南京仙林地区大气PM2.5中金属化学形态分析及其风险评估

Fractionation of airborne PM 2.5-bound metals and associated risks in Xianlin area of Nanjing

采用四步连续提取法提取不同季节南京仙林地区PM2.5中不同化学形态的金属组分。结果显示:(1)PM2.5日均值平均为84.93μg/m3,75%的样品超过了《环境空气质量标准》(GB 3095-2012)中PM2.5日均值二级标准值(75μg/m3)。(2)PM2.5中Fe、Zn和Pb浓度最高,As和Cd浓度最低。(3)Zn、Cd和Mn主要以弱酸提取态(F1)存在,Pb以可还原态(F2)为主,As主要以F1和F2存在,Ni和Cr以F1和可氧化态(F3)为主,Cu主要为F1、F2、F3,Fe和Ti大部分以残渣态(F4)存在。(4)Zn具有非常高的环境风险,Cd、As、Cu和Mn均表现出高风险,Pb、Ni和Cr具有中等风险,Fe、Ti具有低风险。(5)对于儿童,Cr具有潜在致癌风险;对于成人,As和Cr具有潜在致癌风险。

The PM 2.5-bound metals in Xianlin area of Nanjing were fractionated by a four-step sequential extraction procedure(SEP).The result showed that:(1)the daily average PM 2.5 was 84.93μg/m 3,and the concentrations of 75%samples exceeded the secondary standard value of PM 2.5 daily average(75μg/m 3)of“Ambient air quality standard”(GB 3095-2012).(2)The highest concentration elements in PM 2.5 were Fe,Zn,and Pb,whereas the lowest were As and Cd.(3)The elements including Zn,Cd and Mn were mostly present in acid soluble fraction.A relative high percentage of Pb was present in reducible fraction.As were mostly present in both acid soluble fraction and reducible fraction.Ni and Cr were mostly present in both acid soluble fraction and oxidizable fraction.Cu were present in almost all fractions,except residual fraction.Fe and Ti were mostly present in residual fraction.(4)The result of environmental risk assessment showed that Zn presented a very high risk,while Mn,Cd,As and Cu presented a high risk.Meanwhile,Pb,Ni and Cr presented a medium risk,while Fe and Ti presented a low risk.(5)Health risk assessment results indicated that Cr had a potential carcinogenic risk in children,while As and Cr had potential carcinogenic risks in adults.