平原典型垃圾焚烧厂周边土壤重金属分布特征及污染评价

摘要

Incineration of municipal solid waste (MSW) for energy recovery is a desired option in modern societies as increase in quintiles of MSW. However, the gaseous and particulate heavy metals emitted from MSW incinerators may accumulate in the soil entering via dry and wet deposition, which can cause great concern for the population living nearby. In this study, soil samples around the typical municipal solid waste incineration (MSWI) plant in Hangzhou-Jiaxing-Huzhou Plain were collected. The concentrations of heavy metal were determined with X-ray fluorescence spectrometry (XRF), atomic absorption spectrometry (AAS) and mercury analyzer. Mean concentrations of Cr, Mn, Cu, Pb and Fe were 174.05、707.76、47.68、41.95 and 39 057.89 mg·kg-1 in this region, respectively. Compared with background values by Cultural Enrichment Factor (CEF), Pb and Cu concentrations were higher than their corresponding background values, respectively. Factor analysis of geo-statistics was also performed. The results showed that the heavy metal distribution patterns were dominantly affected by three principal components: local geochemical characteristics (Cr, Mn and Fe, 37.88%of variance),impact of the pesticide application (Cu, 22.06%of variance) as well as MSWI plant (Pb, 22.74%of variance). The results also showed that the investigated region has low degree of heavy metal pollution. The major heavy metal pollution contribution is Pb (Pollution index=2.16). MSWI plant has a noticeable impact on heavy metal accumulation in surround areas.%随着固体废弃物的增加，垃圾焚烧逐步成为城市垃圾处理应用一个较为理想可行的选择。垃圾焚烧不仅可以回收能源，且相对其他处理方式其减量效果显著。垃圾焚烧厂排出的尾气中的某些特定重金属可以通过大气干湿沉降进入土壤。采用XRF 荧光光谱仪、岛津原子吸收分光光度计和测汞仪测定了杭嘉湖平原的嘉兴垃圾焚烧厂周边土壤重金属的含量，利用地统计学方法分析了该区域74个土壤样品中Cr、Mn、Cu、Pb、Fe五种重金属元素浓度的空间分布，并采用单因子指数法和内梅罗综合指数法对该地区土壤进行污染评价。结果表明：该垃圾焚烧厂周边表层土壤上述5种重金属平均含量依次为174.05、707.76、47.68、41.95、39057.89 mg·kg-1。表层富集因子分析表明表层土壤中Cu和Pb的含量受到人为影响。因子分析将5种重金属分成3类，并揭示了3类金属在该区域具有不同的空间分布特征，Cr、Mn、Fe以土壤地球化学作用(37.88%方差贡献)为主导影响因素，Cu、Pb分别以农药施用作用为主（22.06%)、垃圾焚烧源尾气排放(22.74%)为主导影响因素。污染评价结果表明该区域土壤重金属复合污染程度为轻度污染，最大污染贡献来自于Pb（单因子污染指数高达2.16），厂区周边土壤中重金属存在累积效应，不容忽视。