•r-
E
1
0
03
1 1
Stratifil
Cruise
CU
(TJ
0
«
.C
o.
o
o
o
3
i.
O
0.
o
Q.
>
•r-
fC
(/)
_)
i-
O
O_
CO
o
Q-
„
E
0
J r—
C ~---
o 01
CJ 3.
O
•r— CO
i. c
-4-> O
21-
•
O r—
CJ 3-
0
S- C.
CU 1—
O i—
C "^
o o>
0 3.
0
•i- CO
•u o
2:
(O
o
I— 1
CM
CO
LO
CM
O
O
CO
CM
CO
&\
l£)
CM
CM
rO
•P
O
•o
CU
«*-
unstrat
r— t
cn
CM
co
CM
CO
CM
CO
^
o
CM
O
cn
VO
rH
i— 1
O
CM
CO
LO
CO
CO
CO
CM
03
O
-a
CU
4-
unstrat
CM
LO
CM
00
-------
CO
cn
QQ
cr~o
cu
o: 3
LU c
3 C
O
•z. o
2
oa
CO
UJ
UJ
t—i
cc
.
p* ^^
0 "?
ra O 3-
u
•r—
£." 2
-I
0
zl~
CU
•r- •
+J c "^S
•r- O OT
•z. <_> =L
CU O
In °«T C
S_ oj O
£ «*-
••- s:
§m
.E? §
o
c
o
£=
•r—
£=
0
(O
CJ
C
s_
oo
O)
CO •
•r- 0
3 Z
S_
O
CU
(—1
CO
o
IO
•
00
o
10
CM
^
o
CO
(^
LO
cn
CO
1O
10
,3.
IO
•5J-
co
CM
«3-
CM
ra
o
•0
CU
4-
ra
"£
c
3
t— 1
cn
CM
^^
CO
1
^-
CM
CO
00
LO
^.
•
co
CO
,_!-
1-1
CM
CM
CM
«0
O
LO
O
cn
o
00
o
CO
co
CO
^J.
CM
ra
o
-a
cu
4-
ra
CO
C
3
CM
^0
^^
LO
1
CM
LO
^0
CO
CM
•
^H
r-H
cn
,*
LO
CM
*>
CO
CO
u>
CT>
•si-
i— I
1-1
00
l«^
^J-
CO
CO
rH
LO
CM
ra
0
4-J
-o
CU
4-
ra
CO
g"
3
co
r^.
^^,
VO
i
CM
<0
O
co
10
•
CT)
(0
CM
co
t— 1
CO
CM
^
10
O
CO
I— 1
1— 1
O
^
co
t— t
CO
^^
^>
CM
^
CO
CM
00
-*
LO
cn
i— H
r-l
O
CO
o
*4*
*0
(0
O
00
^
CM
ra
O
•(->
T3
CU
4-
ra
co
C
3
<0
•=3-
CM
*^^
cn
i
CM
i— 1
cn
o
cn
,— i
o
•
CM
r-H
LO
CM
CO
CO
CO
cn
o
CO
•5t
o
«=»•
o
cn
f— 4
oo
*3-
CM
ra
o
-o
4-
ra
CO
£=
3
r^
,_,
CO
'>>^
o
r-H
|
^*
CM
O
I— 1
o
CM
CO
O
*
O
co
CM
CO
*•
o
(0
I— 1
00
cn
CM
cn
CO
co
cn
V0
LO
CO
cn
10
LO
,3-
CM
ra
•M
O
T3
CU
4-
ra
CO
C
3
00
cn
,__{
>x^
f—H
r-H
|
CM
r-4
i— 1
^.
O
LO
CO
•
cn
co
10
CO
cn
CM
LO
CM
o
CO
CM
CO
CM
10
(0
r^
CT»
.— 1
LO
CM
«3-
CM
ra
o
o>
4-
-p
co
c
3
cn
10
^*^
CM
r— 1
I
co
CM
i — i
-25-
-------
CO
cn
I
>-
•a:
•St.
o-
o;
CQ >=c
»
U -C
CD Q.
i- O
i. i.
0 O
(/)
3
o
o.
CO
cu o
.Q O-
r— CU
O >
00 T-
o
rO
CU
CO
I— t-
0 O.
I— CO
o
Q.
O)
3tn
oJ
Limn ion
Stratification
0)
CO •
•i- O
3 Z
0
&
'Jr-
0 cn
O 3.
o
•r- CO
£_ ^
•(-> O
o
•r- CO
j_ £;
-(-> O
CU 1—
LO
ID
CD
cn
CM
CM
CO
ID
CO
ID
cn
r-
CM
0
CO
*3-
o
CO
to
o
unstratified
-
cn
CM
CO
1
CM
co
1 —
ID
CO
o
o
00
CO
*~
in
ID
LD
o
CO
CO
CO
CO
CO
LO
r-.
co
CO
fO
o
+J
unstratified
CM
CD
LD
CM
LO
s
^~
CM
00
o
co
CO
cn
CM
cn
CO
LD
LO
CM
CM
CO
cn
CD
CM
r-
£
EL
cu
stratified
CO
CO
CM
CO
co o co
co r»» r—
CM CM CM
O CM «tf-
•51- O CM
co o r-«
CO CO
co ^3~ r^
ID r— cn
CM CO CM
cn CM o
cn cn co
CO «5f CO
co cn
co LO cn
co cn r —
LD CO ^1-
oo r^ r-
CM *3" 1^.
£88$
i— CM *3-
r»- i — ID
CM i — i —
r— CO
O O to
CO Q-4->
CU >, O
E J= 4J
CM o m in
CO CO ^J- r-
CM CO ^- CO
^a- co CM CM
«>t cn co CM
«i- CM i— cn
ID i — co cn
CO «* LD LO
•sj- 00 O CO
r— r— CM r—
LO CM CO CO
r^ co co o
O CO ^ CM
CO i— ID
LO r^ co o
CO O CD «S-
r— LO ^ CO
CM O CO CO
r— CM i— *1-
CM "* CO CM
«3- LO CM CM
CM i— *3-
CO O LO CO
r^ co i— co
O co r^ i—
CM CO
O O to
•r- CO O-4->
CL OJ >> O
cu E-c -u
cu
•r™
4-
to
to
-
CO
1
CM
CO
l^> LO O CO
r^ cn i— CM
<3- CM CM ^f
LO «d" CO LO
CM CO r— 1^.
