Stable carbon isotopes

Stable isotope analyses of the organic fraction of bone and of food samples was carried out on a Micromass Prism Mass Spectrometer in the Stable Isotope Laboratory, Department of Physics, University of Calgary, under the direction of H.R. Krouse. Collagen samples were combusted in a Carlo Erba gas analyser which provides information on the carbon and nitrogen content of the samples andintroduces Nior CO gases into the mass spectrometer for analysis of nitrogen or carbon stable isotopes, respectively. 

Figure 14.12 Trends through time in the bulk stable isotope values of collagen (6I3C and 815N), apatite ( 13C) and compound specific 813C values of cholesterol recorded from a number of individuals from the Illinois River Valley, USA, showing contiguous fluctuations in carbon stable isotope composition consistent with differing contributions of maize to the diet (Jim, Ambrose and Evershed unpublished data)...

Fig. 25.4. Oxygen and carbon stable isotopic compositions of calcite ( ) and dolomite ( ) cements from Lyons sandstone (Levandowski et al., 1973), and isotopic trends (bold arrows) predicted for dolomite cements produced by the mixing reaction shown in Figure 25.3, assuming differing CO2 fugacities (25, 50, and 100) for the Fountain brine. Fine arrows, for comparison, show isotopic trends predicted in calculations which assume (improperly) that fluid and minerals maintain isotopic equilibrium over the course of the simulation. Figure after Lee and Bethke (1996).

These delta values (read delta C-13 , or delta carbon-13 ) are typically given in parts per thousand ( permil , %o). For historical reasons, carbon stable isotopes are reported relative to the PDB (Pee Dee Belemnite, a fossil) or the equivalent VPDB (Vienna PDB) standard. Oxygen and hydrogen stable isotopes are reported relative to SMOW (Standard Mean Ocean Water) or the equivalent VSMOW (Vienna SMOW). The VPDB and VSMOW standards are preferred, not only because the original standards, PDB and SMOW, are no longer available, but also because they imply that the measurements have been calibrated according to international conventions. 

Carbon stable isotope ratios in Olivella biplicata shell beads sourcing, 180-185/... 

Carr, R. H., Wright, I. P., Joines, A. W. Pillinger, C. T. 1986 Measurement of carbon stable isotopes at the nanomole level a static mass spectrometer and sample preparation techniques. J. Phys. E 19, 798-808. 

Hiridate, S., Nakadai,T., Shindo, H., and Yoneyama,T. (2004). Carbon source of humic substances in some Japanese volcanic ash soils determined by carbon stable isotope ratio 813C. Geoderma 119,133-141. 

Freeman, K.H. (2001) Isotopic biogeochemistry of marine organic carbon (stable isotope geochemistry). In Reviews in Mineralogy and Geochemistry (Valley, J., and Colemen, D., eds.), pp. 579-606, Mineralogical Society of America, Washington, DC. 

More recently, the carbon stable isotope ratio test (SIRA) has become an easy method to detect adulteration with cane and corn syrup (Carro et al, 1980). Because maple trees are C3 plants with a somewhat different photosynthetic pathway for carbon fixation, the ratio of 13C/12C in the sugar produced is different than cane or com. Maple has a 813C of approximately —24.5, whereas com and cane are closer to a 813C of —8 to —12. Thus, even a small addition of cane or corn syrup is readily detectable. Because beets are also C3 plants, the SIRA test is not able to detect adulteration with beet sugar. Improvement of the SIRA method is possible using malic acid as an internal standard (Tremblay and Paquin, 2007). 

Table 6 Carbon stable isotope compositions of solvent extractable aromatic compounds in carbonaceous...

Figure 2 Carbon stable-isotope compositions of low-molecular-weight hydrocarbons, amino acids, and monocarboxylic acids from the Murchison meteorite plotted against carhon number. Carbon number 1 denotes methane and CO2, 2 denotes ethane, ethanoic acid, glycine, etc. (source Yuen et al., 1984).

