Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography
Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition (δ30Si) of sedimentary biogenic silica has been used to r...
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Copernicus Publications
2012
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00025611 2023-05-15T16:55:52+02:00 Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography Fripiat, F. Cavagna, A.-J. Dehairs, F. de Brauwere, A. André, L. Cardinal, D. 2012-07 electronic https://doi.org/10.5194/bg-9-2443-2012 https://noa.gwlb.de/receive/cop_mods_00025611 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00025566/bg-9-2443-2012.pdf https://bg.copernicus.org/articles/9/2443/2012/bg-9-2443-2012.pdf eng eng Copernicus Publications Biogeosciences -- http://www.bibliothek.uni-regensburg.de/ezeit/?2158181 -- http://www.copernicus.org/EGU/bg/bg.html -- 1726-4189 https://doi.org/10.5194/bg-9-2443-2012 https://noa.gwlb.de/receive/cop_mods_00025611 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00025566/bg-9-2443-2012.pdf https://bg.copernicus.org/articles/9/2443/2012/bg-9-2443-2012.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2012 ftnonlinearchiv https://doi.org/10.5194/bg-9-2443-2012 2022-02-08T22:49:36Z Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition (δ30Si) 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 δ30Si 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 δ30Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ30Si. 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 Niedersächsisches Online-Archiv NOA Southern Ocean Weddell Biogeosciences 9 7 2443 2457 |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Fripiat, F. Cavagna, A.-J. Dehairs, F. de Brauwere, A. André, L. Cardinal, D. Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography |
topic_facet |
article Verlagsveröffentlichung |
description |
Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition (δ30Si) 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 δ30Si 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 δ30Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ30Si. 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. |
format |
Article in Journal/Newspaper |
author |
Fripiat, F. Cavagna, A.-J. Dehairs, F. de Brauwere, A. André, L. Cardinal, D. |
author_facet |
Fripiat, F. Cavagna, A.-J. Dehairs, F. de Brauwere, A. André, L. Cardinal, D. |
author_sort |
Fripiat, F. |
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 |
Copernicus Publications |
publishDate |
2012 |
url |
https://doi.org/10.5194/bg-9-2443-2012 https://noa.gwlb.de/receive/cop_mods_00025611 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00025566/bg-9-2443-2012.pdf https://bg.copernicus.org/articles/9/2443/2012/bg-9-2443-2012.pdf |
geographic |
Southern Ocean Weddell |
geographic_facet |
Southern Ocean Weddell |
genre |
IPY Southern Ocean |
genre_facet |
IPY Southern Ocean |
op_relation |
Biogeosciences -- http://www.bibliothek.uni-regensburg.de/ezeit/?2158181 -- http://www.copernicus.org/EGU/bg/bg.html -- 1726-4189 https://doi.org/10.5194/bg-9-2443-2012 https://noa.gwlb.de/receive/cop_mods_00025611 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00025566/bg-9-2443-2012.pdf https://bg.copernicus.org/articles/9/2443/2012/bg-9-2443-2012.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/bg-9-2443-2012 |
container_title |
Biogeosciences |
container_volume |
9 |
container_issue |
7 |
container_start_page |
2443 |
op_container_end_page |
2457 |
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1766046913223720960 |