| Project/Area Number |
12558070
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
環境保全
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| Research Institution | Gifu University |
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Principal Investigator |
MATSUI Yoshihiko Gifu University, Department of Civil Engineering, Professor, 工学部, 教授 (00173790)
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| Co-Investigator(Kenkyū-buntansha) |
KUBO Toshihiro Kubota Corporation, Ductile Iron Pipe R&D Department, Manager, 鉄管研究部, 副部長(研究職)
YUASA Akira Gifu University, Center of River Basin Environment Research, Professor, 流域環境研究センター, 教授 (10109499)
YAMAMOTO Hiroyuki Shinshu University, Institute of High Polymer Research, Professor, 繊維学部, 教授 (60021151)
MATSUSHITA Taku Gifu University, Department of Civil Engineering, Research Ass., 工学部, 助手 (30283401)
INOUE Takanobu Gifu University, Department of Civil Engineering, Ass. Professor, 工学部, 助教授 (00184755)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2001: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | freshwater mussel / Limnoperna fortunei / anti-fouling / coating / surface property / flow velocity / attachment strength / hydrodynamic drag force / カワヒバリガイ |
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| Research Abstract |
The attachment strength of the freshwater mussel Limnoperna fortunei against water flow was studied. Newton's expression successfully described the hydrodynamic drag force acting on the mussel with a drag coefficient value of 1.03. The drag-resistant force (defined as hydrodynamic drag force at mussel detachment) was smaller than the detachment force measured using a tensile load test. A fairly good correlation was obtained between the drag-resistant force and the number of secreted threads. The drag-resistant force divided by the number of threads increased with shell size, suggesting that byssal thread strength increased with mussel growth. For the mussel specimens obtained from a water transmission pipe, thread width increased with shell size. However, thread width was not dependent on current velocity. There was no correlation between the number of secreted threads and shell length, which indicated that the number of secreted threads did not change with mussel size. Therefore, the
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water velocity needed to detach mussels increases with shell size of the mussel when the number of secreted threads is constant. The increases in the water velocity to detach mussels with larger shell suggested that the mussel becomes more resistant to water flow as it grows. It is estimated that a flow velocity around 1 m/s was critical for attachment/detachment of a juvenile mussel with a shell length of a few millimeters and one hundred byssal threads.
Various anti-fouling substrates were tested for their effectiveness in inhibiting attachment of Limnoperna fortunei. Field experiments revealed that surface properties affected anti-fouling capabilities for nontoxic substrates. Anti-fouling capabilities were observed for 3 silicone-resin-based coatings with smooth surfaces of < 30 μm roughness and low surface free energy of the hydrogen-bonding force component. However, the remaining 3 silicone-resin-based coatings tested, as well as other types of nontoxic coatings, did not show any anti-fouling capabilities. The percentages of mussels that attached in laboratory experiments using juvenile mussels were correlated with the settling densities of mussels in the field experiments. This suggests that the laboratory experiments may be effective as short-term preliminary assays to select promising materials/coatings for longer-term field experiments. Mussel abundance surveys within a water transmission pipe and pipe current velocity simulation revealed that less mussel infestation was observed in the areas with wall-vicinity fluid velocity of > 1.3 m/s. Conversely, pipe surfaces with flows of < 1.2 m/s were heavily fouled by L. fortunei. Less
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