This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. On the west side of the San Joaquin Valley in California, agricultural irrigation water leaches selenate and salts from the highly seleniferous soil. The safe disposal of huge volumes of salt-laden, Se-contaminated agricultural drainage water is one of the most serious problems confronting agriculture in California, and other western states in the USA. Reutilization of this water would be of great benefit, especially because water for crop production is in such limited supply. Thus, in an approach referred to as 'integrated on-farm drainage management', the water is recycled through progressively more salt-tolerant crops and the small volume remaining collected in a solar evaporation pond. This method maximizes the use of the water. In another approach, the use of constructed wetlands has been proposed to remove Se from drainage water that is eventually disposed into evaporation ponds. In both approaches Se may build up to potentially toxic levels in the ecosystem. In order to evaluate the ecotoxicity of Se we need to accurately determine the chemical forms of Se present in the environment and their concentrations, rather than simply measuring total Se concentration. This is because some forms of Se (e.g., selenocysteine) are far more toxic than others (e.g., elemental Se). Therefore, a thorough evaluation of the potential toxicity of Se requires the systematic determination of both the amounts and chemical speciation of Se in different compartments of the ecosystem. In this study, we will combine XAS experiments with HPLC and HPLC-ICP-MS methods to speciate both inorganic and organic forms of Se. This work will provide the most complete Se speciation of Se-contaminated ecosystems to date, and will benefit researchers who are designing solutions for the safe disposal of Se-contaminated agricultural drainage water, and to regulators who must develop informed policy with respect to controlling and minimizing Se ecotoxicity.
Showing the most recent 10 out of 604 publications
