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Hydrogen isotope biogeochemistry (HIBGC) is the scientific study of biological, geological, and chemical processes in the environment using the distribution and relative abundance of hydrogen isotopes. Hydrogen has two stable isotopes, protium 1 H and deuterium 2 H, which vary in relative abundance on the order of hundreds of permil.
All isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table.
Archaeological materials, such as bone, organic residues, hair, or sea shells, can serve as substrates for isotopic analysis. Carbon, nitrogen and zinc isotope ratios are used to investigate the diets of past people; these isotopic systems can be used with others, such as strontium or oxygen, to answer questions about population movements and cultural interactions, such as trade.
A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example, carbon-13 with 6 protons and 7 neutrons. The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, whereas the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear.
Equilibrium isotope fractionation is the partial separation of isotopes between two or more substances in chemical equilibrium. Equilibrium fractionation is strongest at low temperatures, and (along with kinetic isotope effects) forms the basis of the most widely used isotopic paleothermometers (or climate proxies): D/H and 18 O/ 16 O records from ice cores, and 18 O/ 16 O records from calcium ...
Quantity calculation with the Bateman-Function for plutonium-241 While the Bateman formula can be implemented in a computer code, if λ j ≈ λ i {\displaystyle \lambda _{j}\approx \lambda _{i}} for some isotope pair, catastrophic cancellation can lead to computational errors.
Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements. Variations in isotopic abundance are measured by isotope-ratio mass spectrometry , and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between ...
Perrin assumed that the mean free path was much larger than the radius of the sphere. Peierls did not agree, and commenced his own calculations. A key insight came from Frisch, who wondered what would happen if, instead of natural uranium, a sphere of the uranium-235 isotope was used. [42] By definition, the mean free path is: