HR: 1340h
AN: H53A-1201    [Abstracts]
TI: Selenium Speciation, Solubility, and Mobility in Agricultural Evaporation Ponds in California
AU: * Ryu, J
EM: jiryu@ucdavis.edu
AF: Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
AU: Gao, S
EM: sgao@fresno.ars.usda.gov
AF: USDA-ARS, SJVASC-Water Management Research Lab, 9611 S. Riverbend Avenue, Parlier, CA 93648
AU: Tanji, K K
EM: kktanji@ucdavis.edu
AF: Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
AU: Alemdar, C
EM: calemdar@ucdavis.edu
AF: Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
AU: Dahlgren, R A
EM: radahlgren@ucdavis.edu
AF: Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
AB: Constructed evaporation ponds are an important and economic disposal option for subsurface drainage water to sustain irrigated agriculture in the southern portion of the San Joaquin Valley of California. The trace element of most concern in disposing of agricultural drainage water is selenium due to its potential toxicity in the aquatic food chain of evaporation ponds. We investigated selenium biogeochemistry at the Tulare Lake Drainage District's South Evaporation Basin consisting of ten ponds covering a surface area of 7.26 km$^{2}$. The ten ponds represented a wide range of water salinity due to its evapoconcentration sequence. Aqueous selenium speciation was determined for both inorganic species (Se(VI) and Se(IV)) and organic species (org-Se) at representative sites in the ponds. Total selenium concentration was determined in sediments at different depths. The redox environment affecting selenium speciation in the evaporation ponds was evaluated. To understand biological activity and its potential effect on selenium accumulation and speciation in the evaporation ponds, we determined organic carbon, nutrients (N and P), chlorophyll-a, and water temperature. The results from this study have important implications for understanding selenium behavior in natural and managed environments such as evaporation basins, playas and wetlands.
DE: 1842 Irrigation
DE: 1065 Trace elements (3670)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting