紫色土坡地侵蚀产沙过程的7 Be法初探

摘要

利用环境放射性核素示踪技术研究土壤侵蚀是传统土壤侵蚀监测技术的重要补充手段.宇宙成因核素7 Be具有半衰期短和在表土分布浅等特点,能够用于指示短时间尺度的坡面侵蚀堆积过程.采用7 Be技术与泥沙颗粒分析相结合,定量判读了模拟降雨下紫色土坡面侵蚀过程演变.结果表明,对于20°坡面,7 Be法指示的坡面侵蚀方式转折点与侵蚀泥沙颗粒变化得到的结果基本一致.7 Be在表征侵蚀过程演变时具有独特的优势,可以将坡面片蚀发育过程随降雨时间的变化明显地识别出来.这对防治坡面侵蚀,特别是细沟侵蚀的发生具有重要意义.%Fallout radionuclides tracing techniques have been proven to be an important complementally means to conventional soil erosion monitoring methods.Due to its short half-time and shallow distribution in soil profile,the cosmogenic radionuclide 7 Be serves as a useful tool for indicating short-term erosion and sedimentation processes.Based on the combined use of 7 Be measurements and sediment grain size analysis,this paper investigated the erosion and sediment yielding processes using simulated rainfall experiments undertaken on purple soil slopes.The results shown that the turning point of erosion forms estimated from 7 Be measurements was similar to that of the sediment grain size analysis,especially for 20° slope.7 Be approach has unique advantages when indicating the development of erosion processes and the sheet erosion can be clearly identified.This information has great significance in soil erosion prevention,especially rill erosion.