CO co O CVJ
i— r— CO
CM CO CO LO
LO CO 00 CO
r- CO LO CM
^J- ^ CO ^J"
o CM «3- r^
r^ co co co
co CM r*-
co co in co
o cn CM o
CO ^3" i— CO
CO CM O CO
LO cn cn co
i— i— CM CO
cn CM o i —
CO CO i— CO
r^ LD ^3- co
co i— oo co
^1- CM *3- P—
CM CO
O O to
•r- CO D_^-J
a. a> >> o
CU E -C 4->
stratified
ID
r—
r—
cn
cn
CD ^- LO co
co o «d- o
CO CO CM CO
O r^- ^— co
cn o co CM
•— co ^ CO CM
CO O CO *3-
o r^ o co
cn i— co co
•51" LO
o i — co r^
cc o r-. co
CO l— i— r—
CM CO
O O 03
CL CU >l O
CU E: r* 4-*
stratified
CO
•sf
CM
cn
CM
CO
in
r^
CO
CO
CM
in
cn
CO
r—
•=}•
r--
o
00
LO
i^
CO
CO
ea
0
unstratified
r--
CO
o
CM
o'
LO
CM
ID
CD
00
CO
CO
LO
LO
CO
O
CO
O
cn
CM
o
o
CO
CO
r-
CM
r*—
CO
i—
ta
0
+J
unstratified
CO
cn
CM
CO
r—
^
CM
CO
CM
CM
CO
•~
O
co
LD
O
cn
CO
00
CM
ID
<3-
o
CO
to
o
-P
unstratified
cn
CM
CO
CM
-26-
-------
CO
CsL
LU
—I
CQ
-o
cc cu
LD =3
3 4->
C
s: o
I-H (J
COx_^
s~
z
+
•*->
rd
•r*
2T
1
O
>
Limnion
Stratification
Cruise
O)
4->
(O
a
•
O r—
C ~^
O CD
0 E
0
•I- 10
S_ C
a> I—
•
£= --^
o a>
o E
o
s_ c
+-> o
CD 1—
•
O r-
O O)
0 E
•1- (/)
s_ c
+J O
^l~
m
.*£
•
0
z
1^
o
CM
00
CM
LfJ
CM
•*
tO
en
ir>
*±
CO
00
r—
CTi
IO
U3
r^
CO
IT)
•=!•
«*
O
rn
r—
«3
4->
O
+J
unstratified
-
Cn
CM
OO
•3-
CM
OO
5*
r*.
r—
IO
CO
CM
00
o
o
CO
CO
CO
CO
«d-
o
CO
*r
ix)
CO
LO
Cn
l~~
PO
CO
(O
4->
O
4->
unstratified
CM
U3
LO
1
CM
LO
CM «^- CT> r—
o oo i^- r^
i— i— CM i—
CM ^C CO *d-
^- l£> «3" IT)
10 oo CM rv.
O O1 O O
00 ^fr- <5}~
r— CO LO
r— O1 r— CO
r^ I-*. 10 o
r— r— CM CM
<3- i— CO CO
CO LO CM LO
CM CO O P—
O «3- O1 St
CO CM V£)
un (o in r^.
i— 1^- "3- 00
LO VO O I—
(JD CT> «vf O
p^. vo CM r>-
o r>- r— en
CO «*• ii) 00
OO r— LO
i— r— CM «*
r«> rx. r— LO
f^ CM r— r—
r— r— CO
O O (O
•i— Ul Q-4->
Q. CU >~> O
CO E-C -M
stratified
CO
r^
to
i
CM
U3
•* CO 00 CO
^S- U3 CO i—
CM CO ^J- CO
CM O O CM
CO CO CM CO
O VO CTi VO
l^» O CO VO
o co
f^ VO CO 00
LO CO O CM
i— on i—
ID VO LO VO
^t O1 U3 O
CO VO VD CM
r— V£3 r— O
i— CM **•
O CTi CO O
r—
CM CO
o o > o
CD E JC 4->
T3
CU
<+I
+3
(O
4->
Ul
«3-
co
r^
i
•=1-
CM
U3
CM
to
CO
«*
CT>
r—
CM
00
CO
CM
cr>
o
CTi
r-^
vo
<-
CM
LO
<*
CM
<*
0
r-^
oo
r^
oo
<*
CM
•r-
Q-
OJ
T3
O)
•r-
<+-
4J
(0
-M
to
LO
cr>
1
en
t^ o r~.
O CO r—
o r^ to
LO o en
O CM r—
LO CO O
to i~~ to
r— OO CO
CM co en
CM CO 1^-
en co to
oo in CM
co en r^
CM LO r^
«a- •* to
CO CO CO
CM CO
to to i^
to r^ in
o •* oo
cri co en
tO r— CM
LO LO i —
co co en
•SI-
LO «3- tO
r— CO CO
CM «5l- r—
CO
o o
OJ >> O
Ex: 4->
to f en r~»
co r^ to LO
•3- en «3- LO
r—
o«* « LO en cr>
CM 00
co to CM to
i^ en co LO
CO LO CO OO
o CM to o
CM OO
CO ^1- CM CO
«3- CO LO **•
O «fr CM tO
co oo r-» to
en if) LO CM
oo oo to en
O i— CM *3-
*d- **•
o r— to r^
to O r^ co
CO r— i— r—
CM CO
o o
ex co >> o
0) E -C -M
-a
QJ
>T
•13
2
4->
in
to
«a-
CM
en
i
CM
cn
CD
«3-
oo
CO
oo
•3-
o
0
CM
1^
to
CO
LO
CM
CM
LO
O
LO
CO
o
oo
<•
to
r^
CO
oo
P—
O
4->
unstratified
CO
en
r™
1
CM
CM
LO
00
O
00
r~
•51-
o
LO
O
CM
LO
LO
CM
O
CO
0
o
Is-*
CM
VO
•5J-
O •
oo
r—
(O
4->
O
4->
unstratified
cn
to
CM
oo
CM
r—
-27-
-------
TABLE 8
LAKE ERIE WATER QUALITY MEASUREMENTS 1981
WESTERN BASIN CRUISE MEANS CONCENTRATIONS
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Date Statistics
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Temp.
(°C)
2.77
0.15
2.50
40
11.93
0.21
11.6
40
16.73
0.23
16.70
35
20.68
0.16
20.6
40
20.88
0.09
21.00
40
16.84
0.11
17.2
40
10.09
0.12
10.45
40
9.04
0.09
9.1
40
4.92
0.06
4.90
40
DO
(mg/1)
13.45
0.09
13.30
40
10.76
0.14
10.9
40
9.07
0.08
9.20
35
8.11
0.12
8.1
40
8.90
0.15
8.75
40
8.70
0.13
8.8
40
10.46
0.17
10.3
39
11.27
0.17
11.3
40
11.94
0.06
12.00
40
Corrected
DO Conduct. pH
(%) (umhos/cm)
104.2
0.9
102.9
40
97.8
1.2
98.3
40
90.9
0.8
91.4
35
88.6
1.4
87.9
40
97.7
1.7
95.1
40
87.4
1.3
89.0
40
91.9
1.6
90.2
39
97.1
1.4
97.0
40
95.8
0.5
96.3
40
255
15
236
40
267
12
241
40
295
16
264
35
261
6
249
40
249
8
229
40
253
9
236
40
267
15
239
40
268
14
237
40
273
17
245
40
7.93
6.97
7.86
40
8.34
7.05
8.34
40
8.37
7.13
8.34
35
8.22
7.08
8.14
40
8.37
7.28
8.29
40
8.04
6.52
8.04
40
7.97
6.56
7.94
40
8.13
6.99
8.11
40
8.04
6.42
8.03
40
-28-
-------
TABLE 8 (continued)
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
Statistics
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Total
Phos.
(ug/1)
28.1
4.4
19.7
40
37.6
8.4
17.9
40
29.0
5.6
18.0
35
46.4
10.7
22.7
40
65.4
12.8
35.8
40
48.4
8.3
23.8
40
46.2
6.4
34.1
40
37.7
9.9
21.1
40
37.4
6.5
23.7
40
Soluble
Reactive
Phos.
