简易生活垃圾填埋场土壤重金属污染特征及健康风险评价

SOIL HEAVY METAL POLLUTION CHARACTERISTICS AND HEALTH RISK ASSESSMENT OF A SIMPLE DOMESTIC GARBAGE LANDFILL

为评估简易生活垃圾填埋场内原状土壤重金属污染程度及人体健康风险,以浙江省某小型简易生活垃圾填埋场为例,于场内采集18个土壤点位,54份土壤样品,分析土壤样品中Cu、Pb、Cd、Hg、As和Zn含量,综合运用污染负荷指数法(PLI)、地累积指数法(I_(geo))和潜在生态风险指数法(RI)等方法探讨其重金属污染特征,借助USEPA健康风险评价模型,进行成人重金属健康风险评价。结果表明:18个土壤点位6种重金属整体污染程度以无污染和轻度污染为主,引起污染累积和潜在风险的主要指标是Cd、As、Cu和Hg。但需要引起重视的是,中层、下层土壤与表层相比污染均更为严重,少数为高、极高生态风险。经口摄入是致癌风险的主要暴露途径,Cd和As的95%数值显示存在明显致癌风险;非致癌风险中,皮肤接触贡献率最高,3种暴露途径下成人的非致癌指数和总危害指数均<1,无风险。研究结果可为简易生活垃圾填埋场后续整治提供数据参考,无论封场管控、开挖筛分利用还是异地搬迁,均可为原址土壤污染的生态修复提供数据支撑,为风险管控及治理修复提供科学依据。

To assess the degree of heavy metals pollution and human health risk in undisturbed soil of a simple domestic waste landfill,a small-scale domestic waste landfill in Zhejiang Province was taken as an example,and 54 soil samples were collected from 18 soil sites in the landfill.The contents of Cu,Pb,Cd,Hg,As,and Zn in the soil samples were analyzed.Pollution load index(PLI),ground accumulation index(I_(geo)),and potential ecological risk index(RI)were comprehensively used to investigate the characteristics of heavy metals pollution.The health risk assessment of heavy metals in adults was carried out by the USEPA health risk assessment model.The results showed that the overall pollution degree of 6 heavy metals in 18 soil sites was mainly in a non-polluting and light pollution level,and the main indicators of pollution accumulation and potential risk were Cd,As,Cu,and Hg.However,attention should be paid to the middle and lower soil layers,because they are more seriously polluted than the surface layer,and a few have high and extremely high ecological risks.Oral intake is the main exposure pathway for carcinogenic risk.95%of the values of As and Cd showed significant carcinogenic risk;the noncarcinogenic index and total hazard index of adults under the three exposure routes were less than 1,so there was no risk.The research results can provide data reference for the follow-up treatment of simple domestic waste landfills.Whether the site is closed for control,excavation screening,utilization,or relocation,it can provide data support for the ecological restoration of soil pollution at the original site,and provide a scientific basis for risk control and restoration.