Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic
The Subpolar North Atlantic, being a region of deep water mass formation, is a key region for the global thermohaline circulation and is thus sensitive to climate change. In this context, the GEOVIDE cruise was carried out between Portugal, Greenland and Newfoundland as part of the GEOTRACES program...
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Other Authors: | , , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
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HAL CCSD
2019
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Online Access: | https://theses.hal.science/tel-02936462 https://theses.hal.science/tel-02936462/document https://theses.hal.science/tel-02936462/file/2019TOU30226a.pdf |
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ftunivnantes:oai:HAL:tel-02936462v1 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
French |
topic |
GEOTRACES Radionucleides North Atlantic Ocean Radium Barium Actinium Radionucléides Océan Atlantique Nord Baryum [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
GEOTRACES Radionucleides North Atlantic Ocean Radium Barium Actinium Radionucléides Océan Atlantique Nord Baryum [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Le Roy, Emilie Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
topic_facet |
GEOTRACES Radionucleides North Atlantic Ocean Radium Barium Actinium Radionucléides Océan Atlantique Nord Baryum [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
The Subpolar North Atlantic, being a region of deep water mass formation, is a key region for the global thermohaline circulation and is thus sensitive to climate change. In this context, the GEOVIDE cruise was carried out between Portugal, Greenland and Newfoundland as part of the GEOTRACES program (GA01; May 15 to June 30, 2014-R/V Pourquoi Pas?). This cruise, which crossed different topographic features and biogeochemical regions, provided a unique framework for the study of i) ocean mixing, ii) transport of water masses and iii) inputs of chemical elements released by the sediments deposited onto continental margins. Naturally occurring radionuclides is used as tracers: radium-226 (226Ra, t1/2 = 1602 y) and actinium-227 (227Ac, t1/2 = 21.7 y). Due to their different half-lives, these radionuclides behave differently in the ocean and can be used to study these various processes. First, a detailed section of dissolved 226Ra activities associated with dissolved barium (Ba) concentration is reported. Because 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, their behavior in this crucial region is investigated more thoroughly. The use of the 226Ra/Ba ratio as a chronometer of the global circulation is evaluated using an optimum multiparameter analysis. Results show that 226Ra and Ba distributions mainly result from conservative mixing, notably at intermediate depths (i.e., away from the ocean interfaces). 226Ra and Ba can thus be considered as conservative tracers of water mass transport in the ocean interior at basin scales. However, at the ocean boundaries 226Ra and Ba displayed non-conservative behaviors due to sedimentary, river and possibly hydrothermal inputs. Suspended particles that form in the upper water column which settle to the seafloor may also impact the distributions of 226Ra and Ba. Second, the behavior of 227Ac in the North Atlantic is investigated. 227Ac is primarily released by deep-sea sediments. Due to the low abundance of 227Ac in seawater, the analysis of ... |
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) Université Paul Sabatier - Toulouse III Pieter Van Beek François Lacan |
format |
Doctoral or Postdoctoral Thesis |
author |
Le Roy, Emilie |
author_facet |
Le Roy, Emilie |
author_sort |
Le Roy, Emilie |
title |
Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
title_short |
Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
title_full |
Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
title_fullStr |
Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
title_full_unstemmed |
Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic |
title_sort |
distribution of naturally occurring radionuclides (226ra and 227ac) along ga01 section in the north atlantic |
publisher |
HAL CCSD |
publishDate |
2019 |
url |
