Thermodynamic and kinetic constants for isotopic fractionation modeling with or without major isotope hypothesis
نویسندگان
چکیده
The modeling capacities of geochemical speciation and reactive transport software continue to develop, stable isotopes are now increasingly incorporated into these codes. Isotopic fractionation associated with a given chemical reaction is commonly modeled by affecting different calculated rate thermodynamic constants for each explicitly defined isotopologue based on the classical constant factor reaction. This approach has been reliably demonstrated cases in which one isotope much more abundant (i.e. common) than others (e.g. carbon, oxygen, nitrogen, etc.). Such large disparity abundance allows assumption that bearing major essentially equal element. Kinetic isotopologues also frequently determined assuming involving very close overall rate. As our ability accurately measure isotopic systems expands, it becomes necessary define scope validity rare hypothesis errors introduced application elements like chlorine, bromine, zinc or do not present clearly isotope. study reviews mathematical developments kinetic calculations following expands upon this basis provide appropriate parameterization where could introduce errors. results show brought valid without determination constants. verification assures employ codes handle variety elements. stems from typically small deviations relative concentrations differences behavior isotopes. We illustrate an case during sphalerite precipitation performed code Hytec. model scripts used provided offer opportunity future benchmarking explicit fractionation.
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ژورنال
عنوان ژورنال: Chemical Geology
سال: 2021
ISSN: ['0009-2541', '1872-6836']
DOI: https://doi.org/10.1016/j.chemgeo.2021.120143