用^137Cs法探讨苏南坡地的土壤侵蚀

与黄土和红壤地区相比 ,学术界对苏南丘陵区土壤侵蚀的关注要少得多 ,也许是这里的土壤侵蚀的绝对数量不大 ,然而 ,苏南地区的土壤侵蚀引起的生态影响却不容忽视 ,如因土壤侵蚀造成的养分流失对水体的影响及土层减薄都远超过黄土区。为了探讨苏南土壤侵蚀的生态影响 ,首先是要了解土壤侵蚀的状况 ,在这方面 13 7Cs示踪法是一种非常有用的工具 ,可是要使用此法 ,必须要解决两个问题 ,一是确定研究区的背景值 ,二是建立估算土壤侵蚀的模型。经过较长时间的研究 ,确定苏南地区的 13 7Cs背景值为 2 2 0 0 Bq/m2 ;并根据基本物理含义 ,建立了耕地与非耕地的土壤侵蚀模型 ,用这 2个模型并借用其他学者提供的土壤沉积模型 ,对宜兴竹园及茶园两个坡地的土壤侵蚀与沉积作了估算。在此基础上 ,又尝试着简单探讨了土壤侵蚀引起的土层及养分流失的生态影响

Using Tracer Method by 137Cs to Study Soil Erosion of Hillside Fields in South Jiangsu Province

The soil erosion is little concerned in low mountains and hills of south Jiangsu province than in the loess plateau and the red soil area because the absolute erosion is small. However the ecological impact caused by soil erosion in south Jiangsu province can not be ignored since the nutrient loss and the soil layer becoming thin there is greater than that in the loess soil and the red soil area. In order to discuss the ecological impact of the soil erosion there the soil erosion rate should be known. The tracer method of cesium 137 ( 137 Cs) is a useful tool. But the two problems should be solved for using this method. One is to decide the 137 Cs reference inventory in the study area and the other is to set up the models of estimating soil erosion. After careful study the 137 Cs reference inventory is decided as 2 200 Bq/m 2 in our study area. The soil erosion estimating models of the cultivated soil and the uncultivated soil are build based on the fundamental physical content. The soil erosion rate and the soil sedimentation rate of the hillside fields in bamboo forest, in tea plantation and so on can be estimated using above two soil erosion models and a soil sedimentation model provided by the other scholars. Then the ecological impacts caused by soil layer becoming thin and nutrient loss are tried to analyze.