| Project/Area Number |
07555465
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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 | 試験 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
KUSUDA Tetsuya Kyushu Univ., Dept., Civil Eng.Professor, 工学部, 教授 (50037967)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANISHI Hiroyuki Kyushu Univ., Dept., Civil Eng.Associate Professor, 工学部, 助手 (20240062)
OHISHI Kyoko Kyushu Univ., Dept., Civil Eng.Research Associate, 工学部, 助手 (20110835)
MORIYAMA Katsumi Kyushu Kyoritsu Univ., Dept., Civil Eng.Associate Professor, 工学部, 助教授 (80157932)
KUBA Takahiro Kyushu Univ., Dept., Civil Eng.Associate Professor, 工学部, 助教授 (60284527)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Water Quality / Hakata Bay / Simulation / Probability / Observation / Shinji Lake / Nitrogen Oxide / モデリング / 生態系 / フラックス / サンプリング方法 / バクテリア |
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| Research Abstract |
Dissolved oxygen is one of the key factors on water quality for ecosystem. External conditions such as climate conditions including precipitation, temperature, wind direction and speed and nutrient loading, some of which have shorter characteristic time less than one day, influence dissolved oxygen through several paths. The yearly or seasonal average methods are ineffective to estimate hourly change of dissolved oxygen because it has a short characteristic time with some seasonally long ones. In order to estimate dissolved oxygen concentration, a stochastic method, instead of a deterministic one, is considered useful. In this study, occurrence of low dissolved oxygen concentration was stochastically investigated based on observation date in Tokyo Bay, Lake Shinji and Hakata Bay. In Hakata Bay, dissolved oxygen concentration under the thermocline depends on the thickness of the lower layr more than chlorophyll-a concentration, light quantum flux, sediment oxygen consumption rate, etc. Using them, the dissolved oxygen changes were estimated with high accuracy. In Tokyo Bay, "blue tide", which is water body with oxygen-free and contains reduced sulfur, occurs under both of the development of thermocline and water temperature higher than 15 degree when wind of north-east blows. The occurrence of "blue tide" is clearly correlated with wind energy and the change of the center of gravity of water body. The development of a large scale observation system on nitrogen oxide in an estuary was developed by using a method to measure changes of nitrogen oxide in the mixing layr of the atmosphere above the water surface.
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