HR: 1340h
AN: H53A-1202    [Abstracts]
TI: Characterization of Selenium Pollution in the Western United States by Coupling Soil Moisture with Geochemical Transport
AU: * Zhao, M
EM: zhao@berkeley.edu
AF: Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States
AU: Liang, X
EM: liang@ce.berkeley.edu
AF: Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States
AU: Guo, J
EM: jzhguo@berkeley.edu
AF: Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States
AB: Due to the arid conditions of the Western United States, selenium released from sandstone and shale hillslopes is transported by overland runoff and is shown to cause fish and aquatic bird death and reproductive failure. Precipitation in contact with exposed seleniferous soils, carry dissolved and particulate forms of selenium in runoff and groundwater to the valley floor to be redistributed throughout the hillslope and alluvial fan. Impervious clay soils and the arid climate impede the flushing of selenium below the groundwater table so that selenium is continually cycled in the alluvial fan. A physically based model that couples hydrologic land surface interactions and geochemical transport based on soil moisture was developed to characterize the loading, transport, and distribution of selenium. The soil moisture distribution and overland flow patterns determined by the hydrologic model for the watershed are factors that control soil chemical movement and transformation. The main geochemical and physical transport mechanisms of selenite and selenate, dissolution from soil, speciation, adsorption, advection, and mass transfer from pore water to overland form, are characterized as functions of surface flow and the soil moisture of the fifteen centimeter deep soil layer for each model grid. The movement of overland flow within each grid is routed to the outlet of the watershed. Flow patterns and measured selenium concentrations at two sites; the Panoche/ Silver Creek watershed in Central California, and the Leach Creek watershed in Colorado, are compared to model results. Selenium pollution characterization at a watershed scale will add to the understanding of the cycling of selenium within and across watersheds and aid in the mitigation of selenium pollution.
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 1871 Surface water quality
DE: 1065 Trace elements (3670)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting