| Project/Area Number |
20K04713
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22040:Hydroengineering-related
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| Research Institution | Kagawa National College of Technology |
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Principal Investigator |
Yanagawa Ryoichi 香川高等専門学校, 建設環境工学科, 准教授 (70649095)
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| Co-Investigator(Kenkyū-buntansha) |
三好 真千 徳島文理大学, 理工学部, 講師 (40399168)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2022: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2021: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2020: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
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| Keywords | 海底耕耘 / 無機態窒素 / 貧栄養化 / 貧栄養化の改善 / 現地実験 / 栄養塩 / 数値流動モデル / オープンデータ / 物質循環 |
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| Outline of Research at the Start |
本研究では，海底耕耘（海底をかき乱す行為）が貧栄養化した海域での栄養塩濃度上昇に寄与し基礎生産の向上に繋がるのかを定量的に検証するため，以下4テーマについて検討を行う．
①香川県志度湾海域の底質に栄養塩がどの程度含まれているか水質・底質分析を行う．
②耕耘に伴い土粒子や土粒子吸着栄養塩はどの空間範囲にまで拡散するのか室内実験を行う．
③巻き上げられた土粒子と土粒子から脱着した栄養塩との拡散範囲の違いはどの程度となるか室内実験を行う．
④志度湾での海底耕耘の効果を実測するとともに時空間的に挙動を把握する．
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| Outline of Final Research Achievements |
Field experiments were conducted a total of six times and qualitative water quality changes due to cultivating activities could be captured. Specifically, an increase in ammonia concentration in the middle and bottom waters was detected, but the water mass with increased concentration did not reach to the surface layer by advection and diffusion. This was considered to be due to the fact that the extent and intensity of cultivating was insufficient for the size of the sea area, and that the cultivating was carried out at a time when vertical mixing was not sufficient. No clear trends in nitrate or nitrite elution could be detected, and it was considered difficult to clarify the quantitative cultivating effect in the field experiments. On the other hand, the development and implementation of an indoor forced-mixing experiment using sediment and water quality sampling has been initiated and will continue to be carried out in the future.
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| Academic Significance and Societal Importance of the Research Achievements |
植物の基礎生産に必要となる窒素・リン濃度が枯渇している海域でのノリ養殖事業を実現するため，水中栄養塩濃度の上昇を目的とした海底耕耘は，既存の栄養塩に富んだ底質を利用するという視点がこれまでに無かったこと，また海域生態系の物質循環機能を高める事も期待され，事業化に向けての社会的意義は高いと考えている．一方，本検討内では実施規模の小ささや定量的な効果を把握するに至らず，完了後も活動を継続して実用化に向けた取り組みを進めることとしたい．
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