三峡库区紫色土7Be剖面分布及季节变化  

Depth Distribution and Seasonal Variability of 7Be in Purple Soils at Three Gorges Reservoir Region

作　　者：史忠林[1,2] 文安邦[1] 严冬春[1] 苏明[1,2] 

机构地区：[1]中国科学院水利部成都山地灾害与环境研究所,四川成都610041 [2]中国科学院研究生院,北京100049

出　　处：《山地学报》2010年第6期674-679,共6页Mountain Research

基　　金：国家科技支撑计划项目(编号:2008BAD98B01);中科院西部行动计划项目(编号:KZCX2-XB2-07-4)~~

摘　　要：7Be是一种宇宙成因放射性核素。由于其来源明确、半衰期短、测试相对容易,可用于<1a时间尺度内的环境过程示踪和定量研究。7Be在土壤中的剖面分布特征及其本底值是建立定量模型、估算侵蚀沉积速率和调查表土迁移过程的基础。对三峡库区为期1a的无扰动紫色土7Be浓度的测定结果表明,7Be主要分布于质量深度0～20.0kg/m2(0～1.5cm)的表层土壤,其中0～3.0kg/m2(0～2mm)的最表层7Be比活度最高,向下随深度增加呈指数减少,20.0kg/m2以下土层基本不含7Be。采样期间土壤7Be总面积活度介于172.4～328.6Bq/m2,平均246.1Bq/m2,并呈现春季最高,秋季最低;春夏高,秋冬低的季节性变化特征。植被截留可能是减少土壤7Be浓度的重要因素。7Be is a naturally occurring radionuclide of cosmogenic origin. Due to its well-defined source term,short half-life,and relative ease of measurement,7Be serves as a useful tool for tracing and quantifying environmental processes on the <1 a timescale. The characters of its depth distribution and reference inventory in soils are the basis of developing soil redistribution models and investigating movement of topsoil. Measurements of 7Be concentration in undisturbed soils were carried out at Three Gorges Reservoir region over 1 year. The results show that 7Be was predominantly distributed in the surface soil of 0 ~ 20.0 kg/m2 mass depth (0 ~ 1.5 cm). The highest 7Be content was found in the surface horizon of 0 ~ 3.0 kg/m2 mass depth (0 ~ 2 mm) and declined exponentially with depth. The soil horizon below 20.0 kg/m2 mass depth contained little 7Be. The local 7Be reference inventories over the sampling period were 172.4 ~ 328.6 Bq/m2 with a mean of 246.1 Bq/m2. The reference inventories were high in spring and summer and low in autumn and winter,which were highest in summer and lowest in autumn. The interception of vegetation may be an important factor in reducing 7Be flux to soils.

关 键 词：三峡库区 紫色土 剖面分布 季节变化 Three Gorges Reservoir Region SEASONAL Variability 表层土壤 放射性核素 重要因素 时间尺度 迁移过程 浓度 比活度 过程示踪 分布特征 定量研究 定量模型 沉积速率 测定结果 变化特征 

分 类 号：P9[天文地球—自然地理学]