Uranium isotope fractionation by abiotic reductive precipitation

This is the authors' abstract. We don't add key points for this paper.

Significance We use an experimental approach to demonstrate that 238 U/ 235 U is fractionated by abiotic reduction onto the surface of abiotic synthetic iron monosulfide, contradicting the findings of earlier studies. We further demonstrate that for abiotic reduction reactions the aqueous U speciation and removal rate control the extent of isotopic fractionation. U isotopic fractionation is observed when the primary aqueous species are Ca–UO 2 –CO 3 , suggesting that aqueous U speciation affects the relative forward and backward reaction rates and by extrapolation the relative roles of nuclear field shift effect and mass dependent kinetic fractionation.