Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific
Here we present organic export production and nitrogen isotope results spanning the last 30 000 years from a core recovered off Costa Rica (Ocean Drilling Program (ODP) Site 1242) on the leading edge of the oxygen minimum zone of the Eastern Tropical North Pacific. Marine export production reveals g...
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ftdoajarticles:oai:doaj.org/article:87af549eb5df490986189fd719c05530 2023-05-15T13:46:26+02:00 Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific P. Martinez R. S. Robinson 2010-01-01T00:00:00Z https://doi.org/10.5194/bg-7-1-2010 https://doaj.org/article/87af549eb5df490986189fd719c05530 EN eng Copernicus Publications http://www.biogeosciences.net/7/1/2010/bg-7-1-2010.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-7-1-2010 https://doaj.org/article/87af549eb5df490986189fd719c05530 Biogeosciences, Vol 7, Iss 1, Pp 1-9 (2010) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2010 ftdoajarticles https://doi.org/10.5194/bg-7-1-2010 2022-12-31T12:08:37Z Here we present organic export production and nitrogen isotope results spanning the last 30 000 years from a core recovered off Costa Rica (Ocean Drilling Program (ODP) Site 1242) on the leading edge of the oxygen minimum zone of the Eastern Tropical North Pacific. Marine export production reveals glacial-interglacial variations with low organic matter (total organic carbon and total nitrogen) contents during warm intervals, twice more during cold episodes and double peaked maximum during the deglaciation, between ~15.5–18.5 and 11–13 ka B.P. When this new export production record is compared with four nearby cores from within the Eastern Pacific along the Equatorial divergence, good agreement between all the cores is observed. The major feature is a maximum of export during the early deglaciation. As for export production, water-column denitrification, represented by sedimentary δ 15 N records, along the Eastern tropical North and South Pacific between 15° N and 36° S is also coherent over the last deglaciation. Each of the nitrogen isotope profiles indicate that denitrification increased abruptly at 19 ka B.P to a maximum during the early deglaciation, confirming a typical Antarctic timing. It is proposed that the increase in export production and then in subsurface oxygen demand lead to an intensification of water-column denitrification within the oxygen minimum zones in the easternmost Pacific at the time of the last deglaciation. The triggering mechanism would have been primarily linked to an increase in preformed nutrients contents feeding the Equatorial Undercurrent driven by the resumption of overturning in the Southern Ocean and the return of nutrients from the deep ocean to the sea-surface. An increase in equatorial wind-driven upwelling of sub-surface nutrient-rich waters could have played the role of an amplifier. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean Pacific Biogeosciences 7 1 1 9 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 P. Martinez R. S. Robinson Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Here we present organic export production and nitrogen isotope results spanning the last 30 000 years from a core recovered off Costa Rica (Ocean Drilling Program (ODP) Site 1242) on the leading edge of the oxygen minimum zone of the Eastern Tropical North Pacific. Marine export production reveals glacial-interglacial variations with low organic matter (total organic carbon and total nitrogen) contents during warm intervals, twice more during cold episodes and double peaked maximum during the deglaciation, between ~15.5–18.5 and 11–13 ka B.P. When this new export production record is compared with four nearby cores from within the Eastern Pacific along the Equatorial divergence, good agreement between all the cores is observed. The major feature is a maximum of export during the early deglaciation. As for export production, water-column denitrification, represented by sedimentary δ 15 N records, along the Eastern tropical North and South Pacific between 15° N and 36° S is also coherent over the last deglaciation. Each of the nitrogen isotope profiles indicate that denitrification increased abruptly at 19 ka B.P to a maximum during the early deglaciation, confirming a typical Antarctic timing. It is proposed that the increase in export production and then in subsurface oxygen demand lead to an intensification of water-column denitrification within the oxygen minimum zones in the easternmost Pacific at the time of the last deglaciation. The triggering mechanism would have been primarily linked to an increase in preformed nutrients contents feeding the Equatorial Undercurrent driven by the resumption of overturning in the Southern Ocean and the return of nutrients from the deep ocean to the sea-surface. An increase in equatorial wind-driven upwelling of sub-surface nutrient-rich waters could have played the role of an amplifier. |
format |
Article in Journal/Newspaper |
author |
P. Martinez R. S. Robinson |
author_facet |
P. Martinez R. S. Robinson |
author_sort |
P. Martinez |
title |
Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
title_short |
Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
title_full |
Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
title_fullStr |
Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
title_full_unstemmed |
Increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial Pacific |
title_sort |
increase in water column denitrification during the last deglaciation: the influence of oxygen demand in the eastern equatorial pacific |
publisher |
Copernicus Publications |
publishDate |
2010 |
url |
https://doi.org/10.5194/bg-7-1-2010 https://doaj.org/article/87af549eb5df490986189fd719c05530 |
geographic |
Antarctic Southern Ocean Pacific |
geographic_facet |
Antarctic Southern Ocean Pacific |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Biogeosciences, Vol 7, Iss 1, Pp 1-9 (2010) |
op_relation |
http://www.biogeosciences.net/7/1/2010/bg-7-1-2010.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-7-1-2010 https://doaj.org/article/87af549eb5df490986189fd719c05530 |
op_doi |
https://doi.org/10.5194/bg-7-1-2010 |
container_title |
Biogeosciences |
container_volume |
7 |
container_issue |
1 |
container_start_page |
1 |
op_container_end_page |
9 |
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1766242525198155776 |