小尺度农田土壤重金属污染评价与空间分布——以鲁西北阳谷县为例

The Pollution Assessment and Spatial Distribution of Soil Heavy Metals in Field Scale——Case Study in Yanggu County of Northwest Shandong Province

利用地统计学和GIS技术对鲁西北阳谷县十五里园镇农田耕层土壤重金属含量空间变异性进行了研究,并对其土壤环境质量进行评价。结果表明:6种重金属含量算术平均值未超过国家土壤环境质量一级标准(主要适合于农田和菜园),但Cu、Zn、Cr三种元素含量的最大值超出了土壤环境质量的一级标准。内梅罗指数法评价结果表明研究区土壤处于清洁或尚清洁的水平,能满足农业生产的要求。通过变异函数分析,Cu、Cd、Ni三种元素的空间自相关作用较强,元素的空间变异性受人为因素的影响较小,Zn、Pb、Cr三种元素具有中等程度的相关性,其空间变异性受自然因素和人为因素的综合影响。研究区不同重金属元素的变程具有明显的差异,其中具有最大变程的元素是Ni,其最大空间自相关距离达到了6.5km,Zn元素的变程最小,为1.1km。通过普通kriging法对研究区土壤中的重金属含量进行局部插值,除Cu和Cd元素外,其它4种重金属元素在空间上的分布都具有东高西低的特征,这可能和研究区地势西高东低有关。

The spatial distribution of heavy metals in Shiwuliyuan town in Yanggu county of Shandong Province was studied and the soil environmental quality was evaluated by using geostatistics and GIS. The results showed that the average contents of six heavy metals were not exceed the first standard of soil environment quality （used in plant soil and garden soil）, but the max contents of Cu, Zn and Cr in soils were exceed the first standard of soil environment quality. The assessment results from Nemerow index method indicated that the soils in this area were on cleanness level and met the demand of agriculture. The variable function analysis results suggested that the spatial self-correlation of Cu, Cd and Ni were stronger and their spatial variability were less affected by human being. The Zn, Pb and Cr had the moderate correlation, which suggested that their spatial variability were integrative affected by the factors of nature and human being. The range of every heavy metal was different. The element wirh the max correlation length was Ni and the range reached 6.5 kilometers, the min correlation length was Zn （1.1 kilometers）. Using the ordinary Kriging interpolation method to draw the distribution map, four heavy metals had the same distributing characteristics, higher in the west and lower in the east （except Cu and Cd） due to the physiognomy of the region.