137Cs法用于典型流域土壤侵蚀的初步研究——以太湖流域上游西苕溪流域为例

太湖流域上游土壤侵蚀量对于研究太湖流域营养盐输入和水环境效应具有重要意义。论文运用137Cs示踪分析法对太湖流域上游浙江省安吉县西苕溪流域的土壤侵蚀进行了初步研究,结果表明:该流域的137Cs基准值为2148.8±120.7Bq/m₂;对于非耕作土壤,137Cs在土壤剖面中呈指数型分布,分布深度一般在20cm左右;对于耕作土壤,则在耕作层内呈均一分布,耕作层以下则急剧下降,分布深度达30cm。典型断面研究表明:耕地侵蚀强于非耕地;坡面上部侵蚀强于下部;坡度(0°～20°)与土壤侵蚀强度呈对数正相关关系。

Preliminary study on using 137Cs tracter method to estimate soil erosion of typical area:a case study on Xitiaoxi drainage area at up stream of Taihu Lake basin

The absolute erosion of soil at up streams of Taihu lake basin is small,however,the socio-economic and ecological impact caused by soil erosio n in this area can not be ignored.The research of the input of nutritive eleme nts in the upper Taihu lake basin and its environmental effects is very importan t.The substance migration resulted from soil erosion is the main carrier of the input of nutritive elements in this area.Using 137 Cs measurements,a preliminary study was carried out to investigate soil e rosion occurred within Xitiaoxi drainage area of Anji City,Zhejiang Province in this paper.The 137 Cs reference inventory was determinated to be2148.8Bq/m 2 . 137 Cs exhibits exponential vertical distribution in uncultivated soils,the ma ximum distribution depth of 137 Cs in soil section is about 20cm for uncultivated soils. 137 Cs is uniformly distributed within the plough layer,and decteases sharply in activity below the plough layer,the maximum distribution depth of 137 Cs in soil section is about 30cm for cultivated soils.Case study of typi cal sections shows that soil erosion rates in cultivated soils is usually highe r than that in uncultivated soils,soil erosion rates in the upper section is us ually higher than in the lower section,and the relationship between solpe (0 °～20°)and soil erosion rates is logarithms.The outcome of this paper has basic significance for further understanding the ecological impact on Taihu lak e basin,which can help to put forward some better comprehensive countermeasur es to reduce its harm to the possible maximum degree.