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Lake Michigan Mass Balance
Publications
The Lake Michigan Mass Balance Study is made up of a series of sub-studies, the
results of which will feed the mathematical models to produce the ultimate results. Each
of these smaller studies was conducted by top scientists from state, federal, university
and private laboratories to analyze samples for pollutants that are often present in the
environment at barely detectable concentrations. The results from many of the studies that
make up the Mass Balance have been published in peer reviewed journals, agency
publications and conference proceedings. The list below contains references to the results
published to date. Links to the journal abstracts are also available where
indicated.
Final reports
Scientific Papers (with Abstracts)
Achman,
D.R.; Hornbuckle, K.C.; Eisenreich, S.J. 1993. Volatilization
of Polychlorinated Biphenyls from Green Bay, Lake Michigan. Environ. Sci. Technol. 27(1): 75-86.
(ABSTRACT)
Cortes, D.R.; Basu, I.; Sweet, C.W.; and Hites, R.A. 2000. Temporal Trends in and Influence of Wind on PAH
Concentrations Measured near the Great Lakes,
Environ. Sci. Technol. 34(3): 356-360.
Cowell,
S.E.; Hurley, J.P.; Shafer, M.M.; and Hughes, P.E. 1995. Mercury Partitioning and Transport in Lake Michigan Tributaries.
East Lansing, Michigan, International Association for Great Lakes
Research Conference: Programs and Abstracts, May 28 - June 1, 1995. (ABSTRACT)
Franz, T.P.; Eisenreich,
S.J.; Holsen, T. 1998. Dry deposition of particulate polychlorinated biphenyls
and polycyclic aromatic hydrocarbons to Lake Michigan.
Environ. Sci. Technol. 32(23):
3681-3688. (ABSTRACT)
Green, M.L.; DePinto,
J.V.; Sweet, C.W.; Hornbuckle, K.C. 2000. Regional
Spatial and Temporal Interpolation of Atmospheric PCBs: Interpretation
of Lake Michigan Mass Balance
Data. Environ. Sci. Technol. 34(9):
1833-1850. (ABSTRACT)
Hall,
D.W.; Behrendt, T.E.; and Hughes, P.E. 1998. Temperature,
pH, conductance, and dissolved oxygen in cross-sections of 11 Lake
Michigan Tributaries, 1994-5.
U.S. Geological Survey Open-File Report 98-567, 85pp.
(ABSTRACT)
Hall, D.W.; Behrendt,
T.E. 1995. Polychlorinated biphenyls and
pesticides in Lake Michigan Tributaries. East Lansing, Michigan, International
Association for Great Lakes Research Conference: Programs and Abstracts, May 28 - June 1,
1995. (ABSTRACT)
Holsen,
T.M.; Keeler,
G.J.; Noll, K.N.; Fang, G.; Lee, W.; Lin, J. 1993. Dry
Deposition and Particle Size Distributions Measured during the Lake Michigan Urban Air
Toxics Study. Environ. Sci. Technol. 27(7):
1327-1333. (ABSTRACT)
Hornbuckle, K.C.; Sweet,
C.W.; Pearson, R.F.; Swackhamer, D.L.; Eisenreich, S.J. 1995. Assessing Annual Water-Air Fluxes of
Polychlorinated Biphenyls in Lake Michigan, Environ. Sci.
Technol. 29(4): 869-877. (ABSTRACT)
Hornbuckle,
K.C.; Achman, D.R.; Eisenreich, S.J. 1993. Over-Water and
Over-Land Polychlorinated Biphenyls in Green Bay, Lake Michigan. Environ. Sci. Technol. 27(1): 87-98.
(ABSTRACT)
Hurley, J.P.; Cowell,
S.E.; Shafer, M.M.; Hughes, P.E. 1998a. Partitioning
and transport of total and methyl mercury in the Lower Fox River, Wisconsin. Environ.
Sci. Technol. 32(10): 1424-1432. (ABSTRACT)
Hurley, J.P.; Cowell,
S.E.; Shafer, M.M.; Hughes, P.E. 1998b. Tributary
loading of mercury to Lake Michigan: Importance of Seasonal events and phase partitioning. The Science
of the Total Environment. 213(1-3): 129-137. (ABSTRACT)
Hurley, J.P.; Shafer, M.M.; Cowell, S.E.; Overdier, J.T.; Hughes,
P.E.; Armstrong, D.E. 1996. Trace Metal Assessment
of Lake Michigan Tributaries Using Low Level Techniques. Environ. Sci. Technol. 30(6): 2093-2098.
(ABSTRACT)
Madenjian, C.P.;
DeSorcie, T.J.; Stedman, R.M.; Brown, Jr., E.H.; Eck, G.W.; Schmidt, L.J.; Hesselberg,
R.J.; Chernyak, S.M.; Passino-Reader, D.R. 1999.
Spatial Patterns in PCB Concentrations of Lake Michigan Lake Trout. J. Great Lakes Res. 25(1): 149-159.
(ABSTRACT)
Madenjian,
C.P.; Desorcie, T.J; Stedman, R.M. 1998a. Maturity
Schedules of Lake Trout in Lake Michigan. J.
Great Lakes Res. 24(2): 404-410. (ABSTRACT)
Madenjian, C.P.; Desorcie, T.J.; Stedman, R.M. 1998b. Ontogenic and Spatial Patterns in Diet and Growth of
Lake Trout in Lake Michigan. Trans. Amer.
Fisher. Soc. 127: 236-252. (ABSTRACT)
Madenjian, C.P.; Elliot, R.F.; Schmidt, L.J.; Desorcie, T.J.;
Hesselberg, R.J.; Quintal, R.T.; Begnoche, L.J.; Bouchard, P.M.; Holey, M.E. 1998. Net Trophic Transfer Efficiency of PCBs to Lake
Michigan Coho Salmon from Their Prey. Environ.
Sci. Technol. 32(20): 3063-3067. (ABSTRACT)
Madenjian, C.P.; Hesselberg, R.J.; Desorcie, T.J.; Schmidt, L.J.;
Stedman, R.M.; Quintal, R.T.; Begnoche, L.J.; Passino-Reader, D. 1998. Estimate of Net Trophic Transfer Efficiency of PCBs to
Lake Michigan Lake Trout from Their Prey. Environ.
