A 813C-values

NOTE Values for 8l3C given in per rnille relative to VPDB, defined by assigning a 813C value of +1.95%o to NBS 19 carbonate. (See Appendix E for information about obtaining these materials.)... 

In order to illustrate the variations of the carbon isotope ratios measured after execution of the five recovety experiments, Figure 3 presents the differences of the 813C-values of the recovered substances as compared to the untreated compounds noted as A 813C-values. 

GC-C-IRMS was first demonstrated by Matthews and Hayes (1978). However, it was somewhat later that Barrie and others (Barrie et al., 1984) coupled a GC, via a combustion interface, to a dual collector mass spectrometer to produce the forerunner of today s GC-C-IRMS instruments. Even so, true determinations of 815N values of individual compounds by GC-C-IRMS remained elusive until finally demonstrated by Hayes and co-workers (Merritt and Hayes, 1994). More recently the precision of GC-C-IRMS instruments has been improved further still with uncertainties in 813C values as small as 0.5 %o for samples containing 5 pmol C and 0.1 %o for 100 pmol samples having been demonstrated (Merritt and Hayes 1994). Instruments available commercially today, from several manufacturers, all conform to the same general principles of design. 

Figure 14.11 813C values of cholesterol recorded by GC C IRMS from a wide range of skeletal members and teeth confirming the consistency of the signals and potential utility for palaeo dietary reconstruction... 

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stable isotope composition consistent with differing contributions of maize to the diet (Jim, Ambrose and Evershed unpublished data)...

Figure 14.13 8 13C values of the most abundant FAs and cholesterol in the Kwadgy Dan Ts inchj bone and skin samples (determined by GC C IRMS) compared with 813C values determined for the same compounds in individual s bone extracted from rats subjected to a pure C3 terrestrial diet, a 20% marine protein (tuna) diet and a 70% marine (tuna) diet (Jim, unpublished data)... 

Figure 14.19 Scatterplots comparing (a) the 13C values of the fatty acids of the modern British reference animal fats with (b) the 813C values of the fatty acids of the modern Kazakh reference animal fats and (c) the A13C values of the British reference animal fats with (d) the A13C values of the Kazakh reference animal fats. (British reference animal fat values taken from Dudd 1999 and Kazakh values from Outram et al. 2009)...

Corr, L. T., Sealy, J. L., Horton, M. C. and Evershed, R. P. (2005) A novel marine dietary indicator utilising compound specific collagen amino acid 813C values of ancient humans. Journal of Archaeological Science 32, 321 330. 

Dungait, J. A. J., Docherty, G. and Evershed, R. P. (2008) Interspecific variation in bulk tissue, fatty acid and monosaccharide 813C values of leaves from mesotrophic grassland species. Phytochemistry 69, 2041 2051. 

Evershed, R. P., Dudd, S. N., Copley, M. S. and Mukherjee, A. J. (2003b) Identification of animal fats via compound specific 813C values of individual fatty acids assessments of results for reference fats and lipid extracts of archaeological pottery vessels. In Documenta Praehistorica, XXIX 9th Neolithic Studies (Ed. Budja, M.), Ljubljana, pp. 73 96. 

Jim, S. (2000) The development of bone cholesterol 813C values as a new source of palaeodietary information models of its use in conjunction with bone collagen and apatite 813C values. PhD thesis, University of Bristol. 

Mukherjee, A. J., Copley, M. S., Berstan, R. and Evershed, R. P. (2005) Interpretation of 813C values of fatty acids in relation to animal husbandry, food processing and consumption in prehistory. In The Zooarchaeology of Fats, Oils, Milk and Dairying (Eds Mulville, J. and Outram, A. K.), Oxbow Books, Oxford, pp. 77 92. 

Indexes o and s define the ratio of the carbon isotopes in the sample and in the standard. A lithospheric carbonate material was accepted as standard. The closest to this zero point value belongs to standard sample NBS-19 (1.95%c). There are some other standard samples NBS-22 oil (—29.74%c), NBS-18 calcium carbonate (— 5.01%c). Usually 813C values for plants are in the range ( 15%o) to (— 30%c), and for oil (— 20%c) to ( 36%c). Atmospheric methane has the lowest content of 13C. Its 813C value is approximately —47%o. 

Plants are the base of the terrestrial food chain. The body tissue of herbivores feeding on these plants, and subsequently of omnivores and carnivores, is dependent on the isotopic composition of the plant material ingested, and therefore reflects the 813C values of either a C3 or C4 biome. The exact values are modified by metabolically induced fractionation as the food is digested and incorporated into different body tissues. At its simplest, it has been assumed... 

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