Biogeosciences
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2008
10.5194/bg-5-1119-2008
http://www.biogeosciences.net/5/1119/2008/
http://www.biogeosciences.net/5/1119/2008/bg-5-1119-2008.html
http://www.biogeosciences.net/5/1119/2008/bg-5-1119-2008.pdf
1119
1125
2008-08-05
Methane emissions from the upwelling area off Mauritania (NW Africa)
A. Kock
S. Gebhardt
H. W. Bange
hbange@ifm-geomar.de
Forschungsbereich Marine Biogeochemie, IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Düsternbrooker Weg 20, 24105 Kiel, Germany
now at: Atmospheric Chemistry Dept., Max Planck Institute for Chemistry, Mainz, Germany
Coastal upwelling regions have been identified as sites of enhanced CH<sub>4</sub>
emissions to the atmosphere. The coastal upwelling area off Mauritania (NW
Africa) is one of the most biologically productive regions of the world's
ocean but its CH<sub>4</sub> emissions have not been quantified so far. More than
1000 measurements of atmospheric and dissolved CH<sub>4</sub> in the surface layer
in the upwelling area off Mauritania were performed as part of the German
SOPRAN (Surface Ocean Processes in the Anthropocene) study during two
cruises in March/April 2005 (P320/1) and February 2007 (P348). During P348
enhanced CH<sub>4</sub> saturations of up to 200% were found close to the coast
and were associated with upwelling of South Atlantic Central Water. An
area-weighted, seasonally adjusted estimate yielded overall annual CH<sub>4</sub>
emissions in the range from 1.6 to 2.9 Gg CH<sub>4</sub>. Thus the upwelling area
off Mauritania represents a regional hot spot of CH<sub>4</sub> emissions but
seems to be of minor importance for the global oceanic CH<sub>4</sub> emissions.
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