Sulfur, Elemental

CAS RN:7704-34-9

Exposure Summary

Sulfur accounts for 15% of the inner core of the earth and 0.052% of its crust. The total sulfur content of the earth is estimated to be about 18.2X10+15 tons. The world is rich in large and highly pure deposits of elemental sulfur from which commercial sulfur can be mined. Sulfur minerals include gypsum, epsomite, miralulite, pyrite and marcasite, sphalerite, chalcopyrite, cobaltitle, pyrrhalite, galena, arsenopyrite, and pentlandite. Elemental sulfur occurs in salt domes, volcanic deposits and some deposits of calcite, gypsum, and anhydrite. In every state, whether gas, liquid, or solid, elemental sulfur occurs in more than one allotropic form. Three are relevant in nature: -2 (sulfhydryl and sulfide), 0 (elemental sulfur), and +6 (sulfate). The global sulfur cycle involves an atmospheric flux of about (140-350)X10+6 tons/annum, with (40-60)X10+6 tons as anthropogenic sulfur, in the form of sulfur dioxide, sulfuric acid, and sulfate. The rest ((100-290)X10+6 tonns/annum) involves biological decay, sea spray, and volcanism. However, the increasing acid precipitation from industrial stack emissions has seriously disturbed the natural sulfur cycle. Sulfur also paricipates in microbial cycles. Numerous microorganisms and plants use sulfate as their sole source of sulfur, converting it to organic sulfhydryl compounds in the oxidation state of -2. Many microorganisms, mainly Thiobacillus sp., can produce sulfide which under aerobic conditions is oxidized to sulfur and sulfate either spontaneously or through biochemical processes. (SRC)
Find more information on this substance at: Hazardous Substances Data Bank , TOXNET , PubMed