ABSTRACT
Selenium (Se) is a metalloid having properties of both metals and non-metals. It is closely associated, chemically and biogeochemically, with sulfur. Selenium is an important element in the biosphere; it is essential in humans and animals. Production of Selenium is mainly concentrated in Europe, Japan and Russia; global reserves of Selenium total 0.1 Mt. Selenium is mainly used in glass-making, either as a pink-red colorant, to decrease solar glare or, in smaller amounts, as a clarifying agent. Selenium is present in sewage sludge, but concentrations in treated soils, and the plants growing in them, are generally lower than some other metals and metalloids. Selenium concentrations in various amphibian, reptile and mammal species in and around fly-ash landfills and ash settling ponds are elevated compared with control sites. Selenium bioaccumulates in aquatic plants and invertebrates and biomagnifies in food chains causing toxic effects at higher trophic levels in fish and piscivorous birds.
