2004 Fiscal Year Final Research Report Summary
Origin of Methane in Permafrost and Its Effects to Global Warming
| Project/Area Number |
15403009
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Hokkaido University |
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Principal Investigator |
BROUCHKOV Anatoli The Hokkaido University Museum, Prof., 総合博物館, 教授 (80333649)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUDA Masami Hokkaido University, Institute of Low Temperature Science, Prof., 低温科学研究所, 教授 (70002160)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Permafrost / Siberia / Alaska / Methane / global warming / methanogene / Cold adaptation / Large scale thawing |
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| Research Abstract |
Methane content, its distribution and its origin in Siberian and Alaskan permafrost were examined. Permafrost covers large areas of Eurasia and America ; however, its gas content, its origin and influence on atmosphere is poor studied, in spite of significance of methane for the global warming. The values of methane concentration exhibited a high of up to 100000 ppmv in both frozen soil and ice wedges. Highest methane concentration values were found in frozen soil samples, not ice. An estimation shows the diffusion coefficient of permafrost soils is from as about 10^<-9> -10^<-10> cm^2/s, then methane content in permafrost is stable enough even in long term periods, and release if permafrost melts. Older permafrost contained higher values of methane concentration than those found in younger permafrost. Low methane concentration in modern and old thermokarst depressions is related to resent thawing of the soil. Experiments show a slow production of methane in different soils at -5 ℃. A large amount of produced methane is trapped in frozen soil and emitted due to thawing only. Frozen soils were found contained a variety of microorganisms. Living fungi of Penicillium sp. were isolated from permafrost deposits of the Central Siberia, as well as a bacterium of Bacillus sp, which is probably more than 2 million years old ; isolates are able to grow at -5℃. A number of methanogenic clones was identified from local frozen soil producing methane at -5℃ and from Siberian permafrost soil. The methanogenes could be responsible for methane production ; however, total methane production, collection and movement within permafrost still remain unknown. Estimated amount of produced methane in permafrost could be a few times larger than its total annual world CH_4 emission. Thawing permafrost may accelerate future global warming.
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