Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2

Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO 2 by the biological pump. The KEOPS-2 (KErguelen Ocean and Plateau compared Study 2) "process study", took place around the Kerguelen Plateau in the Indian sector o...

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Published in:Biogeosciences
Main Authors: Bowie, A. R., van der Merwe, P., Quéroué, F., Trull, T., Fourquez, M., Planchon, F., Sarthou, G., Chever, F., Townsend, A. T., Obernosterer, I., Sallée, J.-B., Blain, S.
Format: Text
Language:English
Published: 2018
Subjects:
Online Access:https://doi.org/10.5194/bg-12-4421-2015
https://www.biogeosciences.net/12/4421/2015/
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spelling ftcopernicus:oai:publications.copernicus.org:bg27935 2023-05-15T17:02:08+02:00 Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2 Bowie, A. R. van der Merwe, P. Quéroué, F. Trull, T. Fourquez, M. Planchon, F. Sarthou, G. Chever, F. Townsend, A. T. Obernosterer, I. Sallée, J.-B. Blain, S. 2018-09-27 application/pdf https://doi.org/10.5194/bg-12-4421-2015 https://www.biogeosciences.net/12/4421/2015/ eng eng doi:10.5194/bg-12-4421-2015 https://www.biogeosciences.net/12/4421/2015/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bg-12-4421-2015 2019-12-24T09:53:16Z Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO 2 by the biological pump. The KEOPS-2 (KErguelen Ocean and Plateau compared Study 2) "process study", took place around the Kerguelen Plateau in the Indian sector of the Southern Ocean. This is a region naturally fertilised with iron on the scale of hundreds to thousands of square kilometres, producing a mosaic of spring blooms which show distinct biological and biogeochemical responses to fertilisation. This paper presents biogeochemical iron budgets (incorporating vertical and lateral supply, internal cycling, and sinks) for three contrasting sites: an upstream high-nutrient low-chlorophyll reference, over the plateau and in the offshore plume east of the Kerguelen Islands. These budgets show that distinct regional environments driven by complex circulation and transport pathways are responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. Iron supply from "new" sources (diffusion, upwelling, entrainment, lateral advection, atmospheric dust) to the surface waters of the plume was double that above the plateau and 20 times greater than at the reference site, whilst iron demand (measured by cellular uptake) in the plume was similar to that above the plateau but 40 times greater than at the reference site. "Recycled" iron supply by bacterial regeneration and zooplankton grazing was a relatively minor component at all sites (< 8 % of new supply), in contrast to earlier findings from other biogeochemical iron budgets in the Southern Ocean. Over the plateau, a particulate iron dissolution term of 2.5 % was invoked to balance the budget; this approximately doubled the standing stock of dissolved iron in the mixed layer. The exchange of iron between dissolved, biogenic particulate and lithogenic particulate pools was highly dynamic in time and space, resulting in a decoupling of the iron supply and carbon export and, importantly, controlling the efficiency of fertilisation. Text Kerguelen Islands Southern Ocean Copernicus Publications: E-Journals Indian Kerguelen Kerguelen Islands Southern Ocean Biogeosciences 12 14 4421 4445
institution Open Polar
collection Copernicus Publications: E-Journals
op_collection_id ftcopernicus
language English
description Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO 2 by the biological pump. The KEOPS-2 (KErguelen Ocean and Plateau compared Study 2) "process study", took place around the Kerguelen Plateau in the Indian sector of the Southern Ocean. This is a region naturally fertilised with iron on the scale of hundreds to thousands of square kilometres, producing a mosaic of spring blooms which show distinct biological and biogeochemical responses to fertilisation. This paper presents biogeochemical iron budgets (incorporating vertical and lateral supply, internal cycling, and sinks) for three contrasting sites: an upstream high-nutrient low-chlorophyll reference, over the plateau and in the offshore plume east of the Kerguelen Islands. These budgets show that distinct regional environments driven by complex circulation and transport pathways are responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. Iron supply from "new" sources (diffusion, upwelling, entrainment, lateral advection, atmospheric dust) to the surface waters of the plume was double that above the plateau and 20 times greater than at the reference site, whilst iron demand (measured by cellular uptake) in the plume was similar to that above the plateau but 40 times greater than at the reference site. "Recycled" iron supply by bacterial regeneration and zooplankton grazing was a relatively minor component at all sites (< 8 % of new supply), in contrast to earlier findings from other biogeochemical iron budgets in the Southern Ocean. Over the plateau, a particulate iron dissolution term of 2.5 % was invoked to balance the budget; this approximately doubled the standing stock of dissolved iron in the mixed layer. The exchange of iron between dissolved, biogenic particulate and lithogenic particulate pools was highly dynamic in time and space, resulting in a decoupling of the iron supply and carbon export and, importantly, controlling the efficiency of fertilisation.
format Text
author Bowie, A. R.
van der Merwe, P.
Quéroué, F.
Trull, T.
Fourquez, M.
Planchon, F.
Sarthou, G.
Chever, F.
Townsend, A. T.
Obernosterer, I.
Sallée, J.-B.
Blain, S.
spellingShingle Bowie, A. R.
van der Merwe, P.
Quéroué, F.
Trull, T.
Fourquez, M.
Planchon, F.
Sarthou, G.
Chever, F.
Townsend, A. T.
Obernosterer, I.
Sallée, J.-B.
Blain, S.
Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
author_facet Bowie, A. R.
van der Merwe, P.
Quéroué, F.
Trull, T.
Fourquez, M.
Planchon, F.
Sarthou, G.
Chever, F.
Townsend, A. T.
Obernosterer, I.
Sallée, J.-B.
Blain, S.
author_sort Bowie, A. R.
title Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
title_short Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
title_full Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
title_fullStr Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
title_full_unstemmed Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2
title_sort iron budgets for three distinct biogeochemical sites around the kerguelen archipelago (southern ocean) during the natural fertilisation study, keops-2
publishDate 2018
url https://doi.org/10.5194/bg-12-4421-2015
https://www.biogeosciences.net/12/4421/2015/
geographic Indian
Kerguelen
Kerguelen Islands
Southern Ocean
geographic_facet Indian
Kerguelen
Kerguelen Islands
Southern Ocean
genre Kerguelen Islands
Southern Ocean
genre_facet Kerguelen Islands
Southern Ocean
op_source eISSN: 1726-4189
op_relation doi:10.5194/bg-12-4421-2015
https://www.biogeosciences.net/12/4421/2015/
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container_title Biogeosciences
container_volume 12
container_issue 14
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op_container_end_page 4445
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