Sci. Technol. 32(7): 886-891. (ABSTRACT)
Madenjian, C.P.; O'Connor, D.V.; Nortrup, D.A. 2000. A
New Approach Toward Evaluation of Fish Bioenergetics Models. Can. J. Fish. Aquat. Sci. 57:
1025-1032. (ABSTRACT)
Madenjian, C.P.; Schmidt, L.J.; Chernyak, S. M.; Elliott, R.F.;
DeSorcie, T.J.; Quintal, R.T.; Begnoche, L.J.; Hesselberg, R.J. 1999. Variation
in Net Trophic Transfer Efficiencies among 21 PCB Congeners. Environ. Sci. Technol. 33(21): 3768-3773.
(ABSTRACT)
Mason, R.P.; Sullivan, K.A. 1997. Mercury in Lake Michigan. Environ. Sci. Technol. 31(3): 942-947.
(ABSTRACT)
Miller, S.M. 1999. Spatial and Temporal Variability of Organic and Nutrient Compunds in
Atmospheric Media Collected During the Lake Michigan Mass Balance Study.
M.S. thesis. University of New York at Buffalo, Buffalo, New York.
181 pp. (ABSTRACT)
Miller, S.M.; Sweet, C.W.; DePinto, J.V.; Hornbuckle, K.C. 2000. Atrazine and Nutrients in Precipitation:
Results from the Lake Michigan Mass Balance Study. Environ.
Sci. Technol. 34(1): 55-61. (ABSTRACT)
Rossmann, R.. 2002. Lake Michigan 1994-1995 Surficial
Sediment Mercury. J. Great Lakes Res.
28(1): 65-76. (ABSTRACT)
Rygwelski, K.; Richardson, W.; Endicott, D. 1999. A Screening-Level Model Evaluation of Atrazine in the
Lake Michigan Basin. J. Great Lakes Res.
25(1): 94-106. (ABSTRACT)
- Shafer,
M.M.; Overdier, J.T.; Baldino, R.A.; Hurley, J.P.; and Hughes, P.E. 1995. Levels,
Partitioning, and Fluxes of Six Trace Elements in Lake Michigan
Tributaries. East Lansing, Michigan, International Association for
Great Lakes Research Conference: Programs and Abstracts, May 28 - June 1,
1995.
- Simcik, M.F.; Hoff, R.M.; Strachan, W.M.J.; Sweet, C.W.; Basu, I. and Hites,
R.A. 2000. Temporal Trends of Semivolatile Organic Contaminants in Great Lakes
Precipitation. Environ. Sci. Technol.
34(3): 361-367.
Sullivan, K.A.; Mason,
R.P. 1998. The concentration and distribution of
mercury in Lake Michigan. The Science of The
Total Environment. 213(1-3): 213-228. (ABSTRACT)
Swackhamer, D.L.; Schottler, S.; Pearson, R.F. 1999. Air-Water Exchange and Mass Balance of Toxaphene in the
Great Lakes. Environ. Sci. Technol. 33(21):
3864-3872. (ABSTRACT)
Swackhamer, D.L.; Trowbridge, A. 1999. Bioaccumulation of AHH-Inducing PCB Congeners. Anaheim,
CA, 217th American Chemical Society National Meeting: Programs and Abstracts,
March 21, 1999.
LMMB
ABSTRACTS
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Achman,
D.R.; Hornbuckle, K.C.; Eisenreich, S.J. 1993. Volatilization of Polychlorinated Biphenyls from Green Bay, Lake
Michigan. Environ. Sci. Technol.
27(1): 75-86.
ABSTRACT:
The volatization of polychlorinated biphenyls (PCBs) from Green Bay was
estimated as part of the Green Bay Mass Balance Study (U.S. EPA). The
strategy employed was to simultaneously collect air and water samples
above and below the air-water interface, analyze the atmospheric gas
phase and the water column dissolved phase for 85 PCB congeners, and
calculate the direction and magnitude of flux for each congener using
Henry’s law and meteorological and hydrological parameters. Sampling
covered the period of June through October 1989. Air-water transfer
rates were calculated for the 14 individual days spanning the three
cruises by using the stagnant two-film model. Calculated total PCB
volatization rates ranged from 13 to 1300 ng/m2-day. The most
important factors affecting the magnitude of the flux are wind speed and
water concentration. The range of fluxes calculates compares well with
other estimates for the Great Lakes. The results of the study support
the hypothesis that volatization is an important phenomenon controlling
the fate of hydrophobic organic chemicals (HOCs) in aquatic systems.
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Cowell,
S.E.; Hurley, J.P.; Shafer, M.M.; and Hughes, P.E. 1995. Mercury Partitioning and
Transport in Lake Michigan Tributaries.
East Lansing, Michigan, International Association for Great Lakes Research
Conference: Programs and Abstracts, May 28 - June 1, 1995.
ABSTRACT:
Eleven Lake Michigan tributaries were chosen to investigate the effects
of chemical and physical conditions in rivers on mercury partitioning
and transport. The tributaries reflect a range of land use/land cover
patterns and SPM and DOC vary both seasonally for a given tributary and
among tributaries. Preliminary results indicate that mean unfiltered
total Hg concentrations ranged from about 1-2 ng L-1 in the
Manistique and Muskegon Rivers to 10-30 ng L-1 in the St.
Joseph and Fox rivers. Highest Spring 1994 fluxes were observed in the
St. Joseph, Fox, Grand, and Kalamazoo rivers. In some tributaries,
greater fluxes of Hg to the lake were associated with storm events
during summer and fall. Elevated Hg concentrations were generally
associated with increased particle loads. Results from this research
will be compared to those of other researchers investigating atmospheric
inputs, open water and biotic components of the Lake Michigan Hg Mass
Balance.
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Franz,
T.P.; Eisenreich, S.J.; Holsen, T. 1998.
Dry deposition of particulate
polychlorinated biphenyls and polycyclic aromatic hydrocarbons to Lake
Michigan. Environ.
Sci. Technol. 32(23): 3681-3688.
ABSTRACT:
Dry deposition was collected from November 1993 to October 1995 at
multiple sites within the Lake Michigan basin to estimate the fluxes of
particulate polychlorinated biphenyls (PCBs) and polycylic aromatic
hydrocarbons (PAHs) as part of the Lake Michigan Mass Balance Study (LMMBS).
Samples were also collected during the Atmospheric Exchange over Lakes
and Oceans (AEOLOS) project to estimate fluxes to coastal waters
adjacent to the Chicago urban area. Fluxes of particulate PCBs and PAHs
were higher in Chicago than <15 km offshore and at rural sites.
