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

Dissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼ 2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we q...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Fernández-Castro, F. (Francisco), Álvarez, M. (Marta), Nieto-Cid, M. (Mar), Zunino-Rodríguez, P. (Patricia), Mercier, H., Álvarez-Salgado, X.A.
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union (AGU) 2019
Subjects:
Greenland
Iceland
North Atlantic
Online Access:http://hdl.handle.net/10508/14868
https://doi.org/10.1029/2018GL080284
Description
Summary:Dissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼ 2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, 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 Meridional Overturning Circulation exports >15.9 TgN/year of DON downward 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/year. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short transit times in the eSPNA (3 ± 1 year) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.

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