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The Aquitaine Shelf Edge (Bay of Biscay): A Primary Outlet for Microbial Methane Release
Author(s) -
Dupré S.,
Loubrieu B.,
Pierre C.,
Scalabrin C.,
Guérin C.,
Ehrhold A.,
Ogor A.,
Gautier E.,
Ruffine L.,
Biville R.,
Saout J.,
Breton C.,
Floodpage J.,
Lescanne M.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl084561
Subject(s) - methane , oceanography , geology , continental shelf , bay , seafloor spreading , water column , atmospheric methane , diagenesis , carbon cycle , geochemistry , ecology , greenhouse gas , ecosystem , biology
A few thousand (2,612) seeps are releasing microbial methane bubbles from the seafloor at the Aquitaine Shelf edge (Bay of Biscay) at shallow water depths (140–220 m). This methane contributes to the formation of meter‐scale subcircular carbonate structures, which are (sub)outcropping over 375 km 2 . Based on in situ flow rate measurements and acoustic data, and assuming steady and continuous fluxes over time, the methane entering the water column is estimated at 144 Mg/yr. Microbial methane circulation has been ongoing for at least a few thousand years. This discovery highlights the importance of microbial methane generation, disconnected from deep thermogenic sources and gas hydrates, at continental shelves. The shelf edge may be viewed as a focus area for methane circulation and release and related diagenesis, all having an impact on the shaping of continental shelves and potentially on the oceanic and atmospheric carbon budget.