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Modeling Mercury Exposure at Different Scales in the McTier Creek Watershed and Edisto River Basin, SC USA
Citation:
Knightes, C., H. Golden, P. Bradley, G. Davis, C. Journey, AND P. Conrads. Modeling Mercury Exposure at Different Scales in the McTier Creek Watershed and Edisto River Basin, SC USA. Presented at 8th National Monitoring Conference, Portland, OR, April 30 - May 04, 2012.
Impact/Purpose:
Presentation for National Monitoring Conference – Water: One Resource – Shared Effort – Common Future in Portland, OR
Description:
Mercury is the toxicant responsible for the largest number of fish advisories across the United States, with 1.25 million miles of rivers under advisory. The processes governing fate, transport, and transformation of mercury in lotic ecosystems are not well-understood, in large part because these systems are intimately linked with their surrounding watersheds. To understand the mercury exposure concentrations within streams and rivers, mercury fate and transport within the watershed must be understood and linked to the in-stream fate and transport processes. However, current advancements in the science of watershed Hg processing typically develop at distinct spatial scales and lack an understanding of linkages between Hg fate and transport of mercury at three different scales: a focused reach study (0.11 km2), a watershed scale (79 km2) and a basin scale (7,071 km2). These three systems were represented by linking a watershed hydrology and biogeochemical cycling (Hg, N and C) model (VELMA, Visualizing Ecosystems for Land Management Assessment) with a surface water mercury fate and transport model (WASP 7, Water Quality analysis Simulation Program). Both the watershed and water body models simulate three mercury species (Hg(0), Hg(II), and MeHg) and hydrology. The focused reach study used VELMA to parameterize and understand the processes governing Hg fate and transport, tracking mercury deposition and precipitation on the land surface, Hg transformation reactions and loss processes, and subsequent transport to the receiving stream. The process understanding and parameterization of the fucus study were then applied at the watershed-scale to understand and represent mercury fate and transport by modeling individual sub-watersheds and linking them using WASP 7. This work was then further expanded to simulate mercury fate and transport at the basin scale, where state and national management strategies, such as TMDLs and emissions regulations, are applied.
