GEOTRACES at Goldschmidt 2026!

Dear colleagues,

There will be two exciting GEOTRACES sessions at Goldschmidt 2026 (12–17 July 2026, Montréal, Québec, Canada). Discover them below!

Also, stay tuned: an Early Career Scientist mixer is currently being planned!

Best wishes,
GEOTRACES IPO

**GEOTRACES sessions**

12c – The Role of Boundaries Across Scales in Shaping Marine Trace Element Distributions
Description:
Trace elements and isotopes (TEIs) are essential in the ocean, serving as micronutrients and tracers of marine biogeochemical processes. Their distributions are strongly influenced by boundaries – regions where physical, chemical, and biological gradients intersect to control redox states, speciation, and particle reactivity. This boundary concept encompasses large-scale interfaces (e.g. atmosphere-ocean, seafloor-ocean, land-ocean), and biogeochemical gradients, including redox fronts, Oxygen Minimum Zone (OMZ) – oxygenated transitions, particle-seawater microenvironments, and organism-associated microscale, where intense exchange is mediated by chemical gradients and biological activity. At large-scale ocean interfaces, inputs from natural and anthropogenic pathways, rapid transformations (oxidation, complexation, adsorption), and burial occur, thereby modulating oceanic TEI residence times. Within the water column, sharp redox boundaries regulate the solubility, mobility, and bioavailability of several TEIs. At the microscale, particle surfaces and organic exudates define reactive microenvironments that control adsorption-desorption dynamics and trace metal speciation. Additionally, the boundary between seawater and microorganism cells control metabolic processes and the internal cycle of TEIs. Recognizing this spectrum of boundaries highlights the interconnected pathways shaping TEI distributions across spatial scales. Integrating processes from global interfaces to microscale gradients is thus essential for predicting how marine TEI cycling responds to climate change and anthropogenic perturbations. This session welcomes field observations, laboratory experiments, and modelling studies to gain further understanding of how different ocean “boundaries” control TEI distributions, as well as studies focused on proxy development for constraining and reconstructing system behavior in both modern and paleo records.

Conveners:
Zhouling Zhang, GEOMAR Helmholtz Centre for Ocean Research Kiel
Nolwenn Lemaitre, Laboratoire d’Etudes en Géophysique et Oceanographie Spatiales
Ryan Cloete, Stellenbosch University
Anh Le-Duy Pham, University of California, Los Angeles
Wen-Hsuan Liao, National Cheng Kung University
Kassandra Costa, Woods Hole Oceanographic Institution
Jennifer L Middleton, Columbia University
Frank Pavia, University of Washington
Kai Deng, Tongji University

09k – Integrating Biological and Geochemical Perspectives on Trace Metal(loid) Transformations Across Ecosystems
Description:
The biogeochemical cycling of trace metal(loid)s in both terrestrial and aquatic environments plays a central role in regulating ecosystem productivity, elemental speciation, and environmental health. Interactions among microbes, minerals, and dissolved species control the transformation, bioavailability, and isotopic signatures of key trace elements, influencing complex biogeochemical feedbacks from local to global scales. Importantly, trace metal(loid) transformations are tightly coupled to the cycling of carbon, sulfur, and other nutrients, linking redox dynamics and microbial metabolism/detoxification processes to broader ecosystem function. This session unites studies that bridge biological and geochemical perspectives on trace metal(loid) cycling across redox gradients and physical scales—from laboratory experiments to field observations and modeling. We invite contributions examining mineral dissolution and precipitation, redox transformations, the formation of reactive organo-mineral complexes, and methylation–demethylation reactions with a focus on elements including, but not limited to, mercury, uranium, arsenic, selenium, manganese, and iron. We particularly welcome approaches integrating isotopic, spectroscopic, imaging, -omics, biosensor, and modeling techniques to advance molecular understanding of trace element dynamics. By linking microbial and geochemical perspectives, this session aims to provide new mechanistic insights into the speciation and environmental fate of trace metal(loid)s in societally important ecosystems including marine waters, groundwater aquifers, agricultural soils (such as rice paddies), and mining-impacted environments.

Conveners:
Matthew Reid, Cornell University
Tim M. Conway, University of South Florida
Jacqueline Gerson, Cornell University
Phoebe Lam, University of California Santa Cruz
Alexandre Poulain, University of Ottawa
Yeala Shaked, Hebrew University