北碚区菜地表层土壤镉的环境地球化学基线与污染程度研究

The Environmental Geochemical Baseline and Polluting Level of Cadmium in Surface Layer's Soil of Vegetable Fields in Beibei District

通过野外采样、室内测试及数理统计,对北碚区菜地表层土壤镉的基线值、污染程度进行研究。结果表明:(1)研究区菜地表层土壤镉含量平均值为0.212mg/kg,标准差为0.060mg/kg,变异系数为28.3%,处于低度变异;基线值为0.144mg/kg。(2)对研究区菜地表层土壤镉含量进行污染程度分析发现,以国家土壤环境质量一级标准(自然背景)为标准,研究区56.9%的菜地表层土壤样品镉含量受到污染;若以无公害、绿色蔬菜产地土壤环境质量要求为标准,其研究区菜地表层土壤在镉含量水平上基本满足无公害、绿色蔬菜的生产,但存在局部地区的点源污染。(3)对研究区菜地表层土壤镉含量与理化性质数据进行相关分析发现,有机质含量与镉含量呈极显著相关性。

Through the field sampling,test in lab and mathematical statistics,the environmental geochemical baseline and polluting level of cadmium in surface layer＇s soil of the vegetable fields were researched in Beibei district.The results showed that：（1）The average content of cadmium of surface layer＇s soil was 0.212 mg/kg,standard deviation was 0.060 mg/kg,and the coefficient of variation was 28.3%,which was at the low variability;baseline values was 0.144 mg/kg.（2）Analyzed the pollution degree of cadmium in surface layer＇s soil,and showed that,as the standard by baseline values,56.9% of the plough layer＇s soil was polluted by cadmium in the studied area;as the standard by green vegetable soil environmental quality requirements,the surface layer＇s soil basically met the pollution-free,green vegetable production,but the presence of point source pollution in the studied area.（3）Analyzed the influence factors of the content of cadmium and the organic matter of physical and chemical properties of the plough layer＇s soil,the highly significant correlation between the content of cadmium and the organic matter was observed.