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Grosse Ile, MI, United States

Pauer J.J.,ICF International | Anstead A.M.,ICF International | Melendez W.,Large Lakes Research Station | Taunt K.W.,United Road Services | Kreis R.G.,U.S. Environmental Protection Agency
Journal of Great Lakes Research

LM3-Eutro is a high-resolution eutrophication model with several improved features lacking in historical Great Lakes models. We calibrated LM3-Eutro using a 2-year (1994-1995) dataset and performed a hindcast simulation from 1976 to 1995 to evaluate the model's ability to make predictions over an extended period of time. Results show a reasonable agreement between model output and field data over this time period. The model predicted that an annual loading of 5600metric tons (MT) would result in a lake-wide annual total phosphorus (TP) concentration of 7.5μg L -1. Using best estimates of future TP loadings, LM3-Eutro forecasts suggest that Lake Michigan will remain oligotrophic and will continue to meet the 7μg L -1 spring TP concentration Great Lakes Water Quality Agreement objective. © 2010 International Association for Great Lakes Research. Source

Rossmann R.,Large Lakes Research Station | Pfeiffer E.L.,Z Technology Corporation | Filkins J.C.,U.S. Environmental Protection Agency | Filkins J.C.,Large Lakes and Rivers Forecasting Research Branch
Journal of Great Lakes Research

Dated sediment box cores collected in 1994-1996 from 52 locations in Lake Michigan were analyzed to assess storage, trends, and loading history of lead. The results of this study provide information of historic lead loads to the lake for a time period (pre-1960) for which no reliable lead measurements exist. The information can be utilized by those wishing to model lead and to access lead loading trends. Anthropogenic lead storage in the lake's sediments totaled 143,000 t as of 1994. Storage of acid-extractable total (anthropogenic + background) lead totaled 171,000. t between 1850 and 1994. The date of 1850 is the time at which lead loads increased above background loads (219 t/y) to the lake. Anthropogenic loads peaked between 1959 and 1962 at 2440 t/y and were 1170 t/y between 1994 and 1995, illustrating that at the time of collection in 1994, loads were decreasing from previous highs. The load in 1994 to 1995 was equivalent to the load during the time frame of 1922 to 1925. Largest lead loads were to southeastern Lake Michigan in a region downwind of Chicago, illustrating the impact of large populated areas utilizing coal and gasoline on lead loads to the lake. Loading trends were impacted by coal and gasoline consumption, increased industrial activity during World War II, the Clean Air Act of 1970, and the phase-out of leaded gasoline. © 2014 International Association for Great Lakes Research. Source

Rutherford E.S.,National Oceanic and Atmospheric Administration | Allison J.,Pennsylvania Fish and Boat Commission | Ruetz C.R.,Grand Valley State University | Elliott J.R.,National Oceanic and Atmospheric Administration | And 5 more authors.
Transactions of the American Fisheries Society

Abstract: The Walleye Sander vitreus is an important sport fish that has experienced low reproductive success in some Great Lakes tributaries since severe population declines began in the late 1940s. In the Muskegon River, a Lake Michigan tributary, natural reproduction of Walleyes remains low and is largely supplemented by stocking. We evaluated the influence of abiotic factors on Walleye reproductive success in the Muskegon River during April and May 2009 and 2010 by (1) estimating Walleye egg density and survival; (2) estimating the size, density, abundance, and survival of Walleye larvae; and (3) relating our estimates to physical habitat conditions. Egg densities were 70-fold higher in 2009 than in 2010, but eggs experienced colder water temperatures, higher river discharge rates, and lower survival in 2009 relative to 2010. Egg survival in incubators was positively related to temperature and negatively related to flow at most sites. In both years, Walleye larvae that hatched during periods of cooler temperature were smaller than larvae that hatched later during periods of warmer temperature. Walleye larval densities were highest near spawning grounds and decreased downstream. Bayesian estimates of variability in larval densities indicated that temporal variability was twice as high as spatial variability in the Muskegon River. Larval survival was much lower in 2009 than in 2010, resulting in an approximately sevenfold higher production of larvae in 2010 than in 2009. Survival was highest for smaller larvae that hatched early in April 2010, when temperatures were warm and discharges were low and stable; in contrast, survival was much lower for larger larvae hatching later in 2010 or for large and small larvae in 2009, when water temperatures were colder and discharges were higher and more variable. Our results suggest that abiotic factors, primarily temperature and river flow, likely control the early survival of Walleyes in the Muskegon River. Received February 9, 2015; accepted January 11, 2016 Published online April 19, 2016 © 2016, © American Fisheries Society 2016. Source

Zhang X.,Trinity Engineering Associates Inc. | Rygwelski K.R.,U.S. Environmental Protection Agency | Rowe M.D.,U.S. Environmental Protection Agency | Rowe M.D.,University of Michigan | And 2 more authors.
Journal of Great Lakes Research

The Lake Michigan mercury mass balance model, LM2-Mercury, which was calibrated to a comprehensive data set collected from Lake Michigan during 1994-1995, was applied to predict long-term total mercury concentrations in lake water for different mercury loading and air concentration scenarios. The model predictions (volume-weighted, lakewide average total mercury concentrations) appear to be comparable to the available independent measurements from 2005 through 2013. The forecast based on the constant condition scenario, where conditions representative of 1994-1995 were held constant, shows that total mercury concentrations in the lake are near steady-state. The model was used to investigate the relative importance of different global versus regional impact scenarios on total mercury concentrations in Lake Michigan. The results suggest that mercury from global sources could contribute between 30% and 70% of total mercury water concentrations in Lake Michigan. Results for declining global emission scenarios modeled, based on both high and low global contribution estimates and information on mercury emission trends from current observations and the literature, indicate that total mercury concentrations in the water column in Lake Michigan will continue to decrease. © 2015 . Source

Zhang X.,Inc Large Lakes Research Station | Rygwelski K.R.,U.S. Environmental Protection Agency | Kreis R.G.,U.S. Environmental Protection Agency | Rossmann R.,Large Lakes Research Station
Journal of Great Lakes Research

LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended and resuspendable solids (TSRS), dissolved organic carbon (DOC), and total, elemental, divalent, and methylmercury as state variables. Simplified processes among the mercury state variables including net methylation, net reduction of divalent mercury, and reductive demethylation are incorporated in the model. Volatilization of elemental mercury as a kinetic (phase transfer) process and partitioning of total, divalent, and methylmercury as a set of instantaneous equilibrium processes were also simulated. The model was calibrated to data collected in 1994 and 1995 and corroborated by comparing model output generated from a long-term model hindcast to total mercury measured in high quality sediment profiles. Model hindcast predictions of total mercury in the water column were within estimates of total mercury calculated from observed lake trout bioaccumulation factors. Using the model, a mass budget assessment of mercury cycling in the lake was conducted. Atmospheric deposition, including wet and dry (particle) deposition and absorption of gaseous divalent mercury, was the dominant source of total mercury to the lake, followed by sediment resuspension, and then tributary loads. The major loss mechanism of total mercury from the water was associated with the settling of solids, followed by net volatilization. Methylmercury loading associated with wet deposition was the dominant source to the lake, followed by tributary loadings, and in situ net methylation. © 2014. Source

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