GEOTRACES sessions at Goldschmidt 2017

Goldschmidt 2017

13 – 18 August 2017, Paris, France

Abstract submission deadline: 1st April 2017

GEOTRACES and GEOTRACES-relevant sessions:

10i: Cycles of Trace Elements and Isotopes in the Ocean: GEOTRACES and Beyond

Convenors: Tim Conway, Geraldine Sarthou, Tianyu Chen, Gregory de Souza, Aridane G. González, Kristen Buck, Tina van de Flierdt, Walter Geibert, Zhimian Cao, Catherine Jeandel

Trace elements and their isotopes (TEIs) in the ocean are critical for marine life, regulating ocean biogeochemistry and carbon cycling. TEI distributions also provide insight into ocean ventilation and circulation, redox states, productivity and hydrothermal inputs in the present and the past. The GEOTRACES program, which aims to map the world’s oceans for TEIs, has facilitated rapid progress, enabling a coherent picture of TEI cycling to emerge. Accordingly, in celebration of the launch of the GEOTRACES IDP 2017 at Goldschmidt, this session aims to bring together studies addressing pressing questions in marine biogeochemistry. We invite submissions on a range of marine biogeochemical themes: (1) Comparing the distribution, isotopic composition and speciation of the trace metals (Fe, Zn, Cd, Ni, Cu, Ba) with the major nutrients (e.g. C, N, Si) in order to draw parallels and contrasts, and especially to determine the role of the Southern Ocean in creating pre-formed signatures. (2) Investigating the oceanic distribution, composition and interactions of TEI-binding organic ligands, and their role in metal redox cycling, distribution and speciation. (3) Investigating how interactions with oceanic boundaries (sediments, hydrothermal vents, atmosphere), and abiotic/biotic internal cycling influence the distribution of oceanic TEIs, and investigating TEIs which trace rates and particle scavenging. (4) Integrating multi-proxy GEOTRACES datasets including circulation tracers in order to address longstanding questions in biogeochemistry and paleooceanographic proxy calibrations. We encourage submissions with culture and modeling work to interpret TEI distributions, as well as submissions combining interactions of different phases (e.g. particulate and dissolved) and multi-element datasets.

10o: The Role of Scavenging in the Ocean: Chemical Processes, Environmental Controls and Modeling

Convenors: Yves Plancherel, Phoebe Lam

One of the most important process influencing the distribution of elements in the sea is “scavenging”; that is the propensity for dissolved species to stick to particles and sink along with them. New data, emerging as part of GEOTRACES and other efforts, are making it clear that scavenging is a first-order control in coastal, surface, deep and benthic ocean systems. Scavenging is an important process because it is omnipresent (particles are everywhere) and because it can remove, redistribute and fractionate elements within the ocean interior. Unfortunately, the process of scavenging is presently not well understood chemically, particles in seawater are not well characterized and the overall importance of scavenging is difficult to quantify. We are here interested in showcasing studies about all aspects of scavenging, on a multitude of time and space scales, from the open ocean to estuarine settings, to provide a broad overview of the many facets of scavenging and to bring together scientists working on this issue. We invite submissions focusing on the chemical processes involved in scavenging, on the influence of particle composition and particulate fluxes, on investigating the influence of scavenging on modern and past elemental cycles and on modeling particle dynamics and scavenging generally.

10g: Submarine Groundwater Discharge: Forms, Delivery, Timing, Processes, Pathways and Scaling of Biogeochemical Fluxes

Convenors: Hans Dürr, Nils Moosdorf, Michael Böttcher, Hannelore Waska, Jing Zhang, Walter Geibert

Submarine groundwater discharge (SGD) is now an established factor in marine budgets of nutrients as well as trace elements and their isotopes (TEIs). SGD can form subterranean estuaries (STE) where fresh meteoric groundwater mixes with seawater circulating in the sediment. Processes in the STE and at the sediment-water interface strongly influence the resulting net fluxes to the near-shore. The magnitude, speciation and spatial variability of these diffuse biogeochemical inputs can have multiple impacts on biological activity in coastal environments and marginal seas, many of which are considered key areas for regional GEOTRACES projects. However, the temporal and spatial dynamics of processes determining SGD/STE biogeochemistry are poorly understood, attempts of upscaling SGD for regional- to continental budgets have been difficult, and lag behind the development of large-scale hydrogeological models of SGD. We invite contributions by geochemists, hydrogeologists, biologists and geophysicists related to: biogeochemistry (experimental and modeling) of SGD/STE from deep aquifers to the sediment-water interface with regards to distribution, speciation and function of constituents; the dynamics of key biotic and abiotic processes in the STE; resulting net fluxes of SGD of nutrients, micronutrients and tracers in the near-shore and in marginal seas; the behavior of particulates and their associated TEI distributions along coastal circulation and land-ocean gradients; approaches and strategies that connect multiple temporal and spatial scales. Studies related to regional anthropogenic effects and climate change are also welcome. We expect this session to facilitate joint investigations and cooperation of the regional terrestrial, marine biogeochemical and ocean/environmental sciences community.

