Sulphate freshwater

Shukla, J.P. and K. Pandey. 1986b. Effect of a sublethal concentration of zinc sulphate on the growth rate of fingerlings of Channa punctata (Bloch), a freshwater murrel. Acta Hydrochim. Hydrobiol. 14 677-680. 

Holmer M. and Storkholm P. (2001) Sulphate reduction and sulphur cycling in lake sediments a review. Freshwater Biol. 46, 431-451. 

Skyring, G.W. and Chambers, L.A., 1976. Biological sulphate reduction of carbonate sediments of a coral reef. Aust. J. Mar. Freshwater Res., 27 595—602. 

In contrast, in shallow reservoirs bacterial sulfate reduction may occur with degradation of the crude oil (Bailey et al., 1973). The sulphate reducers may not be able to use petroleum per se but only with the participation of petroleum-oxidizing aerobes, transported by freshwater recharge, to provide suitable carbon sources for the sulfate-reducers (see Chapter 6.1). 

Methanogenesis important process in freshwater wetlands, waterlogged soils and in deeply buried low-sulphate marine sediments 2CH20 - CH4 + C02 -58... 

The addition of UV-absorbing organic matter was also discussed to match the presence of humic acids. An attempt to add humic acids to the samples failed, owing to a decomposition of these acids during autoclave sterilisation. It was hence decided to add lauryl sulphate as a compromise for matching the presence of these acids, as was successfully performed for the certification of nitrate in artificial freshwater [5]. The short-term stability study demonstrated that the samples remained stable under the conditions tested. 

Eogenetic magnesite cement in sandstones is relatively rare because its formation requires pore waters to be enriched in Mg " " and depleted in Ca " ", S04 and Cl". These conditions may occur in arid climates in which marine pore waters evaporate and become successively saturated with respect to calcium carbonates, calcium sulphates and halite, such as in sabkha settings (Kinsman, 1969 Morad et al., 1995). Continental brines enriched in Mg + are also suitable for the formation of eogenetic magnesite due to the low sulphate and chloride ion concentrations. Most recent magnesite cements form in the fine-grained sediments of alkaline/saline lakes (Last, 1992 Warren, 1990) and, less commonly, in freshwater lacustrine sediments (Zachmann, 1989). 

This concept of sulphur fractionation in soils has been successfully applied to sewage sludge (Sommers et al., 1977) and to freshwater and marine derived peat-forming systems (Cas ande et al., 1977). In the marine peat, carbon-bonded sulphiu" accounted for 50% of total sulphur while ester sulphate constituted only ca. 25%. These authors noted an overall increase in sulphur in going from plant samples to peat in the marine environment, and concluded that plants were not the dominant sulphur-concentrating mechanism. The sulphur was probably delivered to a large extent by sulphate diffusion and microbial reduction, whereby carbon-bonded sulphur acted as a sink for sulphur in the peat. 

Pore-water concentration profiles of redox-sensitive ions (nitrate, Mn, Fe, sulphate and sulphide) and nutrients (ammonium and phosphate) demonstrate the effects of degradation of OM. In freshwater sediments, the redox zones generally occur on a millimetre to centimetre scale due to the high input of reactive OM and the relatively low availability of external oxidators, especially nitrate and sulphate, compared to marine systems. A typical feature for organic-rich freshwater sediments deposited in aerobic surface waters, is the presence of anaerobic conditions close to the sediment-water interface (SWI). This is indicated by the absence of dissolved oxygen and the presence of reduced solutes (e.g. Mn, Fe and sulphides) in the pore water. Secondary redox reactions, like oxidation of reduced pore-water and solid-phase constituents, and other postdepositional processes, like precipitation-dissolution... 

Respiratory sulphate reduction ideally takes place when all other electron acceptors are exhausted, but significant overlap may occur between the zones of microbial Fe(III) reduction and sulphate reduction due to kinetic constraints, as discussed before. Sulphate concentrations typically decrease to zero within the upper sediment layer (Fig. 1). In freshwater sediments, reduced S formed mainly by reduction of pore-water sulphate, is predominantly present as inorganic S in the form of AVS. Although pyrite is the most stable sulphide mineral, its formation in permanently submerged freshwater sediments is subject to controversy (Rickard et al., 1995). Because, contrary to marine sediments (S-dominated), there is an excess of Fe liberation over HS production in freshwater sediments (Fe-dominated), FeC03 as well as FeS may control pore-water Fe concentrations in the anoxic sediment layer. 

Thus, pore water studies provide evidence that some trace elements (As, Co, Cr) become more soluble on redox dissolution of Mn-Fe oxides in marine and sediments. However, these studies have failed to detect a parallel release of trace elements (other than Co) with Fe and Mn during redox events (Sakata, 1985 Morfett et al., 1988 Achterberg et al., 1997). It appears that in spite of the loss of labile organic matter and oxides of Fe and Mn, the trace elements remain relatively immobile. In oceanic or estuarine sediments it has been proposed that sulphides have a role to play in fixing the trace elements under reducing conditions. This has also been demonstrated in sulphate-rich freshwater systems (Huerta-Diaz et al., 1998). However, Cu and Pb, at least, clearly remain firmly attached to freshwater sediment even in the absence of measurable sulphides, and where Mn and Fe are being actively released via reduction (Sakata, 1985). 

E. Ilhan-Sungur, N. Cansever, A. Cotuk. Microbial corrosion of galvanized steel by a freshwater strain of sulphate reducing bacteria (Desulfovibrio sp.). Corrosion Science, Vol. 49, No. 3, pp. 1097-1109,... 

Ilhan-sungur E, Cansever N, Cotuk A (2007) Microbial Corrosion of Galvanized Steel by a Freshwater Strain of Sulphate Reducing Bacteria Desulfovibrio sp.). Corrosion Scimce, vol. 49, no. 3, pp. 1097-1109, March 2007... 

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