贵阳市秋冬季PM2.5中重金属污染特征、来源解析及健康风险评估

Characteristics,Sources and Health Risk Assessment of Heavy Metals in PM 2.5 Collected between Autumn and Winter in Guiyang City

为掌握贵阳市大气PM 2.5中重金属的污染特征、潜在来源和健康危害,于2017年10月—2018年2月白天(08:00—19:00)、夜间(20:00—翌日07:00)连续采集秋、冬两季大气颗粒物PM 2.5样品(n=202),采用电感耦合等离子体质谱(ICP-MS)法,检测样品中10种重金属(Pb、Cd、Cr、As、Zn、Mn、Co、Ni、Cu和V)含量,分析其昼夜质量浓度特征及变化规律,运用PMF(正定矩阵因子分析)模型和HMHR(健康风险评价模型)分别探讨其来源及健康风险.结果表明:①秋、冬两季大气颗粒物ρ(PM 2.5)日均值分别为(53±18)(62±20)μg/m^3,均低于GB 3095—2012《环境空气质量标准》二级标准(75μg/m^3);ρ(As)、ρ(Zn)和ρ(Mn)均呈冬季高于秋季的特征,其他元素变化不明显.②白天ρ(PM 2.5)为(61±20)μg/m^3,稍高于夜间〔(58±24)μg/m^3〕;ρ(Pb)白天低于夜间,ρ(Ni)、ρ(Mn)、ρ(Zn)和ρ(Cu)则白天高于夜间,其他元素昼夜质量浓度无明显差异.③PMF模型分析表明,交通污染、燃煤、工业冶金和土壤扬尘是采样期间10种重金属的主要来源,其贡献率分别为39%、37%、14%、10%.④HMHR结果表明,Cd和Mn对儿童存在非致癌风险,其他重金属元素对人群无非致癌风险.致癌元素As、Cr和Cd的致癌风险值介于4.3×10^-6~4.4×10^-5之间,对人群可能存在致癌风险;而Ni和Co的致癌风险值均低于可接受水平(10^-6).研究显示,贵阳市秋、冬两季PM 2.5中重金属污染水平整体较低,交通污染和煤炭燃烧是其主要来源,重金属元素中Cd、Mn、As和Cr对人群存在一定的健康风险.

In order to reveal characteristics,potential sources and health risks of heavy metals in atmospheric fine particulate matters(PM 2.5)in Guiyang City,a total of 202 samples were collected during daytime(08:00-19:00)and nighttime(20:00-07:00)from October 2017 to February 2018.Ten heavy metals(Pb,Cd,Cr,As,Zn,Mn,Co,Ni,Cu and V)in the samples were determined by inductively coupled plasma mass spectrometry(ICP-MS)to elucidate their diurnal characteristics.The positive matrix factor analysis model(PMF)and health risk assessment model(HMHR)were used to explore potential sources and health risks.The results showed:(1)The average daily concentration of PM 2.5((53±18)μg/m^3 in autumn and(62±20)μg/m^3 in winter)in Guiyang City was lower than the Ambient Air Quality Standards(GB 3095-2012)secondary grade value(75μg/m^3),and it was slightly higher in the daytime((61±20)μg/m^3)than at nighttime((58±24)μg/m^3).(2)Theρ(As),ρ(Zn)andρ(Mn)in PM 2.5 were higher in winter than those observed in autumn,and theρ(Pb)in daytime was lower than that in nighttime,while theρ(Ni),ρ(Mn),ρ(Zn)andρ(Cu)were higher in daytime than that in nighttime.(3)PMF analysis showed that the main sources of the ten heavy metals in PM 2.5 were traffic(39%),coal combustion(37%),industrial metallurgy(14%)and soil dust(10%).(4)HMHR results showed that Cd and Mn had certain non-carcinogenic health risks for children,and other heavy metals had no non-carcinogenic risks to the population.The carcinogenic risk values of carcinogenic elements As,Cr,and Cd ranged between 4.3×10^-6 and 4.4×10^-5,indicating a carcinogenic risk to the population;while Ni and Co exhibited a low carcinogenic risk at an acceptable level(10-6).The results showed that the levels of heavy metals in PM 2.5 in Guiyang City were low,and the main sources were traffic and coal combustion.Cd,Mn,As and Cr in PM 2.5 posed potential health risks to residents.