Mapping and speciation of cadmium in marine sediments: A key to understanding ancient ocean chemistry

The isotopic composition of cadmium in the oceans (δ114/110Cd) has been proposed as a proxy for ancient nutrient utilization, primary productivity and global-scale marine organic carbon burial. The development of this proxy, however, is held back by not having a detailed understanding of how Cd is buried into marine sediments in association with different mineral phases, and how the distribution of Cd is altered during sediment diagenesis and burial. We seek to tackle this issue by quantifying the distribution and speciation of Cd in organic- and sulfur-rich marine sediments for the first time. The results will enable accurate interpretation of sedimentary Cd isotope signatures and ancient ocean chemistry.