Carbon isotopes controls

Laws, E.A., B.N. Popp, R.R. Bidigare, U. Riesbesell, S. Burkhardt, and S.G. Wakeham. 2001. Controls on the molecular distribution and carbon isotopic composition of alkenones in certain haptophyte algae. Geochemistry Geophysics Geosystems January 25, 2001. 

Corso and Brenna [687] have described an experiment in which intramolecular carbon isotope distributions of chemically pure compounds are investigated by controlled pyrolysis of the analytes emerging from a GC column, followed by a second GC step to separate the pyrolysis products which are then analyzed by the combustion IRMS techniques described above. 

Cotte, J. F., Casabianca, H., Lheritier,J., Perrucchietti, C., Sanglar, C., Waton, FI., and Grenier-Laustalot, M. F. (2007). Study and validity of 13C stable carbon isotope ratio analysis by mass spectrometry and 2H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey. Anal. Chim. Acta 582,125-136. 

Stable carbon isotope ratios have also been used to determine the sources of lake DOC. Baron et al. (1991) used 13C analysis to show that autochthonous sources dominated the DOC of an alpine lake during most periods while allochthonous sources dominated the DOC in a subalpine lake. The high DOC concentrations observed during spring snowmelt and early summer in both lakes, however, were mostly derived from allochthonous sources. As with streams and rivers, synoptic regional studies of 13C and 14C would provide important new information on broad spatial patterns and controls on the sources of DOC in lakes. 

Cerling s primary objective was the identification of the processes controlling the carbon-isotope composition of soil CO2, and a quantitative means of describing the process. In terms of notation, carbon isotopes in compounds are evaluated as the ratio (R) of the rare to common stable isotope of carbon ( C/ C) and are reported in delta notation 8 C(%o) = (RJRstd 1)1,000, where R and R td refer to the carbon-isotope ratios of the sample and the international standard, respectively (Friedman and O Neil, 1977). 

Over the last several decades, the decline in alkalinity in many streams in Europe and in northeastern USA as a result of acid deposition has been a subject of much concern (Likens et al., 1979). The concentration of bicarbonate, the major anion buffering the water chemistry of surface waters and the main component of dissolved inorganic carbon (DIC) in most stream waters, is a measure of the reactivity of the watersheds and reflects the neutralization of carbonic and other acids by reactions with silicate and carbonate minerals encountered by the acidic waters during their residence in watersheds (Garrels and Mackenzie, 1971). Under favorable conditions, carbon isotopes of DIC can be valuable tools by which to understand the biogeochemical reactions controlling carbonate alkalinity in groundwater and watersheds (MUls, 1988 Kendall et al., 1992 see Chapter 5.14). 

Wassenaar L. I., Aravena R., Fritz P., and Barker J. F. (1991) Controls on the transport and carbon isotopic composition of dissolved organic carbon in a shallow groundwater system. Central Ontario, Canada. Chem. Geol. 87, 39-57. 

Measuring the carbon isotope ratio in the calcite tests of bottom dwelling (benthic) foraminifera is perhaps the most widespread method for reconstructing the distribution and properties of deepwater masses. The carbon isotope ratios in the foraminifera reflect that ratio in seawater. In turn, the carbon isotope ratio in the deep sea is primarily controlled by the regeneration of C-poor organic material and has a distribution much like a nutrient such as phosphate in the modern ocean. While a... 

Avery G. B., Jr. and Martens C. S. (1999) Controls on the stable carbon isotopic composition of biogenic methane produced in a tidal freshwater estuarine sediment. Geochim. Cosmochim. Acta 63, 1075-1082. 

Figure 16 Relationship between change in A(A C) of vascular land plants determined experimentally in response to growth under different O2/CO2 atmospheric mixing ratios. A(A C) is the change in carbon isotope fractionation relative to fractionation for the controls at present day conditions (21% O2, 0.036% CO2). The solid line shows the nonlinear curve fitted to the data, given by A(A C) = - 19.94 -h 3.195 X InfOz/COz) ( ) Phaseolus vulgaris, ( ) Sinapis alba, ( ) from Berner et al. (2000) (-I-) from Berry et al. (1972) (Beerling et al., 2002) (reproduced by permission of Elsevier from Geochem. Cosmochim. Acta 2002, 66, 3757-3767).

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