To develop geochemical tracers of hydrogen and carbon isotope systematics by methanogen incubations

Research Project

Project/Area Number	25701004
Research Category	Grant-in-Aid for Young Scientists (A)
Allocation Type	Partial Multi-year Fund
Research Field	Environmental dynamic analysis
Research Institution	Japan Agency for Marine-Earth Science and Technology
Principal Investigator	KAWAGUCCI Shinsuke 国立研究開発法人海洋研究開発機構, 深海・地殻内生物圏研究分野, 研究員 (50553088)
Project Period (FY)	2013-04-01 – 2016-03-31
Project Status	Completed (Fiscal Year 2015)
Budget Amount *help	¥19,760,000 (Direct Cost: ¥15,200,000、Indirect Cost: ¥4,560,000) Fiscal Year 2015: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000) Fiscal Year 2014: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000) Fiscal Year 2013: ¥10,010,000 (Direct Cost: ¥7,700,000、Indirect Cost: ¥2,310,000)
Keywords	メタン / 安定同位体 / 炭素同位体比 / 水素同位体比 / 生命の限界
Outline of Final Research Achievements	1. The hydrogen isotope ratio of CH4 produced by a thermophilic methanogen, Mtc. okinawensis, under high pH2 conditions (~105 Pa-H2) is affected by the isotope ratio of H2, as pointed out in a previous incubation. This pattern is named as the δDH2 effect. This effect also appears to account for the diverse hydrogen isotope fractionation between CH4 and H2O previously observed in H2-enriched culture incubations. 2. The hydrogen isotope fractionation between CH4 and H2O in hydrogenotrophic methanogenesis under low pH2 conditions (<102 Pa) observed in experiments is in the range of 0.66-0.74. 3. Hydrogen isotope fractionation exhibited in laboratory incubations under low-pH2 conditions is consistent with that observed in “young” methane reservoirs but inconsistent with that observed in “aged” methane reservoirs.