典型材料屋面积尘重金属形态分布与风险评估

Speciation Distribution and Risk Assessment of Heavy Metals in Typical Material Roof Dusts

以华南地区4种典型材料屋面(瓷砖、混凝土、金属和沥青)为研究对象,采用改进式BCR连续提取法对其屋面积尘中10种重金属(Ba、Co、Cr、Cu、Mn、Ni、Pb、Sb、Sr和Zn)进行形态分析与风险评估.结果表明,屋面积尘重金属平均含量明显高于道路积尘.形态分析表明,Zn的酸溶态比例明显高于其他重金属,Pb和Cu主要以可氧化态存在,其余重金属均以残渣态为主;屋面积尘重金属可移动态比例表现为Pb>Zn>CuMn>CoSr>Sb>Ni>Ba>Cr,其中Pb、Zn、Cu、Mn和Co可移动态比例均超过50%.环境风险评估发现,污染指数(Cf)与风险评价编码指数(RAC)最大值均为Zn,其生态风险较高.健康风险评估表明,屋面积尘重金属对成人与儿童非致癌风险均表现为:Pb>Cr>Sb>Zn>Mn>Cu>Ba>Ni>Co>Sr,其对成人非致癌风险均小于安全限值,不构成威胁,但Pb对儿童的非致癌风险高于安全限值,形成威胁;屋面积尘中Cr、Co和Ni低于致癌风险阈值,对人体无致癌风险.

With the modified BCR sequential extraction procedure,the chemical speciation and risk for 10 heavy metals( Ba,Co,Cr,Cu,Mn,Ni,Pb,Sb,Sr and Zn) in roof dusts were investigated. The subjects of this study were collected from four typical material paved roofs( i. e.,ceramic tile,concrete,metal and asphalt) in southeast China. The results indicated that the average contents of heavy metals in roof dust significantly exceeded road dust. The analysis of chemical fraction showed that the acid soluble/exchangeable fraction of Zn was much higher than other elements,the existence of Pb and Cu was mainly in oxidization fraction,while other heavy metals dominated by the residual fraction. The mobility sequence percentages for all roof dust samples decreased in the order of Pb > Zn> CuMn > CoSr > Sb > Ni > Ba > Cr,and it should be noted that Pb,Zn,Cu,Mn and Co all have more than 50% proportion in mobility sequence. Based on environmental risk assessment,the highest values of contamination factors( Cf) and risk assessment code( RAC) consistently was observed in Zn,which indicated that Zn had relatively high ecological risk. Health risk assessment showed that the non-carcinogenic hazard indexes( HI) of heavy metals decreased in the order of Pb > Cr > Sb > Zn > Mn > Cu > Ba > Ni > Co >Sr,the HI of heavy metals for adults were lower than safe value while the HI of Pb for children was higher than safe value,suggesting that they will not harm the adult's health except Pb for children. The carcinogenic risk for Cr,Co and Ni were all below the threshold values,which indicated that there was no carcinogenic risk.