Research project SD/CA/05A (Research action SD)
Context
Our perception of the Southern Ocean’s (SO) role as source-sink of atmospheric CO2 and other climate gases has significantly changed in the past years because more observational data and model results have become available. Source-sink strengths are now perceived as more seasonally, inter-annually and spatially variable. Model studies and observations stress the significance of the biological C pump in contributing to CO2 uptake by the SO, and unraveling these intimate links between CO2 sink strength and fate of carbon is critical to assess the ocean’s C sequestration capacity. In particular it is critical to understand the significance of natural Fe fertilization in margin systems and sea ice environments, as well as the role of sea ice biota and associated biogeochemical processes on climate gases production/uptake and carbon export to the underlying water column.
Project Description
Objectives
Sound knowledge of the complex processes controlling the exchanges of carbon and other climate gases between functionally differing SO systems (margin impacted systems, open-ocean, sea ice covered systems) and the atmosphere is critically needed. It is crucial to understand and predict spatial and temporal variability of these processes in order to achieve a realistic integrated view of the SO’s role as sink-source of climate gases and to evaluate the efficiency of carbon sequestration and its evolution in a changing climate.
Therefore, this project focuses on the following key questions: (1) What is the significance of sea ice physical and biogeochemical processes on atmosphere - ocean fluxes of climate gases (CO2, DMS, CH4, N2O) and fluxes of matter (carbon, macro- and micro-nutrients) to the water column? (2) Can we reconstruct paleo-sea ice extension based on sedimentary records and sound knowledge of sea ice biological and physico-chemical processes? (3) How are formation rate, composition, lability and sinking speed of marine biogenic particles related to planktonic community structure and trophic interactions and how do margin systems open ocean and sea ice covered systems, which differ in Fe availability, compare? (4) What are the physical and ecosystem conditions and pathways that lead either to shallow remineralisation or to deep export of organic matter produced in seaice and surface waters? (5) What is the impact of these processes on water column nutrient ratios and nutrient distribution in the Global Ocean?
Methodology
Practically, in order to assess fluxes of carbon and nutrients (N, Si), which are essential components of the biopump, the consortium has developed a unique integrated approach based on key stable isotopes and proxy techniques as well as modeling. This tool-box will be applied in contrasting but representative functional entities of the SO: the Fe-deficient high nutrient low chlorophyll open circumpolar ocean; the Fe-replete areas in vicinity of margins and plateaus (KEOPS 2, Kerguelen Plateau area; 2011) and the sea ice zone (ISPOL2, 2013; YROSIAE, 2011-2013; SIPEX2, Australian sector, 2012).
Interaction between the different partners
To achieve the above stated goals and challenges, this project integrates expertise of a triumvirate of modelers (H. Goosse, UCL; M. Vancoppenolle, UCL; B. Barnier, LEGI Grenoble); biogeochemists (F. Dehairs, VUB; L. André RMCA; B. Delille, ULg; F; Fripiat, ULB) and glaciologists (J.-L. Tison, ULB), that will be used for further interpretation of existing data gathered during previous projects and expeditions and also, importantly, for additional, focused, field studies.
Link International Programmes
The BIGSOUTH project has close links with the following international programmes: GEOTRACES,IMBER, SOLAS, SCAR-ASPeCt, ICED
Expected Results
Broad deliverables of the project will be: (i) an assessment of the physical and biogeochemical processes in sea ice and their impact on exchange of climate gases between ocean and atmosphere and on fluxes and isotopic signature of matter exchanged with the water column and the sediment; (ii) a comparative assessment of the functioning of the carbon biopump for different oceanic functional entities (sea-ice zones, open-ocean zones, margin areas); (iii) an integrated assessment of the deep ocean carbon sequestration magnitude and efficiency (relative to primary production); (iv) an assessment of the impact of biopump processes on nutrient distributions and nutrient ratios in the deep ocean waters, which affect future production once upwelling in the surface; (v) a robust, up to date, sea-ice biogeochemical model for integration in widely used ocean biogeochemistry general circulation models (OPA-LIM-PISCES).
Partners
Activities
Frank Dehairs, Vrije Universiteit Brussel: Biopump processes and impact on C, N fluxes
Jean-Louis Tison, Université Libre de Bruxelles: Physical-biological controls of sea-ice on climate gas fluxes
François Fripiat, Université Libre de Bruxelles: N and Si cycling within and below sea-ice and impact on δ30Si and δ15N proxies
Luc André; Royal Museum for Central Africa: Impact of sea-ice processes on δ30Si proxy
Hugues Goosse & M. Vancoppenolle; Université catholique de Louvain: 3D modeling of ocean and sea-ice biogeochemistry
Bruno Delille; Université de Liège: Sea ice physical-biogeochemical controls on climate gas fluxes; brine carbonate system
Véronique Schoemann; Stichting Koninklijk Nederlands Instituut voor Zeeonderzoek (NIOZ): Trace metal bio-availibility
Bernard Barnier, Laboratoire des Ecoulements Géophysiques et Industriels (LEGI): 3D modeling of ocean and sea-ice biogeochemistry
Contact information
Dehairs Frank, Vrije Universiteit Brussel, Analytical and Environmental Chemistry dept and Earth System Sciences research group; Tel: +32 2 629 1265; Fax: +32 2 629 1811; e-mail: fdehairs@vub.ac.be
Jean-Louis Tison and François Fripiat, Université Libre de Bruxelles
Tel: +32 2 650 22 25
Fax: +32 2 650 22 26
e-mail: jtison@ulb.ac.be
Luc André, Royal Museum for Central Africa
Tel: 02-7695459
Fax: 02-7695432
e-mail: lucandre@africamuseum.be
Hugues Goosse and Martin Vancoppenolle, Université catholique de Louvain
Tel: 010 47 32 98
Fax: 010 47 47 22
email: hugues.goosse@uclouvain.be
Martin.Vancoppenolle@uclouvain.be
Bruno Delille, Université de Liège
Tel: 04 366 31 87
Fax: 04 366 33 67
e-mail: Bruno.Delille@ulg.ac.be
Véronique Schoemann, Stichting Koninklijk Nederlands Instituut voor Zeeonderzoek (NIOZ); e-mail: Veronique.Schoemann@nioz.nl
Bernard Barnier, Laboratoire des Ecoulements Géophysiques et Industriels, BP53, 38041, Grenoble cedex 9, France ; LEGI, CNRS ;
e-mail : bernard.barnier@legi.grenoble-inp.fr
Follow-up Committee
T.W. Trull: Associate Professor in Biogeochemistry at the Institute of Antarctic and Southern Ocean Studies, University of Tasmania; Project leader within Antarctic Climate and Ecosystem Cooperative Research Center (ACE-CRC.
D. Cardinal: Professor at Université Pierre et Marie Curie (Paris VI), dept. LOCEAN.
M. Sigman: Professor of Geological and Geophysical Sciences at the dept. Of Geosciences, Princeton University.
G. Dieckmann: Senior research officer at AWI (Alfred Wegener Institute for Polar- und Meeres Forschung).
L. Bopp: CNRS Research Scientist at the LSCE (Laboratoire des Sciences du Climat et de l’Environnement, Gif-sur-Yvette, France).
Biogeochemical cycles in the Southern Ocean: Role within the Earth system (BIGSOUTH) : final Report
Dehairs, Frank - Tison, Jean-Louis - Fripiat, François ... et al. Brussels : Belgian Science Policy, 2017 (SP2668)
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