georefid:2011-035491SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-07-06T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=2011-035491<gco:CharacterString>Increase in water column denitrification during the last deglaciation; the influence of oxygen demand in the eastern Equatorial Pacific</gco:CharacterString>2010-01-01publicationgeorefid:2011-035491Martinez, PhilippeUniversite de Bordeaux I, Environnements et Paleoenvironnements Oceaniques, Talence, FranceauthorRobinson, Rebecca S.University of Rhode Island, United StatesauthorCopernicus GmbH on behalf of the European Union, Katlenburg-Lindau, InternationalpublisherdocumentDigitalBiogeosciences7 (1)1-9Here we present organic export production and nitrogen isotope results spanning the last 30 000 years from a core recovered off Costa Rica (Ocean Drilling Program (ODP) Site 1242) on the leading edge of the oxygen minimum zone of the Eastern Tropical North Pacific. Marine export production reveals glacial-interglacial variations with low organic matter (total organic carbon and total nitrogen) contents during warm intervals, twice more during cold episodes and double peaked maximum during the deglaciation, between approximately 15.5-18.5 and 11-13 ka B.P. When this new export production record is compared with four nearby cores from within the Eastern Pacific along the Equatorial divergence, good agreement between all the cores is observed. The major feature is a maximum of export during the early deglaciation. As for export production, water-column denitrification, represented by sedimentary delta (super 15) N records, along the Eastern tropical North and South Pacific between 15 degrees N and 36 degrees S is also coherent over the last deglaciation. Each of the nitrogen isotope profiles indicate that denitrification increased abruptly at 19 ka B.P to a maximum during the early deglaciation, confirming a typical Antarctic timing. It is proposed that the increase in export production and then in subsurface oxygen demand lead to an intensification of water-column denitrification within the oxygen minimum zones in the easternmost Pacific at the time of the last deglaciation. The triggering mechanism would have been primarily linked to an increase in preformed nutrients contents feeding the Equatorial Undercurrent driven by the resumption of overturning in the Southern Ocean and the return of nutrients from the deep ocean to the sea-surface. An increase in equatorial wind-driven upwelling of sub-surface nutrient-rich waters could have played the role of an amplifier.completedQuaternary geologybiochemistrycarbonCenozoiccontinental margindeglaciationdenitrificationEast PacificEquatorial PacificHolocenelate-glacial environmentLeg 202marine environmentnitratesnitrogenNorth PacificNortheast Pacificnutrientsocean circulationOcean Drilling ProgramODP Site 1240ODP Site 1242organic carbonoxygenPacific Oceanpaleo-oceanographypaleocurrentsPanama BasinQuaternarysea waterSouthern Oceanthermoclinethermohaline circulationupwellingwindsurn:org.iodp:exp:202urnlargerWorkCitationcampaignurn:org.iodp:exp:202:site:1240urnlargerWorkCitationstudyurn:org.iodp:exp:202urnlargerWorkCitationcampaignurn:org.iodp:exp:202:site:1242urnlargerWorkCitationstudyurn:org.iodp:exp:202urnlargerWorkCitationcampaignEnglishgeoscientificInformation-83.3600-82.28000.01007.5100Published in Biogeosciences Discuss.: 19 May 2009, http://www.biogeosciences-discuss.net/6/5145/2009/bgd-6-5145-2009.html ; accessed in Feb., 2011; abstract: http://www.biogeosciences.net/7/1/2010/bg-7-1-2010.htmlapplication/pdfunknownSEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContacthttp://www.biogeosciences.net/7/1/2010/bg-7-1-2010.pdfdownload