| Project/Area Number |
25281013
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Partial Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
Ogawa Nanako O. 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, 主任技術研究員 (80359174)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKAWA Chisato 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) |
2013-04-01 – 2016-03-31
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| Project Status |
Completed (Fiscal Year 2015)
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| Budget Amount *help |
¥15,990,000 (Direct Cost: ¥12,300,000、Indirect Cost: ¥3,690,000)
Fiscal Year 2015: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2014: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2013: ¥9,360,000 (Direct Cost: ¥7,200,000、Indirect Cost: ¥2,160,000)
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| Keywords | クロロフィル / 光合成 / 窒素同位体比 / 硝酸態窒素 / 化合物レベル同位体比 / 海洋窒素循環 / 硝酸体窒素 / 光合成色素 / 窒素同位体 / 海洋物質循環 / 物質循環 |
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| Outline of Final Research Achievements |
In this study, nitrogen isotopic compositions of chlorophyll and substrate nitrate were determined to investigate the nitrogen cycle in the photic zone, from two Pacific sites (Station K2 and Station S1). Samples were collected during summer blooms in 2012, 2013, 2014, and 2015 (MR12-02, MR13-04, MR14-04, KH15-J01). The observed nitrogen isotopic compositions of chlorophyll at the stations K2 and S2 were -10.5 to +1.9‰ and -0.5 to +2.3‰, respectively. It was suggested that the nitrogen isotopic distribution of chlorophyll can be explained by either (1) large isotopic fractionation during nitrate assimilation by phytoplankton, or (2) significant contribution of ammonia as a substrate for the photosynthetic nitrogen assimilation, at Station K2. By applying a quantitative nitrogen cycle model in the surface ocean (Yoshikawa et al., 2005), it was concluded that there was a large (>50%) contribution of ammonia as a substrate for the phytoplankton.
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