What happens to selenium released into the environment?
The various forms of selenium behave differently in the environment. Heavy metal selenides, selenium sulphides, selenites, and selenates all vary in solubility (that is, their ability to dissolve in water). Selenates (salts containing one Se atom and four atoms of oxygen) are among the most mobile Se compounds due to their high solubility and inability to cling onto soil particles. Thus, they are readily taken up by microorganisms in the soil or leached through the soil. Selenites (salts containing one Se atom and three atoms of oxygen) are less soluble than selenates. Elemental Se is common in some soils, but does not dissolve much in water and therefore is not likely to be taken up by living organisms. While both selenates and selenites are accumulated by terrestrial plants, selenates are more readily taken up from the soil because of their greater solubility. Elemental selenium, organic, and inorganic forms of selenium may be chemically transformed by soil microorganisms into a vapo
