Degradation of organic matter

In the removal of contaminating ions such as (PO or Fe " a precipitate such as Ca2(P0 2 Fe(OH)2, after oxidizing ferrous ion to ferric, is formed and the soHd is removed. The addition of surfactants is usually not essential (nor desirable) since most waters contain natural surfactants that would render the soflds sufficiently hydrophobic for flotation to occur. Such surfactants derive from the degradation of organic matter, and humic substances abundantly available in nature (30). 

Fig. 5.7. In green sulfur bacteria and in some archaebacteria, a reverse citric acid cycle is used for the assimilation of C02. It must be assumed that this was the original function of the citric acid cycle that only secondarily took over the role as a dissimulatory and oxidative process for the degradation of organic matter. A major enzyme here is 2-oxoglutarate ferredoxin for C02 fixation. Note that it, like several other enzymes in the cycle, uses Fe/S proteins. One is the initial so-called complex I which has eight different Fe/S centres of different kinds but no haem (see also other early electron-transfer chains, e.g. in hydrogenases).

Molecular hydrogen is an important intermediate in the degradation of organic matter by microorganisms in anoxic habitats such as freshwater and marine sediments, wet land soils, and the gastrointestinal tract of animals. In these particular conditions H2 is produced during fermentation of carbohydrates, lipids, nucleic acids, and proteins by anaerobic bacteria and,... 

A mixture of hydrogen peroxide and ferrous iron is effective for color and COD removal of dye effluent, which is effective for complete color removal and partial degradation of organic matter. 

The pE-range 2 is representative of many ground and soil waters where 02 has been consumed (by degradation of organic matter), but SO is not yet reduced. In this range soluble Fe(II) and Mn(II) are present their concentration is redox-buffered because of the presence of solid Fe(III) and Mn(IIUV) oxides. 

In anoxic environments with low amounts of sulfate or usable Fe(III), the microbial degradation of organic matter occurs via a complex network of trophic links that collectively terminate in the production of methane... 

Moore-Colyer, M.J.S., Hyslop, J.J., Longland, A.C. and Cuddeford, D. (1997b) The degradation of organic matter and crude protein of four botanically diverse feed-stuffs in the foregut of ponies as measured by the mobile bag technique. In Proceedings of the British Society of Animal Science, Scarborough, p. 120. 

One may hypothesize that the mobilization and accumulation of Mn we observed during stratification was linked to the degradation of organic matter. The degradation rate reaches a maximum in the bathylimnion during summer, as indicated by the sharp increase in conductivity. This process facilitates the release of Mn under suboxic, rather than anoxic, conditions, and is consistent with the incubation experiments reported here. 

Keppler F, Eiden R, Niedan V, Pracht J, Scholer HF (2000) Halocarbons Produced by Natural Oxidation Processes During Degradation of Organic Matter. Nature 403 298... 

Chrost, R. J., U. Munster, H. Rai, D. Albrecht, P. K. Witzel, and J. Overbeck. 1989. Photosynthetic production and exoenzymatic degradation of organic matter in the euphoric zone of a eutrophic lake. Journal of Plankton Research 11 223-242. 

Boetius, A., and K. Lochte. 1994. Regulation of microbial enzymatic degradation of organic matter in deep-sea sediments. Marine Ecology Progress Series 104 299—307. 

As previously mentioned, the primary processes responsible for variations in the deep sea C02-carbonic acid system are oxidative degradation of organic matter, dissolution of calcium carbonate, the chemistry of source waters and oceanic circulation patterns. Temperature and salinity variations in deep seawaters are small and of secondary importance compared to the major variations in pressure with depth. Our primary interest is in how these processes influence the saturation state of seawater and, consequently, the accumulation of CaC03 in deep sea sediments. Variations of alkalinity in deep sea waters are relatively small and contribute little to differences in the saturation state of deep seawater. 

Burrows, and transport of solute in them, may contribute to dissolution by enhancing oxic degradation of organic matter near the burrow walls. However, the situation is complex, and depending on factors such as the type of burrow wall produced, cementation rather than dissolution of carbonates may be promoted. Aller s observation that the best carbonate preservation takes place in the most physically disturbed and biologically underdeveloped environments points to the need for studies of continental shelf and slope environments where carbonate dissolution could be even more intense than that observed at the sites studied in Long Island Sound. 

Studies such as those of Berger and Soutar (1970) and Sholkovitz (1973) also point to the importance of chemical parameters in controlling calcium carbonate preservation. These authors noted that carbonate preservation is substantially greater in the sulfidic Santa Barbara basin sediments than in adjacent slope sediments that are overlain by oxic waters. This observation probably results from the fact that oxic degradation of organic matter and oxidation of sulfides are not likely to occur in this anoxic basin. 

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