2022 Fiscal Year Annual Research Report
Insights into hydrocarbons cycling in the subsurface from isotopologue analysis
| Project/Area Number |
21H01198
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ジルベルト アレキシー 東京工業大学, 理学院, 准教授 (20726955)
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| Co-Investigator(Kenkyū-buntansha) |
中川 麻悠子 東京工業大学, 地球生命研究所, 特任助教 (20647664)
山田 桂太 東京工業大学, 物質理工学院, 准教授 (70323780)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | Hydrocarbons / Carbon cycle / Subsurface / Isotopologue |
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| Outline of Annual Research Achievements |
We sampled at Tokamachi mud volcano (Niigata prefecture) at new gas seeps. We measured bulk and position-specific isotope composition of hydrocarbons at these new seeps. Thanks to the post-doc employed (Dr Naizhong Zhang), we could measure efficiently the doubly-substituted isotopologues of methane from these different seeps.
The data shows a full range of degradation rate from very low biodegradation to >90% biodegradation. This makes Tokamachi a very interesting place to study the impact of hydrocarbons biodegradation on other molecules.
We notably showed that the biodegradation of propane is correlated with the abundance of the doubly-substituted isotopologues of methane,suggesting an involvement of methanogenesis associated with biodegradation.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We tried to sample at Goshogake, a mud volcano in Akita prefecture.
Unfortunately, the sampling appeared difficult, and the only samples that we could measure show high CO2 amounts and low methane amounts, which suggest this setting is not related to hydrocarbons generation.
We therefore decided to focus on Tokamachi mud volcano and take advantage of the numerous gas seeps present to build a quantitative model of hydrocarbon cycling using this setting as a model
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| Strategy for Future Research Activity |
We will continue culture experiments with mud from Tokamachi mud volcano, as the preliminary data show interesting trends, notably regarding methanogenesis and the relationship to the 13C/12C of CO2.
The data obtained so far on Tokamachi allows us to write two articles: one regarding the effect of hydrocarbons biodegradation on the doublysubstituted
isotopologues of methane; another one on the biological organisms involved in the hydrocarbons processes.
The candidate is on sabbatical leave from April 2023 and will take advantage of this to take samples of gas hydrates from the Amazon fan sediments (cruise from May to June 2023). The quantitative model developed for Tokamachi will be used to shed light on processes on hydrate systems.
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