基于蒙特卡罗模拟的拉萨城区土壤重金属健康风险评价

Health risk assessment of soil heavy metals in Lhasa urban area based on Monte Carlo simulation

由于城市化的快速发展,城区土壤中重金属(HMs)的污染问题,目前已成为环境和人类健康风险的主要问题之一.为科学地评价城区土壤重金属的健康风险,降低评价结果的不确定性,研究以拉萨城区土壤为研究对象,将蒙特卡罗模拟引入USEPA模型,构建了土壤重金属不确定性健康风险评价模型.研究表明,拉萨城区表层土壤中Cu、Zn、Cr、Ni、Pb、Cd、As、Hg的含量均值分别为20.25、66.07、35.90、17.35、22.70、0.10、25.64、0.07 mg·kg^(−1).除As和Zn外,均未超过拉萨市土壤背景值,污染负荷指数(PLI_(zone))为0.83,整体为无污染水平.健康风险评价结果表明,拉萨城区表层土壤中,HMs对儿童和成人的总致癌风险(TCR)分别为1.30×10^(−5)—7.60×10^(−5)和1.03×10^(−5)—8.15×10^(−5),处于可接受水平;总非致癌风险(HI)分别为1.82×10^(−1)—1.27和3.91×10^(−2)—3.57×10^(−1),成人均处于可接受水平,但儿童可能存在3.61%的概率高于风险阈值;其中As是最主要的风险元素,皮肤接触和经口摄入分别是成人和儿童的主要暴露途径,皮肤黏附系数和体重分别是成人和儿童的主要影响参数.该模型可有效的降低健康风险评价中的不确定性,更加精确地反映区域健康风险状况,并能获取优先控制因子和暴露途径等信息.

Due to rapid urbanization,the contamination of heavy metals(HMs)in urban soil has emerged as a major environmental and human health concern.To scientifically assess the health risks associated with heavy metals in urban soil and reduce assessment uncertainties,this study focused on the urban soil of Lhasa city and integrated Monte Carlo simulation into the USEPA model,establishing an uncertainty-based health risk assessment model for soil heavy metals.The study indicates that the mean concentrations of Cu,Zn,Cr,Ni,Pb,Cd,As,and Hg in the surface soil of Lhasa city are 20.25,66.07,35.90,17.35,22.70,0.10,25.64,and 0.07 mg·kg−1,respectively.Importantly,with the exception of As and Zn,none of these values exceed the background values for soil in Lhasa city.The Pollution Load Index(PLI_(zone))is calculated to be 0.83,signifying an overall absence of contamination.The health risk assessment results demonstrate that the total carcinogenic risk(TCR)of HMs in the surface soil of the Lhasa urban area ranged from 1.30×10^(−5) to 7.60×10^(−5) for children and from 1.03×10^(−5) to 8.15×10^(−5) for adults,which are considered acceptable.Similarly,the non-carcinogeic risk index(HI)ranged from 1.82×10^(−1) to 1.27 for children and from 3.91×10^(−2) to 3.57×10^(−1) for adult,respectively,also within acceptable ranges for adults,but children might have a 3.61%probability of exceeding the risk threshold.Among the HMs,As emerged as the primary risk element,with adults primarily exposed through skin contact and children through oral ingestion.Skin adherence coefficient and body weight were identified as the main influencing parameters for adults and children,respectively.This model effectively reduces uncertainties in health risk assessment,providing a more accurate depiction of regional health risk conditions while also offering insights into priority control factors and exposure pathways.