The bottom row shows movie frames where a methane gas sample cell is moved by hand across the field - of - view. (sciencedaily.com)
In their 2005 paper Indications for an active petroleum system in the Laptev Sea, NE Siberia, Cramer and Franke (CF5) presented seismic data and analyses of gas samples that showed that there are deep sedimentary basins in this part of the Arctic Ocean that are actively seeping fossil methane. (critical-angle.net)
At 30 minutes intervals the researchers collected gas samples from the mixture and analysed it to see how much hydrogen was being produced. (sciencedaily.com)