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210Pb由于在环境中特殊的分配关系及其在土壤中迁移性小、极易被土壤细颗粒吸附等特性而被视为良好的示踪剂,210Pb的沉降具有连续性和相对稳定性,可示踪百年尺度的平均土壤侵蚀速率。具有初始分布及其在未扰动土壤剖面中均呈现出土表含量最高,随深度增加含量减少的分布特征。在耕作土壤中由于耕作混合作用210Pbex呈均匀分布。评述了目前用到的210Pbex侵蚀模型重量逼近模型和质量平衡模型,210Pbex与其它核素(137Cs、7Be)复合示踪研究土壤侵蚀和泥沙来源是核素示踪的一大亮点。提出了210Pbex示踪土壤的优点和应用210Pbex示踪应注意的问题。
210Pb is regarded as a good tracer because of its special distribution in the environment and its small mobility in the soil, easily adsorbed by fine particles of soil. The 210Pb sedimentation has continuity and relative stability The average soil erosion rate at a hundred-year scale is tracked. It has the initial distribution and its distribution characteristics in the undisturbed soil profile with the highest content of soil surface and the decrease of content with the increase of depth. The 210Pbex is evenly distributed in tillage soils due to tillage and mixing. Reviewing the weight approximation model and the mass balance model of the 210Pbex erosion model currently used, the study of 210Cbe with other radionuclides (137Cs, 7Be) to trace the source of soil erosion and sediment is a major highlight of nuclide tracing. The advantages of 210Pbex tracing soil and the issues that should be noticed when applying 210Pbex tracer are proposed.