Export production in the New-Zealand region since the Last Glacial Maximum
Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand....
Published in: | Earth and Planetary Science Letters |
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Language: | English |
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ftunivqespace:oai:espace.library.uq.edu.au:UQ:57f2167 2023-05-15T13:41:15+02:00 Export production in the New-Zealand region since the Last Glacial Maximum Durand, Axel Chase, Zanna Noble, Taryn L. Bostock, Helen Jaccard, Samuel L. Kitchener, Priya Townsend, Ashley T. Jansen, Nils Kinsley, Les Jacobsen, Geraldine Johnson, Sean Neil, Helen 2017-07-01 https://espace.library.uq.edu.au/view/UQ:57f2167 eng eng Elsevier doi:10.1016/j.epsl.2017.03.035 issn:0012-821X issn:1385-013X orcid:0000-0002-8903-8958 FT120100759 ALNGRA11081 LE0989539 PP00P2-144811 Sub-Antarctic Waters Southern-Ocean Southwest Pacific Atlantic Sector Late Quaternary Biogenic Opal Chatham Rise Deep-Ocean Fluxes Iron 1901 Earth and Planetary Sciences (miscellaneous) 1906 Geochemistry and Petrology 1908 Geophysics 1912 Space and Planetary Science Journal Article 2017 ftunivqespace https://doi.org/10.1016/j.epsl.2017.03.035 2020-12-08T09:13:31Z Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand. For the first time in this region, 230-Thorium-normalised fluxes of biogenic opal, carbonate, excess barium, and organic carbon are presented. In Subtropical Waters and the SAZ, these flux variations show that EP has not changed markedly since the LGM. The only exception is a site currently north of the subtropical front. Here we suggest the subtropical front shifted over the core site between 18 and 12 ka, driving increased EP. To understand why EP remained mostly low and constant elsewhere, lithogenic fluxes at the four sites were measured to investigate changes in dust deposition. At all sites, lithogenic fluxes were greater during the LGM compared to the Holocene. The positive temporal correlation between the Antarctic dust record and lithogenic flux at a site in the Tasman Sea shows that regionally, increased dust deposition contributed to the high glacial lithogenic fluxes. Additionally, it is inferred that lithogenic material from erosion and glacier melting deposited on the Campbell Plateau during the deglaciation (18-12 ka). From these observations, it is proposed that even though increased glacial dust deposition may have relieved iron limitation within the SAZ around New Zealand, the availability of silicic acid limited diatom growth and thus any resultant increase in carbon export during the LGM. Therefore, silicic acid concentrations have remained low since the LGM. This result suggests that both silicic acid and iron co-limit EP in the SAZ around New Zealand, consistent with modern process studies. (C) 2017 Elsevier B.V. All rights reserved. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean The University of Queensland: UQ eSpace Antarctic Campbell Plateau ENVELOPE(171.000,171.000,-50.667,-50.667) New Zealand Pacific Southern Ocean The Antarctic Earth and Planetary Science Letters 469 110 122 |
institution |
Open Polar |
collection |
The University of Queensland: UQ eSpace |
op_collection_id |
ftunivqespace |
language |
English |
topic |
Sub-Antarctic Waters Southern-Ocean Southwest Pacific Atlantic Sector Late Quaternary Biogenic Opal Chatham Rise Deep-Ocean Fluxes Iron 1901 Earth and Planetary Sciences (miscellaneous) 1906 Geochemistry and Petrology 1908 Geophysics 1912 Space and Planetary Science |
spellingShingle |
Sub-Antarctic Waters Southern-Ocean Southwest Pacific Atlantic Sector Late Quaternary Biogenic Opal Chatham Rise Deep-Ocean Fluxes Iron 1901 Earth and Planetary Sciences (miscellaneous) 1906 Geochemistry and Petrology 1908 Geophysics 1912 Space and Planetary Science Durand, Axel Chase, Zanna Noble, Taryn L. Bostock, Helen Jaccard, Samuel L. Kitchener, Priya Townsend, Ashley T. Jansen, Nils Kinsley, Les Jacobsen, Geraldine Johnson, Sean Neil, Helen Export production in the New-Zealand region since the Last Glacial Maximum |
