Spatial and Temporal Variation in the Isotopic Composition of Mercury in the South River, Va.
Speaker: Spencer Washburn (University of Michigan)
As a toxic trace metal with a complex biogeochemical cycle, mercury (Hg) has been the subject of extensive study. Anthropogenic activity has altered the cycling of Hg in the biosphere on a global scale, and locally at industrial sites where Hg discharges to surface waters often lead to biomagnification in aquatic food webs. Measurement of Hg stable isotope ratios in environmental samples represents an excellent tool for gaining insights into the complex biogeochemical cycling of Hg in aquatic ecosystems systems, particularly those impacted by contamination. At the South River (Waynesboro, Virginia), historic point source Hg inputs from industrial processes ended many decades ago, but sediment and surface water Hg concentrations remain highly elevated relative to regional background. To better understand Hg cycling within this complex fluvial ecosystem, we have analyzed THg concentrations and Hg stable isotope compositions of a number of physical reservoirs of Hg within the South River. By improving understanding of the spatial and temporal variations in Hg isotopic composition, this work aims to provide insights into the processes that control Hg sources, mobility, and fate in the South River.
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