Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition
In this study we report full‐depth water column profiles for nitrogen and oxygen isotopic composition (δ15N and δ18O) of nitrate (NO3‐) during the GEOTRACES GA01 cruise (2014). This transect intersects the double gyre system of the subtropical and subpolar regions of the North Atlantic separated by...
Published in: | Global Biogeochemical Cycles |
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American Geophysical Union (AGU)
2021
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Online Access: | https://archimer.ifremer.fr/doc/00688/79966/82897.pdf https://archimer.ifremer.fr/doc/00688/79966/82898.docx https://archimer.ifremer.fr/doc/00688/79966/82899.xlsx https://doi.org/10.1029/2020GB006887 https://archimer.ifremer.fr/doc/00688/79966/ |
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ftarchimer:oai:archimer.ifremer.fr:79966 2023-05-15T17:25:19+02:00 Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition Deman, F. Fonseca‐batista, D. Roukaerts, A. García‐ibáñez, M. I. Le Roy, E. Thilakarathne, E. P. D. N. Elskens, M. Dehairs, F. Fripiat, F. 2021-04 application/pdf https://archimer.ifremer.fr/doc/00688/79966/82897.pdf https://archimer.ifremer.fr/doc/00688/79966/82898.docx https://archimer.ifremer.fr/doc/00688/79966/82899.xlsx https://doi.org/10.1029/2020GB006887 https://archimer.ifremer.fr/doc/00688/79966/ eng eng American Geophysical Union (AGU) https://archimer.ifremer.fr/doc/00688/79966/82897.pdf https://archimer.ifremer.fr/doc/00688/79966/82898.docx https://archimer.ifremer.fr/doc/00688/79966/82899.xlsx doi:10.1029/2020GB006887 https://archimer.ifremer.fr/doc/00688/79966/ info:eu-repo/semantics/openAccess restricted use Global Biogeochemical Cycles (0886-6236) (American Geophysical Union (AGU)), 2021-04 , Vol. 35 , N. 4 , P. e2020GB006887 (15p.) Atlantic isotopy nitrate text Publication info:eu-repo/semantics/article 2021 ftarchimer https://doi.org/10.1029/2020GB006887 2021-11-03T00:06:14Z In this study we report full‐depth water column profiles for nitrogen and oxygen isotopic composition (δ15N and δ18O) of nitrate (NO3‐) during the GEOTRACES GA01 cruise (2014). This transect intersects the double gyre system of the subtropical and subpolar regions of the North Atlantic separated by a strong transition zone, the North Atlantic Current. The distribution of NO3‐ δ15N and δ18O shows that assimilation by phytoplankton is the main process controlling the NO3‐ isotopic composition in the upper 150 m, with values increasing in a NO3‐ δ18O versus δ15N space along a line with a slope of one towards the surface. In the subpolar gyre, a single relationship between the degree of NO3‐ consumption and residual NO3‐ δ15N supports the view that NO3‐ is supplied via Ekman upwelling and deep winter convection, and progressively consumed during the Ekman transport of surface water southward. The co‐occurrence of partial NO3‐ assimilation and nitrification in the deep mixed layer of the subpolar gyre elevates subsurface NO3‐ δ18O in comparison to deep oceanic values. This signal propagates through isopycnal exchanges to greater depths at lower latitudes. With recirculation in the subtropical gyre, cycles of quantitative consumption‐nitrification progressively decrease subsurface NO3‐ δ18O toward the δ18O of regenerated NO3‐. The low NO3‐ δ15N observed south of the Subarctic Front is mostly explained by N2 fixation, although a contribution from the Mediterranean outflow is required to explain the lower NO3‐ δ15N signal observed between 600 and 1500 m depth close to the Iberian margin. Article in Journal/Newspaper north atlantic current North Atlantic Subarctic Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Global Biogeochemical Cycles 35 4 |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
topic |
Atlantic isotopy nitrate |
