ABSTRACT
Ecotoxicological impacts of selenium (Se) resulting from environmental discharge of agricultural drainage water in California’s San Joaquin Valley are well docu mented (Ohlendorf et al., 1986; Presser and Ohlendorf, 1987). The source of the contamination is Se-rich soils, which are more extensive than originally believed and are now known to occur within several states in the western United States (Fujii et al., 1988; National Research Council, 1989; Presser et al., 1994). The major form of Se in the drainwater is selenate (Se042-, Se6+), with lesser amounts of selenite (S e0 32-, Se4+), both of which are soluble, toxic, and able to bioaccumulate (Presser and Ohlendorf, 1987; Weres et al., 1989). Accordingly, research is ongoing to study ways of removing Se oxyanions from agricultural drainage water. Although much has been learned, the goal of finding practical, cost-effective technology for treating Se-contaminated water has not yet been accomplished. Discovering a means for Se removal is fundamental to minimizing environmental contamination and ensuring wildlife protection in this region. An integrated, multiphased approach to the problem will most likely prove necessary.
