Biogenic materials

Biogenic Ma.teria.ls, Deep ocean calcareous or siUceous oo2es are sediments containing >30% of biogenic material. Foraminifera, the skeletal remains of calcareous plankton, are found extensively in deep equatorial waters above the calcium carbonate compensation depth of 4000 to 5000 m. 

In general, single molecule encapsulation techniques could provide integrated biogenic materials for the isolation and stabilization of functional bio-nanostructures. 

Although at first sight, CS2 and COS may seem unlikely metabolites, they have been known as biogenic materials for three decades.6 They warrant a special... 

Parallel (multidimensional) measurements of size- or chemically selected particles permit the simultaneous resolution of biogenic material from fossil sources (14C), discrimination between certain fossil sources and between marine and terrestrial vegetation (13C), and partial separation of agricultural burning sources (K/Fe). The term iMu represents the fraction of modern C based on standard Slk 813C represents the deviation (per mil) of the 13C/12C ratio from standard Sls (2). 

The principal reductant is the biodegradable biogenic material that settles in the deeper portions of the water column ... 

Bischoff, W. D., F. T. Mackenzie, and F. C. Bishop (1987), "Stabilities of Synthetic Magnesian Calcites in Aqueous Solution Comparison with Biogenic Materials," Geochim. Cosmochim. Acfa51, 1413-1423. 

Krahn et al. [479] developed a similar multi-residue scheme for the determination of organochlorines and PAHs in sediments. In this scheme, the preparation is semi-automated with GPC to separate the biogenic material and the sulfur from both the PAHs and organochlorines in the samples. The sterols were separated and purified with an amino-cyano HPLC column prior to derivatiza-tion with bis(trimethylsilyl)trifluoroacetamide (BSTFA). 

On the other hand, gas chromatographic methods may overestimate the concentration of total petroleum hydrocarbons in a sample due to the detection of nonpetroleum compounds. In addition, cleanup steps do not separate petroleum hydrocarbons perfectly from biogenic material such as plant oils and waxes, which are sometimes extracted from vegetation-rich soil. Silica gel cleanup may help to remove this interference but may also remove some polar hydrocarbons. 

Biogenic material derived from bacterial or vegetation sources. 

Metal concentration in biogenic material Metal concentration in seawater... 

Enrichment factor (E.F.) The degree to which a marine organism is enriched in a particular chemical with respect to the seawater concentration, e.g., E.E = [metal concentration in biogenic material]/[metal concentration in seawater]. 

Horizontal segregation The horizontal gradient in biogenic materials, such as nutrients and O2, that is established by the interacUon between the biogeochetnical cycling of pardculate organic matter and meridional overturning circulation. 

The sum of EC and OM contributes another 20-27% (at urban sites) and 18-24% (rural) to the PM mass, with OM dominating EC at most sites. Like in the case of SIA, differences between rural and urban sites appear modest which is probably caused by a considerable natural (biogenic) input. A study by ten Brink et al. [13] on the presence of 14C in PM filter samples revealed that at least 64% of the organic carbon measured at an urban Dutch site was contemporary (i.e. emissions from biogenic material and biomass wood combustion). 

Figure 11. Data documenting the calibration of the carbonate clumped-isotope thermometer for inorganic calcite grown in the laboratory (filled circles) and aragonitic corals grown in nature at known temperatures (an example of one of several biogenic materials we have also calibrated unfilled symbols). The large, gray circle shows the result of analyses of a modern soil carbonate collected from the Bolivian Altiplano plateau. The horizontal position of this data point is based on the mean annual surface temperature near the site of collection between 2004 and the present.

It is essential to understand the isotopic variability within authigenic minerals that form the basis of terrestrial paleoclimate records and between such samples that are isochronous within an outcrop of a stratigraphic formation. Except for variability studies in biogenic materials (teeth, bone, shells) (e.g., Kohn et al. 2002), we know of no paleoaltimetry studies that have examined this natural variability in authigenic or pedogenic proxy materials. Such variability studies should be conducted before any quantitative estimates of paleoelevation can be made. 

Geochemists attempts to understand the chemistry that takes place in the geologic environments where fossil fuels originate and evolve over periods of millions of years. With respect to sulfur this science is concerned with (1) how and when sulfur is introduced into the natural biogenic materials that lead to fossil fuels (2) why and how the abundance and forms of sulfur differ in various geologic environments and (3) how abundance and forms of sulfur evolve (change) with subsequent geologic history. 

Mackenzie (1974) (revised by Thorstenson and Plummer, 1977), a variety of biogenic materials, distilled water, Pco2= 1 atm> 25°C Garrels, Wollast, and KOnig (unpub. data, 1977)... 

The physical and chemical heterogeneities of biogenic materials a priori disqualify them as starting phases for dissolution experiments aimed at understanding the thermodynamics of the CaC03-MgC03 solid solution at low temperature. Comparison of the results of dissolution experiments on... 

The results of Walter and Morse (1984a) and Bischoff et al. (1987) on cleaned, annealed and size-fractionated magnesian calcite skeletons best describe the reactivity of biogenic materials with chemical and physical... 

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