10h: Non-Conventional Stable Isotopes in the Ocean: Novel Applications, Technological Advances and Future Applications

Convenors: Tristan Horner, Christopher Pearce, Philip Pogge von Strandmann, Kathleen Scheiderich, Juan Carlos Silva-Tamayo

The past twenty years have seen an explosion of interest in using non-conventional stable isotope systems (‘non-CHONS’) to understand the relationships between—and temporal evolution of—the input, internal cycling, and output of chemical species from the ocean. These isotope systems have proved to be key tracers of Earth’s biogeochemical cycles, and have provided important breakthroughs in our understanding of chemical fluxes across the major ocean boundaries (e.g. rivers, atmosphere, boundary exchange, hydrothermal vents) as well as (bio)geochemical processes operating within the ocean (e.g. biological uptake and release, speciation, scavenging). This session invites contributions that offer novel perspectives using non-conventional isotope systems and the processes that control their cycling between Earth’s major reservoirs in modern and/or past settings. Submissions that present new analytical tools or experiment-based approaches for studying the mechanisms of elemental and isotope fractionation during mineral-fluid interactions, redox transformations, or biological cycling are strongly encouraged, as are those that demonstrate how these techniques can be used to quantify the flux and internal cycling of chemical species in the ocean through time. We also welcome contributions that offer novel perspectives by synthesizing existing data into new conceptual models, or use isotopic tracer-based approaches to aid constraint of the fluxes of other biogeochemically-cycled elements, particularly those that integrate over a wide range of spatial and temporal scales.

10k: Atmosphere-Ocean Interactions and Impacts on Ocean Chemistry and Biology

Convenors: Adi Torfstein, Sophie Bonnet, Eyal Rahav, William Landing

Many aquatic ecosystems worldwide are frequently subjected to high inputs of wet and dry atmospheric dust. Settling aerosols provide dissolved and particulate constituents to the surface oceans, including inorganic nutrients and organic matter required for sustaining productivity, and supply toxic metals and other pollutants, as well as a wide array of viable airborne microorganisms such as bacteria, fungi and viruses. These inputs may greatly affect marine ecosystem dynamics, which in turn impose strong constraints on global climate changes. The impacts may vary based on the aerosol load and source, and its mineralogical, chemical and biological characteristics. We welcome contributions studying the effects of aerosols on aquatic systems, in particular interdisciplinary studies that target the interplay between inorganic and organic phases, as well as the interactions between aerosols and phytoplankton or heterotrophic bacteria. Approaches may include in situ observations, laboratory experiments and modeling.

10m: Insights into Ocean Processes Through the Application of Radioactive Tracers

Convenors: Paul Morris, Guizhi Wang, Virginie Sanial

The use of radioactive tracers to investigate ocean processes is an increasingly mainstream component of the techniques available to marine chemists. This so-called “nuclear toolbox” has seen continued development, from better sampling and measurement technology to smaller sample volumes, which has opened new avenues of investigation for studying ocean processes. While many of these radioactive tracers occur naturally in the environment, ocean scientists can also use radioactive tracers released through human activities via intentional releases and accidental events. These radioactive tracers can be applied to a range of time-scales in both local case studies and basin-scale investigations that target both boundary and open-ocean processes. This session welcomes submissions that use radioactive tracers as a primary tool to investigate: (1) fluxes of particulate matter and dissolved materials, (2) water mass mixing and mixing rates, (3) processes that occur at the ocean boundaries (including coastline, seabed, and surface), and (4) studies that attempt to constrain geochemical budgets. Contributions that address method development, novel applications of well-established tracers to new systems, transport and fates of anthropogenic radionuclides in the ocean, and issues that arise from the inherent integrating properties of radioactive tracers are also welcomed.

10n: Nutrient Biogeochemistry in the Ocean: Past, Present and Future

Convenors: Scott Wankel, Sinhué Torres-Valdés, Christian März, Damien Cardinal, Wiebke Mohr, C. Mark Moore, Francois Fripiat, Xingchen Wang, Jia-Zhong Zhang

The availability of nutrients, specifically nitrogen (N), phosphorus (P) and silicon (Si), exerts strong control on net primary production in the oceans, the efficiency of carbon export from the euphotic zone, and even the composition of the atmosphere. While the cycling of these elements is intimately coupled, each elemental cycle possesses distinct characteristics regarding oceanic sources and sinks, modes of internal recycling, residence times and bioavailability. Indeed, dynamics of individual nutrients diverge in important ways, leading to formation of distinct regimes in both modern and past ocean systems. For example, our understanding of specific processes (such as N2 fixation) has greatly expanded over the past two decades including delineation of new habitats, description of new organisms, and identification of new lifestyles. Nevertheless, the relative roles of specific groups in various regions of the ocean, their spatial and temporal variability, and factors influencing their activity and distribution remain unclear. Furthermore, while clear changes are often observed in response to contemporary climate change (including ocean warming, acidification and deoxygenation), responses to such alterations and consequences for ecosystem functioning are far from understood. This session brings together new analytical and modeling insights to marine environments advancing our fundamental understanding of nutrients and their importance to the Earth system of the past, present and future. We encourage submissions highlighting novel approaches (especially application of natural abundance and tracer-level stable isotopes) and those dealing with inter-elemental (de)coupling, multiple spatial scales (cells to oceans), and/or multiple temporal scales – from geologic past to the future.