Eddy hotspots 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) Eddy hotspots for fixed nitrogen-loss from the Peru Oxygen Minimum Zone [Talk] In: 2012 Ocean Sciences Meeting, OSM, 20.02.-24.02.2012, Salt Lake City, Utah, USA.

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Abstract

Abstract ID: 10044
Microbially-mediated N-loss in intense oceanic O2 minimum zones (OMZ) accounts for a large fraction of the global sink and is an essential control on the ocean’s N budget. However, major uncertainties exist regarding pathways and their net impact on N-loss magnitude. To address these issues, relevant biogeochemical properties were mapped throughout the Peru OMZ in winter 2009. South of 7 to 10°S, low O2 concentrations in the Peru OMZ enabled N-loss processes as shown by the appearance of nitrite, net removal of nitrate from the water column, and isotopic enrichment in the residual nitrate. However, two stations exhibited uniquely extreme values. Satellite imagery shows these stations to be associated with the seaward edges of coastal mesoscale eddies. We hypothesize that eddies transport productive, nutrient-rich coastal water offshore that create deep-ocean N-loss ‘hotspots’ with extreme N isotope fractionation. As a result, eddies are likely important for overall enhancement of N-loss from the Peru OMZ. Similar transient enhancements of N-loss by eddies likely occur within all other major OMZ’s thereby exerting a major influence on global ocean N and N isotope budgets.

Document Type: Conference or Workshop Item (Talk)
Keywords: Physical Oceanography; Marine chemistry; Oceanography; Biogeochemistry; Pacific Ocean; Peru Oxygen Minimum Zone
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
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Date Deposited: 12 Apr 2012 12:36
Last Modified: 13 Apr 2012 03:58
URI: http://eprints.uni-kiel.de/id/eprint/14203

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