Denitrification, anammox, and DNRA in the hypereutrophic tidal flat: Influences of the dissolved organic matter (DOM) quantity and quality

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K00525
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Environmental dynamic analysis
• Research Institution: Toho University
• Principal Investigator: SENGA Yukiko 東邦大学, 理学部, 准教授 (30434210)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 嫌気的硝酸還元過程 / 脱窒 / アナモックス / DNRA / 大型海藻 / 干潟

Outline of Final Research Achievements

An increase in available nitrogen (NO3-) loading in intertidal ecosystems causes eutrophication and macroalgae blooms. In intertidal ecosystems subjected to excessive loading of NO3-, it is necessary to understand denitrification and anammox which are microbially mediated N removal processes as N2, and DNRA which conserves nitrogen in the sediment as NH4+. However, detailed information regarding these processes is not fully available. In the present study, we investigated 1) the contributions of denitrification and anammox for NO3- removal, 2) the development of sequential method to measure denitrification, anammox and DNRA, 3) the influences of macroalgae on denitrification, anammox and DNRA. Field investigation and sampling were performed in the hypereutrophic Yatsu tidal flat (Chiba Prefecture). The results suggest that the occurrence of macroalgae changes the progress of NO3- removal processes in intertidal ecosystems.

Free Research Field

生物地球化学

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は，脱窒，アナモックス，DNRAの同時測定法の確立に成功し，これまで不明とされていた富栄養化が著しい干潟におけるNO3-の動態が明らかになった点である．本研究により，富栄養化した干潟においてNO3-は主に脱窒を介して除去されること，大型藻類の出現はNO3-除去過程を大きく左右することといった2点の新知見を提示することができた．
近年，世界中の沿岸域において富栄養化が問題となっており，水質を改善するための対策や窒素浄化の技術開発の確立が喫緊の課題となっている．本研究の成果は，そのような対策や技術開発に基礎的知見を提供するものであり，これが本研究の社会的意義である．