Mineralization sulfur cycle

With the many compounds of sulfur found in the atmosphere, in aquatic environments, and in soils and minerals, sulfur cycles through the biosphere in much the same way that nitrogen does. However, unlike the relative abundances of nitrogen—for which the atmosphere is the major reservoir—the relative abundance of sulfur in the atmosphere is small compared with its abundance in other environments. 

Another major process at the Earth s surface not involving rapid exchange is the chemical weathering of rocks and dissolution of exposed minerals. In some instances the key weathering reactant is H30 in rainwater (often associated with the atmospheric sulfur cycle), while in other cases H30" comes from high concentrations of CO2, e.g., in vegetated soils. 

Godfrey JD (1962) The deuterium content of hydrous minerals from the East Central Sierra Nevada and Yosemite National Park. Geochim Cosmochim Acta 26 1215-1245 Goericke R, Fry B (1994) Variations of marine plankton 6 C with latitude, temperature and dissolved CO2 in the world ocean. Global Geochem Cycles 8 85-90 Goldhaber MB, Kaplan IR (1974) The sedimentary sulfur cycle. In Goldberg EB (ed) The sea, vol. 4. WUey, New York... 

Gharacterization of inorganic sulfur speci-ation in marine and freshwater porewaters is critical to our understanding of metal and sulfur cycling in sediments. Since coprecipitation and/or adsorption on FeS(g) and formation of discrete authigenic sulfide minerals can effectively remove trace metals, many metal cycling studies are... 

Heterotrophic respiration fueled by the rain of organic matter from the surface ocean is ubiquitous in marine sediments. Its rate determines one of the important characteristics of the sedimentary environment the depth of redox horizons below the sediment-water interface. Heterotrophic respiration is the process by which carbon and nutrients are returned to the water column it is important in the marine fixed nitrogen and sulfur cycles and the accumulation of metabolic products sets the conditions for the removal of phosphorus from the oceans in authigenic minerals. A great deal of effort has been directed toward quantifying the rates, pathways, and effects of metabolism in sediments. 

Krouse H. R. and McCready R. G. L. (1979b) Reductive reactions in the sulfur cycle. In Biogeochemical Cycling of Mineral-forming Elements (eds. P. A. Trudinger and D. J. Swaine). Elsevier, Amsterdam, pp. 315—358. 

Truper H. G. (1982) Microbial process in the sulfur cycle through time. In Mineral Deposits and the Evolution of the Biosphere (eds. S. H. Holland and M. Schidlowski). Springer, Berlin, pp. 5-30. 

The potential use of sulfur isotope abundances in identifying reductive processes and the origin of sulfide minerals is discussed in Chapter 6.2. Although the majority of laboratory experiments have been carried out with reducing bacteria, there have been a sufficient number of studies with other bacteria to indicate that stable isotopes can play a role in elucidating the whole sulfur cycle. Indeed attempts have been made to use isotopic and mass balances to estimate global sulfur shifts with time (Holser and Kaplan, 1966). 

Hence the Archaean sulfur cycle (Fig. 5.5) would comprise inputs into the atmosphere and oceans from volcanic gases and into the oceans from hydrothermal activity but not river-borne sulfate. In addition, in the anoxic oceans, the oxidative alteration of the ocean floor would not take place. Thus the surface sulfur reservoir would have been small and most sulfur recycled back into the mantle as sulfide minerals. The sulfate part of the sulfur cycle is unlikely to have been fully operational until the late Proterozoic (Canfield, 2004). 

Fig. 2.28 The biogeochemical sulfur cycle. A burial (formation of sediments), B assimilation (bacterial sulfate reduction), C aerobic oxidation, D deposition, E emission, M mineralization, P plant assimilation, O oxidation.

---