Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean
The Southern Ocean hosts complex connections between ocean physics, chemistry, and biology. Changes in these connections are hypothesized to be responsible for significant alterations of ocean biogeochemistry and carbon storage both on glacialâ€interglacial timescales and in the future due to anthro...
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American Geophysical Union
2020
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ftcaltechauth:oai:authors.library.caltech.edu:h62jp-gvg74 2024-09-15T18:36:58+00:00 Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean Pavia, Frank J. Anderson, Robert F. Pinedo-González, Paulina Fleisher, Martin Q. Brzezinski, Mark A. Robinson, Rebecca S. 2020-12 https://doi.org/10.1029/2020gb006760 unknown American Geophysical Union https://www.bco-dmo.org/dataset/813379 https://www.usap-dc.org/view/dataset/601269 http://www.marine-geo.org/tools/entry/NBP1702 https://doi.org/10.1029/2020gb006760 oai:authors.library.caltech.edu:h62jp-gvg74 eprintid:106682 resolverid:CaltechAUTHORS:20201116-140728988 info:eu-repo/semantics/openAccess Other Global Biogeochemical Cycles, 34(12), Art. No. e2020GB006760, (2020-12) thorium protactinium Southern Ocean isopycnal mixing GEOTRACES info:eu-repo/semantics/article 2020 ftcaltechauth https://doi.org/10.1029/2020gb006760 2024-08-06T15:35:05Z The Southern Ocean hosts complex connections between ocean physics, chemistry, and biology. Changes in these connections are hypothesized to be responsible for significant alterations of ocean biogeochemistry and carbon storage both on glacialâ€interglacial timescales and in the future due to anthropogenic forcing. Isotopes of thorium (²³â°Th and ²³²Th) and protactinium (²³¹Pa) have been widely applied as tools to study paleoceanographic conditions in the Southern Ocean. However, understanding of the chemical behavior of these isotopes in the modern Southern Ocean has been limited by a paucity of highâ€resolution observations. In this study, we present measurements of dissolved ²³â°Th, ²³¹Pa, and ²³²Th on a meridional transect along 170°W from 67°S to 54°S in the Pacific sector of the Southern Ocean, with high vertical and meridional sampling resolution. We find Th/Pa fractionation factors below 1, highlighting the preferential removal of Pa relative to Th in a region with low lithogenic inputs where the particle flux is dominated by biogenic opal. We also find steep gradients in all three of these isotopes along neutral density surfaces from north to south, demonstrating the importance of isopycnal mixing in transporting these nuclides to the Southern Ocean. Our results suggest that ²³¹Pa and ²³â°Th in the Southern Ocean are highly sensitive tracers of physical transport that may find use in studies of Southern Ocean biogeochemicalâ€physical connections in the past, present, and future. © 2020 American Geophysical Union. Issue Online: 25 November 2020; Version of Record online: 25 November 2020; Accepted manuscript online: 12 November 2020; Manuscript accepted: 02 November 2020; Manuscript revised: 19 October 2020; Manuscript received: 21 July 2020. This work was supported by U.S. National Science Foundation grant OPPâ€1542962 to LDEO and an NSF Graduate Research Fellowship to F. J. P. (DGEâ€1644869). We thank the captain and crew of the R/V Nathaniel B. Palmer for their support in ... Article in Journal/Newspaper Southern Ocean Caltech Authors (California Institute of Technology) Global Biogeochemical Cycles 34 12 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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unknown |
topic |
thorium protactinium Southern Ocean isopycnal mixing GEOTRACES |
spellingShingle |
thorium protactinium Southern Ocean isopycnal mixing GEOTRACES Pavia, Frank J. Anderson, Robert F. Pinedo-González, Paulina Fleisher, Martin Q. Brzezinski, Mark A. Robinson, Rebecca S. Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
topic_facet |
thorium protactinium Southern Ocean isopycnal mixing GEOTRACES |
description |
The Southern Ocean hosts complex connections between ocean physics, chemistry, and biology. Changes in these connections are hypothesized to be responsible for significant alterations of ocean biogeochemistry and carbon storage both on glacialâ€interglacial timescales and in the future due to anthropogenic forcing. Isotopes of thorium (²³â°Th and ²³²Th) and protactinium (²³¹Pa) have been widely applied as tools to study paleoceanographic conditions in the Southern Ocean. However, understanding of the chemical behavior of these isotopes in the modern Southern Ocean has been limited by a paucity of highâ€resolution observations. In this study, we present measurements of dissolved ²³â°Th, ²³¹Pa, and ²³²Th on a meridional transect along 170°W from 67°S to 54°S in the Pacific sector of the Southern Ocean, with high vertical and meridional sampling resolution. We find Th/Pa fractionation factors below 1, highlighting the preferential removal of Pa relative to Th in a region with low lithogenic inputs where the particle flux is dominated by biogenic opal. We also find steep gradients in all three of these isotopes along neutral density surfaces from north to south, demonstrating the importance of isopycnal mixing in transporting these nuclides to the Southern Ocean. Our results suggest that ²³¹Pa and ²³â°Th in the Southern Ocean are highly sensitive tracers of physical transport that may find use in studies of Southern Ocean biogeochemicalâ€physical connections in the past, present, and future. © 2020 American Geophysical Union. Issue Online: 25 November 2020; Version of Record online: 25 November 2020; Accepted manuscript online: 12 November 2020; Manuscript accepted: 02 November 2020; Manuscript revised: 19 October 2020; Manuscript received: 21 July 2020. This work was supported by U.S. National Science Foundation grant OPPâ€1542962 to LDEO and an NSF Graduate Research Fellowship to F. J. P. (DGEâ€1644869). We thank the captain and crew of the R/V Nathaniel B. Palmer for their support in ... |
format |
Article in Journal/Newspaper |
author |
Pavia, Frank J. Anderson, Robert F. Pinedo-González, Paulina Fleisher, Martin Q. Brzezinski, Mark A. Robinson, Rebecca S. |
author_facet |
Pavia, Frank J. Anderson, Robert F. Pinedo-González, Paulina Fleisher, Martin Q. Brzezinski, Mark A. Robinson, Rebecca S. |
author_sort |
Pavia, Frank J. |
title |
Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
title_short |
Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
title_full |
Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
title_fullStr |
Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
title_full_unstemmed |
Isopycnal Transport and Scavenging of ²³â°Th and ²³¹Pa in the Pacific Southern Ocean |
title_sort |
isopycnal transport and scavenging of â²â³â°th and â²â³â¹pa in the pacific southern ocean |
publisher |
American Geophysical Union |
publishDate |
2020 |
url |
https://doi.org/10.1029/2020gb006760 |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Global Biogeochemical Cycles, 34(12), Art. No. e2020GB006760, (2020-12) |
op_relation |
https://www.bco-dmo.org/dataset/813379 https://www.usap-dc.org/view/dataset/601269 http://www.marine-geo.org/tools/entry/NBP1702 https://doi.org/10.1029/2020gb006760 oai:authors.library.caltech.edu:h62jp-gvg74 eprintid:106682 resolverid:CaltechAUTHORS:20201116-140728988 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1029/2020gb006760 |
container_title |
Global Biogeochemical Cycles |
container_volume |
34 |
container_issue |
12 |
_version_ |
1810480765029318656 |