Possible variation in methane flux caused by gas hydrate formation on the northeastern continental slope off Sakhalin Island, Russia

Abstract

The Sakhalin Slope Gas Hydrate Project (SSGH) is an international collaborative effort by scientists from Japan, Korea and Russia to investigate natural gas hydrates (GHs) that have accumulated on the continental slope off Sakhalin Island. From 2009 to 2011, field operations of the SSGH-09, SSGH-10 and SSGH-11 projects were conducted. GH-bearing and -free sediment cores were retrieved using steel hydro- and gravity corers. The concentrations of sulfate ions in the sediment pore waters obtained during those cruises were measured to investigate the sulfate concentration-depth profile. Seventeen cores showed linear depth profiles of sulfate concentrations, whereas 8 cores and 2 cores showed the concave-up and - down profiles due to a sudden increase and decrease in the methane flux from below, respectively, presumably caused by the formation of gas hydrate adjacent to the core sampling sites.nd. From 2009 to 2011, field operations of the SSGH-09, SSGH-10 and SSGH-11 projects were conducted. GH-bearing and -free sediment cores were retrieved using steel hydro- and gravity corers. The concentrations of sulfate ions in the sediment pore waters obtained during those cruises were measured to investigate the sulfate concentration-depth profile. Seventeen cores showed linear depth profiles of sulfate concentrations, whereas 8 cores and 2 cores showed the concave-up and - down profiles due to a sudden increase and decrease in the methane flux from below, respectively, presumably caused by the formation of gas hydrate adjacent to the core sampling sites.