| Project/Area Number |
06453005
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
地球化学
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
MINAGAWA Masao Hokkaido University, Grad.Env.Earth.Sci, Pro., 大学院地球環境科学研究科, 教授 (10250507)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Shuichi Hokkaido University, Grad.Env.Earth.Sci, Assoc.Pro., 大学院地球環境科学研究科, 助教授 (00167131)
OBA Tadamichi Hokkaido University, Grad.Env.Earth.Sci, Pro., 大学院地球環境科学研究科, 教授 (60013588)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | Nitrogen-isotope / Carbon-isotope / Organic matter / Particulate-matter / Sediment-trap / Carbonate / Foraminifera / Funka-bay / 炭素同位体 / 窒素同位体 / 生物活動 / 同位体分別 / 沿岸堆積物 / 古環境復元 |
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| Research Abstract |
Stable carbon and nitrogen isotopic compositions have been used as a proxy of biological activity or CO2 availability in sea water, although still many questions and argument are retained. The purpose of this project is to reveal the interrelation between such proxies and observational biological change based on tracing chemical and isotopic components of biogeochemical samples in a semi-closed sea.
Biogeochemical researches as well as hydrographic observations have been performed in the Funka Bay, Hokkaido, for 1994 fall to 1996 spring. In the period of spring bloom, the delta^<13>C and delta^<15>N of suspended particles showed significant enrichment in heavy isotopes as expected from previous model. However, we found that nitrogen isotopic change could not be interpreted by the spontaneous enrichment of ^<15>N as described by Reighley distilllation model. The delta^<13>C of total inorganic carbon in sea water risen with progress of primary production, but it was not sufficient factor to explain the isotopic change of particulate organic carbon. We estimated that isotopic fractionation associated with photosynthesis might be changed with stratification of water density.
We found that ^<13>C of POC becomes light by -28%_0 and simultaneously delta^<15>N rises from 5 to + 10%_0 above bottom layr in summer. This change appears to be related with decomposition of particulate matters in near bottom and progress of reduction condition. These recults strongly suggest that delta^<15>N and delta^<13>C values found in bottom sediment should suffer from such isotopic change, accordingly emphasize that it is essential to understand the as a proxy for reconstruction of biological process in the water column.
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