Yoshioka, Hideyoshi et al. (2009): Microbial methane production rates in gas hydrate-bearing sediments from the eastern Nankai Trough, off central Japan

ODP 190
ODP 190 1173
ODP 196 1173
ODP 190 1174
ODP 190 1177

Yoshioka, Hideyoshi
National Institute of Advanced Industrial Science and Technology, Institute for Geo-Resources and Environment, Tsukuba, Japan

Sakata, Susumu
Cardiff University, United Kingdom

Cragg, Barry A.
Japan Oil, Gas and Metals National Corporation, Japan

Parkes, R. John

Fujii, Tetsuya

Microbial methane production rates in gas hydrate-bearing sediments from the eastern Nankai Trough, off central Japan
Geochemical Journal
Geochemical Society of Japan, Nagoya, Japan
Gas hydrates and associated high methane concentrations are widely distributed along the boundary of the Nankai Trough off Japan. Radiotracer activity measurements were conducted to estimate current methane production rates in sediment cores at two sites in the eastern Nankai Trough off Tokai containing gas hydrates. Low rates of methanogenesis from CO (sub 2) reduction and acetate fermentation were detected within the gas hydrate-stability zone and below the Bottom Simulating Reflector (BSR), but not in sediments from shallow depths (<100 mbsf). The detected production rates of methane from acetate were much higher than those from carbon dioxide and hydrogen. Methanol or potentially some other methyl compounds could also be used for microbial methane production. Deep methane production rates from acetate in the gas hydrate-bearing sediments were higher than in pre-accretionary, hydrate-free, sediments at sites 1173, 1174 and 1177 of ODP Leg 190 from the floor of the western Nankai Trough off Shikoku Island. As previously suggested this might be due to upward fluid flow stimulating bacterial activities around and below the base of the gas hydrate zone. In contrast, methanogenesis from carbon dioxide and hydrogen was the main pathway for microbial methane production in the hydrate-free sediments at the ODP Nankai Trough sites.
Coverage:Geographic coordinates:
West:134.0000East: 135.0200

Oceanography; acetates; alcohols; aliphatic hydrocarbons; alkalinity; alkanes; Asia; biogenic processes; bottom-simulating reflectors; carbon dioxide; cores; depth; esters; Far East; gas hydrates; geophysical methods; hydrocarbons; hydrogen; Japan; Leg 190; marine sediments; methane; methanol; microorganisms; Nankai Trough; North Pacific; Northwest Pacific; Ocean Drilling Program; ocean floors; ODP Site 1173; ODP Site 1174; ODP Site 1177; organic compounds; Pacific Ocean; porosity; production; radioactive tracers; sediments; seismic methods; Shikoku Basin; total organic carbon; West Pacific;