Carbon Isotopic Chemistry
نویسندگان
چکیده
منابع مشابه
Isotopic Carbon
biometry are laborious and inefficient." In their place he describes methods, admittedly crude, which serve well for exploratory investigations. These include standardized photographs, pictorialized scatter diagrams, ideographs, hybrid indices, and "radiate indicators." Properly used, these seem not to be laborious or inefficient; more important perhaps is their appeal to many non-mathematical ...
متن کامل20. Isotopic Chemistry of Organic Carbon in Sediments from Leg 184
Carbon isotopes were determined on the organic matter (OM) in sediments recovered from four sites (1143, 1144, 1146, and 1148) in the South China Sea during Ocean Drilling Program Leg 184. Concentrations of finely disseminated OM in the sediments were low (generally 0.1 to 0.5 wt%) and show organic δ13C isotope values (generally –22‰ to –24‰) indicative of marine to mixed marine and land-derive...
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• Fine roots constitute a large and dynamic component of the carbon cycles of terrestrial ecosystems. The reported fivefold discrepancy in turnover estimates between median longevity (ML) from minirhizotrons and mean residence time (MRn using carbon isotopes may have global consequences. • Here, a root branch order-based model and a simulated factorial experiment were used to examine four sourc...
متن کاملQuantitative analysis of carbon isotopic ratios in carbon stars
We present the result of a quantitative analysis of 12C/13C ratios in 26 J-type carbon stars. The 12C/13C ratios are determined from lines of the CN red system around 8000 Å, using the iso-intensity method and line-blanketed model atmospheres. The average of 12C/13C ratios in the 26 stars is 4.7 ± 2.8 (standard deviation). All the stars studied, except for two stars, have 12C/13C ratios smaller...
متن کاملCarbon isotopic composition of individual Precambrian microfossils.
Ion microprobe measurements of carbon isotope ratios were made in 30 specimens representing six fossil genera of microorganisms petrified in stromatolitic chert from the approximately 850 Ma Bitter Springs Formation, Australia, and the approximately 2100 Ma Gunflint Formation, Canada. The delta 13C(PDB) values from individual microfossils of the Bitter Springs Formation ranged from -21.3 +/- 1....
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1992
ISSN: 0074-1809
DOI: 10.1017/s0074180900090008