Geometric mean dry deposition fluxes across the Lake Michigan basin
ranged from 3.6 to 65 mg/m2-day for particle mass, 0.006 to
0.21 Fg/m2-day
for 3-PCBs,
and 0.25 to 18 Fg/m2-for
3-PAHs.
Similarities in both the distribution pattern of PCB congeners and PAHs
and the magnitude of their fluxes between dry deposition and surficial
sediment suggest that dry deposition may dominate loadings to the lake.
Conservative estimates of loadings to Lake Michigan through
particle dry deposition are estimated to be 1100kg/yr for PCBs and 5000
kg/yr for PAHs. These loadings are more than 3x greater than loadings by
wet deposition and, for PCBs, are similar to inputs by air/water
exchange.
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Green,
M.L.; DePinto, J.V.; Sweet, C.W.; Hornbuckle, K.C. 2000. Regional
Spatial and Temporal Interpolation of Atmospheric PCBs: Interpretation
of Lake Michigan Mass
Balance Data. Environ. Sci. Technol. 34(9):
1833-1850.
ABSTRACT:
During the Lake Michigan Mass Balance (LMMB) Project, over 600 atmospheric
samples were collected at eight shoreline sites and during seven cruises.
These samples were analyzed for persistent organic pollutants, including
PCB congeners, atrazine, and trans-nonachlor. We have developed a
method for interpreting the gas-phase data that includes fractionating the
observed PCB concentration into land- and water-based sources. This
approach accounts for differences in gas-phase atmospheric PCB
concentrations over water and over land. Using this fractionation
approach, we have interpolated the measured data over the lake during the
LMMB field period. The results predict gas-phase SPCB
(sum of ~98 congener groups) concentrations for each of 2318 grid cells
over the lake, on a monthly basis. We estimate that lake-wide monthly
average SPCB
gas-phase concentrations range from 0.136 to 1.158 ng/m3, with
an annual average PCB concentration of 0.457 ng/m3. As
expected, the highest concentrations of PCBs over the lake when the winds
are from the southwest (out of the Chicago-Gary region) and when land
surface temperatures are elevated. The predicted influence of Chicago is
described on a monthly basis as a zone of elevated PCB concentrations for
approximately 40 km into Lake Michigan.
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Hall,
D.W.; Behrendt, T.E.; and Hughes, P.E. 1998. Temperature,
pH, conductance, and dissolved oxygen in cross-sections of 11 Lake
Michigan Tributaries, 1994-5.
U.S. Geological Survey Open-File Report 98-567, 85pp.
ABSTRACT:
Temperature, pH, conductance, and dissolved oxygen data were collected
along cross sections at 11 major tributaries to Lake Michigan from April
1994 through October 1995 as part of the U.S. Geological Survey Lake
Michigan Tributary Monitoring Project. Eleven tributary monitoring
stations were installed neat their points of discharge into Lake
Michigan, and were located sufficiently upstream to minimize mixing of
lake and tributary water during most flow conditions. A total of 405
samples were collected from the 11 tributaries. The Grand Calumet,
Kalamazoo, and Pere Marquette Rivers were generally well mixed
throughout the sampling period. The Sheboygan, Menominee, Manistique,
Muskegon, Grand, and St. Joseph Rivers were generally well mixed during
winter months and stratified with respect to temperature and conductance
in summer months. The Milwaukee River, and to a lesser extent the Fox
River, were found to be poorly mixed at irregular intervals throughout
the sampling period.
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Hall,
D.W.; Behrendt, T.E. 1995. Polychlorinated
Biphenyls and Pesticides in Lake Michigan Tributaries, 1993-95. East
Lansing, Michigan, International Association for Great Lakes Research
Conference: Programs and Abstracts, May 28 - June 1, 1995.
ABSTRACT:
Eleven tributaries to Lake Michigan are being sampled from October 1993
through October 1995, for polychlorinated biphenyl congeners (PCBs), and
15 pesticides (organochlorine and triazine) and pesticide degradation
products. The study is being conducted by the U.S. Geological Survey in
cooperation with the Wisconsin and Michigan Departments of Natural
Resources, as part of the U.S. Environmental Protection Agency’s Lake
Michigan Mass Balance Study. Composited, depth-integrated water and
suspended particulate samples are being collected at or near points of
tributary discharge into Lake Michigan that are representative of
stormflow and baseflow conditions. Daily loads were estimated for total
PCBs (congener summation) and selected contaminants from the data
collected thus far, and relative loading of PCBs and selected
contaminants to Lake Michigan from the 11 tributaries was assessed.
PCB-congener distributions were associated with probable Aroclor
composition (Aroclors 1242, 1248, 1254, and 1260) for each tributary.
Significantly decreasing trends in tributary PCB concentrations and PCB
loadings are indicated by comparison of project data to historical data.
Detectable concentrations of DDT compounds (P,P’–DDT; P,P’-DDD;
and/or P,P’-DDE), hexachlorobenzene, and gamma-benzene hexachloride
were present in one or more water samples from each of the ten
tributaries with completed sample analyses.
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Holsen,
T.M.; Keeler, G.J.; Noll, K.N.; Fang, G.; Lee, W.; Lin, J. 1993. Dry
Deposition and Particle Size Distributions Measured during the Lake
Michigan Urban Air Toxics Study. Environ.
Sci. Technol. 27(7): 1327-1333.
ABSTRACT:
The mass and elemental dry depositional flux was measured in Chicago,
IL, in South Haven, MI, and over Lake Michigan onboard the R/V
Laurentian during the Lake Michigan Urban Air Toxics Study. The
average measured mass flux in Chicago (130 mg/m2d) was higher
and more variable than at either South Haven (40 mg/m2d) or
over Lake Michigan (27 mg/m2d). The flux of the crustal
elements (Al, Ca, Fe, Mg, Si, and Ti) in Chicago were 2-3 times higher
than those in South Haven and 3-4 times higher than those measured over
Lake Michigan. The flux of primarily anthropogenic metals (Cd, Cr, Cu,
Mn, Pb, V, and Zn) was on average 1-2 orders of magnitude lower than the
flux of primarily crustal elements at all three sites. A modeling
procedure that used measured atmospheric particle size distributions and
modeled deposition velocities was used to calculate the dry deposition
flux for comparison to the measured flux data. The average ratio of
calculated/measured fluxes for mass and the 13 elements was 1.4. In
general, the flux in Chicago was slightly underestimated, and the flux
in South Haven was slightly overestimated. Modeling results indicate
that the majority of the flux (>98%) was due to particles > 6.5 mm
in size. A comparison of simultaneously measured dry depositional flux
and the concentration of airborne particulate matter <10mm
in aerodynamic diameter (PM10) indicates the PM10 concentrations are not
a good measurement from which to estimate dry deposition flux.
