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Project Progress

The primary focus of this research is to determine if fractionations of transition metal isotopes can be used as biosignatures. Collaborations are pursued with the PSU Team and others outside the institute. We are also interested in the possible use of such fractionations to study changes in metal geochemical cycling, which could provide insight into environmental change and/or biochemical evolution. The latter applications are pursued primarily with the Harvard Team and non-NAI collaborators.

In Year 5, we continued examination of Fe and Mo isotopes.

Major Fe isotope results included developing a model to explain Fe isotope fractionation during hornblende weathering, finding evidence of Fe isotope fractionation during adsorption, and generating theoretical results (in collaboration with researchers at Princeton University) on the equilibrium fractionation factor between Fe(II) and Fe(III) aquo complexes that match experimental data. Major Mo isotope results included continued efforts to explain observed biogenic Mo isotope effects in cultures, and research into Mo isotope fractionation during abiotic aqueous chemistry- especially during interactions with Mn oxides. In collaboration with the Harvard Team, we continued development of Mo isotopes in ancient sediments for paleoredox investigations.