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Mercury bioaccumulation assessment for the St. Louis River Area of Concern (poster)
Janssen, S., G. Hanson, Greg Peterson, J. DeWild, J. Ogorek, R. Lepak, M. Tate, N. Johnson, A. White, B. Monson, D. Krabbenhoft, AND J. Hoffman. Mercury bioaccumulation assessment for the St. Louis River Area of Concern (poster). Great Lakes Area of Concern Conference, Sheboygan, WI, May 15 - 16, 2018.
Sediment remediation sites commonly contain high levels of mercury. Associating related exposure, bioaccumulation, and effect often is confounded by atmospheric and other regional sources of mercury. We applied a new tracer of mercury source (mercury isotopic composition) to assess mercury related sources with respect to bioaccumulation in a Great Lakes Area of Concern, and demonstrate its utility for identifying where legacy mercury from contaminated sediments is the dominant source of bioavailable of mercury.
Elevated mercury concentrations have been documented in fish and invertebrates within the St. Louis River Area of Concern (AOC). Mercury bioavailability is affected by multiple factors, including mercury sources, sediment and water geochemistry, food web structure, individual fish growth and movement, and watershed character. These factors vary both spatially and seasonally in the St. Louis River, and confound mercury assessment. However, a novel assessment approach, particularly an approach that is ecosystem-based and which incorporates mercury stable isotope composition, may be able to evaluate influential factors and source-specific bioaccumulation. Our goal was to use the combined information of mercury concentration and stable isotope composition from water, sediment, and biota samples to perform a comprehensive mercury assessment for Beneficial Use Impairment 1 (Fish Consumption Advisories) within the St. Louis River AOC and Bad River (reference).