ABSTRACT
The abundance of sulfur in the Earth’s crust has been reported to be ∼520 ppm by Goldschmidt (1954) and 880 ppm by Wedepohl (1984). It is thus one of the more common elements in the biosphere. Its concentration (as total sulfur) in rocks, including igneous and sedimentary rocks, can range from 270 to 2400 ppm (Bowen, 1979). The average total sulfur concentrations in freshwater and seawater are ∼3.7 and 905 ppm, respectively (Bowen, 1979). In eld soils in humid, temperate regions, the total sulfur concentration may range from 100 to 1500 ppm, of which 50-500 ppm is soluble in weak acid or water (Lawton, 1955). Most of the sulfur in soil of pastureland in humid to semiarid climates is organic, whereas that in drier soils is contained in gypsum (CaSO4 · 2H2O), epsomite (MgSO4· 7H2O), and in lesser amounts in sphalerite (ZnSO4), chalcopyrite (CuFeS2), and pyrite or marcasite (FeS2) (Freney, 1967).
