几种土壤重金属污染评价方法的对比

土壤重金属污染评价是土壤环境管理的基础性工作,采用合理的污染评价方法,才能识别土壤重金属污染状况,满足土壤环境管理和决策需要。选择单因子指数法、地质累积指数法、次生原生比值法和富集因子法四种方法进行对比分析,并进行实例计算和结果对比评价。结果表明:单因子指数法简单灵活,评价结果能直观反映土壤的污染情况,是比较实用的评价方法,但其将污染等级与元素实际含量简单地看成线性关系,导致评价结果较其它方法偏高。地质累积指数法是在单因子指数法基础上改进而来,计算公式较为简洁,污染评价结果较单因子指数法低。次生原生比值法突出元素形态的影响,未考虑元素总量和背景值,导致评价结果不能有效地与其它评价方法进行比较,在部分数据上还会出现污染浓度高却得到污染等级低的结论。富集因子法不仅考虑了元素的背景值,而且以地球化学过程中人为污染少、化学性质稳定、分析结果精确度高的Fe、Al、Si等元素作为参比元素,评价结果与地质累积指数法具有高度一致性,能够很好地体现土壤污染状况,但参比元素的实测值不易获取。研究结果可为土壤重金属污染评价方法的选取与改进提供基础数据。

Comparison of Evaluation Methods for Soil Heavy Metals Contamination

Soil pollution evaluation is the basic work of soil environment management. Only reasonable soil pollution evaluation methods were utilized can the soil pollution be clearly described and the soil environment management be satisfied. Four normal evaluation methods used in current soil environmental monitoring were compared and analyzed in the paper. Results show that the single factor index evaluation method is a relatively simple and practical approach, which takes the actual pollution levels and elements content as a linear function, leading to a higher results than the other methods. The results of geo-accumulation index method were more reasonable than the single factor index, which was modified on the basis of the latter. Secondary native ratio method only emphasizes the influence of element forms, leading to that the evaluation results can not effectively compare with other evaluation methods. Enrichment factor method considering the element background values and the reference elements can reveal the soil pollution levels as geo-accumulation index method. The results provide basic data for selection and improvement of soil heavy metal pollution evaluation methods.