Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography
International audience Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO 2 variation. In this context, the natural silicon isotopic composition (δ 30 Si) of sedimentary biogenic...
Published in: | Biogeosciences |
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Main Authors: | , , , , , |
Other Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2012
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257/document https://hal.archives-ouvertes.fr/hal-01138257/file/bg-9-2443-2012.pdf https://doi.org/10.5194/bg-9-2443-2012 |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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language |
English |
topic |
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] |
spellingShingle |
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] Fripiat, François Cavagna, Anne-Julie Dehairs, Frank De Brauwere, Anouk André, Luc Cardinal, Damien Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
topic_facet |
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] |
description |
International audience Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO 2 variation. In this context, the natural silicon isotopic composition (δ 30 Si) of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (Bonus-GoodHope) which includes for the first time summer δ 30 Si signatures of suspended biogenic silica (i) for the whole water column at three stations and (ii) in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation) should satisfactorily describe the δ 30 Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ 30 Si. The failures of previous models (Rayleigh and steady state) become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1) a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2) a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large vertical silicic acid gradient, e.g. in the Polar Front Zone and at the Polar Front. |
author2 |
Royal Museum for Central Africa Tervuren (RMCA) Université libre de Bruxelles (ULB) Vrije Universiteit Brussel (VUB) Université Catholique de Louvain = Catholic University of Louvain (UCL) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS Paris) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Fripiat, François Cavagna, Anne-Julie Dehairs, Frank De Brauwere, Anouk André, Luc Cardinal, Damien |
author_facet |
Fripiat, François Cavagna, Anne-Julie Dehairs, Frank De Brauwere, Anouk André, Luc Cardinal, Damien |
author_sort |
Fripiat, François |
title |
Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
title_short |
Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
title_full |
Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
title_fullStr |
Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
title_full_unstemmed |
Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
title_sort |
processes controlling the si-isotopic composition in the southern ocean and application for paleoceanography |
publisher |
HAL CCSD |
publishDate |
2012 |
url |
https://hal.archives-ouvertes.fr/hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257/document https://hal.archives-ouvertes.fr/hal-01138257/file/bg-9-2443-2012.pdf https://doi.org/10.5194/bg-9-2443-2012 |
geographic |
Southern Ocean Weddell |
geographic_facet |
Southern Ocean Weddell |
genre |
IPY Southern Ocean |
genre_facet |
IPY Southern Ocean |
op_source |
ISSN: 1726-4170 EISSN: 1726-4189 Biogeosciences https://hal.archives-ouvertes.fr/hal-01138257 Biogeosciences, European Geosciences Union, 2012, 9 (7), pp.2443-2457. ⟨10.5194/bg-9-2443-2012⟩ |
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info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-9-2443-2012 hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257/document https://hal.archives-ouvertes.fr/hal-01138257/file/bg-9-2443-2012.pdf doi:10.5194/bg-9-2443-2012 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/bg-9-2443-2012 |
container_title |
Biogeosciences |
container_volume |
9 |
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7 |
container_start_page |
2443 |
op_container_end_page |
2457 |
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1766046918784319488 |
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ftccsdartic:oai:HAL:hal-01138257v1 2023-05-15T16:55:52+02:00 Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography Fripiat, François Cavagna, Anne-Julie Dehairs, Frank De Brauwere, Anouk André, Luc Cardinal, Damien Royal Museum for Central Africa Tervuren (RMCA) Université libre de Bruxelles (ULB) Vrije Universiteit Brussel (VUB) Université Catholique de Louvain = Catholic University of Louvain (UCL) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS Paris) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) 2012 https://hal.archives-ouvertes.fr/hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257/document https://hal.archives-ouvertes.fr/hal-01138257/file/bg-9-2443-2012.pdf https://doi.org/10.5194/bg-9-2443-2012 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-9-2443-2012 hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257 https://hal.archives-ouvertes.fr/hal-01138257/document https://hal.archives-ouvertes.fr/hal-01138257/file/bg-9-2443-2012.pdf doi:10.5194/bg-9-2443-2012 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess ISSN: 1726-4170 EISSN: 1726-4189 Biogeosciences https://hal.archives-ouvertes.fr/hal-01138257 Biogeosciences, European Geosciences Union, 2012, 9 (7), pp.2443-2457. ⟨10.5194/bg-9-2443-2012⟩ [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] info:eu-repo/semantics/article Journal articles 2012 ftccsdartic https://doi.org/10.5194/bg-9-2443-2012 2021-11-21T02:58:55Z International audience Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO 2 variation. In this context, the natural silicon isotopic composition (δ 30 Si) of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (Bonus-GoodHope) which includes for the first time summer δ 30 Si signatures of suspended biogenic silica (i) for the whole water column at three stations and (ii) in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation) should satisfactorily describe the δ 30 Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ 30 Si. The failures of previous models (Rayleigh and steady state) become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1) a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2) a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large vertical silicic acid gradient, e.g. in the Polar Front Zone and at the Polar Front. Article in Journal/Newspaper IPY Southern Ocean Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Southern Ocean Weddell Biogeosciences 9 7 2443 2457 |