Trace metal evidence for a poorly ventilated glacial Southern Ocean
Glacial benthic δ 13 C and Δ 14 C measurements from the Atlantic Ocean have been interpreted to indicate the existence of a poorly ventilated Southern Ocean with greater CO 2 and nutrient contents compared to present. Enhanced storage of CO 2 in the deep ocean predicts that oxygen concentrations sho...
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ftcopernicus:oai:publications.copernicus.org:cpd28161 2023-05-15T18:23:45+02:00 Trace metal evidence for a poorly ventilated glacial Southern Ocean Wagner, M. Hendy, I. L. 2018-09-26 application/pdf https://doi.org/10.5194/cpd-11-637-2015 https://cp.copernicus.org/preprints/cp-2014-148/ eng eng doi:10.5194/cpd-11-637-2015 https://cp.copernicus.org/preprints/cp-2014-148/ eISSN: 1814-9332 Text 2018 ftcopernicus https://doi.org/10.5194/cpd-11-637-2015 2020-07-20T16:24:43Z Glacial benthic δ 13 C and Δ 14 C measurements from the Atlantic Ocean have been interpreted to indicate the existence of a poorly ventilated Southern Ocean with greater CO 2 and nutrient contents compared to present. Enhanced storage of CO 2 in the deep ocean predicts that oxygen concentrations should have declined at the same time, although no unequivocal evidence for glacial Southern Ocean suboxia has yet been found. Here we take a novel approach by using concentrations of redox-sensitive trace metals to show that Southern Ocean sediments from two cores in the Atlantic sector were suboxic during deglaciation and the last glacial period, implying reduced ventilation and/or elevated export production that significantly altered deep water chemistry. In the Cape Basin, high concentrations of the authigenically deposited trace metal Re coincide with oldest Δ 14 C values at 3.8 km water depth in the Subantarctic Zone, indicating that poorest Southern Ocean ventilation occurred during the Last Glacial Maximum (~ 23–19 ka). Furthermore, trace metal results suggest that the vertical structure of the glacial Southern Ocean differed from modern deep water mass arrangement such that Lower Circumpolar Deep Water had lower O 2 concentrations, and therefore was the likely reservoir of glacial CO 2 . Text Southern Ocean Copernicus Publications: E-Journals Southern Ocean |
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Copernicus Publications: E-Journals |
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English |
description |
Glacial benthic δ 13 C and Δ 14 C measurements from the Atlantic Ocean have been interpreted to indicate the existence of a poorly ventilated Southern Ocean with greater CO 2 and nutrient contents compared to present. Enhanced storage of CO 2 in the deep ocean predicts that oxygen concentrations should have declined at the same time, although no unequivocal evidence for glacial Southern Ocean suboxia has yet been found. Here we take a novel approach by using concentrations of redox-sensitive trace metals to show that Southern Ocean sediments from two cores in the Atlantic sector were suboxic during deglaciation and the last glacial period, implying reduced ventilation and/or elevated export production that significantly altered deep water chemistry. In the Cape Basin, high concentrations of the authigenically deposited trace metal Re coincide with oldest Δ 14 C values at 3.8 km water depth in the Subantarctic Zone, indicating that poorest Southern Ocean ventilation occurred during the Last Glacial Maximum (~ 23–19 ka). Furthermore, trace metal results suggest that the vertical structure of the glacial Southern Ocean differed from modern deep water mass arrangement such that Lower Circumpolar Deep Water had lower O 2 concentrations, and therefore was the likely reservoir of glacial CO 2 . |
format |
Text |
author |
Wagner, M. Hendy, I. L. |
spellingShingle |
Wagner, M. Hendy, I. L. Trace metal evidence for a poorly ventilated glacial Southern Ocean |
author_facet |
Wagner, M. Hendy, I. L. |
author_sort |
Wagner, M. |
title |
Trace metal evidence for a poorly ventilated glacial Southern Ocean |
title_short |
Trace metal evidence for a poorly ventilated glacial Southern Ocean |
title_full |
Trace metal evidence for a poorly ventilated glacial Southern Ocean |
title_fullStr |
Trace metal evidence for a poorly ventilated glacial Southern Ocean |
title_full_unstemmed |
Trace metal evidence for a poorly ventilated glacial Southern Ocean |
title_sort |
trace metal evidence for a poorly ventilated glacial southern ocean |
publishDate |
2018 |
url |
https://doi.org/10.5194/cpd-11-637-2015 https://cp.copernicus.org/preprints/cp-2014-148/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cpd-11-637-2015 https://cp.copernicus.org/preprints/cp-2014-148/ |
op_doi |
https://doi.org/10.5194/cpd-11-637-2015 |
_version_ |
1766203856697425920 |