Iron Isotope Fractionation by Biogeochemical Processes in Mine Tailings

摘要

The biogeochemical cycling of Fe in the natural environment includes a great number of abiotic and microbial processes, including mineral weathering, redox transformations, complexation reactions, and the formation of secondary Fe minerals. Significant isotopic fractionation of Fe is produced during microbially-mediated Fe oxidation and reduction reactions, as indicated in recent studies of Fe(II) oxidation by Acidithiobacillus ferrooxidans, Fe(II) oxidation by anaerobic, photolitho-autotrophic bacteria, and dissimilatory Fe(III) reduction by anaerobic, chemoorganotrophic bacteria In addition, significant fractionation has also been observed during abiotic processes including Fe(II) oxidation, isotopic exchange between aqueous Fe(II) and Fe(III), Fe(III) precipitation, solid phase Fe(III) dissolution, and probably Fe adsorption.