Sulfur isotopes inverse

McCready, R.G.L., Laishley, E.J. and Krouse, H.R., 1976. Biogeochemical implications of inverse sulfur isotope effects during reduction of sulfur compounds by Clostridium pasteurianum. Geochim. Cosmochim. Acta, 40 979—981. 

Fractionation also occurs during processes in the oxidative part of the sulfur cycle. Sulfide oxidation, which is pervasive in marine enviromnents (for example, 90% or more of the sulfide produced during sulfate reduction in coastal sediments are reoxidized) includes various processes, which are all associated with inverse isotope fractionation effects. These processes include the phototrophic oxidation by a variety of anoxygenic bacteria (-2 to 0%o), the non-phototrophic oxydation (up to -18%o), and the already mentioned disproportionation of sulfur compounds with intermediate oxidation states as... 

---