1993 Fiscal Year Final Research Report Summary
Interaction between volcanic material and fluid
| Project/Area Number |
05044039
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKANO Bokuichiro College of Arts and Sciences, The University of Tokyo, Associate Professor, 教養学部, 助教授 (90012426)
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| Co-Investigator(Kenkyū-buntansha) |
OSIPENKO A.B. Research Scholor at Russian Academy of Science For East Div., 極東支部, 研究員
FAZLULLIN S.M. Research Scholar at Russian Academy of Science For East Div., 極東支部, 主任研究員
SUGIMORI Kenji Toho University, Department of Medicine, 医学部, 講師 (30130678)
SUZUKI Katsuhiko College of Arts and Sciences, The University of Tokyo, 教養学部, 助手 (70251329)
MATSUO Motoyuki College of Arts and Sciences, The University of Tokyo, 教養学部, 助教授 (10167645)
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| Project Period (FY) |
1993
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| Keywords | volcano / crater lake / Thiobacillas thiooxidans / SO_2 / H_2S gas / voloanic gas / sulfur-oxidizing bacteria / heavy metal |
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| Research Abstract |
Japan-Russia Joint Research on Mutnovsky, Karimusky and Maly Semiachik Volcanoes in Kamchatka has been conducted from July to August in both 1992 and 1993. These volcanoes occupy the central part of the Eastern Volcanic Belt of Kamchatka. Among these, Maly Semiachik Volcano is predominantly basaltic stratovolcano containing a strongly acidic crater lake. The lake is 550 m in diameter and the elevation of the lake surface is 1170 m.
The bathymetry by echo sounding in 1993 showed a maximum depth of 117 m, considerably shallower than in 1960s. Only one effervescent area was observed at the deepest point where we sampled floating sulfur com* up to the lake surface from the subaqueous fumarolic vent(s). We measured the temperature of subaqueous molten sulfur pool(s). The observed highest temperature of the pool was 166* in 1992 and 157* in 1993.
Compared with the analytical results in 1973, the lake water in 1992-93 was considerably diluted with snow melt water. The water temperature in the s
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ummer in 1992-93 was less than 10*, much cooler than before. The volcanic activity at the lake during a recent few years have been decreasing. This is also supported by the polythionate data from 1986 to 1993. The years of low polythionates (1986 and 1991) may be either in a high activity. Chloride and sulfate in 1986 are much concentrated than those in 1991. This suggests that the volcanic activity in 1986 was much more intensive than in 1991. In 1986 polythionate concentrations were low because of a high heat flow and probably high SO_2/H_2S gas discharge from the subaqueous fumarole vents. On the other hand, in 1991 injection rate of SO_2 and H_2S into the lake seem to be too weak to produce mamy polythionates in the lake water.
We found only a weak activity of sulfur-oxidizing bacteria sampled at the point closer to the subaqueous fumarolic vents in 1992. In the next year, however, the microbe concentrations in the order of 10^3-10^4/mL were obtained for the water sampled throughout the lake. Cultivation experiments using a various medium suggest that the microbe found in the lake water is Thiobacillus thiooxidans. Less
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