Southern ocean nitrogen and silicon dynamics during the last deglaciation
The reinvigoration of overturning in the Southern Ocean is hypothesized to have returned CO2 from the deep ocean to the atmosphere at the end of the last ice age. Large peaks in opal accumulation have been put forward as evidence for an increase in wind driven upwelling between 10 and 15ka. Here, we...
Published in: | Earth and Planetary Science Letters |
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ftunivrhodeislan:oai:digitalcommons.uri.edu:gsofacpubs-3186 2024-02-11T10:08:47+01:00 Southern ocean nitrogen and silicon dynamics during the last deglaciation Horn, Matthew G. Beucher, Charlotte P. Robinson, Rebecca S. Brzezinski, Mark A. 2011-10-15T07:00:00Z https://digitalcommons.uri.edu/gsofacpubs/2217 https://doi.org/10.1016/j.epsl.2011.08.016 unknown DigitalCommons@URI https://digitalcommons.uri.edu/gsofacpubs/2217 doi:10.1016/j.epsl.2011.08.016 https://doi.org/10.1016/j.epsl.2011.08.016 Graduate School of Oceanography Faculty Publications Deglaciation Nitrogen isotopes Nutrient dynamics Silicic acid supply Silicon isotopes text 2011 ftunivrhodeislan https://doi.org/10.1016/j.epsl.2011.08.016 2024-01-15T19:10:03Z The reinvigoration of overturning in the Southern Ocean is hypothesized to have returned CO2 from the deep ocean to the atmosphere at the end of the last ice age. Large peaks in opal accumulation have been put forward as evidence for an increase in wind driven upwelling between 10 and 15ka. Here, we use coupled nitrogen and silicon isotope records alongside opal accumulation rates to provide quasi-quantitative estimates of Southern Ocean nutrient supply, by upwelling, and nutrient utilization across this interval. Significant changes in the consumption of N and Si across the two opal accumulation peaks indicate major changes in both upwelling and nutrient demand. We find N and Si consumption to be relatively incomplete during peak opal accumulation at the onset of the deglaciation. This indicates that nutrient supply was significantly enhanced. The second deglacial peak in opal accumulation is associated with more complete Si consumption and variable N consumption. We suggest that this peak represents strong upwelling and more complete utilization of the available silicic acid pool. Differences between the Si and N responses during opal peaks may stem from decreasing iron availability across the glacial termination. The nutrient isotope evidence for excess nutrients during the deglaciation indicates that the high export productivity was insufficient to overcome the evasion of CO2 to the atmosphere as a result of physical circulation changes. Previous work has demonstrated that the reinvigoration of overturning circulation during the deglaciation causes a transient peak in nutrient supply to the low latitudes. This is supported by our data, which indicate that relatively high macronutrient concentrations were maintained in the Southern Ocean surface waters that are incorporated into mode waters despite high demand. © 2011 Elsevier B.V. Text Southern Ocean University of Rhode Island: DigitalCommons@URI Southern Ocean Earth and Planetary Science Letters 310 3-4 334 339 |
institution |
Open Polar |
collection |
University of Rhode Island: DigitalCommons@URI |
op_collection_id |
ftunivrhodeislan |
language |
unknown |
topic |
Deglaciation Nitrogen isotopes Nutrient dynamics Silicic acid supply Silicon isotopes |
spellingShingle |
Deglaciation Nitrogen isotopes Nutrient dynamics Silicic acid supply Silicon isotopes Horn, Matthew G. Beucher, Charlotte P. Robinson, Rebecca S. Brzezinski, Mark A. Southern ocean nitrogen and silicon dynamics during the last deglaciation |
topic_facet |
Deglaciation Nitrogen isotopes Nutrient dynamics Silicic acid supply Silicon isotopes |
description |
The reinvigoration of overturning in the Southern Ocean is hypothesized to have returned CO2 from the deep ocean to the atmosphere at the end of the last ice age. Large peaks in opal accumulation have been put forward as evidence for an increase in wind driven upwelling between 10 and 15ka. Here, we use coupled nitrogen and silicon isotope records alongside opal accumulation rates to provide quasi-quantitative estimates of Southern Ocean nutrient supply, by upwelling, and nutrient utilization across this interval. Significant changes in the consumption of N and Si across the two opal accumulation peaks indicate major changes in both upwelling and nutrient demand. We find N and Si consumption to be relatively incomplete during peak opal accumulation at the onset of the deglaciation. This indicates that nutrient supply was significantly enhanced. The second deglacial peak in opal accumulation is associated with more complete Si consumption and variable N consumption. We suggest that this peak represents strong upwelling and more complete utilization of the available silicic acid pool. Differences between the Si and N responses during opal peaks may stem from decreasing iron availability across the glacial termination. The nutrient isotope evidence for excess nutrients during the deglaciation indicates that the high export productivity was insufficient to overcome the evasion of CO2 to the atmosphere as a result of physical circulation changes. Previous work has demonstrated that the reinvigoration of overturning circulation during the deglaciation causes a transient peak in nutrient supply to the low latitudes. This is supported by our data, which indicate that relatively high macronutrient concentrations were maintained in the Southern Ocean surface waters that are incorporated into mode waters despite high demand. © 2011 Elsevier B.V. |
format |
Text |
author |
Horn, Matthew G. Beucher, Charlotte P. Robinson, Rebecca S. Brzezinski, Mark A. |
author_facet |
Horn, Matthew G. Beucher, Charlotte P. Robinson, Rebecca S. Brzezinski, Mark A. |
author_sort |
Horn, Matthew G. |
title |
Southern ocean nitrogen and silicon dynamics during the last deglaciation |
title_short |
Southern ocean nitrogen and silicon dynamics during the last deglaciation |
title_full |
Southern ocean nitrogen and silicon dynamics during the last deglaciation |
title_fullStr |
Southern ocean nitrogen and silicon dynamics during the last deglaciation |
title_full_unstemmed |
Southern ocean nitrogen and silicon dynamics during the last deglaciation |
title_sort |
southern ocean nitrogen and silicon dynamics during the last deglaciation |
publisher |
DigitalCommons@URI |
publishDate |
2011 |
url |
https://digitalcommons.uri.edu/gsofacpubs/2217 https://doi.org/10.1016/j.epsl.2011.08.016 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Graduate School of Oceanography Faculty Publications |
op_relation |
https://digitalcommons.uri.edu/gsofacpubs/2217 doi:10.1016/j.epsl.2011.08.016 https://doi.org/10.1016/j.epsl.2011.08.016 |
op_doi |
https://doi.org/10.1016/j.epsl.2011.08.016 |
container_title |
Earth and Planetary Science Letters |
container_volume |
310 |
container_issue |
3-4 |
container_start_page |
334 |
op_container_end_page |
339 |
_version_ |
1790608384644349952 |