ABSTRACT
Selenium (Se) pollution of soil and water is a major environmental problem in many areas of the world. High concentrations of Se occur naturally in some soils, especially those derived from Cretaceous shale parent materials. In well-aerated alkaline soils, oxidized forms of Se are easily mobilized into solution. With the irrigation of crops, Se concentrations in the agricultural drainage waters may reach hazardous levels. Other anthropogenic activities also lead to Se pollution of water. Selenium contamination of coastal waters is a major problem in areas close to oil refineries, which release substantial amounts of Se in their wastewater discharge. Electric utilities’ aqueous discharges, which result from the storage of coal and other by-products (e.g., coal pile runoff, coal pile seepage, coal ash landfill discharges) present other significant sources of environmental Se pollu tion. Unfortunately, the few available technologies for wastewater treatment (e.g., chemical, microbiological, or electrochemical treatments) are not cost-effective in many cases and produce a large amount of unwanted by-product in the form of hazardous waste that must be shipped to a toxic landfill.
