Nonbiological fractionation of iron isotopes

Laboratory experiments demonstrate that iron isotopes can be chemically fra ctionated in the absence of biology. Isotopic variations comparable to thos e seen during microbially mediated reduction of ferrihydrite are observed. Fractionation may occur in aqueous solution during equilibration between in organic iron complexes. These findings provide insight into the mechanisms of iron isotope fractionation and suggest that nonbiological processes may contribute to iron isotope variations observed in sediments.