(ug/1)
ND
ND
ND
ND
6.9
3.3
2.1
40
3.0
1.1
1.7
35
11.0
3.5
2.7
40
9.0
3.3
2.6
40
9.8
3.0
5.3
40
6.4
2.2
3.4
40
4.7
2.3
1.2
40
8.2
3.7
1.8
40
Nitrate
Nitrite
(ug/1)
763
140
508
40
960
240
400
40
1168
221
531
35
1130
212
433
40
471
103
248
40
430
92
580
40
480
75
379
40
693
164
380
40
628
102
457
40
Ammonia
(ug/1)
80.4
31.8
9.6
40
22.2
7.8
2.7
40
25.8
12.3
6.7
18
28.1
5.7
21.1
40
22.0
13.7
3.2
34
48.2
20.0
18.0
40
48.3
23.2
10.3
40
160.4
94.4
16.7
16
52.9
21.0
4.1
40
Dissolved
Reactive
Silica
(ug/1)
1078
148
1065
40
578
222
50
40
372
166
125
35
1304
245
775
40
1342
294
940
40
1521
282
1110
40
1190
214
915
40
1320
302
1065
40
1504
189
1250
40
-29-
-------
TABLE 8 (continued)
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
Statistics
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Seech i
(m)
1.4
0.1
1.5
36
1.7
0.2
1.7
16
1.9
0.2
1.7
16
1.2
0.1
1.2
20
0.6
0.1
0.8
20
0.8
0.1
0.9
13
0.6
0.1
0.6
17
1.2
0.1
1.1
40
0.9
0.1
0.9
14
Turbidity
(ntu)
7.0
0.8
5.5
40
14.8
4.6
3.8
40
6.1
1.2
3.6
35
34.9
14.6
6.5
40
26.2
6.7
10.4
40
19.1
3.5
10.3
40
20.9
2.1
16.5
40
11.5
2.1
7.9
40
17.7 .
2.2
11.4
40
Susp.
Solids
(mg/1)
5.17
0.38
4.59
29
16.61
5.02
5.20
40
6.62
1.31
3.48
35
29.33
11.65
7.46
40
29.35
8.18
12.17
40
19.57
3.13
11.87
40
21.87
2.37
16.76
39
16.53
5.09
8.11
38
18.00
2.19
11.85
40
Corr.
Chlor.
(ug/1)
10.67
3.02
6.47
40
8.24
1.23
5.65
40
6.61
1.37
3.08
35
6.24
0.87
4.11
40
13.04
1.55
12.39
40
8.09
0.80
7.43
40
8.02
0.69
7.71
40
9.20
0.93
8.61
40
4.46
0.41
4.23
40
SCOR
Chlor.
(ug/1)
11.39
3.14
7.06
40
9.95
1.36
8.07
40
7.74
1.76
3.23
35
6.66
0.70
4.88
40
17.99
1.69
15.55
40
11.67
0.86
10.5
40
11.64
0.93
9.92
40
11.41
1.03
10.57
40
7.27
0.61
6.43
40
-30-
-------
TABLE 9
LAKE ERIE WATER QUALITY MEASUREMENTS 1981
CENTRAL BASIN CRUISE MEAN CONCENTRATIONS
Cruise
No.
1 epi
2 epi
3 epi
hypo
4 epi
hypo
5 epi
hypo
6 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/2-6/7
6/24-7/3
6/24-7/3
9/1-9/11
9/1-9/11
9/12-9/24
Temp.
Statistics (°C)
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
2.54
0.17
2.80
15
8.85
0.42
8.30
33
15.59
0.37
15.5
28
9.17
0.18
9.00
22
19.59
0.17
19.70
60
10.46
0.37
10.1
41
22.14
0.04
22.2
74
12.95
0.48
11.70
31
19.79
0.20
20.4
75
DO
(mg/1)
13.24
0.06
13.30
15
11.63
0.11
11.20
33
9.93
0.13
10.0
28
9.42
0.21
9.60
22
9.10
0.05
9.20
61
7.59
0.24
8.00
41
8.29
0.07
8.40
74
1.54
0.26
1.00
31
8.59
0.08
8.50
75
Corrected
DO Conduct. pH
(%) (umhos/cm)
102.1
0.3
102.2
15
99.9
0.6
99.8
33
97.1
1.1
99.1
28
81.3
1.7
82.8
22
97.1
0.5
97.8
60
67.1
2.1
70.5
41
93.7
0.8
94.8
74
14.5
2.5
9.2
31
92.2
1.2
92.4
75
260
3
263
15
272
3
274
33
270
1
272
28
276
1
277
22
265
1
265
61
275
2
274
41
264
2
261
71
276
1
276
31
271
1
272
72
7.91
6.27
7.90
15
8.07
6.79
8.03
33
8.33
6.80
8.34
28
7.94
6.67
7.94
22
8.41
6.89
8.40
61
7.74
6.61
7.70
41
8.31
6.83
8.33
71
7.26
6.15
7.22
31
8.16
6.89
8.14
72
-31-
-------
TABLE 9 CONT.
Cruise
No.
hypo
7 epi
8 epi
9 epi
Temp.
Date Statistics (°C)
9/12-9/24 mean
st. err.
median
n
10/24-10/31 mean
st. err.
median
n
11/12-11/19 mean
st. err.
median
n
12/3-12/6 mean
st. err.
median
n
14.67
0.83
13.4
17
11.53
0.09
11.55
48
10.26
0.08
10.50
51
6.03
0.15
5.75
18
DO
(mg/1)
3.02
0.74
1.7
18
9.93
0.05
9.9
48
10.59
0.05
10.50
50
11.81
0.06
11.90
17
Corrected
DO Conduct. pH
(%) (umhos/cm)
30.0
8.3
12.4
17
89.6
0.4
88.8
48
93.4
0.3
92.3
50
96.4
0.3
96.6
17
280
1
281
18
268
1
272
48
270
2
273
51
266
3
263
18
7.62
7.11
7.21
18
8.00
6.46
7.99
48
8.23
6.86
8.21
51
8.12
6.44
8.14
18
-32-
-------
TABLE 9 CONT.
Cruise
No.
1 epi
2 epi
3 epi
hypo
4 epi
hypo
5 epi
hypo
6 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/2-6/7
6/24-7/3
6/24-7/3
9/1-9/11
9/1-9/11
9/12-9/24
Statistics
mean
st. err.
med i an
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
med i an
n
mean
st. err.
med i an
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Total
Phos.
(ug/1)
19.5
2.8
14.2
15
17.7
1.6
14.8
33
11.3
1.0
9.5
28
14.2
0.9
12.9
22
9.9
0.5
8.9
61
16.0
0.7
15.1
41
15.5
1.3
12.5
74
20.6
3.5
13.3
31
16.6
0.8
15.1
75
Soluble
Reactive
Phos.
(ug/1)
2.1
0.2
2.0
15
1.6
0.1
1.6
33
2.9
0.6
2.3
22
3.1
0.6
3.0
16
1.5
0.1
1.4
51
2.1
0.2
1.7
33
1.5
0.2
1.1
74
5.9
1.8
2.0
31
1.3
0.1
1.2
75
Nitrate
Nitrite
(ug/1)
369
81
186
15
304
36
305
33
215
32
153
28
145
22
115
22
240
24
150
61
203
15
182
41
152
9
137
74
176
12
170
31
143
8
119
75
Ammonia
(ug/1)
5.9
1.0
5.8
15
10.8
3.9
2.7
32
17.1
6.1
10.0
9
26.1
4.1
23.3
5
5.7
1.0
4.0
48
30.3
5.8
23.6
32
19.2
5.3
7.4
74
58.8
10.5
44.1
31
7.3
0.7
5.4
75
Dissolved
Reactive
Silica
(ug/1)
207
74
30
15
41
3
30
33
102
15
60
28
279
29
263
22
244
25
150
61
488
52
450
41
362
34
250
74
1730
124
1720
31
486
32
440
75
-33-
-------
TABLE 9 CONT.
