2023 Fiscal Year Final Research Report
A New paradigm of nitrogen cycle in the marine subsurface layer controlled by trace metals
| Project/Area Number |
21H03592
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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 | 一般 |
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| Review Section |
Basic Section 63010:Environmental dynamic analysis-related
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| Research Institution | Nagasaki University |
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Principal Investigator |
TAKEDA Shigenobu 長崎大学, 水産・環境科学総合研究科(水産), 教授 (20334328)
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| Co-Investigator(Kenkyū-buntansha) |
塩崎 拓平 東京大学, 大気海洋研究所, 准教授 (90569849)
近藤 能子 長崎大学, 水産・環境科学総合研究科(水産), 准教授 (40722492)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 海洋生態 / 窒素循環 / 微量金属 / 植物プランクトン / 硝化微生物 |
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| Outline of Final Research Achievements |
This study was undertaken to test the hypothesis that iron, copper, and zinc dynamics and light environment have a combined effect on the extracellular release of nitrite from phytoplankton and nitrification by microbial communities in the open ocean sub-surface layer, thereby controlling the formation of the nitrite maximum layer. To this end, detailed vertical distributions of nutrients, trace metals, phytoplankton, and microbial communities were examined at 20, 30, and 41°N in the western North Pacific. The results suggest that the imbalance between ammonia oxidation and nitrite oxidation by microbial communities is a major factor in nitrite accumulation in these waters. However, nitrite release from iron-deficiency stressed phytoplankton may also contribute to some extent. Consequently, it is suggested that micronutrients such as iron and the light environment play an important role in the sub-surface nitrogen cycle in the western North Pacific.
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| Free Research Field |
海洋生物地球化学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究により、亜硝酸塩極大層の形成要因を始めとする窒素循環機構について新たな知見が得られたことから、有光層内の硝化作用を含めた海洋窒素循環の理解が前進した。今後、海洋亜表層における生物窒素代謝の変動メカニズムを適切に評価することで、海洋の新生産の見積もり値が更新されて、海洋における窒素収支のアンバランスに対して新たな解釈が与えられるものと考えられる。また、グローバルな物質循環・生態系モデルに本研究で得られた成果を組み込むことによって、海洋の窒素および微量金属の循環過程と生物相互作用を精度良く再現できるようになり、地球温暖化に伴う海洋生態系の応答・変化の予測にも貢献することが期待される。
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