Seminar: Hannah Whitby – Université de Bretagne Occidentale

UNC-CH’s Department of Marine Sciences is proud to host a seminar by Hannah Whitby, Ph.D. This event is scheduled for Wednesday, April 3rd, at 3:35pm in room G201 on the ground floor of Murray Hall at the University of North Carolina at Chapel Hill. This seminar will also be broadcast live to both UNC’s Institute of Marine Sciences room 222 and online via Zoom.

Presenter Affiliation: Postdoctoral Researcher, Trace Metal Biogeochemist, Laboratoire des Sciences de l’Environnement Marin- LEMAR, Université de Bretagne Occidentale (UBO)

Title:  One ligand to rule them all and in the darkness bind them – The role of humic-like substances in the oceanic iron and copper cycles

Abstract: The sequestration of atmospheric CO2 in the ocean is in great part driven by primary production. In many regions of the world’s ocean, primary production is limited by the availability of iron. As over 99% of iron is complexed to organic ligands, which increase the solubility and microbial availability of dissolved iron, understanding the processes governing ligand dynamics is essential. This is also true for copper, which is required in many cellular functions. Reduced copper availability may also limit growth in some regions, however it is more commonly known for its toxicity to marine life. Copper and iron complexation in terrestrial and freshwater systems have long been linked to humic-like substances. As a major component of dissolved organic carbon (DOC), humic substances play a key role in metal cycling, influencing solubility, offshore transport, toxicity and bioavailability, but their contribution to metal complexation in the open ocean is not well understood. Here we discuss the role of humic substances as ligands for iron and copper on a global oceanographic scale. While important for both metals, we find that humic substances may dominate iron complexation throughout the water column, imposing a concentration threshold that buffers the deep ocean iron inventory.