| Project/Area Number |
17580160
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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 |
General fisheries
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| Research Institution | Tokyo University of Marine Science and Technology |
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Principal Investigator |
ISHIMARU Takashi Tokyo University of Marine Science and Technology, Department of Marine Science, Professor, 海洋科学部, 教授 (90114371)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAMASA Tomoji Tokyo University of Marine Science and Technology, Department of Marine Technology, Professor, 海洋工学部, 教授 (20134851)
HADUKU Tatsuya Tokyo University of Marine Science and Technology, Department of Marine Technology, Associate professor, 海洋工学部, 助教授 (60334554)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Hypoxia / Dissolved Oxygen / Vertical circulation / Water quality / 鉛直混合 |
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| Research Abstract |
The purpose of this study is to develop a system for improving bottom hypoxia in estuarine waters by generating vertical circulations at low energy cost. At the beginning of our study, we designed a riser tube to drive upwelling circulation by heating the water at the bottom by using solar energy at the dock basin of Shinagawa campus, the Tokyo University of Marine Science and Technology. We made a simulation based on the observations of temperature, salinity, dissolved oxygen (DO) in the dock during the first year of our study. We found that the difference between surface and bottom water density (8 kg m^3 in average and more than 17 kg m^3 after heavy rain) was much grater than that we expected and therefore, large energy would be required for driving vertical circulations. So, we changed our plan to make a system to pump down the surface seawater through a tube to near bottom area for supplying high DO water to the bottom to improve hypoxia in neighboring water of the system. We made several improvements in the system and monitored the anomaly of salinity distributions around the system. We finally attached a manifold with many small holes to the outlet of the tube to mix the surface water to near bottom water to increase high density, with high DO. The mixed water was found to retain around the system. However, as it was winter when we completed the final design and bottom hypoxia was already dissolved. So, we are confirming the validity of the system in the following summer.
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