Marine organic matter carbon analysis

Pathways of carbon flow in natural environments have also been reconstracted using bulk stable carbon and nitrogen isotopes as well as compound-specific isotopic analysis of individual biomarker lipid component (Hayes et al, 1990) based on the fractionations involved during primary (photosynthetic) and secondary (heterotrophic) processes. Recently, compound-specific radiocarbon analysis of individual biomarker hpid has been shown to be a valuable technique to determine the source of marine organic matter (Eglinton et al., 1997). 

Weliky et al. [154] described a procedure for the determination of both organic and inorganic carbon in a single sample of a marine deposit. Carbonate carbon is determined from the carbon dioxide evolved by treatment of the sample with phosphoric acid the residue is then treated with a concentrated solution of dichromate and sulfuric acid to release carbon dioxide from the organic matter. The carbon dioxide produced at the two stages of the analysis is estimated using a carb on analyser based on the thermal conductivity principle. In addition, total carbon content is determined on another subsample using the dry combustion furnace. This provides a check on the values determined by the phosphoric acid dichromate technique. 

On a time series of Quaternary marine terraces in northern California, Brimhall et al. (1992) conducted the first mass balance analysis of soil formation over geologic time spans. This analysis provided quantitative data on well-known qualitative observations of soil formation (i) the earliest stages of soil formation (on timescales of 10 -10 yr) are visually characterized by loss of sedimentary/rock structure, the accumulation of roots and organic matter, and the reduction of bulk density and (ii) the later stages of soil development (>10 yr) are characterized by the accumulation of weathering products (iron oxides, silicate clays, and carbonates) and the loss of many products of weathering. 

OC and K series), non-marine (D, Ca and C series) and transitional (B series) deposits. Within each series organic matter is often found in quite different facies, for instance acid treatment (Table III) indicates that within the Lothians Upper Oil Shale group samples Cal and Ca6 are carbonate rich (>40%) whereas Cal5 is carbonate poor (2.5%) 5 these differences are obvious within other series as noted in Table III. Microscopical analysis of polished blocks in white and blue light allowed the data in Table II to be compiled. 

Boron can be extracted from natural or synthetic calcium carbonate (or other geologic materials) before analysis by mass spectrometry. The extraction method depends on the analytical technique to be used. For any method, natural samples (typically foraminifera, a single-celled marine invertebrate whose shells accumulate in ocean sediments) must be cleaned of organic matter. This is... 

Gas-chromatography-combustion-mass-spectrometry (GC-C-MS) enables the carbon-isotope analysis of n-alkanes of each carbon number, and therefore, the separate analysis of alkanes derived from alga] acterial and vascular plant sources. This ability has previously been utilized to determine the origin of waxy n-alkanes in a variety of sediments 85,86). The carbon-isotope composition of n-alkanes derived fi-om vascular plants can, therefore, be used to determine the relative contributions of C3- and C4-derived carbon to organic matter in marine, terrestrial or composite sediment samples. This approach has been applied in a preliminary manner to representative samples fi om the Amazon Basin (Bird and Summons, unpublished data). 

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