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Hornbuckle,
K.C.; Sweet, C.W.; Pearson, R.F.; Swackhamer, D.L.; Eisenreich, S.J. 1995. Assessing Annual Water-Air Fluxes of
Polychlorinated Biphenyls in Lake Michigan, Environ. Sci.
Technol. 29(4): 869-877.
ABSTRACT:
Air-water exchange of PCBs was determined in Lake Michigan on an event
and seasonal basis in 1991-1993. Instantaneous fluxes of SPCB
(sum of 77 congener peaks) based on air-water concentration gradients
drawn from air and water samples collected simultaneously aboard ship
demonstrated net volatization in September 1991. Air samples collected
on the northeastern shore of Lake Michigan (Sleeping Bear Dunes State
Park) between December 1991 and July 1993 showed no seasonal trend in
vapor-phase SPCB
concentrations and ranged from 30 to 400 pg/m3. These air
concentrations were used to calculate seasonal water-air fluxes of SPCB
that ranged from -18 ng m-2 day-1 (net deposition)
to 60 ng m-2 day-1 (net volatization). The
seasonal variation of vapor-phase and dissolved-phase PCBs in the
impacted southern quarter of the lake are unknown, thereby hindering
estimation of fluxes in this region. The estimated annual net SPCB
flux is 12.3 mg
m-2 yr-1, which corresponds to 520 kg for the
northern three-quarters of Lake Michigan.
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Hornbuckle,
K.C.; Achman, D.R.; Eisenreich, S.J. 1993. Over-Water
and Over-Land Polychlorinated Biphenyls in Green Bay, Lake Michigan. Environ.
Sci. Technol. 27(1): 87-98.
ABSTRACT:
Air samples were simultaneously collected over water and over nearby
land in the Green Bay, Lake Michigan, region and analyzed for 85
polychlorinated biphenyls (PCBs). The concentration and distribution of
PCB congeners collected from vapor over water, over land, and dissolved
in the water support the hypothesis that volatization of PCBs from
contaminated waters is a major source of PCBs to the local atmosphere.
Concentrations of PCB congener (SPCBs)
over the water are higher over southern Green Bay (670-2200 pg/m3)
and lower over the northern bay (160-520 pg/m3) while SPCB
concentrations over the land ranged from 70 to 760 pg/m3. The
PCB concentration differences over land and over water were
statistically significant for congener sums and for homolog groups in
southern Green Bay. Regressions of air and water PCB distributions show
high correlations (R2 = 0.73-0.96) in southern Green Bay.
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Hurley,
J.P.; Cowell, S.E.; Shafer, M.M.; Hughes, P.E. 1998a. Partitioning and transport of total and methyl mercury in the Lower Fox
River, Wisconsin. Environ.
Sci. Technol. 32(10): 1424-1432.
ABSTRACT:
To investigate transport and partitioning processes of HgT in
the Fox River, we coupled detailed time series data of total mercury (HgT)
at the river mouth with transect sampling in the Lower Fox River.
Unfiltered HgT concentrations in the Fox River during the
study period (April 1994- October 1995) ranged from 1.8 to 182 ng L-1
with a median of 24.8 ng L-1, predominantly (93.6%) in the
particulate phase. These levels were significantly elevated compared
with other large tributaries to Lake Michigan (Hurley, J.P.; Shafer, M.M.;
Cowell, S.E.; Overdier, J.T.; Hughes, P.E.; Armstrong, D.E. Environ.
Sci Technol. 1996, 30, 2093-2098). Transect sampling revealed progressively increasing
water column HgT concentrations and HgT
particulate enrichment downstream, which were consistent with trends in
sediment HgT levels in the river. Resuspended sediments are
likely the predominant source of Hg from the Fox River into Green Bay.
Despite elevated HgT concentrations, methyl mercury (MeHg)
concentrations were relatively low, suggesting limited bioavailability
of HgT associated with sediments.
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Hurley,
J.P.; Cowell, S.E.; Shafer, M.M.; Hughes, P.E. 1998b. Tributary loading of mercury to Lake Michigan: Importance of Seasonal
events and phase partitioning. The
Science of the Total Environment. 213(1-3): 129-137.
ABSTRACT:
As a component of a lakewide mass balance study for Lake Michigan, we
measured total mercury (HgT) concentrations and fluxes in 11
selected tributaries.
Unfiltered HgT concentrations ranged from 0.56 ng l-1
at the Pere Marquette River to 182 ng l-1 at the Fox River.
Highest mean HgT concentrations were observed in the Fox R.,
Indiana Harbor Ship Canal, Grand R. and the Kalamazoo R. Mean
particulate matter HgT content ranged from about 0.1 to 1.5 mg
g-1, with highest levels from the industrialized basins of
the Indiana Harbor and Fox River. Highest tributary loading rates (g day-1)
were observed from the Fox, Grand, Kalamazoo and St. Joseph Rivers.
Increased loading rates during spring melt and summer/fall storm events
in these tributaries were generally associated with particulate loading
from either sediment resuspension or erosional processes. In contrast,
filtered HgT represented 80% of the HgT flux in
the Manistique R., whose watershed is comprised almost entirely of
wetlands and forest.
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Hurley,
J.P.; Shafer, M.M.; Cowell, S.E.; Overdier, J.T.; Hughes, P.E.; Armstrong,
D.E. 1996. Trace Metal Assessment of
Lake Michigan Tributaries Using Low Level Techniques. Environ. Sci. Technol. 30(6): 2093-2098.
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Madenjian,
C.P.; DeSorcie, T.J.; Stedman, R.M.; Brown, Jr., E.H.; Eck, G.W.; Schmidt,
L.J.; Hesselberg, R.J.; Chernyak, S.M.; Passino-Reader, D.R. 1999.
Spatial Patterns in PCB Concentrations of Lake Michigan Lake Trout. J.
Great Lakes Res. 25(1): 149-159.
ABSTRACT:
Most of the PCB body burden in lake trout (Salvelinus namaycush) of the
Great Lakes is from their food. PCB concentrations were determined in
lake trout from three different locations in Lake Michigan during
1994-1995, and lake trout diets were analyzed at all three locations.
