Biogeochemical characteristics of a long-lived anticyclonic eddy in the eastern South Pacific Ocean

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dc.contributor.authorCornejo D'Ottone, Marcela
dc.contributor.authorBravo, Luis
dc.contributor.authorRamos, Marcel
dc.contributor.authorPizarro, Oscar
dc.contributor.authorKarstensen, Johannes
dc.contributor.authorGallegos, Mauricio
dc.contributor.authorCorrea-Ramirez, Marco
dc.contributor.authorSilva, Nelson
dc.contributor.authorFarias, Laura
dc.contributor.authorKarp-Boss, Lee
dc.date.accessioned2025-01-23T21:32:27Z
dc.date.available2025-01-23T21:32:27Z
dc.date.issued2016
dc.description.abstractMesoscale eddies are important, frequent, and persistent features of the circulation in the eastern South Pacific (ESP) Ocean, transporting physical, chemical and biological properties from the productive shelves to the open ocean. Some of these eddies exhibit subsurface hypoxic or suboxic conditions and may serve as important hotspots for nitrogen loss, but little is known about oxygen consumption rates and nitrogen transformation processes associated with these eddies. In the austral fall of 2011, during the Tara Oceans expedition, an intrathermocline, anticyclonic, mesoscale eddy with a suboxic (< aEuro-2aEuro-A mu molaEuro-kg(-1) of O-2), subsurface layer (200-400aEuro-m) was detected similar to aEuro parts per thousand aEuro-900aEuro-km off the Chilean shore (30A degrees aEuro-S, 81A degrees aEuro-W). The core of the eddy's suboxic layer had a temperature-salinity signature characteristic of Equatorial Subsurface Water (ESSW) that at this latitude is normally restricted to an area near the coast. Measurements of nitrogen species within the eddy revealed undersaturation (below 44aEuro-%) of nitrous oxide (N2O) and nitrite accumulation (> aEuro-0.5aEuro-A mu M), suggesting that active denitrification occurred in this water mass. Using satellite altimetry, we were able to track the eddy back to its region of formation on the coast of central Chile (36.1A degrees aEuro-S, 74.6A degrees aEuro-W). Field studies conducted in Chilean shelf waters close to the time of eddy formation provided estimates of initial O-2 and N2O concentrations of the ESSW source water in the eddy. By the time of its offshore sighting, concentrations of both O-2 and N2O in the subsurface oxygen minimum zone (OMZ) of the eddy were lower than concentrations in surrounding water and "source water" on the shelf, indicating that these chemical species were consumed as the eddy moved offshore. Estimates of apparent oxygen utilization rates at the OMZ of the eddy ranged from 0.29 to 44aEuro-nmolaEuro-L(-1)aEuro-d(-1) and the rate of N2O consumption was 3.92aEuro-nmolaEuro-L(-1)aEuro-d(-1). These results show that mesoscale eddies affect open-ocean biogeochemistry in the ESP not only by transporting physical and chemical properties from the coast to the ocean interior but also during advection, local biological consumption of oxygen within an eddy further generates conditions favorable to denitrification and loss of fixed nitrogen from the system.
dc.fuente.origenWOS
dc.identifier.doi10.5194/bg-13-2971-2016
dc.identifier.eissn1726-4189
dc.identifier.issn1726-4170
dc.identifier.urihttps://doi.org/10.5194/bg-13-2971-2016
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/101492
dc.identifier.wosidWOS:000378354900008
dc.issue.numero10
dc.language.isoen
dc.pagina.final2979
dc.pagina.inicio2971
dc.revistaBiogeosciences
dc.rightsacceso restringido
dc.subject.ods14 Life Below Water
dc.subject.ods13 Climate Action
dc.subject.odspa14 Vida submarina
dc.subject.odspa13 Acción por el clima
dc.titleBiogeochemical characteristics of a long-lived anticyclonic eddy in the eastern South Pacific Ocean
dc.typeartículo
dc.volumen13
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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