Isotopic Characterization of Mercury Downstream of Historic Industrial Contamination in the South River, Virginia

Historic point source mercury (Hg) contamination from industrial processes on the South River (Waynesboro, Virginia) ended decades ago, but elevated Hg concentrations persist in the river system. In an effort to better understand Hg sources, mobility, and transport in the South River, we analyzed total Hg (THg) concentrations and Hg stable isotope compositions of streambed sediments, stream bank soils, suspended particles, and filtered surface waters. Samples were collected along a longitudinal transect of the South River, starting upstream of the historic Hg contamination point-source and extending downstream to the confluence with the South Fork Shenandoah River. Analysis of the THg concentration and Hg isotopic composition of these environmental samples indicates that the regional background Hg source is isotopically distinct in both Δ199Hg and δ202Hg from Hg derived from the original source of contamination, allowing the tracing of contamination-sourced Hg throughout the study reach. Three distinct en...