The PCB concentrations were also determined in alewife (Alosa
pseudoharengus), rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi),
slimy sculpin (Cottus cognatus), and deepwater sculpin (Myoxocephalus
thompsoni), five species of prey fish eaten by lake trout in Lake
Michigan, at three nearshore sites in the lake. Despite the lack of
significant differences in PCB concentrations of alewife, rainbow smelt,
bloater, slimy sculpin, and deepwater sculpin from the southeastern
nearshore site near Saugatuck (Michigan) compared with the corresponding
PCB concentrations from the northwestern nearshore site near Sturgeon
Bay (Wisconsin), PCB concentrations in lake trout at Saugatuck were
significantly higher than those at Sturgeon Bay. The difference in the
lake trout PCB concentrations between Saugatuck and Sturgeon Bay could
be explained by diet differences. The diet of lake trout at Saugatuck
was more concentrated in PCBs than the diet of Sturgeon Bay lake trout,
and therefore lake trout at Saugatuck were more contaminated in PCBs
than Sturgeon Bay lake trout. These findings were useful in interpreting
the long-term monitoring series for contaminants in lake trout at both
Saugatuck and the Wisconsin side of the lake.
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Madenjian,
C.P.; Desorcie, T.J; Stedman, R.M. 1998a. Maturity
Schedules of Lake Trout in Lake Michigan. J. Great Lakes Res. 24(2): 404-410.
ABSTRACT:
We determined maturity schedules of male and female lake trout (Salvelinus
namaycush) in Lake Michigan from nearshore populations and from an
offshore population on Sheboygan Reef, which is located in midlake. Gill
nets and bottom trawls were used to catch lake trout in fall 1994 and
1995 from two nearshore sites and Sheboygan Reef. Each lake trout was
judged immature or mature, based on visual examination of gonads. Probit
analysis, coupled with relative potency testing, revealed that
age-at-maturity and length-at-maturity were similar at the two nearshore
sites, but that lake trout from the nearshore sites matured at a
significantly earlier age than lake trout from Sheboygan Reef. However,
length at maturity for the nearshore populations was nearly identical to
that for the offshore population, suggesting that rate of lake trout
maturation in Lake Michigan was governed by growth rather than age. Half
of the lake trout males reached maturity at a total length of 580 mm,
whereas half of the females were mature at a length of about 640 mm.
Over half of nearshore males were mature by age 5, and over half the
nearshore females matured by age 6. Due to a slower growth rate,
maturity was delayed by 2 years on Sheboygan Reef compared with the
nearshore populations. Documentation of this delay in maturation may be
useful in deciding stocking allocations for lake trout rehabilitation in
Lake Michigan.
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Madenjian,
C.P.; Desorcie, T.J.; Stedman, R.M. 1998b. Ontogenic
and Spatial Patterns in Diet and Growth of Lake Trout in Lake Michigan.
Trans. Amer. Fisher. Soc. 127:
236-252.
ABSTRACT:
Lake trout Salvelinus namaycush in
nearshore waters of Lake Michigan grow faster than lake trout residing
offshore on Sheboygan Reef, which is in midlake. We examined the
stomachs of lake trout, spanning ages 1 through 16, caught in both
nearshore and offshore environments of Lake Michigan during 1994 and
1995 to determine whether diet differences may be responsible for the
difference in growth rate. A comparison of the diets, coupled with
bioenergetics modeling, indicated that juvenile lake trout on Sheboygan
Reef experienced slow growth due to low food availability rather than to
cold water temperatures. The availability of appropriate-size prey
appeared to regulate lake trout growth. Small prey fish were probably
not readily available to small (200- to 399-mm total length) lake trout
on Sheboygan Reef, a substantial portion of whose diet consisted of
invertebrates; in contrast, nearshore juveniles had a nearly 100% fish
diet. Growth rate on the reef remained slow through intermediate lake
trout sizes (400-599mm total length), presumably due to low availability
of rainbow smelt Osmerus mordax on the reef. Once lake trout achieved total lengths
of approximately 600mm, they grew slightly faster on Sheboygan Reef than
near shore, indicating that large (>170-mm total length) prey fish
were readily available to lake trout in the reef area. On a wet-weight
basis, alewife Alosa
pseudoharengus dominated the diet of large ($600
mm total length) lake trout from both the nearshore and offshore regions
of the lake, although bloater Coregonus
hoyi composed over 30% of the diet on Sheboygan Reef and in
southeastern nearshore Lake Michigan. Size of alewife prey increased
with lake trout size. The bloater population currently represents the
bulk of the biomass of the adult prey fish community, so out diet
analysis suggests that large lake trout are continuing to select
alewives.
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Madenjian,
C.P.; Elliot, R.F.; Schmidt, L.J.; Desorcie, T.J.; Hesselberg, R.J.;
Quintal, R.T.; Begnoche, L.J.; Bouchard, P.M.; Holey, M.E. 1998. Net Trophic Transfer Efficiency of PCBs to Lake Michigan Coho Salmon
from Their Prey. Environ. Sci.
Technol. 32(20): 3063-3067.
ABSTRACT:
Most of the polychlorinated biphenyl (PCB) body burden accumulated by
coho salmon (Oncorhynchus kisutch)
from the Laurentian Great Lakes is from their food. We used diet
information, PCB determinations in both coho salmon and their prey, and
bioenergetics modeling to estimate the efficiency with which Lake
Michigan coho salmon retain PCBs from their food. Our estimate was the
most reliable estimate to date because (a) the coho salmon and prey fish
sampled during our study were sampled in spring, summer, and fall from
various locations throughout the lake, and (b) detailed measurements
were made on the PCB concentrations of both coho salmon and prey fish
over wide ranges in fish size, and (c) coho salmon diet was analyzed in
detail from April through November over a wide range of salmon size from
numerous locations throughout the lake. We estimated that coho salmon
from Lake Michigan retain 50% of the PCBs that are contained within
their food.
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Madenjian,
C.P.; Hesselberg, R.J.; Desorcie, T.J.; Schmidt, L.J.; Stedman, R.M.;
Quintal, R.T.; Begnoche, L.J.; Passino-Reader, D. 1998. Estimate of Net Trophic Transfer Efficiency of PCBs to Lake Michigan
Lake Trout from Their Prey. Environ.
Sci. Technol. 32(7): 886-891.
