Microorganism and silica in geothermal environments

Research Project

Project/Area Number	08044159
Research Category	Grant-in-Aid for international Scientific Research
Allocation Type	Single-year Grants
Section	Joint Research
Research Field	資源開発工学
Research Institution	KYUSHU UNIVERSITY
Principal Investigator	IZAWA Eiji Kyushu University, Faculty of Engineering, Professor, 工学部, 教授 (50037751)
Co-Investigator(Kenkyū-buntansha)	LOWE Donald スタンフォード大学, 地質学科, 教授 TAGUCHI Sachihiro Fukuoka University, Faculty of Science, Professor, 理学部, 教授 (00108771) MOTOMURA Yoshinobu Kyushu University, Faculty of Science, Ass.Researcher, 理学部, 教授 (20037237) WATANABE Koichiro Kyushu University, Faculty of Engineering, Ass.Professor, 工学部, 助教授 (10182916) OGATA Seiya Kyushu University, Faculty of Agriculture, Professor, 農学部, 教授 (20038277) LOW Donald R. Stanford University, Department of Geology and Environmental Sciences, Professor
Project Period (FY)	1996 – 1997
Project Status	Completed (Fiscal Year 1997)
Budget Amount *help	¥5,400,000 (Direct Cost: ¥5,400,000) Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000) Fiscal Year 1996: ¥2,800,000 (Direct Cost: ¥2,800,000)
Keywords	Yellowstone National Park / thermophillic bacteria / siliceous deposit / thermal water / マクラフリン / 地熱地域 / シンター
Research Abstract	1.Observations of sedimentary features, measurements of temperature and pH of waters, and sampling of siliceous sinter, thermal waters, gases, associated volcanic rocks, and microbes on and in siliceous deposits were done in thermal areas of Yellowstone National Park, Wyoming, USA.A degree of saturation with respect to amorphous silica increases through evaporation along the drainage channel, and controls the rate of silica deposition. Aluminum concentrations in siliceous deposits shows positive correlation with temperatures of thermal waters. 2.Various bacterial assemblages were found in siliceous deposits of different temperature conditions from Cistern Spring, Norris Geyser Basin. Also, it is recognized that the rate of silica deposition correlates with the amount of thermophillic bacteria. This concides with the result obtained from a thermal pool at a geothermal power plant, suggesting impoartanc of a study of the mechanism of bacterial control on silica deposition. 3.During the investigation at Yellowstone it is shown that the different thermophillic bacteria dominate in different temperature conditions. Then the fabric and structure of siliceous deposits in geologic past can tell the depositional environments. Ikiryu sinter, 0.5 Ma old deposit in Kuju volcanic area, was investigated as a case study. In addition, siliceous deposits formed in pipes at geothermal power plants were precisely observed. 4.Inactive sinters at Beowawe Geyser area and Steamboat Springs were studied and samples were collected. Chemical analysis and study of structures for these samples are in progress..