Selenium & compounds: Sources of emissions
Industry sources
Selenium compounds are released to the air and water in flue gas and fly ash during the combustion of coal and petroleum fuels (e.g. in coal-fired power stations), during the smelting and refining of metals such as copper, lead and zinc, from glass and ceramics manufacturing, and from refuse incinerators. It also accumulates in the residues from sulphuric acid manufacture.
Diffuse sources, and industry sources included in diffuse emissions data
Selenium can enter waterways through use of some anti-dandruff shampoos. Application as fungicides and insecticides may contribute to elevated selenium levels in the environment. Electronic and photographic waste, and photocopying accessories may be other contributors if improperly disposed of. Cigarette smoke may be another source of selenium in air.
Natural sources
Selenium is a naturally occurring element, widely but unevenly distributed in the earth's crust and commonly found in sedimentary rock formations. However, there are no true deposits of selenium from which selenium can be directly and economically recovered. Selenium usually occurs combined with other compounds in the environment, such as in sulfide ores of other metals (silver, copper, lead, and nickel). Soils in the neighbourhood of volcanos tend to have enriched amounts of selenium. It occurs in water as a result of natural weathering of soils and rocks. Selenium is enriched in coal.
Transport sources
Emissions may result from burning petrol in cars.
Consumer products
Anti-dandruff shampoos, home entertainment equipment, photographic equipment.
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