Marine Sedimentary Environments

Kniewald, G. and Branica, M. (1988) Role of uranium (V) in marine sedimentary environments a geochemical possibility. Mar. Chem., 24, 1-12. 

The conversion of opal-CT to quartz has been studied experimentally with conflicting results. Mizutani (1966) concluded that the reaction takes place through a solution-reprecipitation mechanism. Ernst and Calvert (1969) concluded that the mechanism is by solid-solid conversion. In a re-evaluation of the data presented by Ernst and Calvert (1969), Stein and Kirkpatrick (1976) concluded that the evidence more closely supports a solution-reprecipitation mechanism. At present, it is unclear which of these two processes, if either, dominates in the marine sedimentary environment. 

The losses of magnesium and phytol through the combined effects of cellular senescence and predation (i.e. aerobic heterotrophy) in the water column lead to pheophytin-a and pheophorbide-a becoming the primary chlorophyll-a derivatives deposited in marine sedimentary environments. Though it is not known at present, the heterotrophic processes which cleave phytol more than likely also affect the 10-carbomethoxy group. Studies are underway to investigate the amounts of pyro-pheophorbides in water column detritus and surface sediments. 

Van Kranendonk, M.J., Webb, G.E., and Kamber, B.S., 2003. Geological and trace element evidence for a marine sedimentary environment of deposition and biogenicity of 3.45 Ga stromatolitic carbonates in the Pilbara Craton and support for a reducing Archaean ocean. Geobiology, 1, 91-108. 

Ellis, C. W. (1962). Marine sedimentary environments in the vicinity of the Norwalk islands, Connecticut. Bull. No. 94, State Geol. and Natural Hist. Survey of Connecticut. 

Sulfate reduction is the principal pathway of sulfide formation in marine sedimentary environments. 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Bioavailability from Environmental Media. No information on the presence of 3,3 -dichloro-benzidine in foods was located in the available literature. The Canadian Government s Priority Substances List Assessment Report for 3,3 -dichlorobenzidine (Government of Canada 1993) also reports that no data on the levels of 3,3 -dichlorobenzidine in drinking water or foodstuffs were identified within either Canada or the United States. Because 3,3 -dichlorobenzidine has been found to bind strongly to soil constituents (Berry and Boyd 1985 Chung and Boyd 1987), Law (1995) concluded that it would also bind strongly to sedimentary material in the marine aquatic environment and thus may have limited bioavailability. 

Luther III, G. W., J. E. Kostka, T. M. Church, B. Sulzberger, and W. Stumm. 1992. Seasonal iron cycling in the salt-marsh sedimentary environment the importance of ligand complexes with Fell and Felll in the dissolution of Felll minerals and pyrite, respectively. Marine Chem. 40 81-103. 

Sellwood B. W. (1986) Shallow marine carbonate environments. In Sedimentary Environments and Facies (ed. H. G. Reading). Blackwell, UK, chap. 10, pp. 283-342. 

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. 

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