Nitrate Supply Routes and Impact of Internal Cycling in the North Atlantic Ocean Inferred From Nitrate Isotopic Composition
15 pages, 6 figures, 1 table 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...
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American Geophysical Union
2021
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Online Access: | http://hdl.handle.net/10261/242850 https://doi.org/10.1029/2020GB006887 |
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ftcsic:oai:digital.csic.es:10261/242850 2024-02-11T10:06:00+01:00 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, Maribel I. Le Roy, Emilie Thilakarathne, E. P. D. N. Elskens, M. Dehairs, Frank Fripiat, F. 2021 http://hdl.handle.net/10261/242850 https://doi.org/10.1029/2020GB006887 en eng American Geophysical Union Postprint https://doi.org/10.1029/2020GB006887 Sí Global Biogeochemical Cycles 35(4): e2020GB006887 (2021) 0886-6236 http://hdl.handle.net/10261/242850 doi:10.1029/2020GB006887 1944-9224 open artículo http://purl.org/coar/resource_type/c_6501 2021 ftcsic https://doi.org/10.1029/2020GB006887 2024-01-16T11:09:36Z 15 pages, 6 figures, 1 table 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 toward 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 The GEOVIDE project was co-funded by the French national program LEFE/INSU (GEOVIDE), ANR Blanc (GEOVIDE) and RPDOC, LabEX MER and IFREMER. F. Deman was supported by the Belgian Federal Science Policy Office (Belspo contract BL/12/C63) while writing the manuscript. This work was financed by Flanders Research Foundation (FWO contract G0715.12N) and Vrije Universiteit Brussel, R&D, Strategic Research ... Article in Journal/Newspaper north atlantic current North Atlantic Subarctic Digital.CSIC (Spanish National Research Council) Global Biogeochemical Cycles 35 4 |
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Digital.CSIC (Spanish National Research Council) |
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English |
description |
15 pages, 6 figures, 1 table 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 toward 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 The GEOVIDE project was co-funded by the French national program LEFE/INSU (GEOVIDE), ANR Blanc (GEOVIDE) and RPDOC, LabEX MER and IFREMER. F. Deman was supported by the Belgian Federal Science Policy Office (Belspo contract BL/12/C63) while writing the manuscript. This work was financed by Flanders Research Foundation (FWO contract G0715.12N) and Vrije Universiteit Brussel, R&D, Strategic Research ... |
format |
Article in Journal/Newspaper |
author |
Deman, F. Fonseca-Batista, D. Roukaerts, A. García-Ibáñez, Maribel I. Le Roy, Emilie Thilakarathne, E. P. D. N. Elskens, M. Dehairs, Frank Fripiat, F. |
spellingShingle |
Deman, F. Fonseca-Batista, D. Roukaerts, A. García-Ibáñez, Maribel I. Le Roy, Emilie Thilakarathne, E. P. D. N. Elskens, M. Dehairs, Frank Fripiat, F. Nitrate Supply Routes and Impact of Internal Cycling in the North Atlantic Ocean Inferred From Nitrate Isotopic Composition |
author_facet |
Deman, F. Fonseca-Batista, D. Roukaerts, A. García-Ibáñez, Maribel I. Le Roy, Emilie Thilakarathne, E. P. D. N. Elskens, M. Dehairs, Frank 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 |
publishDate |
2021 |
url |
http://hdl.handle.net/10261/242850 https://doi.org/10.1029/2020GB006887 |
genre |
north atlantic current North Atlantic Subarctic |
genre_facet |
north atlantic current North Atlantic Subarctic |
op_relation |
Postprint https://doi.org/10.1029/2020GB006887 Sí Global Biogeochemical Cycles 35(4): e2020GB006887 (2021) 0886-6236 http://hdl.handle.net/10261/242850 doi:10.1029/2020GB006887 1944-9224 |
op_rights |
open |
op_doi |
https://doi.org/10.1029/2020GB006887 |
container_title |
Global Biogeochemical Cycles |
container_volume |
35 |
container_issue |
4 |
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1790603383692853248 |