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dc.contributor.authorMoore, J. Keith  Concept link
dc.contributor.authorDoney, Scott C.  Concept link
dc.date.accessioned2010-05-06T18:57:04Z
dc.date.available2010-05-06T18:57:04Z
dc.date.issued2007-04-04
dc.identifier.citationGlobal Biogeochemical Cycles 21 (2007): GB2001en_US
dc.identifier.urihttps://hdl.handle.net/1912/3403
dc.descriptionAuthor Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 21 (2007): GB2001, doi:10.1029/2006GB002762.en_US
dc.description.abstractRecent upward revisions in key sink/source terms for fixed nitrogen (N) in the oceans imply a short residence time and strong negative feedbacks involving denitrification and N fixation to prevent large swings in the ocean N inventory over timescales of a few centuries. We tested the strength of these feedbacks in a global biogeochemical elemental cycling (BEC) ocean model that includes water column denitrification and an explicit N fixing phytoplankton group. In the northern Indian Ocean and over longer timescales in the tropical Atlantic, we find strong stabilizing feedbacks that minimize changes in marine N inventory over timescales of ∼30–200 years. In these regions high atmospheric dust/iron inputs lead to phosphorus limitation of diazotrophs, and thus a tight link between N fixation and surface water N/P ratios. Maintenance of the oxygen minimum zones in these basins depends on N fixation driven export. The stabilizing feedbacks in other regions are significant but weaker owing to iron limitation of the diazotrophs. Thus Fe limitation appears to restrict the ability of N fixation to compensate for changes in denitrification in the current climate, perhaps leading the oceans to lose fixed N. We suggest that iron is the ultimate limiting nutrient leading to nitrogen being the proximate limiting nutrient over wide regions today. Iron stress was at least partially alleviated during more dusty, glacial times, leading to a higher marine N inventory, increased export production, and perhaps widespread phosphorus limitation of the phytoplankton community. The increased efficiency of the biological pump would have contributed to the glacial drawdown in atmospheric CO2.en_US
dc.description.sponsorshipThis work was supported by grants from the U.S. National Science Foundation (OCE-0222033 and OCE-0452972). Computations supported by Earth System Modeling Facility (NSF ATM-0321380) and by the Climate Simulation Laboratory at the National Center for Atmospheric Research.en_US
dc.format.mimetypeapplication/pdf
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dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.urihttps://doi.org/10.1029/2006GB002762
dc.subjectClimateen_US
dc.subjectBiological pumpen_US
dc.subjectEcosystem modelen_US
dc.titleIron availability limits the ocean nitrogen inventory stabilizing feedbacks between marine denitrification and nitrogen fixationen_US
dc.typeArticleen_US
dc.identifier.doi10.1029/2006GB002762


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