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Joel C Hoffman

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This data release includes mercury concentrations and mercury stable isotope measurements measured in sediments and biological tissues collected from the Saint Louis River located in Minnesota. Sediments and biota were collected by the U.S. Geological Survey, U.S. Environmental Protection Agency, U.S. Army Corps of Engineers, and federal contractors (Battelle) from 2017-2021. Collection regions included nearshore zones within the main estuary, remedial sites within the lower river, and upstream reservoir sites. Sediments were analyzed for total mercury, methylmercury, and mercury stable isotopes by the U.S. Geological Survey Mercury Research Laboratory (MRL, Madison, Wisconsin). Biological samples were analyzed...
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Under the Great Lakes Restoration Initiative, the U.S. Geological Survey Mercury Research Lab (USGS MRL) conducted a multiyear assessment of mercury across the Laurentian Great Lakes. Biannual sampling was conducted across all five lakes onboard the U.S. Environmental Protection Agency (US EPA) research vessel Lake Guardian (in years 2010–2014, 2018) at pelagic sampling locations established by the long-term US EPA Great Lakes monitoring program. In addition to the regularly scheduled biannual sampling, in September 2013 and 2014 Lake Michigan and Lake Erie (respectively) were sampled with increased focus on shallow nearshore locations. Throughout these sampling efforts, sediments, mussels, surface water, and plankton...
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The St Louis River (SLR) is the second largest tributary to Lake Superior and a designated area of concern (AOC) due to past industrial contamination of organic chemicals and heavy metals, including mercury (Hg). Sediments, prey items (odonates, mixed benthic invertebrates, and spiders), and game fish were targeted within this study to determine if industrial sources of Hg were bioaccumulating into the food web. Samples from SLR were directly compared to a reference site in the Bad River, WI to assess if legacy contamination resulted in elevated Hg concentrations in comparisons to background regions with no known point sources. Carbon and nitrogen isotopes were also employed as food web tracers to determine if dietary...
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