Methane emissions from the upwelling area off Mauritania (NW Africa)

A. Kock (1) , S. Gebhardt (1) , H. W. Bange (1)

1 Forschungsbereich Marine Biogeochemie IFM-GEOMAR

Coastal upwelling regions have been indentified as sites of enhanced CH₄ 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 CH₄ emissions have not been quantified so far. More than 1000 measurements of atmospheric and dissolved CH₄ 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 CH₄ saturations of up to 179% 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 CH₄ emissions in the range from 0.7 to 1.4 Gg CH₄. Thus the upwelling area off Mauritania represents a regional hot spot of CH₄ emissions but seems to be of minor importance for the global oceanic CH₄ emissions.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

A. Kock, S. Gebhardt, H. W. Bange. Methane emissions from the upwelling area off Mauritania (NW Africa). Biogeosciences Discussions, 2008, 5 (1), pp.297-315. ⟨hal-00297964⟩