粤北石漠化地区137Cs分布特征与背景值研究

137Cs Distribution and Its Reference Inventory in Rocky Desertification Land in North Guangdong

土壤侵蚀是决定土壤中^137Cs含量及其再分配的主要因素。粤北岩溶山区^137Cs背景值为1433.60±131.40 Bq/m^2,低于北半球的平均值,^137Cs剖面分布基本符合指数分布型式。石漠化地区土壤137Cs活度平均为6.54±0.57 Bq/kg,土壤中^137Cs水平随石漠化程度增加有先降低然后升高的趋势,表明在重度石漠化阶段。

Soil erosion is the key factor that determined the ^137Cs content in soil and its re-distribution. In karst rocky mountain areas in North Guangdong, the value of ^137Cs reference inventory is calculated to be 1433.60±131.40 Bq/m^2, which is lower than the global average value of Northern Hemisphere. The depth distribution of ^137Cs there approximatively agrees to the exponential type. And the 13r Cs activity of rocky desertification land ranges from 0.65 ± 0. 29 Bq/kg to 17.48± 1.03 Bq/kg, and average to be 6.54±0.57 Bq/kg. Along with the intensification of rocky desertification, ^137Cs activity in soil decreases in earlier stage and increases later. It indicates that the process of soil erosion has gradually changed into the process of soil deposition.