蔬菜产地土壤重金属含量空间分布研究

以浙江省湖州市长兴县为例,应用GIS技术研究了蔬菜产区土壤重金属污染状况及空间分布规律。结果表明:长兴县蔬菜产地平均土壤汞和镉含量明显大于本地背景值,锌平均含量也超过背景值,而砷、铬、铅、铜4种重金属的平均含量则低于或接近背景值。长兴县大部分蔬菜产区土壤重金属含量在国家无公害蔬菜基地标准以下,汞、镉超标的样点分别占总样点的10.4%和4.5%,分别有43%和58.0%的样点超过当地汞、镉背景值,土壤汞、镉含量的最大值分别达到945.85 ng/g和478.88 ng/g。蔬菜产区土壤汞、镉污染呈明显的区域空间分布特征,且与乡镇工业区分布相一致,表明工业污染是引起蔬菜产区土壤重金属超标的主要原因。在长兴县部分地区还存在铬、锌、铜区域性积累趋势。

Study on Spatial Distribution of Soil Heavy Metal Content in Vegetable Plantation

The observations of a study of soil heavy metal pollution situation and its spatial distribution regulation with sample as Changxing County of Huzhou City of Zhejiang Province on the GIS platform showed that: the averaged Hg and Cd as well as Zn contents in vegetable-cultivated soil were obviously higher than the local background values,and the average contents of As,Cr,Pb and Cu were near or lower than the local background values.Also,the heavy metal contents in the vegetable-cultivated soil of Changxing County mostly were lower than the accepted standard values for national non-hazard vegetable production bases.As an exception,Hg and Cd contents in 10.4% and 4.5 % of sampling sites were higher than the standard values,and Hg and Cd contents in 43% and 58.0 % of sampling sites were higher than the local background values.The maximum values of Hg and Cd in soils were as high as 945.85 ng/g and 478.88 ng/g,respectively.We found that the spatial distribution features of soil Hg and Cd in the vegetable-cultivated region were agreed with the distribution of industry regions.This implied that industry pollution will be the main factor of higher contents of heavy metals in the vegetable-cultivated soils.Besides,we have found a accumulation tendency in soil Cr,Zn and Cu contents in some parts of Changxing County.