Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean
In wide parts of the ocean, iron is a limiting element for phytoplankton growth due to its very low dissolved concentrations. It is thus a fundamental element of the global carbon cycle and climate. However, its cycle is still not well known. We thus used iron isotopes in order to better constrain i...
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Other Authors: | , , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
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HAL CCSD
2014
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Subjects: | |
Online Access: | https://theses.hal.science/tel-01221871 https://theses.hal.science/tel-01221871/document https://theses.hal.science/tel-01221871/file/Cyril%20Abadie_%20thesis.pdf |
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ftunivnantes:oai:HAL:tel-01221871v1 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
French |
topic |
Geochemistry Isotope iron cycle carbon cycle Phytoplankton Climate southern ocean Geochimie cycle du fer cycle du carbonne Phytoplancton Climat ocean austral GEOTRACES [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
Geochemistry Isotope iron cycle carbon cycle Phytoplankton Climate southern ocean Geochimie cycle du fer cycle du carbonne Phytoplancton Climat ocean austral GEOTRACES [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Abadie, Cyril Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
topic_facet |
Geochemistry Isotope iron cycle carbon cycle Phytoplankton Climate southern ocean Geochimie cycle du fer cycle du carbonne Phytoplancton Climat ocean austral GEOTRACES [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
In wide parts of the ocean, iron is a limiting element for phytoplankton growth due to its very low dissolved concentrations. It is thus a fundamental element of the global carbon cycle and climate. However, its cycle is still not well known. We thus used iron isotopes in order to better constrain its cycle in the Southern Ocean. Our measurement of iron isotopic compositions allowed us to characterize each iron source in this area, but also to evidence processes that we could not have evidenced using iron concentrations only. We have shown that the non reductive release of dissolved iron from the South African margin sediments is a major source of dissolved iron in the vicinity of this margin. A hydrothermal contribution above the mid-oceanic ridge, and lithogenic inputs of different origins in the Weddell Gyre compared to the rest of the section have been characterized. We have estimated the isotopic fractionation factors associated to key processes of the iron cycle, notably in surface waters for the biological uptake of iron by phytoplankton, at intermediate depths for the organic matter remineralization, and in deeper samples for the sorption processes. Our results suggest that the main process releasing dissolved iron in the deep ocean is iron desorption from inorganic particles, contrary to the commonly accepted hypothesis according to which it would be in situ organic matter remineralization. Dans certaines parties de l’océan, le fer est un élément limitant pour la croissance du phytoplancton en raison de ses très faibles concentrations. C’est donc un élément fondamental pour le cycle global du carbone, et par conséquent le climat. Cependant, son cycle est encore mal connu. Nous avons donc utilisé les isotopes du fer afin de mieux contraindre son cycle dans l’océan Austral. Les compositions isotopiques obtenues nous ont permis de caractériser chaque source de fer dans cette zone, mais également de mettre en évidence des processus que nous n’aurions pas pu repérer en utilisant seulement les ... |
author2 |
Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Universite Toulouse III Paul Sabatier Lacan Francois Poitrasson Franck |
format |
Doctoral or Postdoctoral Thesis |
author |
Abadie, Cyril |
author_facet |
Abadie, Cyril |
author_sort |
Abadie, Cyril |
title |
Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
title_short |
Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
title_full |
Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
title_fullStr |
Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
title_full_unstemmed |
Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean |
title_sort |
iron isotopes as tracers of the iron cycle in the atlantic sector of the southern ocean |
publisher |
HAL CCSD |
publishDate |
2014 |
url |
https://theses.hal.science/tel-01221871 https://theses.hal.science/tel-01221871/document https://theses.hal.science/tel-01221871/file/Cyril%20Abadie_%20thesis.pdf |
geographic |
Austral Southern Ocean Weddell |
geographic_facet |
Austral Southern Ocean Weddell |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
https://theses.hal.science/tel-01221871 Océan, Atmosphère. Universite Toulouse III Paul Sabatier, 2014. Français. ⟨NNT : ⟩ |
op_relation |
tel-01221871 https://theses.hal.science/tel-01221871 https://theses.hal.science/tel-01221871/document https://theses.hal.science/tel-01221871/file/Cyril%20Abadie_%20thesis.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766206327696130048 |
spelling |
ftunivnantes:oai:HAL:tel-01221871v1 2023-05-15T18:25:07+02:00 Iron isotopes as tracers of the iron cycle in the Atlantic sector of the Southern ocean Les isotopes du fer comme traceurs du cycle du fer dans le secteur Atlantique de l’océan Austral Abadie, Cyril Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Universite Toulouse III Paul Sabatier Lacan Francois Poitrasson Franck 2014-11-25 https://theses.hal.science/tel-01221871 https://theses.hal.science/tel-01221871/document https://theses.hal.science/tel-01221871/file/Cyril%20Abadie_%20thesis.pdf fr fre HAL CCSD tel-01221871 https://theses.hal.science/tel-01221871 https://theses.hal.science/tel-01221871/document https://theses.hal.science/tel-01221871/file/Cyril%20Abadie_%20thesis.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01221871 Océan, Atmosphère. Universite Toulouse III Paul Sabatier, 2014. Français. ⟨NNT : ⟩ Geochemistry Isotope iron cycle carbon cycle Phytoplankton Climate southern ocean Geochimie cycle du fer cycle du carbonne Phytoplancton Climat ocean austral GEOTRACES [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2014 ftunivnantes 2023-02-22T10:38:11Z In wide parts of the ocean, iron is a limiting element for phytoplankton growth due to its very low dissolved concentrations. It is thus a fundamental element of the global carbon cycle and climate. However, its cycle is still not well known. We thus used iron isotopes in order to better constrain its cycle in the Southern Ocean. Our measurement of iron isotopic compositions allowed us to characterize each iron source in this area, but also to evidence processes that we could not have evidenced using iron concentrations only. We have shown that the non reductive release of dissolved iron from the South African margin sediments is a major source of dissolved iron in the vicinity of this margin. A hydrothermal contribution above the mid-oceanic ridge, and lithogenic inputs of different origins in the Weddell Gyre compared to the rest of the section have been characterized. We have estimated the isotopic fractionation factors associated to key processes of the iron cycle, notably in surface waters for the biological uptake of iron by phytoplankton, at intermediate depths for the organic matter remineralization, and in deeper samples for the sorption processes. Our results suggest that the main process releasing dissolved iron in the deep ocean is iron desorption from inorganic particles, contrary to the commonly accepted hypothesis according to which it would be in situ organic matter remineralization. Dans certaines parties de l’océan, le fer est un élément limitant pour la croissance du phytoplancton en raison de ses très faibles concentrations. C’est donc un élément fondamental pour le cycle global du carbone, et par conséquent le climat. Cependant, son cycle est encore mal connu. Nous avons donc utilisé les isotopes du fer afin de mieux contraindre son cycle dans l’océan Austral. Les compositions isotopiques obtenues nous ont permis de caractériser chaque source de fer dans cette zone, mais également de mettre en évidence des processus que nous n’aurions pas pu repérer en utilisant seulement les ... Doctoral or Postdoctoral Thesis Southern Ocean Université de Nantes: HAL-UNIV-NANTES Austral Southern Ocean Weddell |