title: Mercury and methylmercury stream concentrations in a Coastal Plain watershed: a multi-scale simulation analysis.
abstract: Mercury is a ubiquitous global environmental toxicant responsible for most US fish advisories. Processes governing mercury concentrations in rivers and streams are not well understood, particularly at multiple spatial scales. We investigate how insights gained from reach-scale mercury data and model simulations can be applied at broader watershed scales using a spatially and temporally explicit watershed hydrology and biogeochemical cycling model, VELMA. We simulate fate and transport using reach-scale (0.1 km(2)) study data and evaluate applications to multiple watershed scales. Reach-scale VELMA parameterization was applied to two nested sub-watersheds (28 km(2) and 25 km(2)) and the encompassing watershed (79 km(2)). Results demonstrate that simulated flow and total mercury concentrations compare reasonably to observations at different scales, but simulated methylmercury concentrations are out-of-phase with observations. These findings suggest that intricacies of methylmercury biogeochemical cycling and transport are under-represented in VELMA and underscore the complexity of simulating mercury fate and transport.
authors: US Environmental Protection Agency, Office of Research and Development, Ecosystems Research Division, Athens, GA 30324, USA. Electronic address: Knightes.Chris@epa.gov.
authors: C D
authors: CD
authors: Knightes
authors: US Environmental Protection Agency, Office of Research and Development, Ecological Exposure Research Division, Cincinnati, OH, USA.
authors: H E
authors: HE
authors: Golden
authors: US Geological Survey, South Carolina Water Science Center, Columbia, SC, USA.
authors: C A
authors: CA
authors: Journey
authors: US Environmental Protection Agency, Office of Research and Development, Ecosystems Research Division, Athens, GA 30324, USA.
authors: G M
authors: GM
authors: Davis
authors: US Geological Survey, South Carolina Water Science Center, Columbia, SC, USA.
authors: P A
authors: PA
authors: Conrads
authors: US Geological Survey, Menlo Park, CA, USA.
authors: M
authors: M
authors: Marvin-DiPasquale
authors: US Geological Survey, Mounds View, MN, USA.
authors: M E
authors: ME
authors: Brigham
authors: US Geological Survey, South Carolina Water Science Center, Columbia, SC, USA.
authors: P M
authors: PM
authors: Bradley
mesh_terms: D004777:Environment; D004784:Environmental Monitoring / Q000379:methods*; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D008956:Models, Chemical; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D014881:Water Supply / Q000706:statistics & numerical data
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Exposure; Mercury; Modeling; Scale; Watershed