| Project/Area Number |
10680100
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
自然地理学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
WATANABE Makiko Tokyo Institute of Technology Interdisciplinary Graduate School of Science and Technology Associate Professor, 大学院・総合理工学研究科, 助教授 (10175119)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITAKE Nobuhide Kobe University Faculty of Agriculture Associate Professor, 農学部, 助教授 (50243332)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Humic acid Pg / Tepnra-soil sequence / Loess-soil sequence / Paleo-environmental indicator / Pg signal / Pg composition |
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| Research Abstract |
The following four subjects were promoted in this project to evaluate the validity of hurmic acid Pg as an environmental indicator.
1) Morphological feature and chemical composition of sclerotia grains, the origin of Pg
2) Factors regulating the distribution of Pg fraction in surface soils
3) Chronological sequence of humic acid Pg in tephric and loessic paleosols
4) Difference of the composition of humic acid Pg in various humic acids
Aluminum concentration was significantly recognized in the collected sclerotia grains, which are the origin of Pg, and the its development revealed to be regulated by the amount of exchangeable aluminum in soils. Moreover, it was clarified that the strength of Pg absorption in surface soils was regulated by the amount of exchangeable aluminum in soils. Based on these findings, it is suggested that Pg formation is promoted under leaching process in soil, or under cool and wet condition. According to the results obtained by examining the chronological sequence of tephra and loess paleosol in Japan and Germany, Pg revealed to remain in the buried humic layers aged 140-150 ka and showed a strong Pg absorption strength in buried tephra and loess paleosols aged 50-60 ka. The fluctuation of Pg, named as Pg signal/had a tendency to correspond to the fluctuation curve of past temperature obtained by MIOS. The study on composition of humic acid Pg using HPLC performed to separate Pg (humic acid green fraction) into 10 fractions by HPLC. The identification of Pg fraction formed in different environment can be discussed in-further studies.
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