Selenium, Elemental

CAS RN:7782-49-2

Environmental Fate

AQUATIC FATE: In aqueous solution, selenium forms oxyanions and exhibits anionic chemistry(1). Volatilization of the ionic forms of selenium is not expected to be an important fate process(SRC). Speciation of selenium is determined by the pH and redox potential of the solution; elemental selenium is favored by low pH and reducing conditions(1). At pHs <7 and under mildly reducing conditions, selenites are reduced to elemental selenium(1). Reducing conditions in surface sediments of ponded laboratory sediment columns promoted reduction of soluble Se(VI) to soluble Se(IV) to insoluble Se(0), allowing a net accumulation of insoluble elemental selenium(2). In sediments, reduced and tightly bound selenium will remain relatively immobile unless the sediments are chemically or biologically oxidized(3).
ATMOSPHERIC FATE: Hydrogen selenide released to the air is unstable and will be oxidized to elemental selenium and water. Selenium dioxide released to the air from the combustion of fossil fuels is expected to be reduced to elemental selenium by sulfur dioxide formed during the combustion(1).
Find more information on this substance at: Hazardous Substances Data Bank , TOXNET , PubMed