Award: OCE-1435056

The distribution of dissolved cobalt was studied in the Arctic Ocean as part of the US GEOTRACES Arctic Expedition from Dutch Harbor Alaska to the North Pole and back in 2015. Dissolved cobalt was high in the upper water column reaching values of approximately 400pM, approximately 10-fold higher than other oceanic environments. These high cobalt in the upper water column was found to have a large fraction of labile dissolved cobalt (not bound to strong organic complexes) as determined by cobalt speciation techniques. The enriched surface concentrations appear to be sourced from sediments and sea ice. Intermediate and deep concentrations of dissolved cobalt were lower than the surface layers, typical of a scavenged-type vertical profile. Based on these findings, microbial and phytoplankton populations in the Arctic Ocean likely utilize cobalt significantly relative to the typically more abundant zinc micronutrient. In addition, the Arctic Ocean appears to be an important source of dissolved cobalt to the North Atlantic Ocean. These results were incorporated into a global ocean model and parameterizations were developed for cobalt scavenging and sediment fluxes specific to high-latitude environments. Broader outreach efforts included the production of a children's book about life as a ocean scientists and the study of biogeochemical cycles, and copies were distributed to rural libraries. A graduate student and postdoctoral scientist also received training from this grant. Last Modified: 06/23/2017 Submitted by: Mak A Saito