Check out this article by Claresta Joe-Wong. As part of Claresta's PhD she conducted in interesting set of experiments reducing hexavalent chromium with different iron species. The changes in the chromium isotope fractionation are related to the Gibbs free energy of reaction. Thermodynamic controls on redox-driven kinetic stable isotope fractionation
Mike Antonelli is the lead author on a new paper we have out in PNAS that explores the relationship between seawater composition and chemical exchange in mid ocean ridge hydrothermal systems. We are now working on a related NSF funded project to better understand chemical and isotopic exchange at ocean ridges. Read Mike's paper here.
Kim recently finished her PhD at Stanford and completed calcium isotope measurements at UCB with Don DePaolo and myself. Initially we thought that the isotopic measurements would reveal something about seawater chemistry after the Permian-Triassic mass extinction. Through careful work Kim has shown that the observed variation in Ca isotopes and Sr/Ca are partially controlled by local mineralogy and diagenetic effects in addition to seawater composition. Congrats Kim!