Sedimentary organic compounds

Hayes, J.M. 1993 Factors controlling contents of sedimentary organic compounds Principles and evidence. Marine Geology 113 111-125. 

Hayes JM (1993) Eactors controlling C contents of sedimentary organic compounds principles and evidence. Afar GeoZ 113 111-125. 

Valuable contributions were made by two Canadian agencies, particularly by the National Research Council Canada (NRCC) who, from about 1976, provided marine and marine biological CRMs certified for metals, metal species and organic constituents (Berman 1984 Willie 1997). More recently their Halifax laboratories have issued a highly respected range of CRMs for the determination of shellfish toxins. Another Canadian producer, the National Water Research Institute (NWRI) specialized in marine (water and sedimentary) CRMs, and from the late 1980 s their matrix materials certified also for organic compounds (Chau et al. 1979 Lee and Chau 1987). 

Inorganic and organic compounds are often present in the environment in complex forms. Levels of contaminating metals and molecules are variable, depending on the natural conditions and anthropogenic activities. The contaminants may be airborne as vapour, droplets or dust particles, and in the soil in aqueous or particulate forms. In the case of aqueous systems, they can exist as emulsions, as dissolved ions or molecules and as suspended or sedimentary particles. Environmental particles have been reviewed in the first two volumes of this series [1,2]. 

Because the vast majority of the sedimentary organic compounds are not amenable to direct study by current analytical techniques, organic geochemists rely on operational approaches to characterize them, such as measuring the %OC, %ON, OC/ON ratio and humin content. Other strategies include molecular analysis of the small fraction of sedimentary organic compounds that are detectable. Some of these compounds make... 

Hites RA, Lopez-Avila V. 1980. Sedimentary accumulation of industrial organic compounds discharged into a river system. In Baker Ra, ed. Contaminants and sediments. Vo1. 1. Fate and transport case studies, modeling, toxicity. Ann Arbor, Ml Ann Arbor Sci., 53-66. 

The mixture of sedimentary organic compounds, as a whole, is not in thermodynamic equilibrium. This does not preclude the participation of many metastable but long-lived compounds in reversible equilibria. A typical case is acetic acid as a thermodynamically unstable compound it should disproportionate ... 

Gagosian, R.B., Nigrelli, G.E., and Volkman, J.K. (1983) Vertical transport and transformation of biogenic organic compounds from sediment trap experiment off the coast of Peru. In Coastal Upwelling Its Sediment Record. Part A. Response of the Sedimentary Regime to Present Coastal Upwelling (Suess, E., and Thiede, J., eds.), pp. 241-272, Plenum Press, New York. 

In recent years some data have been obtained on the content of organic compounds (hydrocarbons, carbohydrates, paraffins and aromatic compounds, alcohols, etc.) in Precambrian sedimentary rocks, including the rocks of the cherty iron-formations. 

When thermal volcanic waters react with aerated surface waters, the appearance of ferric iron colloids is quite permissible. However, there are no organic compounds of fulvic acid t)q)e in volcanic waters and only colloidal silica could act as a stabilizer. At the same time there often is sulfur in thermal solutions, the stable form of which in the presence of free oxygen is the S04 ion—the main coagulant of colloidal iron. For this reason the possibilities of colloidal transport of iron from volcanic sources to sedimentary basins are limited. A high COj content in the hydrosphere and atmosphere does not exert a stabilizing effect on Fe(OH)3 colloids. 

By virtue of where, when, and how the various organic matter inputs were formed and transported to the underlying sediments, it is possible to exploit specific chemical and isotopic characteristics to make inferences about the sources and composition of sedimentary organic matter. Much of this information is inaccessible at the bulk level. For example, bulk elemental compositions and stable carbon isotopic compositions are often insufficiently unique to distinguish and quantify sedimentary inputs. Abundances and distributions of source-specific organic compounds ( biomarkers ) can help to identify specific inputs. However, this molecular marker approach suffers from the fact that the source diagnostic marker compounds are... 

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