Goldschmidt 2022

Goldschmidt is the foremost annual, international conference on geochemistry and related subjects, organized by the Geochemical Society and the European Association of Geochemistry. Given the exceptional circumstances due to the current Covid-19 pandemic, the Goldschmidt2022 Conference will take place in Honolulu and also online.

GEOTRACES and GEOTRACES-related sessions:

12a – The interplay between terrigenous fluxes and the biological pump as reflected by trace elements and their isotopes in the oceans

Conveners:

Adi Torfstein
Hebrew University of Jerusalem

Zanna Chase
Institute for Marine and Antarctic Studies

The importance of the oceanic biological pump as a modulator of atmospheric CO2 levels and global climate cannot be overstated, yet, some fundamental aspects of its dyanamics are still not well understood, such as the quantitative and qualitative impacts of terrigenous inputs into the oceans. These include dust, river outflow, glacial meltwater, submarine groundwater discharge (SGD), and other processes along the margins, all of which impose strong controls over the efficiency of the biological pump. Constraining their rates, sources, sinks and role in biogeochemical cycles is critical for achieving a full understanding of the dynamics of the biological pump.
Here we seek contributions that utilize trace elements and their isotopes to describe the following non-exclusive topics: 1) Quantification and characterization of terrigenous inputs (dust, rivers, SGDs, etc.) into the oceans and their impact on the marine environemnt, 2) Studies of temporal and spatial patterns of terrigenous fluxes and their interplay with marine productivity and export production, 3) Macro and micro scale interactions between terrigenous material and organic carbon, 4) New methodologies and approaches to studying the role of trace elements in the marine biological pump.

The submission of multidisciplinary studies is encouraged, including applications of organic geochemistry, radionuclides, experimental and analytical isotope geochemistry, modeling, and trace element phase partitioning. In addition, we welcome time series –based studies, both in the modern oceans as well as paleo records.

12d – The Role Of Trace Metal Speciation (Physical And Chemical) At Marine Geochemical Interfaces

Conveners:

Catherine Jeandel
LEGOS (Université de Toulouse, CNRS/CNES/IRD/UPS)

Rebecca Zitoun
GEOMAR Helmholtz Centre for Ocean Research Kiel

Hélène Planquette
University Brest, CNRS, IRS

Sylvia Sander
GEOMAR Helmholtz Centre for Ocean Research Kiel

William M. Landing
Florida State University

Andrea Koschinsky
Jacobs University Bremen

Trace metals exhibit a wide range of chemical, physical, and biological reactivities (e.g. oxidation, precipitation, sorption, complexation, toxicity) depending on their chemical and physical speciation (e.g. ions, ion pairs, organic and inorganic complexes, colloids, suspended particles). Thus, the speciation of metals is of great importance not only to substantiate the geochemical fate of trace metals in the world’s ocean but also to estimate their availability and toxicity to marine biota. Geochemical interfaces are of particular interest because they exert a great control on trace metal cycling, fluxes, and rates and a full understanding of trace metal speciation along these boundaries is necessary for a more holistic understanding of the fate of trace metals in the marine environment. However, despite decades of marine trace metal research, we are still lacking knowledge of the speciation along geochemical interfaces (i) in space and time; (ii) the underlying driving processes; and (iii) their role for the global marine biogeochemical element cycles. Geochemical interfaces include sediment-water and atmosphere-water boundaries as well as regions with physicochemical gradients of density, redox conditions, temperature, pH, or salinity, such as hydrothermal systems, ground water discharges, deep sea environments, estuaries, and coastal embayments.

This session brings together transdisciplinary scientists, exploring trace metal speciation at various marine geochemical interfaces. We encourage contributions relating to novel analytical tools, modelling approaches, and laboratory-based experiments.

14b: “Transport of particle-reactive elements from estuaries to open ocean: role of boundary exchange and oceanic internal cycling”

Convenors:
Kai Deng
ETH Zürich

Milena Horvat
Jožef Stefan Institute

Jianghui (JD) Du
ETH Zürich

Igor Živković
Institute Rudjer Bošković
Jožef Stefan Institute

Jennifer L Middleton
Columbia University

Particle-reactive metals such as rare earth elements (REE), thorium (Th), mercury (Hg) etc. and their isotopes are powerful tracers for investigating the ocean biogeochemical cycles and can be applied to track e.g. continental weathering input, transport of water mass and particle flux, and anthropogenic emissions. For their robust applications across space and time, it is crucial to obtain a comprehensive understanding of the physical-chemical processes controlling the behaviors of individual particle-reactive elements; the emphasis is on exchange at ocean interfaces via e.g. rivers, atmospheric fallout and benthic dynamics and on internal cycling via e.g. scavenging and remineralization. Such knowledge based on the modern ocean can: 1) help resolve the long-standing debate arising from conflicting records of multiple particle-reactive isotopic systems in the geological past; 2) predict how anthropogenic emission and climate change scenarios will affect the cycling of key trace metals (e.g. toxic monomethylmercury; MMHg) in marine ecosystems.

This session invites observational, experimental and modelling contributions on the distribution, speciation, flux and controls of particle-reactive metals from estuaries to open ocean, with a particular interest in the interaction between seawater/porewater (including colloids) and lithogenic/biogenic particles. Multi-disciplinary and multi-proxy studies and contributions on advances in geochemical proxy development and in determination of metal speciation are especially welcome. This session focuses on processes and fluxes in the modern oceans, but submissions on paleo-oceanographic and paleo-environmental reconstructions are also welcome. Early career scientists are particularly encouraged to contribute to this session.