Cruise
No.
hypo
7 epi
8 epi
9 epi
Total
Phos.
Soluble
Reactive Nitrate
Phos. Nitrite Ammonia
Date Statistics (ug/1) (ug/1)
9/12-9/24 mean
st. err.
median
n
10/24-10/31 mean
st. err.
med i an
n
11/12-11/19 mean
st. err.
median
n
12/3-12/6 mean
st. err.
med i an
n
17.1
3.0
14.1
18
22.3
0.9
21.5
47
18.4
1.1
15.8
51
16.9
0.6
16.5
18
2.8
0.8
1.6
18
5.7
0.6
3.9
48
3.6
0.5
1.7
51
1.7
0.1
1.55
18
(ug/1)
152
15
156
18
205
17
153
48
180
16
135
51
202
25
188
18
(ug/1)
39.1
13.4
17.0
18
7.2
0.9
5.5
48
11.2
3.7
4.4
51
5.0
0.7
4.5
18
Dissolved
Reactive
Silica
(ug/1)
1469
179
1750
18
349
29
400
48
176
22
120
51
152
27
115
18
-34-
-------
TABLE 9 CONT.
Cruise
No. Date
1 epi 3/24-3/29
2 epi 5/2-5/6
3 epi 6/2-6/7
hypo 6/2-6/7
4 epi 6/24-7/3
hypo 6/24-7/3
5 epi 9/1-9/11
hypo 9/1-9/11
6 epi 9/12-9/24
Statistics
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Seech i
(m)
2.9
0.8
3.3
5
3.3
0.6
3.1
8
4.6
0.5
4.5
11
ND
ND
ND
ND
5.8
0.3
5.7
28
ND
ND
ND
ND
2.9
0.2
2.8
25
ND
ND
ND
ND
2.6
0.2
2.8
28
Turbidity
(ntu)
3.3
0.8
1.6
15
2.7
0.5
1.5
33
1.5
0.3
0.9
28
1.5
0.3
1.1
22
1.1
0.2
0.7
61
3.2
0.4
2.3
41
2.1
0.3
1.1
71
1.8
0.1
1.7
31
2.5
0.2
1.9
72
Susp.
Solids
(mg/1)
3.82
0.71
2.29
15
3.26
0.54
1.92
27
1.39
0.31
0.82
28
1.82
0.24
1.60
21
1.22
0.23
0.75
61
3.42
0.37
2.78
39
2.28
0.27
1.21
72
1.91
0.17
1.54
31
3.24
0.29
5.12
75
Corr.
Chlor.
(ug/1)
5.54
1.05
2.72
15
5.74
0.64
4.74
33
1.74
0.19
1.47
28
2.70
0.37
3.10
22
2.62
0.49
1.67
61
4.45
0.39
3.89
41
4.77
0.32
4.04
74
2.18
0.22
2.01
31
6.36
0.50
4.86
75
SCOR
Chlor.
(ug/1)
6.16
1.20
2.89
15
6.37
0.72
5.60
33
1.82
0.20
1.60
28
3.20
0.23
3.35
22
2.50
0.32
1.72
61
4.71
0.39
4.25
41
5.62
0.35
4.79
74
2.77
0.24
2.51
31
8.13
0.57
6.53
75
-35-
-------
TABLE 9 CONT.
Cruise
No.
hypo
7 epi
8 epi
9 epi
Date Statistics
9/12-9/24 mean
st. err.
median
n
10/24-10/31 mean
st. err.
median
n
11/12-11/19 mean
st. err.
median
n
12/3-12/6 mean
st. err.
median
n
Seech i
(m)
ND
ND
ND
ND
2.1
0.2
2.2
11
3.3
0.3
3.8
9
2.1
0.4
2.1
4
Susp.
Turbidity Solids
(ntu)
1.8
0.2
1.3
18
4.3
0.3
3.7
48
2.7
0.2
2.0
51
4.1
0.4
4.0
18
(rng/1)
1.95
0.30
1.48
18
4.74
0.33
4.02
46
3.42
0.38
2.66
50
5.23
0.36
5.16
18
Corr.
Chlor.
(ug/1)
2.45
0.26
2.33
18
5.16
0.32
5.35
48
5.25
0.31
4.65
51
7.13
0.25
7.25
18
SCOR
Chlor.
(ug/1)
3.58
0.33
3.30
18
6.72
0.34
6.80
46
6.44
0.35
5.85
51
8.46
0.25
8.43
18
-36-
-------
o:
LU
O
>-
LU
C£
to
CJ
f—I
I—
UJ
o 5
'— I
o
LJLl O_
CQ 1C
i—i
t/)
CO
CJ
CO
CTl
Lu
O
« (O 1
co i- E
> CD
CsO
O 0
*»w
•OI-H
O^ 1* £
> CD
CJ
O O
o
CO CJ
CD
ra
s_ •
CU Q-
1—
CM
m o
CU r—
X
^~
IT3 r—
0 CJ
CU
cn v>
**^
<: o
cu
Jj
"o
racM
cu E
i. ^.
^
cu
CO •
•r- 0
3 Z
O
CU
-4_>
(Q
Q
CT>
CO
•
O
f^»
CO
•
CO
CO
.
CT>
0
O
ty\
^*
o
o
1—
•
CT>
«^
•
OJ
r— •
O
^J-
•
f^^
CJ
•—
r--
CJ
f i
A
LD
CO
r^
vo
1
CJ
lo
CO
LO
•
o
^J"
o^
•
CO
CO
.
fs^.
CTl
•
CJ
LO
O
cn
•
CTv
^J"
•
CO
0
r>-
CJ
•
LO
LO
r—
O
LO
fs^ •
«»>.
CO
^1-
CO
f^
1
«a-
CJ
vo
CO
10
•
CO
CJ
LO
•
LO
^
•
CM
P-XS.
•
CO
o
VJ0
fs,.
•
CJ
p>~
cn
•
f"s.
1—
vo
CO
•
«c^
co
LO
CM
n
I —
LO
i—
cn
i
•—
cn
CO
•
^-
CO
•
^f
CO
r" •
CVJ
r~~
•
CO
00
cn
•
CO
r—
fs^
•
Lf>
^d"
CM
O
4
CO
5
vo
CO
M
LO
vo
CM
CTl
1
CM
<—
cn
-37-
-------
TABLE 11 ESTIMATED AREA OF THE ANOXIC HYPOLIMNION
OF THE CENTRAL BASIN OF LAKE ERIE 1930-1981
/EAR
1930
1959
1960
1961
1964
1970
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
AREA
(km2)
300
3,600
1,660
3,640
5,870
6,600
7,970
11,270
10,250
400
7,300
2,870
3,980
N.A.
4,330
4,820
PERCENT OF CENTRAL SASIN
Hypolimnion
3.0
33.0
15.0
33.0
53.0
60.0
72.5
93.7
87.0
4.1
63.0
24.8
71.7
N.A.
35.9
37.4
Total Basin
1.9
22.3
10.3
22.5
36.3
40.4
49.3
69.8
63.4
2.5
53.0
20.8 "
24.6
N.A.
