重庆岩溶槽谷区山坡土壤的漏失研究

Soil Erosion and Loss on Slope in Karst Valley Area,Chongqing with ^(137)Cs

岩溶地区区别于非岩溶地区水土流失的关键是岩溶地区土壤存在地下漏失.本文运用同位素137Cs和配比法研究土壤地下漏失机理,得出以下结论:岩溶槽谷区土壤存在地下漏失现象,但土壤漏失现象并不随处可见,地表土壤漏失难以通过裂隙垂直渗漏到达土石界面,这可从137Cs剖面分布深度以及溶洞壁上土壤137Cs含量几乎为0看出;在有落水洞发育的溶蚀洼地内,通过分析土壤剖面分层137Cs含量,证明土壤从落水洞流失明显;土石界面的土壤可以通过裂隙进入地下河,但量很少;研究区运用137Cs配比法得出地表流失和地下漏失比例分别为75%和25%.

Soil loss phenomenon is distinctive soil erosion in karst area,rather than in non-karst area.In current study,the isotope of137 C and the ration methods were used to study the mechanisms of soil loss. Our results conclude：（ 1） Soil loss phenomenon does exist in some area of karst area but not everywhere;（ 2） Surface soil reaches to earth-rock interface through the fissure vertical seepage is almost impossible based on the137 C depth distribution profile in soil and zero concentration of137 C content in soil of cave wall;（ 3） The conclusion that soil loss significantly through sinkhole is made from the137 Cs distribution of soil profile in karst depression;（ 4） The soil in earth-rock interface can get into underground river through the crack,but the amount is limited;（ 5） Based on the137 Cs match method,the ratio between surface erosion and soil leakage is 75% and 25%,respectively.