^(137)Cs示踪技术在滦河源区栗钙土风蚀速率估算中的应用

Application of ^(137)Cs tracer technique to estimate the wind erosion rate of Castanozem in Luanhe River Source Area

对采集于滦河源区 3个栗钙土剖面中的 2 7个土层样品的pH、有机碳含量、碳酸钙含量、密度及质地进行了化验分析 ,运用ADCOM10 0超低本底γ谱仪测定了土壤样品1 37Cs的比活度 .结果表明 ,自然栗钙土以及被风蚀土壤剖面中1 37Cs比活度随深度呈指数递减式分布 ,其最大渗透深度可达约 3 0cm ;利用1 37Cs示踪技术估算的研究区土壤风蚀速率在 0 1842cm·a- 1 和 0 2 897cm·a- 1 之间 ;栗钙土不同粒径土壤颗粒中1 37Cs的比活度差异显著 ,即细粒 (粒径≤ 0 10mm的极细砂、粉粒和黏粒 )中1 37Cs比活度大于细砂 (0 10～ 0 2 5mm)中1 37Cs比活度大于粗粒 (0 2 5～2 0 0mm的中砂、粗砂和极粗砂 )中1 37Cs比活度 .可见 ,运用1 37Cs示踪法可以定量估算区域土壤风蚀速率 ,但需综合考虑1 37Cs在土壤中的分布、土壤有机质含量和质地等因素 。

Cs has been widely used for estimating the soil erosion and sediment rate. However, the depth distribution patterns of ^(137)Cs in the soil profile and the ^(137)Cs activities in different particle fractions of soil have not been investigated, so the erosion rate may be over-estimated or underestimated. Based on the investigation of the soil and soil-forming environment of Luanhe River Source Area in North China, the experimental results show that the depth distribution pattern of ^(137)Cs in the natural Castanozem (undisturbed soil) and eroded soils is an exponential decrease with soil depth. The estimated wind erosion rates in Luanhe River Source Area range between 0.1842cm·a^(-1) and 0.2897cm·a^(-1). The ^(137)Cs concentration of the fine fraction which includes the clay, silt and very fine sand is higher than that of the middle size sand, coarse sand and very coarse sand of the same soil. Therefore, the depth distribution pattern, the grain-size distribution and the soil characteristic should also be considered when soil erosion rate is estimated by using ^(137)Cs.