spellingShingle |
Atlantic isotopy nitrate Deman, F. Fonseca‐batista, D. Roukaerts, A. García‐ibáñez, M. I. Le Roy, E. Thilakarathne, E. P. D. N. Elskens, M. Dehairs, F. Fripiat, F. Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
topic_facet |
Atlantic isotopy nitrate |
description |
In this study we report full‐depth water column profiles for nitrogen and oxygen isotopic composition (δ15N and δ18O) of nitrate (NO3‐) during the GEOTRACES GA01 cruise (2014). This transect intersects the double gyre system of the subtropical and subpolar regions of the North Atlantic separated by a strong transition zone, the North Atlantic Current. The distribution of NO3‐ δ15N and δ18O shows that assimilation by phytoplankton is the main process controlling the NO3‐ isotopic composition in the upper 150 m, with values increasing in a NO3‐ δ18O versus δ15N space along a line with a slope of one towards the surface. In the subpolar gyre, a single relationship between the degree of NO3‐ consumption and residual NO3‐ δ15N supports the view that NO3‐ is supplied via Ekman upwelling and deep winter convection, and progressively consumed during the Ekman transport of surface water southward. The co‐occurrence of partial NO3‐ assimilation and nitrification in the deep mixed layer of the subpolar gyre elevates subsurface NO3‐ δ18O in comparison to deep oceanic values. This signal propagates through isopycnal exchanges to greater depths at lower latitudes. With recirculation in the subtropical gyre, cycles of quantitative consumption‐nitrification progressively decrease subsurface NO3‐ δ18O toward the δ18O of regenerated NO3‐. The low NO3‐ δ15N observed south of the Subarctic Front is mostly explained by N2 fixation, although a contribution from the Mediterranean outflow is required to explain the lower NO3‐ δ15N signal observed between 600 and 1500 m depth close to the Iberian margin. |
format |
Article in Journal/Newspaper |
author |
Deman, F. Fonseca‐batista, D. Roukaerts, A. García‐ibáñez, M. I. Le Roy, E. Thilakarathne, E. P. D. N. Elskens, M. Dehairs, F. Fripiat, F. |
author_facet |
Deman, F. Fonseca‐batista, D. Roukaerts, A. García‐ibáñez, M. I. Le Roy, E. Thilakarathne, E. P. D. N. Elskens, M. Dehairs, F. Fripiat, F. |
author_sort |
Deman, F. |
title |
Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
title_short |
Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
title_full |
Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
title_fullStr |
Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
title_full_unstemmed |
Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition |
title_sort |
nitrate supply routes and impact of internal cycling in the north atlantic ocean inferred from nitrate isotopic composition |
publisher |
American Geophysical Union (AGU) |
publishDate |
2021 |
url |
https://archimer.ifremer.fr/doc/00688/79966/82897.pdf https://archimer.ifremer.fr/doc/00688/79966/82898.docx https://archimer.ifremer.fr/doc/00688/79966/82899.xlsx https://doi.org/10.1029/2020GB006887 https://archimer.ifremer.fr/doc/00688/79966/ |
genre |
north atlantic current North Atlantic Subarctic |
genre_facet |
north atlantic current North Atlantic Subarctic |
op_source |
Global Biogeochemical Cycles (0886-6236) (American Geophysical Union (AGU)), 2021-04 , Vol. 35 , N. 4 , P. e2020GB006887 (15p.) |
op_relation |
https://archimer.ifremer.fr/doc/00688/79966/82897.pdf https://archimer.ifremer.fr/doc/00688/79966/82898.docx https://archimer.ifremer.fr/doc/00688/79966/82899.xlsx doi:10.1029/2020GB006887 https://archimer.ifremer.fr/doc/00688/79966/ |
op_rights |
info:eu-repo/semantics/openAccess restricted use |
op_doi |
https://doi.org/10.1029/2020GB006887 |
container_title |
Global Biogeochemical Cycles |
container_volume |
35 |
container_issue |
4 |
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1766116710086082560 |