Selenium natural resources

Lewis LN. 1989. Preface. In Tanji KK, Valoppi L, Woodring RC, eds. Selenium contents in animal and human food crops grown in California. CA Cooperative Extension University of California, Division of Agriculture and Natural Resources. Publication 3330. 

NCDNR. 1986. North Carolina water quality standards documentation The freshwater chemistry and toxicity of selenium with an emphasis on its effects in North Carolina. North Carolina Department of Natural Resources and Community Development Division of Environmental Management, Water Quality Section. Water Quality Technical Reports. Report No. 86-02. 

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

Abstract Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments in the universe. The common sources of Se in earth crust occurs in association with sulfide minerals as metal selenide whereas, it is rarely seen in elemental form (Se°). Furthermore, Se is considered a finite and non-renewable resource on earth, and has been found to be an essential element for humans, animals, micro-organisms and some other eukaryotes but as yet its essentiality to plants is in dispute. Thus, plauts vary considerably in their physiological and... 

This chapter has outlined the main effects of arsenic and selenium on human and animal health, their abundance and distribution in the environment, sampling and analysis, and the main factors controlling speciation and cycling. Such information should help to identify aquifers, water resources and soils at risk from high concentrations of arsenic and selenium, and areas of selenium deficiency. Human activity has had, and is likely to continue to have, a major role in releasing arsenic and selenium from the geosphere and in perturbing the natural distribution of these and other elements over the Earth s surface. 

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