典型固废处理处置场周边土壤重金属污染特征和成因分析

为探讨典型固废处理处置场周边表层土壤重金属污染特征和污染来源,以浙江两家典型危废处理处置场和一家生活垃圾处理处置场周边作为研究区域,采集并测定表层土壤样品中5种重金属(Cd、Hg、As、Pb、Cr)的含量。运用单因子污染指数法、内梅罗综合污染指数法和潜在生态风险指数法对重金属的污染特征进行评价;采用多元统计法分析重金属来源。结果表明:研究区土壤中Cd为首要污染物,三家固废处理处置场分别有56.25%、50.00%和58.82%的点位达轻度污染等级及以上;多元统计分析表明,不同处理处置场周边重金属来源不同,其中危废处理处置场周边Cd、Hg、As和Pb主要受处置危废种类、处置模式等因素影响,Cr主要受自然因子和历史原因影响。研究区土壤Cd潜在生态风险程度最高,三场地潜在生态风险指数分别为604.26、1 473.08和165.13,其次为Hg,三场地分别为202.99、441.83和139.64。研究表明,危废处理处置场周边土壤污染比生活垃圾处理处置场周边严重,为重度污染,主要污染物为Cd、As和Cr。危废处理处置场周边土壤潜在生态风险程度较生活垃圾处理处置场高,且分布较不均匀,应引起警惕,予以重视。

Pollution characteristics and source analysis of heavy metals in soils surrounding a typical solid waste disposal plant

In this study, we explored heavy metal pollution characteristics and sources in surface soils surrounding the typical solid waste disposal plant. Two hazardous waste disposal plants and one municipal solid waste plant were selected in this study, and five types of heavy metals (Cd, Hg, As, Pb, Cr)were determined in the soil surrounding them. Single factor pollution index, Nemerow comprehensive pollution index and potential ecological risk index were used to investigate the pollution characteristics. Multivariate statistical analysis was used to investigate the pollution sources in the study area. The results showed that Cd was the primary pollutant in the soil, with 56.25%, 50.00%, and 58.82% of total pollutants for each of the plants. The soil pollution around the hazardous waste disposal plant was more serious than that in the municipal solid waste plant, with Cd, As, and Cr being the obvious pollutants. The results of the multivariate statistical analysis indicated that the sources of heavy metals in different solid waste disposal was plants were different. Cd, Hg, As, and Pb pollutants originated from hazardous waste and disposal, while Cr primarily originated from natural sources. The potential ecological risk assessment showed that risks Cd and Hg were high around the study area, and the contribution of Cd to risk was the highest among the five heavy metals. The E_rⁱ of Cd and Hg were 604.26, 1 473.08, 165.13 and 202.99, 441.83, 139.64, of three plants respectively. The hazardous waste disposal plant had high levels of potential ecological risk; therefore, methods to control the effects of hazardous waste disposal plant pollution must be developed.