Understanding the physical chemistry controlling the isotopic composition of natural archives is, to me, one of the most exciting aspects of being a geochemist. It is how new ways of studying the Earth system are made possible. A major part of my current research is devoted to studies of these types. A few examples include: Measuring the uranium ‘stable’ (238U/235U) ratios of new archives that could reflect the isotopic composition of the deep ocean, and thus deep ocean redox state, since the Phanerozoic; Deducing mechanisms of 238U/235U fractionation in different materials by linking measured isotope ratio shifts to in-situ U bonding environment; and determining the U isotopic composition of porewaters in marine sediments.
Most of these projects are still in their early stages, but with exciting preliminary results. Check back here as this work evolves for more updates!