ABSTRACT
In the mid-1980s, great concern arose regarding the ecological consequences and potential human health impact associated with selenium derived from agricultural drainage on the west side of the San Joaquin Valley, California. Groundwater contamination was one of the key issues, both because humans and livestock might drink the water, and because the water is an important pathway for contaminant transport within the San Joaquin Valley ecosystem. Over the past decade, much has been learned about the behavior of selenium in the San Joaquin Valley (also known as the Central Valley), including its geologic origins and transport pathways (Presser, 1994), the distribution and mobility of selenium in groundwater (Deverel and Fujii, 1988; Deverel and Millard, 1988), the important oxidation-reduction controls on selenium mobility (Dubrovsky et al., 1991; White and Dubrovsky, 1994), microbial transformations of selenium (Karlson and Frankenberger, 1988; Oremland, 1994; Zawislanski et al., 1996), and its behavior in soils and groundwater at Kesterson Reservoir (Long et al., 1990; White et al., 1991; Tokunaga et al., 1991).
