| Project/Area Number |
16201002
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MATSUMOTO Ryo The University of Tokyo, Graduate School of Science, Professor (40011762)
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| Co-Investigator(Kenkyū-buntansha) |
OGIHARA Shigenori The University of Tokyo, Graduate School of Science, Research Associate (50214044)
TOKUYAMA Hidekazu The University of Tokyo, Ocean Research Institute, Professor (10107451)
ASHI Juichiro The University of Tokyo, Ocean Research Institute, Associate Professor (40251409)
MACHIYAMA Hideaki Japan Agency for Marine Earth Science and Technology, Organization of the Institute for Research on Earth Evolution, Scientist (00344284)
NUMANAMI Hideki Tokyo Kasei Gakuin University, Department of home economics, Associate Professor (10266554)
小池 義夫 東京海洋大学, 海洋学部, 教授 (30017074)
大出 茂 琉球大学, 理学部, 教授 (20117568)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥46,020,000 (Direct Cost: ¥35,400,000、Indirect Cost: ¥10,620,000)
Fiscal Year 2006: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000)
Fiscal Year 2005: ¥15,600,000 (Direct Cost: ¥12,000,000、Indirect Cost: ¥3,600,000)
Fiscal Year 2004: ¥22,880,000 (Direct Cost: ¥17,600,000、Indirect Cost: ¥5,280,000)
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| Keywords | Gas hydrare / Methane plume / Pockmarks / Bacterial mat / Eastern margin of Japan Sea / Umitaka spur / BSRs / Shimokita peninsula / メタンハイドレート / メタンハイドレート・バブル / 日本海 / 黒色頁岩 / オルドビス-シルル紀境界事変 / 化学合成生物 / BSR / チンハイ湖 / 大量絶滅 / 富山湾 / メタンプリューム / 硫酸還元 / 熱分解起源 / 氷期-間氷期 |
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| Research Abstract |
The main objective of this program is to make an assessment of the environmental impact of marine gas hydrates through the geological, geophysical, and marine biological approaches and integration of newly obtained data sets. The following are the summary and results of the 3 years program.
1. We conducted hydrate-research cruises in the gas hydrate field off Naoetsu by "T/V Umitaka-maru" of Tokyo University of Marine Science and Technology and "Natsushima" and "Kaiyo" of JAMSTEC.
2. We identified strong methane seep sites off Naoetsu in Japan Sea. Plumes of methane bubbles stand about 600 meter high on the sea floor of about 900 meter below sea level. The plumes were observed to supply significant amount of methane to shallow waters. The bottom and intermediate waters are very low, -0.2℃, which allows gas bubbles to form gas hydrate in the water masses. This is the main reason why the plumes reach up to shallow waters.
3. Submersible dives by "Hyper dolphin" found gas hydrate exposed on the sea floor for the first time around Japan islands. This finding suggests strong methane fluxes in the study area.
4. Probably because of low temperatures, benthic communities are relatively simple and monotonous, but characterized by chemosynthetic communities and bacterial mats. Crabs ("Beni-zuwai-gani") are extremely abundant on and near the methane seep sites.
5. Large pockmarks, approximately 500 m in diameter, develop on the Umitaka spur where methane seeps and gas hydrate were observed. The pockmarks are inactive, partly buried by mud, implying that extremely violent methane seeps occurred in the past.
6. We also conducted gas hydrate cruise off Shimokita peninsula, northwestern Pacific by "Tansei-maru" of JAMSTEC. We could not identify methane seeps or plumes but strong and unusual BSRs seem to indicate development of subsurface gas hydrate and methane generation.
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