土壤重金属污染评价方法研究——以广州市为例

目前土壤环境质量评价方法按照评价对象可归纳为单因子指数法和综合评价法两类若干种。以广州市208个土壤样品8种重金属为研究对象,创新性地采用分级统计、相关性分析、评价等级差值分析、综合排序分析等方法对目前主要的土壤环境质量评价方法进行定性和定量研究,旨在推荐最适合的土壤环境质量评价方法。结果表明:从评价结果的分级程度看,单因子指数法中富集指数法最优,综合评价法中内梅罗指数法和模糊数学法最优;相关性分析结果表明,物元分析法与其他4种综合评价法的平均相关性系数为0.477,大于其他综合评价法的平均相关性系数,按照评价结果一致性原则,物元分析法最优;评价等级差值分析表明,模糊数学法与其他4种综合评价法评价等级的平均差值最小,为0.71,按照评价等级接近的原则,模糊数学法最优;通过综合排序比较各综合评价法的排序得出,模糊数学法平均排名最优,其次为物元分析法、内梅罗指数法、灰色聚类法、潜在生态危害指数法。综上所述,富集指数法和模糊数学法是两种首选方法,在土壤重金属污染评价中可以组合使用。

Research on assessment methods for soil heavy metal pollution: A case study of Guangzhou

Based on assessment objects, current methods for soil environmental quality assessment can be grouped two types:single factor index methods (Single factor index, Potential ecological risk assessment, Geoaccumulation index and Enrichment factor) and comprehensive assessment methods (Nemerow index, Fuzzy mathematics, Grey clustering method, and Matter element analysis). In this study, we qualitatively and quantitatively evaluated different assessment methods by applying graduation statistics, correlation analysis, grade difference analysis and complex sorting analysis to data of 8 heavy metals in 208 surface soil samples from Guangzhou, China. Results showed:Based on the grading degree, Enrichment index is the optimal single factor method for evaluating single heavy metal, while Nemerow index and Fuzzy mathematics methods were the best integrative assessment methods; Correlation analysis showed that the average correlation coefficient of Matter element analysis model with the other four integrative assessment methods was 0.477, which was the greatest for integrative assessment methods. This indicates that Matter element analysis model was the best; Grade difference analysis showed that the average difference value of assessment grades of Fuzzy mathematics method (0.71) is minimum, indicating that Fuzzy mathematics method was the best; Ranking integrative assessment methods indicated that Fuzzy mathematics method ranked the first, followed by Matter element analysis model, Nemerow index method, Grey clustering method and Potential ecological risk index. In conclusion, Enrichment index method and Fuzzy mathematics method are the optimal methods. Both methods could be combined while assessing soil heavy metal contamination.