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Modeling Sediment-Water Interactions and Biogeochemical Reactive Contaminant Transport of Mercury Species in Riverine System

Author(s): Arash Massoudieh; Fabian A. Bombardelli; Timothy R. Ginn

Linked Author(s): Fabian Bombardelli

Keywords: Mercury fate and transport; Sediments; Methylation; Biogeochemistry

Abstract: Sediments play a major role in fate and transport of heavy metals with high affinity to solid particles such as mercury in water bodies. Sediment-associated mercury can be released gradually due to diffusive processes, or may be re-entrained in the watercolumn as a result of high flows or anthropogenic activities. In addition biotic and abiotic geochemical transformations in the bed sediments control both the mobility and toxicity of mercury in the water. Therefore to quantify the fate and transport of mercury in water bodies, various processes ranging from hydrodynamic and sediment transport to biogeochemical transformation of contaminants in the sediments need to be considered. In the research being presented, an integrated water column-benthic sediment, multi-scale, multi-component biogeochemical reactive transport model is presented, with description of both theory and numerical implementation. The model includes aqueous water column, suspended sediment, aqueous bed porewater, and sediment bed phases, with associated contaminant transformation and transport, as well as sediment resuspension, deposition and burial. The sediment bed domain is modeled using a set of vertical one-dimensional sub-models which take into account burial and compaction as well as diffusive-reactive transport of solutes. Reactions include speciation, sorption/desorption, and microbially-mediated multiple terminal-electron accepting processes as kinetically-controlled redox reactions. Applications of this multiscale modeling strategy to mercury transport and transformations in water bodies in California is also presented.


Year: 2009

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