| Project/Area Number |
14380246
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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 | Nihon University |
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Principal Investigator |
NAGAI Hisao Nihon University, College of Humanities and Sciences, Professor, 文理学部, 教授 (10155905)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Takashi Nihon University, College of Humanities and Sciences, Research Assistant (Full-Time), 文理学部, 助手 (00366543)
齊藤 敬 日本大学, 文理学部, 助手 (00343616)
松村 宏 日本大学, 文理学部, 助手 (30328661)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥12,900,000 (Direct Cost: ¥12,900,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2003: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Accelerator Mass Spectrometry / Cosmogenic Nuclide / Beryllium-7 / Beryllium-10 / Aerosol / Seawater / Deep Sea Sediment / 大気 / 雨水 / 加水器質量分析 |
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| Research Abstract |
1.For the ocean surface layer of the Pacific Ocean and Antarctic Sea : (1)Depth profiles of ^7Be concentration were similar to water temperature profiles. In summer, they decrease from the surface and reach to zero around 100m. In winter, they keep constant value from 0 to 100m and decrease rapidly beyond this depth. (2)Depth profiles of ^<10>Be concentration showed constant or slight increase with increasing depth. (3)Latitudinal distribution of ^7Be concentration was similar to that in the atmosphere. The minimum and maximum were 5-10 and 20-40 atoms cm^<-3>, respectively. (4)Latitudinal distribution of ^<10>Be concentration in the southern hemisphere was similar to that in the atmosphere. The minimum and maximum were 300-500 and 1500 atoms cm^<-3>, respectively. Beryllium-10 concentrations in the equatorial region and northern hemisphere were almost constant within 500 to 900 atoms cm^<-3>.
2.Atmospheric concentrations for ^7Be and ^<10>Be and isotopic ratio ^<10>Be/^7Be in Tokyo and Hachijo Island were similar to each other all through the year. The isotopic ratios 1.81 for Tokyo and 1.75 for Hachijo Island were higher than 1.5 for marine air. Correction for resuspension of soil with Al content and ^<10>Be/Al were effective to fit these ratios. Different seasonal variations of ^<10>Be flux to the land surface estimated from ^<10>Be concentration in rain were observed in Tokyo and Hachijo Island.
3.Berylium-10 fluxes across sea floor estimated from excess ^<230>Th age and ^<10>Be concentration for sediments in the Western North Pacific were 0.018-0.037 and 0.10-0.15 atoms cm^<-2> s^<-1> for 20 and 40°N, respectively. The former values agree with the flux across the sea surface, but the latter values were 3 to 4 times higher than that. This imply that ^<10>Be flux to the sediment depend on the sedimentation rate.
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