26.8
29.0
Data Sources:
1930—Fish (1960)
1959-1961—Thomas (1963)
1964--FWPCA (1968)
1970—CCIW (Burns and Ross, 1972)
1972-1977, 1981, OSU/CLEAR
1978--ANL vZaootosky and Whits, 1980)
-38-
-------
TABLE 12 TRENDS IN NET OXYGEN DEMAND OF THE CENTRAL AND
EASTERN BASIN HYPOLIMNIONS OF LAKE ERIE 1930-1981
DATA
SOURCE*
1
i
1
1
2
3,4
3,4
3,4
3,4
3
2
5
2
5
3
3
YEAR
1930
1940
1950
1960
1970
1973
1974
1975
1976
1977
1977
1978
1978
197-9
1980
1981
Rate Per
Cg_0a m
Central
Basin
0.08
0.15
0.25
0.37
0.38
0.53
0.60
0.67
0.75
0.58
0.48
0.51
0.54
0.41
0.63
0.47
NET OXYGEN
Unit Area '
-2 day-1)
Eastern
Basin
-
-
-
-
0.70
0.23
0.57
0.76
-
0.63
0.51
0.58
0.61
0.58
-
DE-MAM D
Rate Per
(ing Oa
Central
Basin
0.054
0.067
0.070
0.093
0.110
0.120
0.130
0.100
0.130
0.130
0.120
0.092
0.111
0.090
0.109
Oo085
Unit Volume
1-1 day-1)
Eastern
Basin
-
-
-
-
0.055
0.016
0.026
0.040
0.032
0.060
0.065
0.048
0.047
0.049
-
''Data sources: 1) Dobson and Gilbertson, 1971; 2} CCIW--Noel
Burns, personal communication; 3) OSU/CLEAR—Central Basin, 1973-
1977; Eastern Basin, 1977; 4) SUNY/GLL—Eastern Basin, 1973-1976;
5) USEPA/GLMPO—rate calculation OSU/CLEAR.
-39-
-------
TABLE 13
COMPARISON OF 1981 AVAILABLE AND NON-AVAILABLE
PHOSPHORUS FRACTIONS BY PERCENT TO HISTORIC DATA
NAIP
Reactive NaOH P
+ CDB P
APATITE
Acid Extractable
P
ORGANIC
Nonreactive NaOH P
+ Residual P
Lake Erie
water column
Central Basin
Western Basin
Ohio
Tributaries
Sediments
Maumee +
Sandusky R.
DePinto, 1981
Tributaries
Sediments
Western Lake
Erie
(Logan 1979)
Lake Erie
Bottom Sed.
(Williams 1976)
Central Basin
Western Basin
22%
27%
11%
23%
63%
45%
43%
7%
21%
51%
10%
30%
49%
40%
38%
35%
18%
26%
-40-
-------
TABLE 14. LAKE ERIE TRANSPARENCY MEASUREMENTS 1973-1981
Date Year
6/23- 7/12 1973
• 7/17- 7/23
7/25- 8/2
3/7 - 8/1 1
8/29- 9/4
9/19- 9/29
10/14-10/24
11/7 -11/15
12/4
4/7 - 4/17 1974
4/25- 5/4
5/14- 5/24
6/1 - 6/10
6/28- 7/7
7/26- 8/4
8/12- 8/19
8/26- 9/7
9/24- 9/27
10/21-11/1
12/11-12/14
3/19- 3/31 1975
4/21- 4/25
6/9 - 6/19
7/13- 7/21
8/30- 9/7
9/27-10/6
12/2 -12/10
3/22- 3/30 1976
6/2 - 6/10
8/21- 8/29
9/8 - 9/17
10/18-10/30
3/20- 3/31 1977
4/29- 5/8
6/20- 6/30
7/12- 7/22
8/11- 8/21
9/11-10/8
11/7 -11/20
Cruise No.
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
10
12
1A
IB
2
3
4
5
6
1
2
3
4
5
1
2
3
4
5
6
7
Area -Weighted Transparency,
Secchi Disk (m)
Western Central Eastern
1.92
N.A.
1.78
N.A.
2.12
1.14
0.87
1.01
1.30
0.56
0.60
1.05
2.35
1.31
2.16'
1.54 •
1.25
1.08
1.96
0.56
0.64
0.45
1.28
1.56
0.79
0.94
0.44
0.81
2.78
N.A.
0.85
1.01
1.75
N.A.
N.A.
N.A.
N.A.
1.09
1.36
4.31
6.72
5.86
5.85
4.53
3.77
3.35
2.26
1.75
1.62
3.03
3.34
4.38
6.28
5.93
6.36
5.51
N.A.
3.31
0.76
0.90
1.65
4.92
7.99
3.63
2.70
1.03
2.27
4.39
4.42
3.12
2.08
4.90
4.56
5.41
6.55
4.69
4.01
2.22
N.A.
N.A.
N.A.
N.A. •'
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.'A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A. •
N.A.
N.A.
N.A.
N.A.
4.98
3.69
7.21
5.91
4.50
2.88
(continued)
-41-
-------
TABLE 14 CONT.
Date Year
1978
5/18- 5/27
5/5 - 6/15
6/23- 7/1
7/19- 7/29
8/8 - 8/16
8/29- 9/6
10/3 -10/12
10/24-11/1
11/10-11/19
1979
4/17- 4/20
5/15- 5/26
6/12- 6/21
7/11- 7/19
7/31- 8/4
8/23- 9/4
9/11- 9/21
10/2 -10/14
11/7 -11/16
6/29- 7/6 1980
7/28- 8/8
8/18- 8/23
6/24- 7/3 1981
9/1 - 9/11
9/12- 9/24
Cruise No.
1
• 2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
4
5
6
4
5
6
Area-Weighted Transparency,
Seech i Disk (m)
Western Central Eastern
N.A.
2.50
2.02
2.00
2,06
2.68
1.94
1.58
2.08
0.65
N.A.
0.67
U81
1.44
3.03.
2.38
1.91
1.29
1.59
0.96
1.51
1.73
1.50
1.19
0.59
0.83
N.A.
3.37
4.31
4.22
6.93
6.60
5.16
4.31
2.93
3.42
N.A.
1.28'
2.82
3.49
5.80
5.78
N.A. .
3.92
3.50
5.03
7.02
5.95
4.66
6.08
3.22
2.77
N.A.
3.96
4.22
6.87
5.95
7.03
4.65
3.20
3.63
3.16
N.A.
N.A.
3.16
3.07
6.91
N.A.
' N.A.
5.82
4.26
3.67 :
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
-42-
-------
TABLE 15
LAKE ERIE WATER QUALITY MEASUREMENTS 1981
WESTERN BASIN CRUISE MEAN CONCENTRATIONS
STATIONS 202 AND 401 EXCLUDED
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Temp.
Date Statistics (°C)
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
2.62
0.08
2.5
36
11.82
0.17
11.6
36
16.53
0.19
16.7
31
20.69
0.16
20.6
36
20.94
0.08
21.0
36
16.91
0.11
17.20
36
10.15
0.12
10.45
36
9.02
0.08
9.10
36
4.93
0.06
4.95
36
DO
(rag/1)
13.32
0.02
13.3
36
10.93
0.07
10.9
36
9.10
0.08
9.20
31
8.18
0.10
8.1
36
9.02
0.13
8.75
36
8.85
0.05
8.8
36
10.62
0.15
10.3
35 '
11.49
0.10
11.1
36
11.98
0.06
12.0
36
Corrected
DO Conduct. pH
(%} (umhos/cm)
102.9
0.2
102.8
36
99.2
0.8
98.5
36
90.8
0.9
91.3
31
89.4
1.3
87.9
36
99.1
1.6
95.2
36
89.0
0.5
89.0
36
93.5
1.4
90.5
35
99.0
0.8
97.6
36
96.1
0.5
96.4
36
235
3
236
36
256
8
241
36
276
6
264
31
259
5
249
36
242
5
229
36
242
3
236
36
248
4
239
36
250
6
237
36
252
5
245
36
7.85
0.01
7.86
36
8.35
0.02
8.36
36
8.36
0.02
8.34
31
8.21
0.03
8.14
36
8.36
0.03
8.32
36
8.05
0.01
8.06
36
7.96
0.02
7.94
36
8.12
0.03
8.11
36
8.03
0.01
8.03
36
-43-
-------
TABLE 15 CONT.
