Organic sediments

Binder, C. R. "Electron Spin Resonance Its Application to the Study of Thermal and Natural Histories of Organic Sediments", Ph.D. Thesis, Pennsylvania State University, 1965,... 

Toxicity in estuarine sediments—use of Mutatox and Microtox to evalu- 173 ate the acute toxicity and genotoxicity of organic sediments Toxicity tests for the analysis of pore water sediment a comparison of 4 174... 

For instance, 2-methylpropene reacted with acetic acid at 18°C in the presence of Al-bentonite to form the ester product (75). Ion-exchanged bentonites are also efficient catalysts for formation of ketals from aldehydes or ketones. Cyclohexanone reacted with methanol in the presence of Al-bentonite at room temperature to give 33% yield of dimethyl ketal after 30 min of reaction time. On addition of the same clay to the mixture of cyclohexanone and trimethyl orthoformate at room-temperature, the exothermic reaction caused the liquid to boil and resulted in an almost quantitative yield of the dimethyl ketal in 5 min. When Na- instead of Al-bentonite is used, the same reaction did not take place (75). Solomon and Hawthorne (37) suggest that elimination reactions may have been involved in the geochemical transformation of lipid and other organic sediments into petroleum deposits. 

Stable radicals were formed during diagenesis of the organic sediment, and they have persisted ever since. The detailed mechanism of enzymatic reactions is not well understood, but it is known that stable free radicals can be produced. Steelink (18) has found that humic acids from soils, peats, and lignites have moderately high concentrations of free radicals, and since the... 

The range of fusinites studied here is relatively small, being restricted to samples from thick fusain lenses in bituminous coals of Carboniferous age taken from two coal basins in the northern hemisphere. The present data, therefore, do not justify any general statement about the origin of fusinites. It can be stated, however, that the properties noted for the fusinites studied are consistent with the view that they were subjected to some kind of pyrolysis to perhaps 400-600°C. before incorporation in the organic sediment. 

HgCl2 in the presence of estuarine sediments showed distinct seasonal variation, whose rhythm apparently relates to the seasonal ability of the microorganisms to carry out biomethylation (755, 156). The ability of different river sediments to perform biomethylation depended markedly on the nature of the sediments (157, 158) thus, organic sediments reacted appreciably faster than coarse sand. Activated sludge will methylate inorganic mercury compounds under both sterile and nonsterile conditions, suggesting the presence of both biotic and abiotic pathways (159). 

In a more recent, alternate theory, Thomas Gold (Cornell University) suggests tii.il. in contrast with the organic sediments theory, tire prime source of natural gas is primordial, abiotic methane rising from deep within the earth s mantle. This is discussed in further detail in tile article on Natural Gas. 

Estuarine A term used to describe structures, organisms, sediments, and other features associated with estuaries. 

Flue gas desulfurization The injection of calcium or other sorbents to remove sulfur from flue gases. Fluorescent probe A chemical that can produce light when being acted upon by a source of energy. Fluvial A term used to describe structures, organisms, sediments, and other features associated with rivers. 

Nitrogen supplies in water bodies are replenished due to the bacterial decomposition of organic sediments and dissolved organic matter. Let us consider component D as the content of dead organic matter in water. On such a basis, we can write Hf = DD [Pg.239]

Gagne, F., Pardos, M., Blaise, C., Turcotte, P., Quemerais, B. and Fouquet, A. (1999b) Toxicity evaluation of organic sediment extracts resolved by size exclusion chromatography using rainbow trout hepatocytes, Chemosphere 39(9), 1545-1570. 

Aller, R.C., Aller, J.Y., and Kemp, P.F. (2001) Effects of particle and solute transport on rates and extent of remineralization in bioturbated sediments. In Organism-Sediment Interactions (Aller, J.Y., Woodin, S.A., and Aller, R.C., eds.), pp. 315-334, University of South Carolina Press, Columbia, SC. 

Habicht, K.S., and Canfield, D.E. (1997) Sulfur isotope fractionation during bacterial sulfate reduction in organic sediments. Geochim. Cosmochim. Acta 24, 5351-5361. 

Rhoads, D.C. (1974) Organism-sediment relations on the muddy sea floor. Oceanogr. Mar. Biol. Annu. Rev. 12, 263-300. 

Organic sediments are those that result from the activities of living things. The most common of these are the carbonate rocks, limestone and dolomite, which are largely composed of calcium carbonate and calcium magnesium... 

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