July 10 – July 15
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
Hebrew University of Jerusalem
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.
12b – Sources, Distribution and physico-chemical speciation of geochemical tracers in the Indian sector of the Southern Ocean
LEGOS (Université de Toulouse, CNRS/CNES/IRD/UPS)
University Brest, CNRS, IRS
William M. Landing
Florida State University
The Southern Ocean is a key area in terms of climate, but also nutrient distribution. In this context, several recent cruises explored this remote ocean from the south of South Africa and the south of Australia, among them the South West Indian Geotraces Section (SWINGS). The latter is a multidisciplinary 4-year project dedicated to elucidate trace element sources, transformations and sinks along a section crossing key areas of the Southern Ocean (SO) and an important contribution to the international GEOTRACES program (www.geotraces.org). As core action of SWINGS, the SWINGS cruise (R/V Marion-Dufresne, MD229, Geotraces section GS02) started from La Reunion on January 11th 2021 and ended at La Reunion 57 days later (March 8th, 2021).
We invite contributions to this session on the first results of the cruise and other cruises conducted in the Southern Ocean which will contribute to 1) establish the relative importance of sedimentary, atmospheric and hydrothermal sources of trace elements and isotopes (TEIs) in the Indian sector of the SO 2) investigate the drivers of the internal trace element cycles: biogenic uptake, remineralization, particle fate, and export, and 3) quantify TEI transport by the Antarctic Circumpolar Current and the numerous fronts at the confluence between Indian and Atlantic Oceans.
12c – Mercury biogeochemistry, transport, and transformations in the marine environment – filling key knowledge gaps in the frame of the Minamata convention
Jožef Stefan Institute
Institute Rudjer Bošković
Jožef Stefan Institute
Biogeochemical mercury (Hg) cycle is complex and strongly influenced by anthropogenic emissions and natural process of biomethylation that generates toxic monomethylmercury (MMHg). Understanding the mechanisms that drive Hg species dynamics in the coastal and open ocean is of major importance in order to predict how Hg emission and global change scenarios will affect MMHg formation and bioaccumulation in marine ecosystems.
Within this session, we welcome research that:
-fill key knowledge gaps in biogeochemical Hg cycling linking anthropogenic emissions and Hg in marine food webs including modeling of methylation, demethylation, reduction, partitioning and bio-accumulation of Hg in the marine environment,
-improve the understanding of Hg dynamics in coastal and open ocean marine environments,
-assess the origins and transformations of all Hg species in the marine environment
-origin and transformations of methylated Hg,
-characterize the production and the exchange fluxes of gaseous Hg species at the ocean-atmosphere interface,
-investigate reactivity of (terrestrial) Hg and MMHg complexed to DOM along land-to-sea transects,
-address comparable and traceable measurement results of mercury speciation/fractionation in the marine environment,
-novel sensors and passive samplers for mercury speciation in seawater,
-remote sensing and mercury biogeochemical cycle in the marine environment,
-multidimensional isotopic analysis, Hg methylation and MMHg degradation studies,
-oceanographic field campaigns in coastal, shelf, and open ocean environments,
-climate induced changes in the marine food webs: observations and modelling,
-effectiveness evaluation indicators for Minamata Convention.
12d-The role of trace metal speciation (physical and chemical) at marine geochemical interfaces
GEOMAR Helmholtz Centre for Ocean Research Kiel
GEOMAR Helmholtz Centre for Ocean Research Kiel
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”
Jianghui (JD) Du
Jennifer L Middleton
Particle-reactive elements, such as rare earth elements (REEs), Th, Pa, Pb, Po, Be and their isotopes are powerful tracers for investigating the ocean biogeochemical cycles and can be applied to track e.g. continental weathering input, water mass transport and particle flux. 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 also help resolve the long-standing debate arising from conflicting records of multiple particle-reactive isotopic systems in the geological past.
This session invites observational, experimental and modelling contributions on the distribution, flux and controls of particle-reactive elements 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 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.