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GEOVIDE

by Webmaster Legos last modified Nov 21, 2019 03:12 PM

Published by François Lacan, November 2019


Objectives :

In the Subpolar North Atlantic:
•    Contributing to a better knowledge of the MOC using “non-traditional” tracers
•    Mapping of the Trace Element and Isotope (TEI) distributions
•    Characterization of the TEI sources and sinks and quantification of their fluxes
•    Investigation of the link between TEIs, and production, export and remineralization of particulate organic matter
•    Better understanding of the cycle of TEIs used for paleoreconstruction

 

Scientific Rationale


Trace elements and their isotopes (TEIs) play a crucial role in the ocean and can be used as tracers for past and modern oceanic processes. Studying their biogeochemical cycles has direct implications in diverse research areas such as carbon cycling, climate, ocean ecosystems and environmental contamination. In this context, GEOVIDE proposes to undertake an integrated oceanographic transect in the North Atlantic and Labrador Sea. This area is crucial for the Earth climate and the thermohaline circulation as it represents a major overturning area of the so-called Meridional Overturning Circulation (MOC). Moreover, TEI distribution is poorly constrained in this area. GEOVIDE is an international collaborative program which aims at better constraining the uncertainties on water and heat fluxes across the cruise section, notably by adding information on the deep water mass export and circulation, but also in providing new information on chemical element fluxes. GEOVIDE will allow the quantification of processes that influence the distribution of key TEIs in this area, in particular advective and scavenging processes, biological uptake, exchanges with the margins, and atmospheric deposition.

 

Strategy/organization


GEOVIDE is a multidisciplinary project, coupling geochemistry to physics and biology. It is mainly based on a cruise, carried out on board the R/V Pourquoi Pas?  in June July 2014 (Fig. 1). The project, led by LEMAR and LOPS (Brest) involves a large number of investigators, from 15 laboratories, from 7 countries.

 

Results and perspectives

 

 

Fig. 3 227Ac section along GEOVIDE, with 3 selected 231Pa-227Ac profiles (231Pa from Deng et al.)

 

227Ac activities have been measured along the transect. The 227Ac distribution can be compared to that of its radioactive parent 231Pa (Fig. 3). While both are in secular equilibrium in most part of the water column, especially from the surface to ~2500m, indicating that these waters did not encounter recent (<100 years) lithogenic enrichment, significant discrepancy are evidenced in some places (Le Roy et al a & b in prep).
Iron isotopes are being measured by Jessica Klar. REE concentrations and Nd isotopes are the subject of M. Lagarde's PhD.

 

Participants:

F. Lacan, P. van Beek, C. Jeandel, E. Le Roy, J. Klar, M. Largarde, V. Sanial, C. Pradoux, M. Souhaut, M. Belhadj

 

Collaborations:

LEGOS; LEMAR; LOPS; VUB (Belgium), LSCE, MIT, AWI, WHOI

 

Funding:

INSU, IPEV, ANR, IFREMER 


Peer review articles related to this project:

  • Le Roy E., Sanial V., Lacan F., van Beek P. Souhaut M., Charette M.A., Henderson P.B.. Insight on the measurement of dissolved 227Ac in seawater using Radium Delayed Coincidence Counter. Submitted to Marine Chemistry.
  • Le Roy, E., Sanial, V., Charette, M.A., van Beek, P., Lacan, F., Jacquet, S.H.M., Henderson, P.B., Souhaut, M., García-Ibáñez, M.I., Jeandel, C., Pérez, F.F., Sarthou, G., 2018. The 226Ra–Ba relationship in the North Atlantic during GEOTRACES-GA01. Biogeosciences 15, 3027–3048. https://doi.org/10.5194/bg-15-3027-2018
  • Menzel Barraqueta, J.-L., Schlosser, C., Planquette, H., Gourain, A., Cheize, M., Boutorh, J., Shelley, R., Contreira Pereira, L., Gledhill, M., Hopwood, M.J., Lacan, F., Lherminier, P., Sarthou, G., Achterberg, E.P., 2018. Aluminium in the North Atlantic Ocean and the Labrador Sea (GEOTRACES GA01 section): roles of continental inputs and biogenic particle removal. Biogeosciences 15, 5271–5286. https://doi.org/10.5194/bg-15-5271-2018
  • Sarthou, G., Lherminier, P., Achterberg, E.P., Alonso-Pérez, F., Bucciarelli, E., Boutorh, J., Bouvier, V., Boyle, E.A., Branellec, P., Carracedo, L.I., Casacuberta, N., Castrillejo, M., Cheize, M., Contreira Pereira, L., Cossa, D., Daniault, N., Saint-Léger, E.D., Dehairs, F., Deng, F., Desprez de Gésincourt, F., Devesa, J., Foliot, L., Fonseca-Batista, D., Gallinari, M., García-Ibáñez, M.I., Gourain, A., Grossteffan, E., Hamon, M., Heimbürger, L.E., Henderson, G.M., Jeandel, C., Kermabon, C., Lacan, F., Bot, P.L., Goff, M.L., Roy, E.L., Lefèbvre, A., Leizour, S., Lemaitre, N., Masqué, P., Ménage, O., Menzel Barraqueta, J.-L., Mercier, H., Perault, F., Pérez, F.F., Planquette, H.F., Planchon, F., Roukaerts, A., Sanial, V., Sauzède, R., Shelley, R.U., Stewart, G., Sutton, J.N., Tang, Y., Tisnérat-Laborde, N., Tonnard, M., Tréguer, P., Beek, P. van, Zurbrick, C.M., Zunino, P., 2018. Introduction to the French GEOTRACES North Atlantic Transect (GA01): GEOVIDE cruise. Biogeosciences Discussions 1–24. https://doi.org/10.5194/bg-2018-312
  • Zurbrick, C.M., Boyle, E.A., Kayser, R.J., Reuer, M.K., Wu, J., Planquette, H., Shelley, R., Boutorh, J., Cheize, M., Contreira, L., Menzel Barraqueta, J.-L., Lacan, F., Sarthou, G., 2018. Dissolved Pb and Pb isotopes in the North Atlantic from the GEOVIDE transect (GEOTRACES GA-01) and their decadal evolution. Biogeosciences 15, 4995–5014. https://doi.org/10.5194/bg-15-4995-2018

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