| Project/Area Number |
06680495
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Kagoshima University |
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Principal Investigator |
ICHIKAWA Toshihiro Kagoshima University, Faculty of Science, Professor, 理学部, 教授 (30109110)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Marine Snow / Volcanic Ash / Material Cycling / Particulate Organic Carbon / Dissolved Organic Carbon / Nutrients / 一次生産 / 鹿児島湾 / 溶存有機物 / 基礎生産 / 沈降速度 / 桜島 |
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| Research Abstract |
Active volcano, Mt. Sakurajima located in Kagoshima Prefecture, has continuously erupted with heavy ash fall in the neighboring area including marine environment in Kagoshima Bay. The purpose of the present study is to evaluate possible effect of volcanic ashes on material cycling in sea water.
The underwater observation showed that large abundant of macroscopic aggregates (marine snow) markedly occurred in the surface sea water during the ash falling ejected from Mt. Sakurajima. The large particles tended to disappeared in surface water in a few days and were observed in deeper layr (25m) near to the sea bottom. The measured sinking speed of marine snow was significantly larger than that of fecal pellet of zooplankton. It is estimated that ash containing marine snow accelerate the sinking speed of particulate material suspended in sea water. Further, laboratory studies indicated that volcanic ashes influenced on quality of sea water. Firstly, volcanic particles release significant amount of nutrients into sea water. The experimental sea water that were contained volcanic particles rapidly increased nitrate, ammonia, and phosphate concentration within one hour. However, significant increase of silicate concentration was not observed in a week. Secondly, the volcanic particles adsorb organic carbon dissolved in sea water into surface of the particles. It is concluded that volcanic particles possibly influenced on marine environment in Kagoshima Bay.
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