基于土壤地球化学分区的重金属污染风险评价——以山东省郯城县某镇为例

Risk Assessment of Heavy Metal Pollution Based on Soil Geochemical Zoning——Setting a Town in Tancheng County of Shandong Province as an Example

摘要:

以郯城县某镇生态地球化学调查取得的土壤地球化学数据为基础，利用因子分析法将研究区划分为3个土壤地球化学分区，10个土壤地球化学亚区。每个土壤地球化学亚区的元素间彼此存在相关性，而重金属元素的含量往往决定了该土壤地球化学分区或亚区的污染状况。首次尝试以土壤地球化学分区为评价单元，对郯城县某镇耕地土壤中8项重金属污染状况进行了评价。结果表明，该区耕地土壤重金属元素含量属弱至低等变异程度，均一化程度较高，重金属污染风险低，但个别土壤分区存在Hg，Ni，Cr含量分异程度大，点位高于背景比例偏高的现象；单项污染指数中Ni，Cr的值相对偏高，表明存在单个因子人为污染的现象；内梅罗污染指数指示I3亚区为该镇最高，存在一定的污染隐患；地累积指数指示了I3亚区中Ni、II1亚区中Hg的值均>1,为轻微污染等级。此次评价工作也表明，基于土壤地球化学分区的耕地土壤重金属污染评价结果与土壤环境质量评价图件反映的信息较为吻合。

Abstract:

Based on the soil geochemical data obtained from ecological geochemical survey of a town in Tancheng county, by using factor analysis, the study area has been divided into three soil geochemical zones and 10 soil geochemical sub-zones . There is a correlation between elements in each soil geochemical sub-region, and the content of heavy metals often determines the ecological risk conditions of the soil geochemical sub-region or sub-region. For the first time, eight heavy metals in cultivated soil of a town in Tancheng county have been evaluated by using soil geochemical zoning as evaluation unit. As showed by the results, the contents of heavy metals in cultivated soils in this area are weak to low, and the degree of homogenization is high, and the environmental quality is generally clean. However, the contents of Hg, Ni and Cr in individual soil zones are highly differentiated, and the point position is higher than the background proportion. The values of Ni and Cr in single pollution index are relatively high. It is indicated that there is a single factor of human pollution. As indicated by Nemerow pollution index, I-3 sub-region is the highest in the town, and there are some potential pollution hazards. As indicated by Ground Accumulation Index, the values of Hg in Ni and II-1 sub-regions in I-3 sub-region are more than 1, which is a slight pollution level. The assessment also shows that the assessment results of heavy metal pollution in cultivated soil based on soil geochemical zoning are in good agreement with the information reflected by soil environmental quality assessment maps.