An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone.

Altabet, M. A., Ryabenko, Evgeniya, Stramma, Lothar , Wallace, Douglas W.R., Frank, Martin , Grasse, Patricia and Lavik, G. (2012) An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone. Open Access Biogeosciences (BG), 9 . pp. 4897-4908. DOI 10.5194/bg-9-4897-2012.

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Abstract

Fixed nitrogen (N) loss to biogenic N2 in intense oceanic O2 minimum zones (OMZ) accounts for a large fraction of the global N sink and is an essential control on the ocean's N budget. However, major uncertainties exist regarding microbial pathways as well as net impact on the magnitude of N-loss and the ocean's overall N budget. Here we report the discovery of a N-loss hotspot in the Peru OMZ associated with a coastally trapped mesoscale eddy that is marked by an extreme N deficit matched by biogenic N2 production, high NO2− levels, and the highest isotope enrichments observed so far in OMZ's for the residual NO3−. High sea surface chlorophyll (SSC) in seaward flowing streamers provides evidence for offshore eddy transport of highly productive, inshore water. Resulting pulses in the downward flux of particles likely stimulated heterotrophic dissimilatory NO3− reduction and subsequent production of biogenic N2. The associated temporal/spatial heterogeneity of N-loss, mediated by a local succession of microbial processes, may explain inconsistencies observed among prior studies. Similar transient enhancements of N-loss likely occur within all other major OMZ's exerting a major influence on global ocean N and N isotope budgets.

Document Type: Article
Additional Information: WOS:000312668100001
Keywords: Peru Oxygen Minimum Zone; ANAEROBIC AMMONIUM OXIDATION; TROPICAL NORTH PACIFIC; ARABIAN SEA DENITRIFICATION; CHEMICAL CONVERSION; CONTINENTAL-SHELF; MESOSCALE EDDIES; DEFICIENT WATERS; SOUTH-PACIFIC; SARGASSO SEA; NITRATE
Research affiliation: OceanRep > SFB 754 > A3
OceanRep > SFB 754 > B4
OceanRep > SFB 754
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > SFB 754 > A5
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > SFB 574 > N01
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-9-4897-2012
ISSN: 1726-4170
Projects: SFB754, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 26 Nov 2012 12:33
Last Modified: 26 Apr 2016 10:28
URI: http://oceanrep.geomar.de/id/eprint/19304

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