ABSTRACT:
Most of the polychlorinated biphenyl (PCB) body burden accumulated by
lake trout (Salvelinus namaycush)
from the Laurentian Great Lakes is from their food. We used diet
information, PCB determinations in both lake trout and their prey, and
bioenergetics modeling to estimate the efficiency with which Lake
Michigan lake trout retain PCBs from their food. Our estimates were the
most reliable estimates to date because (a) the lake trout and prey fish
sampled during our study were all from the same vicinity of the lake,
(b) detailed measurements were made on the PCB concentrations of both
lake trout and prey fish over wide ranges in fish size, and (c) lake
trout diet was analyzed in detail over a wide range of lake trout size.
Our estimates of net trophic transfer efficiency of PCBs to lake trout
from their prey ranged from 0.73 to 0.89 for lake trout between the ages
of 5 and 10 years old. There was no evidence of an upward or downward
trend in our estimates of net trophic transfer efficiency for lake trout
between the ages of 5 and 10 years old, and therefore the efficiency
appeared to be constant over the duration of the lake trout’s adult
life in the lake. On the basis of our estimates, lake trout retained 80%
of the PCBs that are contained within their food.
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Madenjian,
C.P.; O'Connor, D.V.; Nortrup, D.A. 2000. A
New Approach Toward Evaluation of Fish Bioenergetics Models. Can. J. Fish. Aquat. Sci. 57:
1025-1032.
ABSTRACT:
A new approach was used to evaluate the Wisconsin bioenergetics model
for lake trout (Salvelinus namaycush). Lake trout in laboratory
tanks were fed alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus
Mordax), prey typical of lake trout in Lake Michigan. Food
consumption and growth by lake trout during the experiment were
measured. Polychlorinated biphenyl (PCB) concentrations of the alewife
and rainbow smelt, as well as of the lake trout at the beginning and end
of the experiment, were determined. From these data, we calculated that
lake trout retained 81% of the PCBs contained within their food. In an
earlier study, application of the Wisconsin lake trout bioenergetics
model to growth and diet data for lake trout in Lake Michigan, in
conjunction with PCB data for lake trout and prey fish from Lake
Michigan, yielded an estimate of PCB assimilation efficiency from food
of 81%. This close agreement in the estimates of efficiency with which
lake trout retain PCBs from their food indicated that the bioenergetics
model was furnishing accurate predictions of food consumption by lake
trout in Lake Michigan.
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Madenjian,
C.P.; Schmidt, L.J.; Chernyak, S. M.; Elliott, R.F.; DeSorcie, T.J.;
Quintal, R.T.; Begnoche, L.J.; Hesselberg, R.J. 1999. Variation in Net Trophic Transfer Efficiencies among 21 PCB Congeners.
Environ. Sci. Technol. 33(21):
3768-3773.
ABSTRACT:
We tested the hypothesis that the efficiency with which fish retain
polychlorinated biphenyl (PCB) congeners from their food strongly
depends on Kow and degree of chlorination of the congener. We used
diet information, determinations of concentrations of individual PCB
congeners in both coho salmon (Oncorhynchus
kisutch) and their prey, and bioenergetics modeling to estimate the
efficiencies with which Lake Michigan coho salmon retain various PCB
congeners from their food. The retention efficiency for the tetrachloro
congeners averaged 38%, whereas retention efficiencies for higher
chlorinated congeners ranged from 43 to 56%. Not including tetrachloro
congeners, we found neither decreasing nor increasing trends in the
efficiencies with which the coho salmon retained the PCB congeners from
their food were either increasing Kow or increasing degree of chlorination of the PCB
congeners. We concluded that (a) for PCB congeners with 5-8 chlorine
atoms/molecule, Kow
and degree of chlorination had little influence on the efficiency with
which coho salmon retained tetrachloro PCB congeners in their food
appeared to be slightly lower than that for higher chlorinated PCB
congeners.
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Mason,
R.P.; Sullivan, K.A. 1997. Mercury
in Lake Michigan. Environ. Sci.
Technol. 31(3): 942-947.
INTRO:
Mercury contamination of aquatic systems is an important worldwide
health concern (1,2). Recent
research has demonstrated that many freshwater lakes in North America,
Europe, and Asia contain fish with elevated mercury (Hg) concentrations,
i.e., concentrations that exceed state, federal, or international health
guidelines (3-12). In the United States in the last decade, an ever-increasing
number of states have issues health advisories for freshwater fish
consumption, based primarily on the elevated Hg concentrations in
piscivorous fish (11). In
conjunction, the U.S. Environmental Protection Agency (EPA) has lowered
the reference dose for Hg in fish, based on EPA’s Integrated Risk
Information System, and many states in the United States-for example,
Minnesota (12)-have also
lowered the acceptable criteria for Hg in fish. These regulatory actions
have proven to be contentious (11)
and have led to a re-evaluation of the sources of Hg to U.S. waters and
the factors controlling Hg accumulation in fish, as there are
significant gaps in our knowledge of the sources of Hg to aquatic
systems and the role of atmospheric deposition and anthropogenic
emissions in providing “bioavailable “ Hg to aquatic systems (11-15).
A
number of studies, focused primarily of smaller lakes, have sought to
correlate elevated concentrations of mercury in fish with environmental
parameters (e.g., refs 7-10
and 15-17) and have
demonstrated the importance of anthropogenic inputs to the atmosphere in
contributing to mercury contamination of both nearby and remote
watersheds (13, 18). There is, however, little published data for Hg in Lake
Michigan and the other Great Lakes. A previous study of mercury and
other trace metals in the Great Lakes (19)
reported average total mercury concentrations ranging from 10 pM (2 ng/L)
for Lake Superior to 225 pM for Lake Michigan (data collected in
1980-1983). Our data, collected in 1994 and 1995 from offshore waters
(Figure 1) during the EPA-sponsored Lake Michigan Mass Balance Study (LMMB;
20), averaged 1.6 pM total Hg and are 2 orders of magnitude lower
than these earlier data for similar sites in Lake Michigan. The
concentration is more comparable to that of the open ocean (e.g., ref
21). Historical
contamination of samples likely accounts for the differences between our
values and previous data, as has been found in Lake Michigan for some of
the other trace metals, most obviously for lead (22). It has occurred even recently during the analysis of open ocean
waters for trace metals (23).