https://theses.hal.science/tel-02936462 https://theses.hal.science/tel-02936462/document https://theses.hal.science/tel-02936462/file/2019TOU30226a.pdf |
long_lat |
ENVELOPE(135.783,135.783,-66.083,-66.083) ENVELOPE(-67.450,-67.450,-67.700,-67.700) ENVELOPE(135.750,135.750,-66.200,-66.200) |
geographic |
Greenland Pourquoi Pas Pourquoi-Pas Pourquoi-Pas? |
geographic_facet |
Greenland Pourquoi Pas Pourquoi-Pas Pourquoi-Pas? |
genre |
Greenland Newfoundland North Atlantic |
genre_facet |
Greenland Newfoundland North Atlantic |
op_source |
https://theses.hal.science/tel-02936462 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2019. Français. ⟨NNT : 2019TOU30226⟩ |
op_relation |
NNT: 2019TOU30226 tel-02936462 https://theses.hal.science/tel-02936462 https://theses.hal.science/tel-02936462/document https://theses.hal.science/tel-02936462/file/2019TOU30226a.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766020144396500992 |
spelling |
ftunivnantes:oai:HAL:tel-02936462v1 2023-05-15T16:30:25+02:00 Distribution of naturally occurring radionuclides (226Ra and 227Ac) along GA01 section in the North Atlantic Distribution des radionucléides naturels (226Ra et 227Ac) le long de la section GA01 dans l'Atlantique Nord Le Roy, Emilie 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) Université Paul Sabatier - Toulouse III Pieter Van Beek François Lacan 2019-02-15 https://theses.hal.science/tel-02936462 https://theses.hal.science/tel-02936462/document https://theses.hal.science/tel-02936462/file/2019TOU30226a.pdf fr fre HAL CCSD NNT: 2019TOU30226 tel-02936462 https://theses.hal.science/tel-02936462 https://theses.hal.science/tel-02936462/document https://theses.hal.science/tel-02936462/file/2019TOU30226a.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-02936462 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2019. Français. ⟨NNT : 2019TOU30226⟩ GEOTRACES Radionucleides North Atlantic Ocean Radium Barium Actinium Radionucléides Océan Atlantique Nord Baryum [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2019 ftunivnantes 2023-02-22T04:46:35Z The Subpolar North Atlantic, being a region of deep water mass formation, is a key region for the global thermohaline circulation and is thus sensitive to climate change. In this context, the GEOVIDE cruise was carried out between Portugal, Greenland and Newfoundland as part of the GEOTRACES program (GA01; May 15 to June 30, 2014-R/V Pourquoi Pas?). This cruise, which crossed different topographic features and biogeochemical regions, provided a unique framework for the study of i) ocean mixing, ii) transport of water masses and iii) inputs of chemical elements released by the sediments deposited onto continental margins. Naturally occurring radionuclides is used as tracers: radium-226 (226Ra, t1/2 = 1602 y) and actinium-227 (227Ac, t1/2 = 21.7 y). Due to their different half-lives, these radionuclides behave differently in the ocean and can be used to study these various processes. First, a detailed section of dissolved 226Ra activities associated with dissolved barium (Ba) concentration is reported. Because 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, their behavior in this crucial region is investigated more thoroughly. The use of the 226Ra/Ba ratio as a chronometer of the global circulation is evaluated using an optimum multiparameter analysis. Results show that 226Ra and Ba distributions mainly result from conservative mixing, notably at intermediate depths (i.e., away from the ocean interfaces). 226Ra and Ba can thus be considered as conservative tracers of water mass transport in the ocean interior at basin scales. However, at the ocean boundaries 226Ra and Ba displayed non-conservative behaviors due to sedimentary, river and possibly hydrothermal inputs. Suspended particles that form in the upper water column which settle to the seafloor may also impact the distributions of 226Ra and Ba. Second, the behavior of 227Ac in the North Atlantic is investigated. 227Ac is primarily released by deep-sea sediments. Due to the low abundance of 227Ac in seawater, the analysis of ... Doctoral or Postdoctoral Thesis Greenland Newfoundland North Atlantic Université de Nantes: HAL-UNIV-NANTES Greenland Pourquoi Pas ENVELOPE(135.783,135.783,-66.083,-66.083) Pourquoi-Pas ENVELOPE(-67.450,-67.450,-67.700,-67.700) Pourquoi-Pas? ENVELOPE(135.750,135.750,-66.200,-66.200) |