Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise)
The Southern Ocean (SO) is of global importance to the carbon cycle, and processes such as mesopelagic remineralisation that impact the efficiency of the biological carbon pump in this region need to be better constrained. During this study early austral winter barium excess (Baxs) concentrations we...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/558288 2023-05-15T18:25:41+02:00 Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) van Horsten, Natasha René Planquette, Hélène Sarthou, Géraldine Ryan-Keogh, Thomas James Lemaitre, Nolwenn Mtshali, Thato Nicholas Roychoudhury, Alakendra Bucciarelli, Eva 2022-07 application/application/pdf https://hdl.handle.net/20.500.11850/558288 https://doi.org/10.3929/ethz-b-000558288 en eng Copernicus info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-19-3209-2022 info:eu-repo/semantics/altIdentifier/wos/000822749000001 http://hdl.handle.net/20.500.11850/558288 doi:10.3929/ethz-b-000558288 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Biogeosciences, 19 (13) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2022 ftethz https://doi.org/20.500.11850/558288 https://doi.org/10.3929/ethz-b-000558288 https://doi.org/10.5194/bg-19-3209-2022 2023-02-13T01:07:09Z The Southern Ocean (SO) is of global importance to the carbon cycle, and processes such as mesopelagic remineralisation that impact the efficiency of the biological carbon pump in this region need to be better constrained. During this study early austral winter barium excess (Baxs) concentrations were measured for the first time, along 30° E in the southern Indian Ocean. Winter Baxs concentrations of 59 to 684 pmol L−1 were comparable to those observed throughout other seasons. The expected decline of the mesopelagic Baxs signal to background values during winter was not observed, supporting the hypothesis that this remineralisation proxy likely has a longer timescale than previously reported. A compilation of available SO mesopelagic Baxs data, including data from this study, shows an accumulation rate of ∼0.9 µmol m−2 d−1 from September to July that correlates with temporally integrated remotely sensed primary productivity (PP) throughout the SO from data spanning ∼20 years, advocating for a possible annual timescale of this proxy. The percentage of mesopelagic particulate organic carbon (POC) remineralisation as calculated from estimated POC remineralisation fluxes over integrated remotely sensed PP was ∼2-fold higher south of the polar front (19 ± 15 %, n=39) than north of the polar front (10 ± 10 %, n=29), revealing the higher surface carbon export efficiency further south. By linking integrated remotely sensed PP to mesopelagic Baxs stock, we could obtain better estimates of carbon export and remineralisation signals within the SO on annual and basin scales. ISSN:1726-4170 ISSN:1726-4170 Article in Journal/Newspaper Southern Ocean ETH Zürich Research Collection Austral Indian Southern Ocean |
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Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
description |
The Southern Ocean (SO) is of global importance to the carbon cycle, and processes such as mesopelagic remineralisation that impact the efficiency of the biological carbon pump in this region need to be better constrained. During this study early austral winter barium excess (Baxs) concentrations were measured for the first time, along 30° E in the southern Indian Ocean. Winter Baxs concentrations of 59 to 684 pmol L−1 were comparable to those observed throughout other seasons. The expected decline of the mesopelagic Baxs signal to background values during winter was not observed, supporting the hypothesis that this remineralisation proxy likely has a longer timescale than previously reported. A compilation of available SO mesopelagic Baxs data, including data from this study, shows an accumulation rate of ∼0.9 µmol m−2 d−1 from September to July that correlates with temporally integrated remotely sensed primary productivity (PP) throughout the SO from data spanning ∼20 years, advocating for a possible annual timescale of this proxy. The percentage of mesopelagic particulate organic carbon (POC) remineralisation as calculated from estimated POC remineralisation fluxes over integrated remotely sensed PP was ∼2-fold higher south of the polar front (19 ± 15 %, n=39) than north of the polar front (10 ± 10 %, n=29), revealing the higher surface carbon export efficiency further south. By linking integrated remotely sensed PP to mesopelagic Baxs stock, we could obtain better estimates of carbon export and remineralisation signals within the SO on annual and basin scales. ISSN:1726-4170 ISSN:1726-4170 |
format |
Article in Journal/Newspaper |
author |
van Horsten, Natasha René Planquette, Hélène Sarthou, Géraldine Ryan-Keogh, Thomas James Lemaitre, Nolwenn Mtshali, Thato Nicholas Roychoudhury, Alakendra Bucciarelli, Eva |
spellingShingle |
van Horsten, Natasha René Planquette, Hélène Sarthou, Géraldine Ryan-Keogh, Thomas James Lemaitre, Nolwenn Mtshali, Thato Nicholas Roychoudhury, Alakendra Bucciarelli, Eva Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
author_facet |
van Horsten, Natasha René Planquette, Hélène Sarthou, Géraldine Ryan-Keogh, Thomas James Lemaitre, Nolwenn Mtshali, Thato Nicholas Roychoudhury, Alakendra Bucciarelli, Eva |
author_sort |
van Horsten, Natasha René |
title |
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
title_short |
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
title_full |
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
title_fullStr |
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
title_full_unstemmed |
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) |
title_sort |
early winter barium excess in the southern indian ocean as an annual remineralisation proxy (geotraces gipr07 cruise) |
publisher |
Copernicus |
publishDate |
2022 |
url |
https://hdl.handle.net/20.500.11850/558288 https://doi.org/10.3929/ethz-b-000558288 |
geographic |
Austral Indian Southern Ocean |
geographic_facet |
Austral Indian Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Biogeosciences, 19 (13) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-19-3209-2022 info:eu-repo/semantics/altIdentifier/wos/000822749000001 http://hdl.handle.net/20.500.11850/558288 doi:10.3929/ethz-b-000558288 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/558288 https://doi.org/10.3929/ethz-b-000558288 https://doi.org/10.5194/bg-19-3209-2022 |
_version_ |
1766207300818698240 |