HR: 09:30h
AN: B31A-05    [Abstracts]
TI: Differential Solubilization of As and Se in a Drained and Urbanized Wetland
AU: * Moller, J S
EM: moller.jennifer@epa.gov
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521 United States
AU: Meixner, T
EM: tmeixner@hwr.arizona.edu
AF: University of Arizona, Department of Hydrology & Water Resources, Tucson, AZ 85721 United States
AU: Hibbs, B
AF: California State University, Los Angeles, Department of Geological Sciences, Los Angeles, CA 90032 United States
AU: Amrhein, C
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521 United States
AU: Walker, J
AF: California State University, Los Angeles, Department of Geological Sciences, Los Angeles, CA 90032 United States
AU: Zhang, Y
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521 United States
AB: There is concern over elevated As and Se in surface and ground waters of the arid western United States due to their detrimental impacts on wildlife and human health. While much research has examined trace element mobility on a catchment scale, this project provides a specific case study of the hydrologic regime and groundwater biogeochemistry of a catchment bearing the effects of urbanization. Land use changes paired with the draining of a large historic swamp in the central area of the San Diego Creek - Newport Bay catchment have caused mobilization of As and Se which had accumulated in the former wetland. Major and trace ion geochemical analysis was completed on groundwater and soil samples from the catchment. Results indicate that arsenic and selenium had accumulated within the historic swamp region. Also, the data suggest that two areas, one more - and the other less - regularly inundated, impact the spatial distribution of groundwater As and Se concentrations. Though previous data suggests metal sulfide oxidation as the source of contemporary As and Se concentrations in groundwater, the highest concentrations of As and Se could not be associated with a metal sulfide oxidation mechanism. Additionally, As and Se concentrations, though spatially correlated, are not mechanistically linked. The data indicate competitive ligand exchange between As and Si and the flushing of vadose zone Se as the key processes solubilizing these trace elements. Furthermore, because wetland biogeochemistry is a reflection of certain hydrologic conditions that may be difficult to ever duplicate, wetland mitigation strategies need to incorporate trace element biogeochemistry into their design. This research was conducted while the primary author was at the University of California, Riverside from 2002-2004. The author is now an employee of the United States Environmental Protection Agency.
DE: 0400 Biogeosciences
DE: 1045 Low-temperature geochemistry
DE: 1065 Trace elements (3670)
DE: 1829 Groundwater hydrology
SC: Biogeosciences [B]
MN: 2005 Joint Assembly