Carbon isotopic distribution of methane in deep-sea hydrothermal plume, Myojin Knoll Caldera, Izu-Bonin arc: implications for microbial methane oxidation in the oceans and applications to heat flux estimation

Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

“…4b), almost all the methane we observed could be explained by a combination of the plume dilution by ambient seawater and a kinetic carbon isotope effect (KIE) of 1.007. The KIE of 1.007 is slightly higher, but comparable with those determined by previous plume observations in the Myojin Knoll Caldera hydrothermal field (1.005 ± 0.001: Tsunogai et al, 2000), the Yonaguni Knoll IV hydrothermal field (1.005 and 1.012: Gamo et al, this issue, Geochemical Advances: Following Prof. Sakai, 2010), and the East Pacific Rise 27.5°-32.5°S area (1.004~1.006: Gharib et al, 2005). Parts of samples at Stns.…”

“…The measurement consisted of a combination of purge-and-trap technique, continuous-flow isotope ratio mass spectrometry, a gas chromatograph (HP6850), and an isotope ratio mass spectrometer (Finnigan MAT252) (Tsunogai et al, 2000. The stable carbon, nitrogen, and oxygen isotope ratios are presented in the standard delta-notation in the permil scale with respect to Vienna-PDB, Air, and Vienna-SMOW, respectively.…”

A Compilation of the Stable Isotopic Compositions of Carbon, Nitrogen, and Sulfur in Soft Body Parts of Animals Collected from Deep-Sea Hydrothermal Vent and Methane Seep Fields: Variations in Energy Source and Importance of Subsurface Microbial Processes in the Sediment-Hosted Systems

“…The concentration and carbon isotope composition of the dissolved methane in the water samples were determined following the methods of Tsunogai et al (2000), using an isotope-ratio-monitoring-GC/MS (MAT 252, Thermo Quest, USA). The methane content in the samples was calculated by comparing the 44 CO 2 output with that of a working standard gas containing c. 500 ppm methane in nitrogen.…”

Origin and fate of deep-sea seeping methane bubbles at Kuroshima Knoll, Ryukyu forearc region, Japan

“…The distribution of the concentration and stable carbon isotopic composition (δ 13 C) of CH 4 in a CH 4 -enriched plume are good tracers for determining the fate of CH 4 in a water column, especially for quantitatively determining the progress of microbial oxidation (Tsunogai et al, 1998(Tsunogai et al, , 2000Nishimura et al, 1999). Indeed, CH 4 oxidation consumes 12 CH 4 preferentially, leaving the residual CH 4 enriched in 13 CH 4 (Silverman and Oyama, 1968), while δ 13 C C1 does not vary through eddy diffusion.…”

“…Indeed, CH 4 oxidation consumes 12 CH 4 preferentially, leaving the residual CH 4 enriched in 13 CH 4 (Silverman and Oyama, 1968), while δ 13 C C1 does not vary through eddy diffusion. In addition, it was shown that the kinetic isotope effect (KIE) α is around 1.005 at the bottom of the water column (Tsunogai et al, 2000). α is defined as the ratio of the relative reaction rates of molecules containing different isotopes: Machiyama et al, 2001).…”