ex20: Example 20-Distribution of Isotopes Between Water and Calcite

Description Source References See Also Examples


The database iso.dat implements the approach to isotope reactions described by Thorstenson and Parkhurst (2002, 2004), in which minor isotopes are treated as individual thermodynamic components. The aqueous and solid species of minor isotopes have slightly different equilibrium constants than those of the major isotopes, which account for fractionation processes. The treatment of isotopes in gases requires a separate species for each isotopic variant of a gas; for example, the isotopic variants of carbon dioxide are CO2, C18OO, C18O2, 13CO2, 13C18OO, and 13C18O2. Similarly, every isotopic variant of a mineral must be included as a component of a solid solution to represent completely the isotopic composition of the solid. The equilibrium constants in iso.dat are derived from empirical fractionation factors, from statistical mechanical theory, or, where no data are available (the most common case), by assuming no fractionation. However, the database is a framework that can be expanded as additional isotopic thermodynamic data become available. The example can be run using the phrRunString routine.





See Also

Other Examples: ex10, ex11, ex12, ex13a, ex14, ex15, ex16, ex17, ex18, ex19, ex1, ex21, ex22, ex2, ex3, ex4, ex5, ex6, ex7, ex8, ex9



phreeqc documentation built on July 1, 2020, 11:46 p.m.