ABSTRACT
Sulfur (S) is one of the Earth's most abundant elements and, although most is concentrated in the planet's interior, the lithosphere is the major environmental reservoir. The sulfur content of coal can be up 5%; it is present in both the organic matter which formed the coal and within incorporated sulfide minerals, particularly pyrite. Sulfur is an essential element and is found in all living organisms as a constituent of two amino acids, cysteine and methionine. Sulfur exists in several oxidation states and undergoes transformations between these states in the natural environment. Sulfur dioxide is used as a food preservative and in the production of sulfuric acid, the world's most heavily produced industrial chemical. Sulfur dioxide emissions from motor vehicles have decreased in most countries as a result of the widespread introduction of low sulfur petrol in recent times levels of sulfur in fuels are still high in some areas, particularly Africa.