Figure 3 Carbon stable-isotope compositions of solvent extractable aromatic and PAHs plotted against carbon number from the Murchison and Asuka-881458 CM2 carhonaceous chondrites (sources Yuen et al., 1984 Gilmour and Pillinger, 1994 Sephton et al., 1998 ...

Figure 4 Carbon stable-isotope compositions of solvent extractable n-alkanes from the Orgueil (Cl), Cold Bokkeveld (CM2), Murchison (CM2), Vigarano (CV3), Ornans (CO), and Tagish Lake carbonaceous chondrites plotted against carbon number (sources Sephton et al., 2001 PizzareUo et al, 2001).

Table 8 Carbon stable isotope compositions of individual aromatic molecules released by the pyrolysis of...

Figure 12 DOM cycling in the ocean. DOM is initially produced as a by-product of marine production in the mixed layer. Carbon stable isotope data suggests that some fraction of this organic matter becomes incorporated into the longer-term reservoir of rather refractory DOM to be subducted into the deep ocean. Newly produced DOM may also assemble into particles to enter the POM cycle. POM is oxidized, or transported into the deep ocean on large, rapidly sinking particles where biological activity may cause further oxidation, or drive re-dissolution to HMW DOM.

Carbon stable isotope data for the burial diage-netic dolomite cements (Worden Matray, 1995) indicate that isotopically depleted carbon has been... 

Fig. 11. Plot of oxygen and carbon stable isotopic compositions of bulk carbonate samples. Note the small range in isotopic compositions of calcite in lenses despite variable ratios between early and late calcite cement. This points to similar physical and chemical conditions during replacement of early diagenetic CaC03 cement by low-Mg calcite and late calcite cement precipitation.

Fig. 10. (A) Oxygen and carbon stable isotopic composition of calcite cements from the San Joaquin basin margins. Data sources from Table 1. (B) Oxygen and carbon stable isotopic composition of calcite cements from the San Joaquin basin centre. Data sources from Table 1. Note the restricted range of carbon isotopes compared with basin margin cements (cf. with (A)).

Carbon stable isotope analysis of riverine contaminants - 223... 

Further on, the matrix within the extracts might also affect the carbon stable isotope ratios. However, further purification or fractionation applied in order to minimize matrix effects is critical due to the low to very low amounts of the contaminants. A significant loss of numerous individual... 

Mackensen, A. 2001. Oxygen and carbon stable isotope tracers of Weddell Sea water masses new data and some paleoceanographic implications. Deep-Sea Research I, 48, 1401-1422. 

Chandler, G. T., Williams, D. F., Spero, H. 1. XiAODONG, G. 1996. Sediment microhabitat effects on carbon stable isotopic signatures of microcosm-cultured benthic foraminifera. limnology and Oceanography, 41, 680—688. 

Fielding AS, Turpin DH, Guy RD, Calvert SE, Crawford DW, Harrison PJ (1998) Influence of the carbon concentrating mechanism on carbon stable isotope discrimination by the marine diatom Thalassiosira pseudonana. Canadian J Botany 76 1098-1103... 

Fig. 4.15 Carbon stable isotope data in different compartments of a continental margin settings with the Congo Fan as an example. Data for 5 C values of biota and sediments are from measurements in the Congo Fan and the Congo River catchment area (Mariotti et al. 1991, Muller et al. 1994, Muzuka 1999, Schwartz et al. 1986, Westerhausen et al. 1993).

An important application of carbon stable isotope ratios lies in the reconstruction of the carbon dioxide concentration in surface waters and subsequently in the atmosphere at the time the organic matter was produced. Experimental and field studies have shown that the fractionation of stable car-... 

Fig. 5. Methane to pentane carbon stable isotope composition of gases produced from wells of the Voelkersen field (Cl, methane C2, ethane C3, propane i-C4, wo-butane -C4, n-butane i-C, iso-pentane n-C, n-pentane).

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