Other
recent measurements in Lake Michigan (24)
found values for mercury ranging from 5 to 50 pM at a station within 6
km of Chicago. These concentrations are elevated as compared to our
measurements, but this site likely receives enhanced inputs, both
fluvial and from the atmosphere, from Chicago. One of our sites,
approximately 20km offshore, did not however show any enhancement in
concentration as compared to sites more remote from urban influence (20).
Gill and Bruland (25) found
values of 4.5 and 18 pM for samples collected from the shores of Lake
Ontario and Lake Erie, respectively, somewhat elevated relative to the
open Lake Michigan water. A limited survey of Lake Superior found total
Hg concentrations around 5 pM. (26).
Studies
in the Great Lakes have generally focused on fish and the higher trophic
levels of the food chain (e.g., ref 27). The National Contaminant Biomonitoring Program (NCBP) has
measured total mercury concentrations in pooled samples of whole fish at
a number of sites in the Great Lakes between 1976 and 1984 (28), and there has been no significant decrease in fish
concentration over the study period. The concentrations of mercury in
bloater and perch (0.04-0.07 ppm wet weight) for the three Lake Michigan
sites are lower than those found in lake trout (0.2-0.22 ppm), likely
reflecting the food preferences of the different species. Fish Hg
concentration data for Lake Ontario collected between 1977 and 1988 (29)
are similar to those found by the NCBP.
We report here the results obtained during
the LMMB study. In addition to our charge under the project of measuring
total and particulate Hg in the water column, we were able to collect
and analyze invertebrate and fish samples for their total and
methylmercury (MMHg) concentration. Water samples were also analyzed for
MMHg. Here we present the overall data and discuss the bioaccumulation
of Hg in Lake Michigan organisms. Our water column data will be
discussed in further detail elsewhere (20).
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Miller, S.M. 1999. Spatial and Temporal Variability of Organic and Nutrient Compunds in
Atmospheric Media Collected During the Lake Michigan Mass Balance Study.
M.S. thesis. University of New York at Buffalo, Buffalo, New
York. 181 pp.
ABSTRACT:
As part of the Lake Michigan Mass Balance (LMMB) study, others obtained
atmospheric samples (gas, particulates, and precipitation) at sites on
the shore around the lake and at sites on the lake from April 1994 to
October 1995. Samples were later analyzed by others for a suite of
organic (PCBs, trans-Nonachlor, and Atrazine) and nutrient (Total
Phosphorus, Total Kjeldahl Nitrogen, and Nitrate) compounds. The
interpretation of these data is best summarized in terms of ten major
conclusions. All measures of quality (i.e., recovery of known mass,
analytical reproducibility, number and quality of blanks, and
replicates) exceed the standards set for the study. With respect to gas
exchange, SPCBs
are near chemical equilibrium, except near Chicago where the net flux is
into the lake and statistically greater than zero (~334 mg/yr
m2). Much more PCB mass (~2 to 54 mg/yr
m2 gross volatization and 65 to 334 mg/yr
m2 gross deposition) crosses the air-water interface through
gas exchange than through particulate deposition (~0.010 to 0.075 mg/yr
m2) or precipitation deposition (~0.002 to 0.090 mg/yr
m2). Much more Atrazine mass (~12 to 190 mg/yr
m2) crosses the air-water interface through precipitation
deposition than through gas exchange (~7 mg/yr
m2 net deposition) or particulate deposition
(~1 to 12 mg/yr
m2). Since gas Atrazine concentrations were near or below the
method detection limit and the detection limit was used gas flux
calculation, 7 mg/yr
m2 is the maximum deposition flux. Actual flux for gas
Atrazine is possibly lower. While the concentration of Total Phosphorus
in precipitation has decreased from 56 mg/L
in 1976 to 6.36 mg/L
in 1994-95, loading estimates have remained nearly the same (2.5x105
kg/yr in 1976 versus 2.9x105 kg/yr for 1994-95). This lower
than expected loading for 1976 is due to low average annual
precipitation amount and the method used.
Flux
calculations for gas exchange and particulate deposition yield
statistically similar results for samples collected at shoreline sites
and aboard the R/V Lake Guardian, meaning that there is no ship
effect when the yardarm sampler is used. There may be a ship effect
when the air sampler is located on the bow, an artifact that is
obvious during the LMMB 1994-95 field sampling effort; however, there
no evidence of it prior to or after that time. Estimation of annual
whole-lake fluxes requires an interpolation of data collected around
and over the lake. Averaging the the flux calculations from each of
the sampling sites does not introduce large errors except for gas PCBs
near Chicago. Use of data collected only from the Sleeping Bear Dunes
sampling site, the site used by the Integrated Atmospheric Deposition
Network since 1990, to describe chemical fluxes for the entire lake
will tend to underestimate fluxes. This is due, in part to observed
concentrations that are routinely lower at this site than at any of
the other seven shoreline and R/V Lake Guardian sites included
in the LMMB.
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Miller, S.M.; Sweet,
C.W.; DePinto, J.V.; Hornbuckle, K.C. 2000. Atrazine and Nutrients in Precipitation:
Results from the Lake Michigan Mass Balance Study. Environ.
Sci. Technol. 34(1): 55-61.
ABSTRACT: Atmospheric
deposition of anthropogenic air pollutants contributes to degradation of
water quality in the Great Lakes and other water bodies and is
indicative of atmospheric pollution. In this paper, we discuss
deposition of three air pollutants: atrazine; total phosphorus; and
nitrogen (total Kjeldahl nitrogen and nitrate) to Lake Michigan.
Throughout 18 months in 1994-1995, over 600 atmospheric samples (gas,
particulate, and precipitation combined) were collected and analyzed for
persistent organic pollutants and nutrients. Here the measurements and
modeled deposition estimates are presented for atrazine, phosphorus, and
nitrogen. Results indicate that concentrations of atrazine in
precipitation have remained constant over 5 years (0.10-0.40 mg
L-1), consistent with the nearly constant sales rate of the
herbicide over that time period. Actual loading of atrazine to the lake
was less in 1994-1995 (1.04 x 103 kg yr-1) than in
1990-1991 (2.6 x 103 kg yr-1 ). This difference in
loading is due to lower overall precipitation in 1994-1995. Phosphorus
concentrations in precipitation, on the other hand, have decreased from
an average of 57 mg
as P L-1 in 1976 to an average of 6.36 mg
as P L-1 for 1994-1995. Nitrate deposition has decreased by a
small, but not statistically significant, amount since the late 1970s.
