Potential impact of changes in river nutrient supply on global ocean biogeochemistry.

Da Cunha, Leticia Cotrim; Buitenhuis, Erik T.; Le Quere, Corinne; Giraud, Xavier; Ludwig, Wolfgang. 2007 Potential impact of changes in river nutrient supply on global ocean biogeochemistry. Global Biogeochemical Cycles, 21 (4), GB4007. 15, pp. 10.1029/2006GB002718

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Abstract/Summary

The growing world population increases the demand for water, energy, and land. This demand for natural resources impacts the transport of material and the supply of nutrients in the coastal ocean by rivers. We assess the potential impact of river N, Si, Fe, and organic carbon (OC) fluxes on the global and coastal ocean biogeochemistry, using an ocean biogeochemistry model and observations, in eight different scenarios. We assess two extreme scenarios, one with no river nutrients, corresponding to a complete stop of nutrient input by rivers, and one with high nutrient fluxes, corresponding to a world population of 12 billion people. Compared to today’s scenario values, primary production (PP) changes from 5% to +5% for the open ocean, and from 16% to +5% for the coastal ocean. In the coastal ocean the impact of river nutrients on PP depends on regional nutrient limitation. River inputs have a larger impact on PP in areas where upwelling and high runoff are combined. The coastal ocean is typically N- or Si-limited. River Fe not assimilated by the phytoplankton is exported to open ocean areas, and its fertilizing effect depletes coastal and open ocean surface waters from N and Si. The impact on PP is reflected on global ocean low-O2 areas whose extent changes from 16% to +23% across the range of scenarios. River nutrients have a modest impact on the global ocean CO2 sink of up to 0.4 Pg C a1, depending on the amount of inorganic and organic carbon transported by the rivers.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2006GB002718
Programmes:	BAS Programmes > Other Special Projects
ISSN:	0886-6236
NORA Subject Terms:	Marine Sciences
Related URLs:	Author's Homepage
Date made live:	19 Nov 2008 16:32 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/3102

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