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
Statistics
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Total
Phos.
(ug/1)
22.6
1.7
19.7
36
28.5
5.2
17.9
36
21.6
2.2
17.4
31
33.8
5.4
22.7
36
52.2
8
35.8
36
37.9
2.4
32.8
36
38.8
2.3
34.1
36
24.8
2.5
21.1
36
29.2
3.2
21.5
36
Soluble
Reactive
Phos.
(ug/1)
ND
2.3
0.1
2.1
36
1.9
0.2
1.7
31
6.7
1.5
2.7
36
4.7
1.3
2.6
36
5.9
0.5
5.3
36
3.4
0.3
3.4
36
1.5
0.2
1.2
36
3.0
0.6
1.8
36
Nitrate
Nitrite
(ug/1)
572
45
480
36
726
178
400
36
914
116
531
31
962
174
433
36
334
38
221
36
304
24
235
36
364
16
360
36
458
48
358
36
502
36
457
36
Ammonia
(ug/1)
39.2
11.3
9.6
36
14.9
5.9
2.7
36
9.4
3.2
6.7
14
24.3
3.4
21.1
36
3.6
0.5
2.9
32
20.9
2.8
18.0
36
15.8
2.8
10.3
36
25.9
10.2
16.7
12
26.0
7.4
3.8
36
Dissolved
Reactive
Silica
(ug/1)
886
84
1035
36
252
80
40
36
125
13
120
31
1022
160
765
36
916
106
735
36
1111
46
1105
36
867
57
880
36
877
81
990
36
1249
69
1245
36
-44-
-------
TABLE 15 CONT.
Cruise
No.
1 epi
2 epi
3 epi
4 epi
5 epi
6 epi
7 epi
8 epi
9 epi
Date
3/24-3/29
5/2-5/6
6/2-6/7
6/24-7/3
9/1-9/11
9/12-9/24
10/24-10/31
11/12-11/19
12/3-12/6
Statistics
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
mean
st. err.
median
n
Seech i
(m)
1.4
0.1
1.6
17
1.8
0.2
1.8
15
1.9
0.2
1.7
15
1.3
0.1
1.4
18
0.7
0.1
0.8
18
0.9
0.1
0.9
11
0.7
0.1
0.7
16
1.1
0.1
1.1
17
1.0
0.1
1.0
12
Turbidity
(ntu)
6.2
0.7
5.1
36
9.9
3.3
3.4
36
4.7
0.8
3.1
31
15.5
5.7
6.0
36
19.4
4.5
10.4
36
15.0
2.3
10.0
36
20.2
1.8
16.9
36
9.2
1.0
7.6
30
16.5
2.3
10.4
36
Susp.
Solids
(tig/1)
5.07
0.39
4.49
28
13.15
4.78
4.11
36
5.06
1.04
2.93
31
13.72
3.76
6.84
36
24.5
7.9
12.2
36
16.07
2.23
17.07
36
19.95
1.92
16.76
35
9.95
1.23
7.85
34
16.63
2.33
10.67
36
Corr.
Chlor.
(ug/1)
6.53
0.30
6.47
36
8.72
1.34
6.00
36
5.20
0.96
2.81
31
6.68
0.94
4.90
36
14.17
1.61
12.84
36
8.55
0.84
7.78
36
8.02
0.69
7.12
36
9.97
0.95
8.76
36
4.24
0.33
4.23
36
SCOR
Chlor.
(ug/1)
7.06
0.34
7.06
36
10.37
1.49
8.07
36
5.77
1.09
3.11
31
7.05
0.74
5.44
36
19.31
1.73
16.89
36
12.13
0.88
10.51
36
11.50
0.87
9.92
36
11.99
1.09
11.67
36
6.86
0.48
6.44
36
-45-
-------
c
i_
01
c
o
fa
4->
oo
00
2;
3
-------
Surface
May 2 - 6 (2)
Bottom
May 2 - 6 (2)
Surface
June 2 - 7 (3)
7 (3)
Figure 2. Limnion horizontal distribution maps, for temperature (°C),
1981
-47-
-------
Bottom
June 24 - July 3 (4)
Surface
September 1
- 11 (5)
Bottom
September 1
- 11 (5)
Figure 2 (continued). Limnion horizontal distribution maps, for temperature
(°C), 1981
-48-
-------
Surface
September 12 -24 (7)
Bottom
September 12 - 24 (7)
Figure 2 (continued),,
Limnion horizontal distribution maps, for
temperature (°C), 1981
-49-
-------
September 1 - 11 (5)
September 12 -24 (6)
Figure 3. Distribution maps of Hypolimnion thickness (m), 1981.
The Dashed line shows the hypolimnion boundary.
-50-
-------
I
o
I
to
o
O
O
01
CO
c
o
4J
oo
i.
LU
CD
IO —I
•
U
3
-)-J
V)
aioo
-ECTl
O)
S-
3
CD
O
C\i
UO
C\J
(Ul)
-51-
-------
n
CM
O)
C
O)
in
OJ
S-
LU
O)
_i£
to
_i
(O
c
O)
O
4J
O
I
10
t/)
o
O
0) CO
Lf)
O)
3
cn
-------
130-
120-
100«
80-
-------
Bottom
June 24-July 3 (4)
Bottom
September 1-11 (5)
Bottom
September 12-24 (6)
Bottom composite
June 24-September 24
Figure 7. Limnion horizontal distribution maps for dissolved oxygen (mg/1)
and for the composite anoxic area, 1981.
-------
1200
1000
800
O)
600
c
_o
4J
eo
c 400
o
u
200
Wfestern B.asin
Epilimnion
Central Basin
Epilimnion
Hypolimnion
* WB
V
X
X
CB
MAMJ J ASONDJ F
Figure 8. N03 + N0£ Basin Comparison of Epi and Hypolimnion Concentrations,
-55-
-------
18
150-
120^
90
60-
30'
Western Basin
Epilimnion
Central Basin
Epilimnion
Hypolimnion
MAMJ j ASONDJ
Figure 9. Ammonia Basin Comparison of Epi and Hypolimnion Concentrations,
-56-
-------
20
10
Western Basin
Epilimnion
Central Basin
Epilimnion
Hypolimnion ""'•
. WB
M
M J J A S O
N D J
Figure 10. Soluble Reactive Phosphorus Basin Comparison of Epi and
Hypolimnion Concentrations.
604
50'
40
30
2Q4
10
A
Western Basin
Epilimnion
Central Basin
Epilimnion
Hypolimnion
... WB
M
M J
SON
Figure 11. Total Phosphorus Basin Comparison of Epi and Hypolimnion
Concentrations. -57-
-------
1800-
Western Basin
Epilimnion
Central Basin
Epilimnion
Hypclimnion •—- — -
1500-
1200-
CT
900-
600-
300-
M
M
O N
Figure 12. Soluble Reactive Silica Basin Comparison of Epi and Hypolimnion
Concentrations.
