Factors Affecting Mercury Stable Isotopic Distribution in Piscivorous Fish of the Laurentian Great Lakes

• DOI: 10.1021/acs.est.7b06120
• Publication Date: 2018-02-15T05:10:21Z
• Authors: Ryan F. Lepak; Sarah E. Janssen; Runsheng Yin; David P. Krabbenhoft; Jacob M. Ogorek; John F. DeWild; Michael T. Tate; Thomas M. Holsen; James P. Hurley
• Keywords: Methylmercury; Mercury; Forage fish; Sedimentary organic matter; Mass-independent fractionation; Coregonus clupeaformis; Biogeochemical Cycle

Identifying the sources of methylmercury (MeHg) and tracing transformations mercury (Hg) in aquatic food web are important components effective strategies for managing current legacy Hg sources. In our previous work, we measured stable isotopes (δ202Hg, Δ199Hg, Δ200Hg) Laurentian Great Lakes estimated source contributions to bottom sediment. Here, identify isotopically distinct signatures trout (Salvelinus namaycush) walleye (Sander vitreus), driven by both food-web water-quality characteristics. Fish contain high values odd-isotope mass independent fractionation (MIF) with averages ranging from 2.50 (western Lake Erie) 6.18‰ (Lake Superior) Δ199Hg. The large range odd-MIF reflects variability depth euphotic zone, where is most likely incorporated into web. Even-isotope MIF (Δ200Hg), a potential tracer precipitation, appears disconnected lake sedimentary comparable fish among five lakes. We suggest that similar open ocean, water-column methylation also occurs Lakes, possibly transforming recently deposited atmospheric deposition. conclude degree photochemical processing controlled phytoplankton uptake rather than dissolved organic carbon quantity