Density functional theory estimation of isotope fractionation of Fe, Ni, Cu, and Zn among species relevant to geochemical and biological environments

This paper reports the values of reduced partition function ratios (as 1000 ln beta) for Fe, Ni, Cu, and Zn bound to a number of inorganic and organic ligands. We used Density Functional Techniques to update the existing data and calculate ln beta for new ligands. This work allows for the mass-dependent isotope fractionation to be predicted for various inorganic (hydrated cation, hydroxide, chloride, sulfate, sulfide, phosphate) and organic (citrate, amino acid) complexes of Fe, Ni, Cu, and Zn. Isotope fractionation among coexisting complexes of these metals was evaluated from the ln beta values in a variety of geochemical and biological environments. The results provide a framework for interpretation of isotope fractionation observed in seawater and chemical sediments, in the roots and aerial parts of plants, and among the organs and body fluids of mammals. (C) 2014 Elsevier Ltd. All rights reserved.