| Project/Area Number |
17H01851
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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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| Research Field |
Environmental dynamic analysis
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
Toyoda Sakae 東京工業大学, 物質理工学院, 准教授 (30313357)
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| Co-Investigator(Kenkyū-buntansha) |
吉川 知里 国立研究開発法人海洋研究開発機構, 生物地球化学研究分野, 技術研究員 (40435839)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥18,590,000 (Direct Cost: ¥14,300,000、Indirect Cost: ¥4,290,000)
Fiscal Year 2019: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2018: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2017: ¥13,390,000 (Direct Cost: ¥10,300,000、Indirect Cost: ¥3,090,000)
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| Keywords | 一酸化二窒素 / 安定同位体 / 海洋酸性化 / 硝化 / 生成過程 / 地球温暖化 |
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| Outline of Final Research Achievements |
This study focused on nitrous oxide (N2O), one of the important greenhouse gases produced by microorganisms as well as CO2 and methane. For the purpose of elucidating the response of microbial production and consumption processes to ocean acidification, incubation experiments were conducted with pure microbial culture in the laboratory and with in situ seawater on board.
When incubated under three pH conditions (8.3, 8.0, 7,7), pure culture of oceanic nitrifying bacteria showed increased production rate of N2O. Isotope ratios of N2O suggested that the production pathway is not changed by the acidification but isotope effect might depend on pH.
In the western North Pacific and the eastern Indian Ocean, seawater was collected and incubated onboard with addition of 15N-labeled reagents. In the western North Pacific, N2O production rate was found to increase with acidification.
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| Academic Significance and Societal Importance of the Research Achievements |
大気中CO2濃度の増加による海洋酸性化が海洋生物へ影響を及ぼす影響は広く知られるようになってきたが、微生物の窒素代謝反応，とりわけN2Oの生成過程への影響については研究例が未だに乏しい状況にある。2011年に米国の研究者らによって海洋酸性化によってN2O生成は弱まるとの仮説が発表されていたが，本研究では少なくとも西部北太平洋においては，この仮説とは逆にN2O放出量が増加する可能性を明らかにした。これはCO2の増加が間接的に別の温室効果気体を増加させる，正のフィードバックが起きうることを示しており地球環境化学の分野だけでなく，温暖化防止のための政策決定においても重要な意義をもつ。
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