Chromium isotopes and the fate of hexavalent chromium in the environment

Measurements of chromium (Cr) stable-isotope fractionation in laboratory experiments and natural waters show that lighter isotopes reacted preferentially during Cr(VI) reduction by magnetite and sediments. The ⁵³Cr/⁵²Cr ratio of the product was 3.4 ± 0.1 per mil less than that of the reactant.⁵³Cr/⁵²Cr shifts in water samples indicate the extent of reduction, a critical process that renders toxic Cr(VI) in the environment immobile and less toxic.