摘要
Be主要分布于0-20 mm深度的表层土壤,其中0-2 mm的表层土壤7Be的含量最高,向下随深度呈指数减少,20 mm以下土层基本不含7Be。我们的测定结果表明:四川盐亭农耕地和草地紫色土的7Be深度分布存在一定差异,草地表层土壤的7Be含量高于农耕地,其随深度递减的速率也高于农耕地。这可能是农耕地土壤较草地土壤疏松,降水易于入渗的缘故。四川盐亭7Be季节性本底值,春季和秋季分别为117.4 Bq·m-2和169.9 Bq·m-2。与国内外已有的报道相比,四川盐亭7Be本底值偏低,这可能是7Be含量较低的西南气流的水汽和基本不含7Be的本地水汽对降水贡献较大的缘故,并且四川盆地阴天多,云层厚,不利于宇宙射线的穿透并产生7Be。
7Be fallout is predominantly distributed in the surface soil of 0-20 mm in depth. The highest 7Be content occurs in the surface horizon of 0-2 mm in depth and it exponentially declines with depth. The soil horizon below 20 mm in depth contains little 7Be. Our measurements show that there is a clear difference in 7Be depth distributions in purple soil between grass land and cultivated land in Yanting, Sichuan. 7Be contents in the surface horizon on grassland are higher and decline more rapidly with depth than those in cultivated land, because the cultivated soil is more porous and prone to infiltration of precipitation than the grass soil. 7Be seasonal reference inventories are 117.4 Bq ·m-2 in spring and 169.9 Bq · m-2 in autumn, respectively in Yanting. By comparison with the reported 7Be seasonal reference inventories in other regions in the world, the reference inventories in Yanting are quite lower. Probably this is attributed to the facts that the air moistures of the south-western currents from the low latitude area, which have a low 7Be concentrations, and the air moistures of local evaporation, which contains little 7Be, make great contributions to the precipitation in Sichuan Basin, and that the thick cloud layers and the cloudy climate in the Basin prevent cosmic ray penetration from producing 7Be nuclide.
出处
《核技术》
CAS
CSCD
北大核心
2004年第11期873-876,共4页
Nuclear Techniques
基金
国家自然科学基金(40271015)
中国科学院知识创新重要方向项目(KZCX2-SW-330
KZCX3-SW-422)
中国科学院地球环境研究所黄土与第四纪地质国家重点实验室开放基金(SKLLQG0206)
中国科学院研究生社会实践创新类资助项目
国际原子能机构项目(12322/R0)部分研究成果
关键词
川中丘陵
^7Be
本底值
Hilly Area of Sichuan Bbasin, 7Be, Reference inventory
