Ocean Sciences Meeting 2026

***GEOTRACES and GEOTRACES related sessions***

*OB020 – Multi-tracer approaches to understanding and quantifying marine biogeochemical processes
https://agu.confex.com/agu/osm26/prelim.cgi/Session/256137

Co-conveners
William M Landing, Florida State University
Hélène Planquette, IUEM Institut Universitaire Européen de la Mer, LEMAR, CNRS
Anne Leal, Lamont Doherty Earth Observatory at Columbia University

Description
There is a long history on the use of multiple tracers to investigate and quantify biogeochemical processes in the oceans, from the use of carbon, nutrient and trace element stoichiometries to demonstrate uptake and regeneration processes, to studies of the microbial impacts on trace element speciation and distributions, to the coupling of natural radionuclide cycling with particle chemistry to quantify fluxes, among many others. Our understanding of the rates and mechanisms of trace element and isotope (TEI) input, biogeochemical cycling, and removal is improved by multi-tracer data from basin-wide research cruises, data from more focused process studies, and synthesis and modeling of these data. In addition to contributions in these topical areas, we particularly encourage submissions that integrate multiple tracers or isotope systems to provide constraints on biogeochemical processes in the oceans and that highlight the benefits of multi-proxy approaches.

*CB002 – Coastal, Shelf, and Island Mass Effects on Trace Element Biogeochemistry in the Ocean
https://agu.confex.com/agu/osm26/prelim.cgi/Session/254981

Co-conveners
David González-Santana, IOCAG Universidad de Las Palmas de Gran Canaria
Aridane G. González, IOCAG. Universidad de Las Palmas de Gran Canaria
Emilie Le Roy, IUEM Institut Universitaire Européen de la Mer
Gabriel Dulaquais, IUEM Institut Universitaire Européen de la Mer

Description
The marine biogeochemical cycles of trace elements, their stable isotopes compositions and organic binding ligands are affected by the island mass effects. With terrigenous, shelf and even glaciogenic inputs, islands are natural laboratories for studying the importance of lateral fluxes of trace elements, their impact on the physico-chemical processes and associated biological responses. This session aims to bring together researchers from diverse fields to discuss the latest findings on the biogeochemical processes occurring in the ocean and related to the island and shelf effects, from the coast to the open ocean. The aim is to improve our knowledge, identify biogeochemical impacts, and characterise physico-chemical speciation of metals and redox chemistry. We welcome research studies and experiments focusing on processes affecting trace metal chemistry, the nutrient cycle and organic ligands.

*HE004 – Mercury in Polar Waters: Sources, Transformations, and Bioaccumulation in Food Webs
https://agu.confex.com/agu/osm26/prelim.cgi/Session/254233

Co-conveners
Emily Seelen, University of Alaska Fairbanks
Marissa Despins, University of California Santa Cruz
Stephen Kohler, Norwegian University of Science and Technology
Marissa Despins, University of California Santa Cruz

Description
High latitude environments are undergoing profound changes driven by climate warming. The impact of this change–sea ice loss, permafrost thaw, and shifting ocean circulation–is expected to alter the concentration and distribution of mercury (Hg) in polar marine waters. While models indicate that Hg concentrations will rise in the Arctic under current emission climate scenarios, the processes influencing Hg mobility and speciation remain poorly understood, especially in the Antarctic, where data is even more limited. To accurately model the fate of Hg in a warming climate and risk for human exposure, it is imperative that we understand the mechanisms governing Hg cycling, particularly methylation and demethylation pathways, which still remain elusive. This session invites contributions that explore the biogeochemical cycling of Hg in both the Arctic and Antarctic, with a focus on the release and delivery of Hg species to coastal zones, processes that influence Hg transformations, and bioaccumulation in marine food webs. Interdisciplinary perspectives that incorporate Indigenous knowledge and community-based monitoring are also encouraged, as are studies addressing the vulnerability of subsistence-dependent communities to changing Hg exposure.