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Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 12
Biogeosciences, 12, 3869–3883, 2015
https://doi.org/10.5194/bg-12-3869-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: KEOPS2: Kerguelen Ocean and Plateau Study 2

Biogeosciences, 12, 3869–3883, 2015
https://doi.org/10.5194/bg-12-3869-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 25 Jun 2015

Research article | 25 Jun 2015

High variability in dissolved iron concentrations in the vicinity of the Kerguelen Islands (Southern Ocean)

F. Quéroué1,2,3,4, G. Sarthou2, H. F. Planquette2, E. Bucciarelli1,2, F. Chever2, P. van der Merwe4, D. Lannuzel3,4, A. T. Townsend5, M. Cheize2, S. Blain6,7, F. d'Ovidio8, and A. R. Bowie3,4 F. Quéroué et al.
  • 1Université de Bretagne Occidentale, IUEM, 29200 Brest, France
  • 2LEMAR-UMR 6539, CNRS-UBO-IRD-IFREMER, Place Nicolas Copernic, 29280 Plouzané, France
  • 3Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001, Australia
  • 4Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, TAS 7001, Australia
  • 5Central Science Laboratory, University of Tasmania, Hobart, TAS 7001, Australia
  • 6Laboratoire Océanographie Biologique de Banyuls sur Mer, Université Pierre et Marie Curie, Paris 06, quai Fontaulé, 66650 Banyuls sur Mer, France
  • 7Laboratoire Océanographie Biologique de Banyuls sur Mer, CNRS, Paris 06, quai Fontaulé, 66650 Banyuls sur Mer, France
  • 8Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, LOCEAN-IPSL, 4 place Jussieu, 75005 Paris, France

Abstract. Dissolved Fe (dFe) concentrations were measured in the upper 1300 m of the water column in the vicinity of the Kerguelen Islands as part of the second KErguelen Ocean Plateau compared Study (KEOPS2). Concentrations ranged from 0.06 nmol L−1 in offshore, Southern Ocean waters to 3.82 nmol L−1 within Hillsborough Bay, on the north-eastern coast of the Kerguelen Islands. Direct island runoff, glacial melting and resuspended sediments were identified as important inputs of dFe that could potentially fertilise the northern part of the plateau. A significant deep dFe enrichment was observed over the plateau with dFe concentrations increasing up to 1.30 nmol L−1 close to the seafloor, probably due to sediment resuspension and pore water release. Biological uptake was shown to induce a significant decrease in dFe concentrations between two visits (28 days apart) at a station above the plateau. Our work also considered other processes and sources, such as lateral advection of enriched seawater, remineralisation processes, and the influence of the polar front (PF) as a vector for Fe transport. Overall, heterogeneous sources of Fe over and off the Kerguelen Plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.

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Dissolved Fe (dFe) concentrations were measured in the vicinity of the Kerguelen Islands. Direct island runoff, glacial melting, and resuspended sediments were identified as important inputs of dFe that could potentially fertilise the northern part of the plateau. Overall, heterogeneous sources of Fe over and off the plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.
Dissolved Fe (dFe) concentrations were measured in the vicinity of the Kerguelen Islands. Direct...
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