Opal-based isotopic proxies of paleoenvironmental conditions
International audience The delta Si-30 and delta N-15(diatom) of diatom opal provide a view of nutrient utilization in past oceans and are used to formulate and test hypotheses concerning Southern Ocean productivity and fluctuations in atmospheric CO2 over glacial cycles. Water column profiles of th...
Published in: | Global Biogeochemical Cycles |
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ftccsdartic:oai:HAL:hal-00467266v1 2023-05-15T18:25:53+02:00 Opal-based isotopic proxies of paleoenvironmental conditions De La Rocha, Christina Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI) Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) This work was done as a part of EPICA-MIS. 2006-09-20 https://hal.univ-brest.fr/hal-00467266 https://hal.univ-brest.fr/hal-00467266/document https://hal.univ-brest.fr/hal-00467266/file/De_la_Rocha_2006._Opal-based_isotopic_proxies_of_paleoenvironmental_conditions.pdf https://doi.org/10.1029/2005GB002664 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/2005GB002664 hal-00467266 https://hal.univ-brest.fr/hal-00467266 https://hal.univ-brest.fr/hal-00467266/document https://hal.univ-brest.fr/hal-00467266/file/De_la_Rocha_2006._Opal-based_isotopic_proxies_of_paleoenvironmental_conditions.pdf doi:10.1029/2005GB002664 info:eu-repo/semantics/OpenAccess ISSN: 0886-6236 EISSN: 1944-8224 Global Biogeochemical Cycles https://hal.univ-brest.fr/hal-00467266 Global Biogeochemical Cycles, American Geophysical Union, 2006, 20, pp.GB4S09. ⟨10.1029/2005GB002664⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/article Journal articles 2006 ftccsdartic https://doi.org/10.1029/2005GB002664 2021-12-19T03:53:45Z International audience The delta Si-30 and delta N-15(diatom) of diatom opal provide a view of nutrient utilization in past oceans and are used to formulate and test hypotheses concerning Southern Ocean productivity and fluctuations in atmospheric CO2 over glacial cycles. Water column profiles of the Si and N isotopic composition of nutrients and the delta N-15(diatom) of sediment core tops support the use of delta Si-30 and delta N-15(diatom) as tracers of silicic acid and nitrate utilization, but some issues remain concerning the use of these proxies for paleoceanographic reconstructions. If average marine delta Si-30 changes over time, it could contribute to the observed down core variations in delta Si-30. Reconstruction of deepwater delta Si-30 using opal from sponges or deep-dwelling radiolarians would address this concern. Cleaning and measurement methods for delta N-15(diatom) need to be standardized between laboratories and in general suffer from our lack of knowledge of how much organic matter a clean diatom frustule should contain and what its C/N ratio should be. Corresponding shifts in the delta N-15 and C/N of diatom opal with species composition suggests that changes in species composition contributes to the measured down core variations in N and possibly Si as well. This could be due to changes in the ecological niche represented in the sediments or, in the case of N, to species specific fractionation factors. Separation of opal sediments into something more closely resembling monospecific samples is a key development that needs to be made and may be possible using laminar flow systems like "split-flow lateral-transport thin fractionation'' (SPLITT). In the meantime, information on the species composition of each sieved and cleaned sample analyzed needs to be collected alongside the isotopic data. Article in Journal/Newspaper Southern Ocean Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Southern Ocean Global Biogeochemical Cycles 20 4 n/a n/a |
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Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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ftccsdartic |
language |
English |
topic |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
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[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography De La Rocha, Christina Opal-based isotopic proxies of paleoenvironmental conditions |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience The delta Si-30 and delta N-15(diatom) of diatom opal provide a view of nutrient utilization in past oceans and are used to formulate and test hypotheses concerning Southern Ocean productivity and fluctuations in atmospheric CO2 over glacial cycles. Water column profiles of the Si and N isotopic composition of nutrients and the delta N-15(diatom) of sediment core tops support the use of delta Si-30 and delta N-15(diatom) as tracers of silicic acid and nitrate utilization, but some issues remain concerning the use of these proxies for paleoceanographic reconstructions. If average marine delta Si-30 changes over time, it could contribute to the observed down core variations in delta Si-30. Reconstruction of deepwater delta Si-30 using opal from sponges or deep-dwelling radiolarians would address this concern. Cleaning and measurement methods for delta N-15(diatom) need to be standardized between laboratories and in general suffer from our lack of knowledge of how much organic matter a clean diatom frustule should contain and what its C/N ratio should be. Corresponding shifts in the delta N-15 and C/N of diatom opal with species composition suggests that changes in species composition contributes to the measured down core variations in N and possibly Si as well. This could be due to changes in the ecological niche represented in the sediments or, in the case of N, to species specific fractionation factors. Separation of opal sediments into something more closely resembling monospecific samples is a key development that needs to be made and may be possible using laminar flow systems like "split-flow lateral-transport thin fractionation'' (SPLITT). In the meantime, information on the species composition of each sieved and cleaned sample analyzed needs to be collected alongside the isotopic data. |
author2 |
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI) Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) This work was done as a part of EPICA-MIS. |
format |
Article in Journal/Newspaper |
author |
De La Rocha, Christina |
author_facet |
De La Rocha, Christina |
author_sort |
De La Rocha, Christina |
title |
Opal-based isotopic proxies of paleoenvironmental conditions |
title_short |
Opal-based isotopic proxies of paleoenvironmental conditions |
title_full |
Opal-based isotopic proxies of paleoenvironmental conditions |
title_fullStr |
Opal-based isotopic proxies of paleoenvironmental conditions |
title_full_unstemmed |
Opal-based isotopic proxies of paleoenvironmental conditions |
title_sort |
opal-based isotopic proxies of paleoenvironmental conditions |
publisher |
HAL CCSD |
publishDate |
2006 |
url |
https://hal.univ-brest.fr/hal-00467266 https://hal.univ-brest.fr/hal-00467266/document https://hal.univ-brest.fr/hal-00467266/file/De_la_Rocha_2006._Opal-based_isotopic_proxies_of_paleoenvironmental_conditions.pdf https://doi.org/10.1029/2005GB002664 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
ISSN: 0886-6236 EISSN: 1944-8224 Global Biogeochemical Cycles https://hal.univ-brest.fr/hal-00467266 Global Biogeochemical Cycles, American Geophysical Union, 2006, 20, pp.GB4S09. ⟨10.1029/2005GB002664⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2005GB002664 hal-00467266 https://hal.univ-brest.fr/hal-00467266 https://hal.univ-brest.fr/hal-00467266/document https://hal.univ-brest.fr/hal-00467266/file/De_la_Rocha_2006._Opal-based_isotopic_proxies_of_paleoenvironmental_conditions.pdf doi:10.1029/2005GB002664 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/2005GB002664 |
container_title |
Global Biogeochemical Cycles |
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20 |
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4 |
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1766207588374937600 |