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Study for material cycle with cosmogenic nuclides as tracers

以宇宙成因核素为示踪剂的物质循环研究

基本信息

批准号：
14380246
负责人：
NAGAI Hisao
金额：
$ 8.26万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

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.

1.对于太平洋和南极海的海洋表层：（1）^7Be浓度的深度分布与水温分布相似。在夏季，它们从表面开始减少，并在100米左右达到零。在冬季，它们在0 - 100米之间保持恒定值，并在此深度之后迅速下降。（2）~ 3Be<10>浓度随深度的增加呈恒定或略有增加的趋势。（3）^7Be浓度的垂直分布与大气中的相似。最小值和最大值分别为5-10和20-40个原子cm-2<-3>。（4）南半球大气中^ Be浓度的垂直分布<10>与大气中相似。最小值和最大值分别为300-500和1500原子cm-2<-3>。在赤道地区和北方半球，大气中的铍-10浓度在500 ~ 900原子cm^2范围内基本恒定<-3>。东京和八丈岛大气中的^7 Be和^ Be浓度<10>以及同位素比值^<10>Be/^7 Be全年基本相似。东京和八丈岛的同位素比率分别为1.81和1.75，高于海洋空气的1.5。用Al含量和^ Be/Al对土壤再悬浮进行校正<10>，可以有效地拟合这些比值。根据<10><10>降水中的铍浓度估算的铍通量在东京和八条岛的季节变化不同。3.根据沉积物中的过剩<230>钍年龄和<10>铍浓度估算的北太平洋西部的铍-10海底通量在20 ° N和40°N分别为0.018-0.037和0.10-0.15原子cm·<-2>s<-1>·前者的值与通过海面的通量相一致，而后者的值要比前者高出3 ~ 4倍。这意味着~<10>（13）Be向沉积物的通量取决于沉积速率。