Isotopic composition of organic

Macko A, Estep MLF (1984) Microbial alteration of stable nitrogen and carbon isotopic compositions of organic matter. Org Geochem 6 787-790... 

Alison S. Bateman, Simon D. Kelly, and Mark Woolfe. Nitrogen Isotope Composition of Organically and Conventionally Grown Crops Journal of Agric. Food Chemistry, 55 (7), 2664-2670, 2007. 

Figure 2. Isotopic composition of organic sulfur in Permian Australian coals containing <1% total sulfur.

Hodell, D.A., and Schelske, C.L. (1998) Production, sedimentation and isotopic composition of organic matter in Lake Ontario. Limnol. Oceanogr. 43, 200-214. 

Kienast, M. (2000). Unchanged nitrogen isotopic composition of organic matter in the South China Sea during the last climatic cycle Global implications. Paleoceanography. 15(2), 244—253. 

Table 3 Carbon, nitrogen, and hydrogen stable isotope compositions of organic fractions from the Murchison...

Battaglin W. A., Kendall C., Chang C. C. Y., Silva S. R., and Campbell D. H. (2001) Chemical and Isotopic Composition of Organic and Inorganic Samples from the Mississippi River and its Tributaries, 1997—98. USGS Water Resources Investigation Report 01-4095, 57p. 

Franks S. G., Dias R. F., Freeman K. H., Boles J. R., Holba A. G., Fincannon A. L., and Jordan E. D. (2001) Carbon isotopic composition of organic acids in oilfield waters, San Joaquin Basin, California. Geochim. Cosmochim. Acta 65, 1301-1310. 

Jahren et al, 2001). Today most C4 plants are tropical grasses, and most CAM plants are submerged aquatic plants and desert succulents. Most other kinds of plants use the C3 photosynthetic pathway. There is the potential to recognize these various metabolic pathways from the isotopic composition of organic carbon in paleosols and in fossil plants, and in the fossils of animals which ate the plants (Ceding et al, 1997 MacFadden et ah, 1999 Krull and Retallack, 2000). 

Wang X.-C. and Druffel E. R. M. (2001) Radiocarbon and stable carbon isotope compositions of organic compound classes in sediments from the NE Pacific and Southern Oceans. Mar. Chem. 73, 65-81. 

Ravizza G. and Turekian K. K. (1992) The osmium isotopic composition of organic-rich marine sediments. Earth Planet. Sci. Lett. 110, 1-6. 

Figure 9 Plot of the sulfur isotopic composition of organic sulfur in marine sediments versus the sulfur isotopic composition of pyrite in the same sediments (reproduced by permission of American Chemical Society from Geochemical Transformations of Sedimentary Sulfur, 1994, 612, 378-396).

Beaumont V. and Robert F. (1998) Nitrogen isotopic composition of organic matter from Precambrian cherts new keys for nitrogen cycle evolution Bull. Soc. Geol. Fr. 169(2), 211-220. 

Carbon isotope compositions of organic carbon in the stromatolites of the Macgregor Member of the Cheshire Formation are variable, but... 

Stable carbon isotope compositions of organic substances are measured via isotope ratio mass spectrometry. Samples are combusted to convert organic matter into gases (e.g. CO2, N2) that are then ionized and admitted into the isotope ratio-mass spectrometer (IR-MS) where the ratios of the isotopes are quantified (see Chapter 5 for further information). Owing to the low abrmdances of some of the isotopes, the precision and accuracy of the measurements is important (Merritt and Hayes, 1994). One of the most common and informative isotopes is because it is not readily altered by equilibration or degradation processes. Hence, values are most commonly employed as indicators of ultimate plant or geographic sources. In... 

First studies combining gas chromatography and mass spectrometry in order to determine variations in the stable carbon isotope composition of organic compounds were reported in 1976 and 1978 (Sano et al. 1976 Matthwes and Hayes 1978). Matthews and Hayes referred to their analytical approach as isotope ratio monitoring mass spectrometry (irmMS) and approx. 10 years later this technique was commercially implemented. Subsequently the GC/irmMS technique and the... 

Compound-specific isotope analysis (CSIA) is a rather new tool in environmental analysis. It is not used for quantitative analysis of organic compoimds but rather for the characterization of environmental fate by monitoring changes in the isotopic composition of organic molecules. Analytical aspects are covered here because this rather new area of research is expected to mature to a standard tool in environmental analysis that will complement the quantitative analysis in the environment [70]. 

The isotopic composition of the H transferred from NADPH to biosynthetic substrates must be one of the most important factors controlling the hydrogen-isotopic composition of organic matter. 

Strauss H, Beukes NJ (1996) Carbon and sulfur isotopic compositions of organic carbon and pyrite in sediments from the Transvaal Supergroup, South Africa. Precamb Res 79 57-71 Strauss H, Des Marais DJ, Sutmnons RE, Hayes JM (1992a) The eatbon isotopic record. In Schopf JW, Klein C (eds) The Porterozoic Biosphere A Multidisciplinary Study. Cambridge University Press, New York, p 117-127... 

Van Kaam-Peters HME, Schouten S, Koster J, Damste JSS (1998) Controls on the molecular and carbon isotopic composition of organic matter deposited in a Kimmeridgian euxinic shelf sea Evidence for preservation of carbohydrates through sidfurisation. Geochim Cosmoschim Acta 62 3259-3283... 

Carbon isotope ratios are principally useful to distinguish between marine and terrestrial organic matter sources in sediments and to identify organic matter from different types of land plants. The stable carbon isotopic composition of organic matter reflects the isotopic composition of the carbon source as well as the discrimination (fractionation) between and... 

Fontugne, M.R., Calvert, S.E., 1992. Late Pleistocene variability of the carbon isotopic composition of organic matter in the eastern Mediterranean Moni-... 

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