-58-
-------
Surface
May 2 - 6 (2)
Surface
June 2 - 7 (3)
Bottom
June 2 - 7 (3)
Figure 13. Limnion horizontal maps for nitrate plus nitrite (ug/1),
1981
-59-
-------
Bottom
June 27 - July 3 (4)
Surface
September 1
Bottom
September 1 - 11 (5)
Figure 13 (continued),, Limnion horizontal maps for nitrate plus nitrite
(ug/1), 1981
-60-
-------
Surface
September 12
Bottom
September 12
Surface
October 24 - 31 (7)
Bottom
October 24 - 31 (7)
Figure 13 (continued). Limnion horizontal maps for nitrate plus nitrite
(ug/1), 1981
-61-
-------
Surface
November 12
- 19 (8)
Surface
December 3
- 6 (6)
Figure 13 (continued),, Limnion horizontal maps for nitrate plus nitrite
(ug/1), 1981
-62-
-------
Surface
May 2-6 (2)
Surface
June 2-7 (3)
Surface
June 27-Ju1y 3 (4)
Bottom
June 27-July 3 (4)
Figure 14. Limnlon horizontal distribution maps for ammonia (ug/1), 1981
-63-
-------
Surface
September 1-11 (5)
Bottom
September 1-11 (5)
Surface
September 12-24 (6)
Bottom
September 12-24 (6)
Figure 14. Limnion horizontal distribution maps for ammonia (ug/1), 1981
-64-
-------
Surface
October 24-30 (7)
Surface
November 12-19 (8)
Surface
December 3-6 (9)
Figure 14 (continued). Limnion horizontal distribution maps for ammonia (ug/1),
1981• -65-
-------
Surface
May 2 - 6 (2)
Surface
June 2 - 7 (3)
Bottom
June 2 - 7 (3)
Figure 15. Limnion horizontal distribution maps for soluble reactive
phosphorus (ug/1), 1981.
-66-
-------
Surface
June 27 - July 3 (4)
Bottom
June 27 - July 3 (4)
Surface
September 1 - 11 (5)
Bottom
September 1
- 11 (5)
Figure 15 (continued). Limnion horizontal distribution maps for soluble
reactive phosphorus (ug/1), 1981
-67-
-------
Surface
September 12 - 24 (6)
Bottom
September 12 - 14 (6)
Surface
October 24 - 31 (7)
Bottom
October 24
- 31 (7)
Figure 15 (continued)
Limnion horizontal distribution maps for soluble
reactive phosphorus (ug/1), 1981
-68-
-------
Surface
November 12
- 19 (8)
Surface
December 3 - 6 (9)
Figure 15 (continued).
Limnion horizontal distribution maps for soluble
reactive phosphorus (ug/1), 1981.
-69-
-------
Surface
May 2-6 (2)
Bottom
May 2-6 (2)
Surface
June 2-9 (3)
Bottom
June 2-7 (3)
Figure 16. Limnion horizontal distribution maps for total phosphorus
(ug/1), 1981. .70-
-------
Surface
June 24-July 3 (4)
Bottom
June 24-July 3 (4)
Surface
September'1-11 (5)
Bottom
September 1-11 (5)
Figure 16 (continued). Limnion horizontal distribution maps for total
phosphorus (ug/1), 1981.
-71-
-------
Surface
September 12-24 (6)
Bottom
September 12-24 (6)
Surface
October 24-31 (7)
Bottom
October 24-31 (7)
Figure 16 (continued). Li'mnion horizontal distribution maps for total
phosphorus (ug/1), 1981'.
-72-
-------
Surface
November 12-19 (8)
Surface
December 3-6 (9)
Figure 16 (continued).
Limnion horizontal distribution maps for total
phosphorus (ug/1), 1981.
-73-
-------
Surface
May 2-6 (2)
Surface
June 2-7 (3)
Surface
June 27-July 3 (4)
Figure 17. Limnion horizontal distribution maps for soluble reactive Silica
fun/1 ]. 1QR1 . -7/1
-------
Bottom
June 27-July 3 (4)
Surface
September 1-11 (5)
Bottom
September 1-11 (5)
Surface
September 12-24 (6)
Figure 17 (continued). Limnion horizontal distribution maps for soluble reactive
Silica (ug/1), 1981.
-------
Bottom
September 12-24 (6)
Surface
October 24-30 (7)
Surface
November 12-19 (8)
Surface
December 3-6 (9)
Figure 17 (continued). Limnion horizontal distribution maps for soluble reactive
Silica (ug/1), 1981.
-------
I
oo
csa
c\J
csa
csa
OD
C9
csa
J_
CSS
CvJ
U
LU
a
o
u
o
CL
UJ
CD
a:
a.
m
LU
U.
csa
o
GO
O
O ~
Q_
O
1C m «
CJ -,
a
LU
u
LU
cr
o
CJ
a:
UJ
UJ
O)
3
-77-
-------
0)
o g
rg O
M-l 4J
M 4J
3 O
w m
i , i
I
U
LU
Q
O
2
I—
U
O
Q_
LU
o
13
n °°
r=^ ^
LJ »-•
cr z
0
(/)
-I -
<
o:
o_
LU
o:
o
u
m
LU
o5
ca csa ca ca
00 C*~» tr? LO
C53 S3
cn CNJ
NOIlVdlN33N03
-78-
-------
0)
o e
ra o
M 4J
3 O
OT «
o
o
o
o
Q_
LU
Cfl
Q_
QQ
LU
U.
CO
a
o
CO ~
oo
a 2
o
C\J
(U
=3
en
O
h-
NOUVaiN33N03
-79-
-------
<0
o e
to o
<4-l -P
H 4J
3 O
W BQ
o NOIlVdiN33N03
-80-
-------
O 6
m O
IH 4J
n -P
3 O
L
J_
J_
LU
a
>
O
u
O
CL
LU
(fl
CO
Q
_J
ID
O
CO ~
03
Q 2
z LU m CM
a ~ ^
CO
-J
a:
a.
h-
O
GO
LU
csa in
in co
LO
in
O)
csa
to
in
csa
CO
in
ca
csa
u
-------
0)
o g
ro o
m 4-1
M 4J
SI O
W CQ
o
I I I T-l
a -r
£ u 5
z Q_ m
i CO ,
Z)
a
U
cr
ro
CM
a>
3
cn
.
I LU
— 1 U
n\DW) NOIlVaiN33N03
-82-
-------
0 §
rtJ O
'M 4J
M -M
3 O
CO «
o
O
U
O
CL
UJ
(fi
CD
13
>-
<
a:
a.
OQ
LU
LL.
CO
a
O
CO
Q 8
Q z
z: ~
X lit CD
i- yj <
Z Q_ QQ
i CO Z
Z) &
co y
CO
Ol
01
^^ fj^|i pig^ O ^J PQ ^^ Q^ 1*^ I^Z^
• *••••**••
CTCDt^coLn-^-mru^-iCsa
NOIlVdlN33N03
-83-
-------
0)
O 0
m o
O
U
o
a.
LU
CC
Q.
a:
<:
LU
LL
in
csa
CSJ
a
-J
o
CO
f—1
n oo
S 2
U)
2 CL m
O
=> £
a) I
LU W
o
CM
S_
3
C1\3W) NOIiVyiN33N03
-84-
-------
0)
o g
io o
•w -p
H 4J
3 O
I
j_
csa csa
00
csa
csa
csa
LU
a
>
o
u
o
CL
LU
CD
Z)
a:
a.
