Dissolved organic nitrogen production and export by meridional overturning in the eastern subpolar North Atlantic

Type Article
Date 2019-04
Language English
Author(s) Fernández-Castro Bieito1, 2, Álvarez Marta3, Nieto-Cid Mar3, Zunino PatriciaORCID5, Mercier HerleORCID4, Álvarez-Salgado Xosé Antón1
Affiliation(s) 1 : Departamento de Oceanografía; Instituto de Investigacións Mariñas (IIM-CSIC); Vigo 36208 ,Spain
2 : Physics of Aquatic Systems Laboratory, Margaretha Kamprad Chair, Ecole Polytechnique Fédérale de Lausanne, Institute of Environmental Engineering; Lausanne ,Switzerland
3 : Centro Oceanográfico de A Coruña; Instituto Español de Oceanografía; A Coruña 15001, Spain
4 : Laboratoire d'Océanographie Physique et Spatiale, UMR 6523 CNRS/Ifremer/IRD/UBO, Ifremer Centre de Bretagne; Plouzané 29280 ,France
Source Geophysical Research Letters (0094-8276) (American Geophysical Union (AGU)), 2019-04 , Vol. 46 , N. 7 , P. 3832-3842
DOI 10.1029/2018GL080284
WOS© Times Cited 5
Keyword(s) dissolved organic matter, nitrogen cycle, meridional overturning circulation, subpolar North Atlantic, metabolic balance
Abstract

Dissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼2 PgC yr−1 to the global carbon export. Due to its central role in the Meridional Overturning Circulation (MOC), the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we quantify the transport and budget of dissolved organic nitrogen (DON) in the eSPNA, in a box delimited by the OVIDE 2002 section and the Greenland‐Iceland‐Scotland sills. The MOC exports >15.9 TgN yr−1 of DON downwards and, contrary to the extended view that these are materials of subtropical origin, up to 33% of the vertical flux derives from a net local DON production of 7.1 ± 2.6 TgN yr−1. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short‐transit times in the eSPNA (3 ± 1 yr) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.

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Fernández-Castro Bieito, Álvarez Marta, Nieto-Cid Mar, Zunino Patricia, Mercier Herle, Álvarez-Salgado Xosé Antón (2019). Dissolved organic nitrogen production and export by meridional overturning in the eastern subpolar North Atlantic. Geophysical Research Letters, 46(7), 3832-3842. Publisher's official version : https://doi.org/10.1029/2018GL080284 , Open Access version : https://archimer.ifremer.fr/doc/00485/59622/