GEOTRACES Cobalt Biogeochemistry

PROJECT SUMMARY

The Saito laboratory has been participating in the international GEOTRACES program through the study of the biogeochemistry of cobalt and protein biomarkers. We have contributed data in the Atlantic, Pacific, and Arctic Oceans, and are currently participating in planning for the upcoming Southern Ocean US GEOTRACES expeditions (GP17). Cobalt is one of the scarcest micronutrients in the oceans, and has a complex biogeochemistry and microbial ecology. Cobalt has a complex geochemistry, often described as hybrid type where its role as a micronutrient competes with scavenging removal and other input processes.  In these studies we have been broadening the state of knowledge for cobalt marine biogeochemistry by investigating surface depletion, cobalt-phosphate correlations with stoichiometries that vary significant based on geographic location, redox cycling that occurs in oxygen minimum regions, and complexation chemistry.  In addition, there are distinctly different biological requirements for cobalt, cadmium and zinc that appear to manifest themselves as a cobalt preference for cyanobacteria and a zinc preference for eukaryotic phytoplankton, with biological demand and recycling for each element in the subtropical gyres and coastal environments, respectively. In the Saito laboratory total dissolved cobalt and cobalt speciation measurements are conducted by voltammetric techniques. Ocean sections from GEOTRACES that the Saito laboratory has contributed to can be accessed at eGEOTRACES.org here, and data can be found on BCO-DMO.  Example 3D section of dissolved cobalt in the Atlantic and Pacific Oceans combining contributions from laboratories around the world.

Selected Saito laboratory publications on GEOTRACES are available as embedded links: North Altantic Co GA03, North/South GA03/GAc01 synthesis, South Pacific Co GP16, Arctic Ocean Co GIPY14, South Atlantic CoFeMUG Expedition GAc01 hydrothermal iron plume, South Atlantic Co Fe, and Mn CoFeMUG Expedition GAc01, Co scavenging synthesis, Co biogeochemical model, Hydrothermal inputs and Fe, Mn, Zn, Cu, Ni, Cd on METZYME expedition GPc03, dissolved Co on the METZYME expedition GPc03, and GEOTRACES Pacific meridional transect GP15.

On recent US GEOTRACES expeditions (GP15 and GP17) we have been collecting and analyzing metaproteomic data. This data is in preparation as of 2021, and will be made available through Ocean Protein Portal in the coming years.