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dc.contributor.authorMoutin, T.  Concept link
dc.contributor.authorKarl, David M.  Concept link
dc.contributor.authorDuhamel, Solange  Concept link
dc.contributor.authorRimmelin, P.  Concept link
dc.contributor.authorRaimbault, P.  Concept link
dc.contributor.authorVan Mooy, Benjamin A. S.  Concept link
dc.contributor.authorClaustre, Hervé  Concept link
dc.identifier.citationBiogeosciences 5 (2008): 95-109en
dc.description© 2008 Author(s). This work is distributed under the Creative Commons Attribution License. The definitive version was published in Biogeosciences 5 (2008): 95-109, doi:10.5194/bg-5-95-2008en
dc.description.abstractDue to the low atmospheric input of phosphate into the open ocean, it is one of the key nutrients that could ultimately control primary production and carbon export into the deep ocean. The observed trend over the last 20 years has shown a decrease in the dissolved inorganic phosphate (DIP) pool in the North Pacific gyre, which has been correlated to the increase in di-nitrogen (N2) fixation rates. Following a NW-SE transect, in the Southeast Pacific during the early austral summer (BIOSOPE cruise), we present data on DIP, dissolved organic phosphate (DOP) and particulate phosphate (PP) pools along with DIP turnover times (TDIP) and N2 fixation rates. We observed a decrease in DIP concentration from the edges to the centre of the gyre. Nevertheless the DIP concentrations remained above 100 nmol L−1 and T DIP was more than 6 months in the centre of the gyre; DIP availability remained largely above the level required for phosphate limitation to occur and the absence of Trichodesmium spp and low nitrogen fixation rates were likely to be controlled by other factors such as temperature or iron availability. This contrasts with recent observations in the North Pacific Ocean at the ALOHA station and in the western Pacific Ocean at the same latitude (DIAPALIS cruises) where lower DIP concentrations (<20 nmol L−1) and T DIP <50 h were measured during the summer season in the upper layer. The South Pacific gyre can be considered a High Phosphate Low Chlorophyll (HPLC) oligotrophic area, which could potentially support high N2 fixation rates and possibly carbon dioxide sequestration, if the primary ecophysiological controls, temperature and/or iron availability, were alleviated.en
dc.description.sponsorshipThis research was funded by the Centre National de la Recherche Scientifique (CNRS), the Institut des Sciences de l’Univers (INSU), the Centre National d’Etudes Spatiales (CNES), the European Space Agency (ESA), The National Aeronautics and Space Administration (NASA) and the Natural Sciences and Engineering Research Council of Canada (NSERC). This work is funded in part by the French Research and Education council.en
dc.publisherCopernicus Publications on behalf of the European Geosciences Unionen
dc.rightsAttribution-NonCommercial-ShareAlike 2.5 Generic*
dc.titlePhosphate availability and the ultimate control of new nitrogen input by nitrogen fixation in the tropical Pacific Oceanen

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