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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 ...
Since its original descriptions, the Urey–Bigeleisen–Mayer equation has taken many forms. Given an isotopic exchange reaction + = +, such that designates a molecule containing an isotope of interest, the equation can be expressed by relating the equilibrium constant, , to the product of partition function ratios, namely the translational, rotational, vibrational, and sometimes electronic ...
Of the 25 known isotopes of sulfur, four are stable. [1] In order of their abundance, those isotopes are 32 S (94.93%), 34 S (4.29%), 33 S (0.76%), and 36 S (0.02%). [2] The δ 34 S value refers to a measure of the ratio of the two most common stable sulfur isotopes, 34 S: 32 S, as measured in a sample against that same ratio as measured in a known reference standard.
Theoretically, such stable isotopes could include the radiogenic daughter products of radioactive decay, used in radiometric dating. However, the expression stable-isotope ratio is preferably used to refer to isotopes whose relative abundances are affected by isotope fractionation in nature. This field is termed stable isotope geochemistry.
Measurement of natural variations in the abundances of stable isotopes of the same element is normally referred to as stable isotope analysis. This field is of interest because the differences in mass between different isotopes leads to isotope fractionation, causing measurable effects on the isotopic composition of samples, characteristic of their biological or physical history.
Isotope fractionation occurs during a phase transition, when the ratio of light to heavy isotopes in the involved molecules changes.When water vapor condenses (an equilibrium fractionation), the heavier water isotopes (18 O and 2 H) become enriched in the liquid phase while the lighter isotopes (16 O and 1 H) tend toward the vapor phase.
Stable isotope ratios of trace metals can be used to answer a variety of questions spanning diverse fields, including oceanography, geochemistry, biology, medicine, anthropology and astronomy. In addition to their modern applications, trace metal isotopic compositions can provide insight into ancient biogeochemical processes operated on Earth ...
In geochemistry, hydrology, paleoclimatology and paleoceanography, δ 15 N (pronounced "delta fifteen n") or delta-N-15 is a measure of the ratio of the two stable isotopes of nitrogen, 15 N: 14 N. [1]