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The standard established for carbon-13 work was the Pee Dee Belemnite (PDB) and was based on a Cretaceous marine fossil, Belemnitella americana, which was from the Peedee Formation in South Carolina. This material had an anomalously high 13 C: 12 C ratio (0.0112372 [4]), and was established as δ 13 C value of zero.
δ 13 C sample is the delta-value of the organism for 13 C composition; δ 13 C atm is the delta-value of atmospheric CO 2, which is = -7.8‰ the discrimination due to diffusion a = 4.4‰ the carboxylation discrimination b = 30‰ c a is the partial pressure of CO 2 in the external atmosphere, and; c i is the partial pressure of CO 2 in the ...
Carbon-13 has a non-zero spin quantum number of 1 / 2 , and hence allows the structure of carbon-containing substances to be investigated using carbon-13 nuclear magnetic resonance. The carbon-13 urea breath test is a safe and highly accurate diagnostic tool to detect the presence of Helicobacter pylori infection in the stomach. [4] The ...
If an animal (or human) eats only C3 plants, their δ 13 C values will be from −18.5 to −22.0‰ in their bone collagen and −14.5‰ in the hydroxylapatite of their teeth and bones. [16] In contrast, C4 feeders will have bone collagen with a value of −7.5‰ and hydroxylapatite value of −0.5‰.
One of these, the standard for normalizing δ 13 C values, is Pee Dee Belemnite (PDB), a fossil which has a 13 C / 12 C ratio of 1.12372%. [3] δ 13 C for some sample is then calculated by dividing the amount of 13 C by 1.12372% and then subtracting 1 and multiplying by 1000 to give a value in "per mil". [4]
Similarly, marine fish contain more 13 C than freshwater fish, with values approximating the C 4 and C 3 plants respectively. The ratio of carbon-13 and carbon-12 isotopes in these types of plants is as follows: [11] C 4 plants: −16‰ to −10‰ CAM plants: −20‰ to −10‰ C 3 plants: −33‰ to −24‰
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2 becomes more soluble and hence more available to the marine organisms; fractionation increases and δ 13 C values can be as low as −32‰. [13] The δ 13 C value for animals depends on their diet. An animal that eats food with high δ 13 C values will have a higher δ 13 C than one that eats food with lower δ 13 C values. [9]