Gas Seepage along the Edge of the Aquitaine Shelf (France): Origin and Local Fluxes

Table 3

Comparison of gas-bubble fluxes from different settings.

Setting	Water depth (m)	Gas flux (×10^3 mol⋅yr^−1)	Flux measurement technique	Gas origin	Comment	Reference
Aquitaine shelf	140–180	38.2	Video recording of gas bubbling through a graduated volume	Biogenic	Measurement for 9 individual streams	This work
Eastern Mediterranean Sea; (Hydrate site)	1500–1800	230–2300	Combination of gas analysis, ship-based hydroacoustic surveys, bubble size modeling, and ROV observations	Biogenic	Average measurement for 20 individual streams	[76]
Hakon Mosby MV; (Hydrate site)	1250	6307	ROV observations	Biogenic	Measurement of gas discharge from open faults; and mud volcano	[77]
Makran continental margin; (Hydrate site)	575–2870	10330	Combination of gas analysis, ship-based hydroacoustic surveys, bubble size modeling, and ROV observations	Biogenic	Measurement from 3 gas flares composed of several streams and extrapolation to all identified flares (>20)	[78]
Don-Kuban paleo-fan (Black Sea); (Hydrate site)	890	2000–87000	Combination of gas analysis, ship-based hydroacoustic surveys, bubble size modeling, and ROV observations	Biogenic	Average measurement from ~600 acoustic flares over 10^6 m^2 surface area	[79]
Northern summit of Hydrate Ridge; (Hydrate site)	1250	21900	Video recording of gas displacing a fluid through a PVC funnel	Biogenic	Measurement for 10 individual streams over 80 m^2 surface area	[80]
UK Block 15/25	167	1064	Gas rate measurements	Thermogenic	Surveyed area of surface area	[81]