topic_facet |
Sub-Antarctic Waters Southern-Ocean Southwest Pacific Atlantic Sector Late Quaternary Biogenic Opal Chatham Rise Deep-Ocean Fluxes Iron 1901 Earth and Planetary Sciences (miscellaneous) 1906 Geochemistry and Petrology 1908 Geophysics 1912 Space and Planetary Science |
description |
Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand. For the first time in this region, 230-Thorium-normalised fluxes of biogenic opal, carbonate, excess barium, and organic carbon are presented. In Subtropical Waters and the SAZ, these flux variations show that EP has not changed markedly since the LGM. The only exception is a site currently north of the subtropical front. Here we suggest the subtropical front shifted over the core site between 18 and 12 ka, driving increased EP. To understand why EP remained mostly low and constant elsewhere, lithogenic fluxes at the four sites were measured to investigate changes in dust deposition. At all sites, lithogenic fluxes were greater during the LGM compared to the Holocene. The positive temporal correlation between the Antarctic dust record and lithogenic flux at a site in the Tasman Sea shows that regionally, increased dust deposition contributed to the high glacial lithogenic fluxes. Additionally, it is inferred that lithogenic material from erosion and glacier melting deposited on the Campbell Plateau during the deglaciation (18-12 ka). From these observations, it is proposed that even though increased glacial dust deposition may have relieved iron limitation within the SAZ around New Zealand, the availability of silicic acid limited diatom growth and thus any resultant increase in carbon export during the LGM. Therefore, silicic acid concentrations have remained low since the LGM. This result suggests that both silicic acid and iron co-limit EP in the SAZ around New Zealand, consistent with modern process studies. (C) 2017 Elsevier B.V. All rights reserved. |
format |
Article in Journal/Newspaper |
author |
Durand, Axel Chase, Zanna Noble, Taryn L. Bostock, Helen Jaccard, Samuel L. Kitchener, Priya Townsend, Ashley T. Jansen, Nils Kinsley, Les Jacobsen, Geraldine Johnson, Sean Neil, Helen |
author_facet |
Durand, Axel Chase, Zanna Noble, Taryn L. Bostock, Helen Jaccard, Samuel L. Kitchener, Priya Townsend, Ashley T. Jansen, Nils Kinsley, Les Jacobsen, Geraldine Johnson, Sean Neil, Helen |
author_sort |
Durand, Axel |
title |
Export production in the New-Zealand region since the Last Glacial Maximum |
title_short |
Export production in the New-Zealand region since the Last Glacial Maximum |
title_full |
Export production in the New-Zealand region since the Last Glacial Maximum |
title_fullStr |
Export production in the New-Zealand region since the Last Glacial Maximum |
title_full_unstemmed |
Export production in the New-Zealand region since the Last Glacial Maximum |
title_sort |
export production in the new-zealand region since the last glacial maximum |
publisher |
Elsevier |
publishDate |
2017 |
url |
https://espace.library.uq.edu.au/view/UQ:57f2167 |
long_lat |
ENVELOPE(171.000,171.000,-50.667,-50.667) |
geographic |
Antarctic Campbell Plateau New Zealand Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Campbell Plateau New Zealand Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
doi:10.1016/j.epsl.2017.03.035 issn:0012-821X issn:1385-013X orcid:0000-0002-8903-8958 FT120100759 ALNGRA11081 LE0989539 PP00P2-144811 |
op_doi |
https://doi.org/10.1016/j.epsl.2017.03.035 |
container_title |
Earth and Planetary Science Letters |
container_volume |
469 |
container_start_page |
110 |
op_container_end_page |
122 |
_version_ |
1766148193863598080 |