QQ
LU
LL
C\J T-t
csa
csa
CO
Q
O
CO
Q
LU g
Q CD
•—7» «-i
LLl Z
01
UJ
LU
10
CVJ
d)
s_
-J
O
sanos aaaNBdsns iviai do
-85-
-------
0 §
nj O
GO t^
(O
CO
ca
ca
U
LU
a
>
a
u
o
CD
>-
<
m
LU
u_
ca
ca
ru I-H
ca
ca
CO
a
o
en
a -
u 8
LJ 1-1
£ CL
-------
CJ
LU
d
>
O
u
O
a.
LU
CD
i QQ
CE
00
O)
z
t—i
(/)
m
z
LU
cn
LU
03
OJ
O)
en
a:
o_
m
LU
u.
BJ
ca
in
m
CS3
irf
OJ
ca
in
ca
in
cnm
-87-
-------
0)
0 i
10 o
>M -P
M 4J
3 O
w cu
ca
cs
(O
cs
in
CS3
(J
LU
a
o
z
u
o
a.
LU
en
00
GQ
00
I
LU
U
en
CM
01
s-
CT)
a:
a.
m
LU
u.
cnir) Aiiaiaani
-88-
-------
d>
o g
10 o
'M 4J
c/l P3
OO'
csa
en
ca
csa
OJ
csa
ca
in
csa
csa
CO
csa
csa
in
csa ca
csa in
en *-i
U
LU
a
>
a
u
o
a.
LU
o
o:
a.
m
LU
u.
csa
csa
O
OQ
U
r-l
UQO
C3)
i o
LU
rf^^ ^^
CD Sg
m
Z)
U
o:
<
Q_
en
LU
o
n
-------
<0
O t:
10 o
•H 4J
M *J
3 O
C/l ftJ
o
^1
I w
d u
U
QJ
S_
3
CD
iZ
CL
m
LU
C9
§
00
ea
ea cs
c>- to
C9
ca
C9
in
oa
CT)
ca
ca ca
NOIlVdlN33N03
-90-
-------
5.0 - 5.0-
4.0 - 4.0-
3.0 - 3.0-
2.0- 2.0«
1.0 - 1.0*
Turbidity
TSS
1/Secchi
•0.4
•0.2
0.1
M
O N
Figure 32. Station 037, 1981. Surface concentrations of Total
Suspended Solids, Turbidity and reciprocal of Secchi.
-91-
-------
«
12-
m
lU *
,-,
vE I5
in
"o 1.6 iol 8"
•r~
'o ^
•o 14 c- -
QJ O
T3 S_
c o
O) i—
^ 1.2 5 6-
3
i — (_>•
£ 10 « -
(0 S_
i— O
0 0
> .8 4-
6
.4 2-
2
.,-,..-, ^ , , ~ , . ,
Corrected Chlorophyll a^ ~"
Particulate Organic Carbon
*
•
•
m
•
\ A
/ \
//\
\ ^j1 * ^s ^V**»
\ • *"'^^^^ ^^*» ^
\ ^-^^ .<^r^ *X%»jf
\ I ^^**y^s ^ \/ ***
\^ ***** x ^ *L
\*»*** X \ 7\
v«— •••• *"" \ / \
\ /
\/
AMJJASONDJ
Figure 33. Station 037, 1981. Surface concentrations of Volatile
»
•1200
•1000
• 800
• 600
• 400
• 200
01
3
t-
re
o
c:
03
O
+J
(O
o
i.
to
D-
Suspended Solids, Particulate Organic Carbon, and Corrected
Chlorophyll a^.
-92-
-------
Surface
May 2-6 (2)
Surface
June 2-7 (3)
Surface
June 24-July 3 (4)
Surface
September 1-11 (5)
Figure 34. Limnion horizontal distribution maps for corrected chlorophyll a
(ug/1), 1981.
-93-
-------
Surface
September 12-24 (6)
Surface
October 24-31 (7)
Surface
November 12-19 (8)
Surface
December 3-6 (9)
Figure 34 (continued). Limnion horizontal distribution maps for corrected
chlorophyll a_ (ug/1), 1981.
_Q/L-
-------
o
o
a. oJ X
X D
X D D
AX 78 •
79 Y
H X *
A * 80 D
X A 81 A
MAMJJASONDJI
Figure 35. Western Basin Secchi Area weighted cruise values, 1978-1981.
-95-
-------
7.0-
6.0-
5.0'
4.0'
o
3.0-
2.0-
1.0-
D
n
X X
n
• 78
X 79
D 80
A 81
MAMJ
T T T T f f^
SONDJF
Figure 36. Central Basin secchi area weighted cruise values, 1978-1981.
-96-
-------
g
00
f>.
at
O)
in
r^.
CO
CO
CO
CO
«—I
CJ
CO
CO
csa
OJ
ca
oo
csa
c\l
ca
ca
ca
GO
ca
cd
ca
•
ca
c\I
ca
ca
a:
UJ
GO
O)
«-i
I
O)
r-t
W
UJ
U
n L»-
O §
a: «
a z
m
u
Qoc:
UJ
LU b
UJ
UJ
a:
U
LU
cr
o:
o
u
CO
s_
3
CT
NOIlVaiN33N03
-97-
-------
LOROPHYLl a
CORRECTED CM
i I — I — I* 1
N
1 < i i '
O)
-------
I
OO
07
s
O)
GO
r>.
O)
O)
T-S
.
O)
r-.
o>
CO
en
»—i
OJ
en
O)
O)
ca
C53 Cd
CD 00
00
O)
v-4
CD
»-H
\S
LJ
U
<
O z
iH ^ ^
>- (_j m
Q ^
jf! |
LU en
cr Ld
o s
u >.
LU
CO
(II
3
CT
ca ca
-------
^3
, *
O)
M
O
I J 1 1 lt0 1
UJ
""" LU **
CD < ' ' ' ' '
ee. -J
O
=J 2 10
< 1- ' ' 1 i 1 I
0 °°
UJ
S < *
O LU
O
1— ~~ • I .. . 1 J
— .
3
C O)
S ° ~c=
ro
S- •
O -t-> •—
co c co
*" U i—
0 O
g °c7;
Q) •»
E.tu
S S- £
<2 O) LU
-Q
E OJ
01 ^:
t- > re
a o — i •
9 2: s-
O (O i-
<0 -M S- S_
*" c QJ XJ
3 O i-
'O ro
« , O)
S -C 4-> 10
S CL ro -t->
™ 0 2 C
S-
-------
_L
L
00
CO
C3
CD
CO
CO
f^.
CO
*—I
00
r^
CO
CO
(O
CO
in
p>.
CO
CO
»—I
en
pv.
CO
»—I
e\j
r-.
CO
CSJ
c->.
CO
o
in
in
in
ca
in
ess csa csa
in csa in csa
oo ro e\J CM
in
cs
cs
ca
csi
GO
O)
(/) K
—\ o
Q^ a
o ^
n: 5
a. -
_J
o:
<
UJ
Q_
3
O)
NOIlVdlN33N03
-101-
-------
L
CS3
S3
J_
00
CO
C3
CO
CO
at
00
p^
CO
CO
(O
r--
CO
in
r^
CO
CO
f-1
CO
r-«-
CO
OJ
t-«.
CO
CO
csa
t^-
CO
in
oo
ca
si
CO
in
OJ
SJ
cs£
OJ
ca
in
csa
ca
in
csa
LU
CO
CO
O)
O)
T-t
w
CL %
CO m
O ,
H-
O
a:
LU
U
UJ
^
>-
_l
a:
<
UJ
CM
5-
NOIlVdlN33N03
-102-
-------
U.S. Environmental Protection Agency
GLNPO Library Collection (PL-12J)
77 West Jackson Boulevard,
Chicago, IL 60604-3590
------- |