sulphur

Symbol: S. A nonmetallic solid yellow element, atomic number 16, atomic weight 32.06. It is essential to growth, being found in the amino acids cystine and methionine, in the iron-sulphur proteins, e.g. ferredoxin, which are important in electron transport, and in *coenzyme A. Sulphur is also found in various secondary metabolites, e.g. the mustard-oil glycosides. Sulphur is absorbed from soil as the sulphate (S0₄^2-) ion. Various nitrogen and potassium fertilizers are applied as sulphates and sulphur deficiency is not commonly a problem.
Sulphur is used to control various pathogens and pests (see sulphur dust , dithiocarbamate fungicide ). Sulphur dioxide, a by-product of many industrial processes, is an important atmospheric pollutant (see also acid rain ).