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ABSTRACT:
Between 1994 and 1996, sediment samples were collected from 118 stations
in Lake Michigan. Samples were collected using both a box corer
and a PONAR grab sampler. Samples were collected for the purpose
of describing the current spatial variation of mercury in surficial
sediment and for comparing current concentrations and fluxes to historic
data. This work includes the first description of the spatial
variation of mercury fluxes to the lake's sediment. It also
provides a more recent description of the spatial distribution of
mercury concentrations within the lake's sediments. For the 118
sites sampled and analyzed, the surficial sediment mercury concentration
averaged 78 ng/g and ranged between 2 and 260 ng/g. Concentrations
were highest in depositional basins and exhibited a distribution that
conformed to the lake's bathymetry. The spatial distribution of
mercury fluxes did not conform to the bathymetry. Instead maximum
fluxes were shifted toward the southeastern shore. Fluxes to and
concentrations in surficial sediment of each depositional basin were not
significantly different from one another. Fluxes averaged 7.2 ng/cm2/y
and ranged between 0.85 and 32 ng/cm2/y. Regional
atmospheric fluxes account for roughly 50 percent of the total mercury
flux to surficial sediment.
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Rygwelski,
K.; Richardson, W.; Endicott, D. 1999. A
Screening-Level Model Evaluation of Atrazine in the Lake Michigan Basin.
J. Great Lakes Res. 25(1):
94-106.
ABSTRACT:
Atrazine, a widely used herbicide in the agricultural regions of the
Lake Michigan basin, was selected as a priority toxic chemical for study
in the United States Environmental Protection Agency (U.S.
EPA)-sponsored Lake Michigan Mass Balance Project. A surface-water,
screening-level model for atrazine in the Lake Michigan basin was
developed to obtain an initial insight into its transport behavior and
ultimate fate. Estimates of tributary loadings and atmospheric loadings
for model computations were made for the period-of-usage of the chemical
beginning in 1964. Most of these loading estimates were based on total
annual usage rates in the United States. Data from the literature were
used to estimate these historical loadings. Approximately 30% of the
total load of atrazine entering the lake is associated with
precipitation, and the remainder is from tributary loads. An unsteady
state, Water Quality Simulation Program (WASP) model based on the
principle of conservation of mass, was used to predict concentrations of
atrazine in Lake Michigan and Green Bay, Wisconsin. Model predictions
agree with recent field measured atrazine concentrations in the lake
when atrazine assumed to be conservative in the lake. The persistence of
atrazine predicted for Lake Michigan contrasts sharply with the
relatively short half-lives of the chemical measured on agricultural
fields as reported in the literature. It was estimated that if loadings
of atrazine were to continue into the future at a rate equivalent to
that of 1993, the lake would reach steady-state concentrations of 160 ng/L
in approximately 300 years.
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Shafer,
M.M.; Overdier, J.T.; Baldino, R.A.; Hurley, J.P.; and Hughes, P.E. 1995. Levels,
Partitioning, and Fluxes of Six Trace Elements in Lake Michigan
Tributaries. East Lansing, Michigan, International Association for
Great Lakes Research Conference: Programs and Abstracts, May 28 - June 1,
1995.
ABSTRACT:
Levels of arsenic, cadmium, chromium, copper, lead, and zinc in
filterable and particulate phases are measured, using validated trace
metal clean techniques, in eleven Lake Michigan tributaries, as a
component of the Lake Michigan Tributary Monitoring Program. The eleven
rivers drain watersheds which represent a wide range of surficial
geologies and land use, and one focus of our research will concern the
relationships between metal signatures and land use-land cover.
Preliminary data indicate that for many systems trace metals levels and
partition coefficients vary within relatively narrow characteristic
ranges, and that correlations with river discharge are poor. Principal
trace metal loading events over the 94 calendar year occurred during
summer and fall storms, not during the spring melt, with the Grand R.,
Kalamazoo R., and St. Joseph R. contributing the large majority of the
flux to the lake proper. Order-of-magnitude differences in metal levels
are seen between the study rivers, with the low end represented by the
Manistique, Muskegon, and Pere Marquette rivers, and high end by the
Fox, Kalamazoo, and Milwaukee rivers. Significant variations in KD are
also evident between study sites, however, partitioning relationships
between the metals are generally consistent, following the pattern Pb>
Zn > Cd > Cu > Cr > As.
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ABSTRACT:
Total and particulate mercury (Hg) concentrations were determined for
the water column of Lake Michigan as part of the EPA Lake Michigan Mass
Balance Project. Concentrations for total Hg averaged 1.60±0.25 pM
while the particulate was 0.60±0.18 pM (20¯50% of the total). Overall,
fluctuations in total Hg both spatially and vertically showed no
consistent trends, while particulate Hg may have been affected by
calcium carbonate precipitation in late summer and sediment resuspension
late in the season. Dissolved methylmercury (MMHg) concentrations ranged
from the detection limit (25 fM) to 210 fM and the particulate fraction
was from 5 fM (DL) to 45 fM (2% of total Hg). Dissolved gaseous Hg (DGHg)
concentrations during one cruise averaged 140±85 fM. Incubation
experiments suggest that biotic processes are primarily responsible for
elemental Hg production (2.6-6.5% per day) in Lake Michigan. Overall,
the cycling and speciation of Hg in Lake Michigan is more akin to that
of the open ocean, than smaller lakes in the mid-western USA.
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Swackhamer, D.L.;
Schottler, S.; Pearson, R.F. 1999. Air-Water Exchange and Mass Balance of Toxaphene in the
Great Lakes. Environ. Sci. Technol. 33(21):
3864-3872.
ABSTRACT:
This study determined the importance of air-water exchange of
toxaphene in the Great Lakes by comparing this flux to other inputs and
outputs in a mass balance model. Our overall goal was to test the
hypothesis that the current water concentrations of Lake Superior are
due to physical limnological differences between it and the lower Great
Lakes and secondarily to evaluate whether nonatmospheric inputs of
toxaphene have had an impact on current toxaphene burdens in lakes
Superior and Michigan. A series of water samples from the Great Lakes
were analyzed for toxaphene. A static mass budget is presented for lakes
Superior, Michigan, and Ontario. A dynamic model of toxaphene behavior
in lakes Superior and Michigan from 1950 to 1995 is then presented. The
results of this model support our hypothesis that the colder
temperatures and lower sedimentations rates in Lake Superior are
responsible for its high water concentrations of toxaphene to Lake
Superior. However, the model supports the conclusion that there were
nonatmospheric sources of toxaphene to Lake Michigan.
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