我国中西部典型城市PM_(2.5)中痕量金属的时空分布特征和健康影响

Temporal-spatial variation and health effects of trace metals in PM_(2.5) in four central-western cities of China

为研究我国中西部地区大气细颗粒物中的痕量金属区域分布、季节分布特征以及健康风险,在西安、乌鲁木齐、洛阳以及兰州四城市布点采样,利用ICP-AES(电感耦合等离子体原子发射光谱仪)测定了PM_(2.5)中9种痕量金属(V、Cr、Cd、Mn、Ni、Cu、Zn、As、Pb)的质量分数.结果表明:在痕量金属的时空分布特征方面,各城市主导痕量金属存在差异,西安、乌鲁木齐、洛阳以及兰州的主导痕量金属为Mn、Zn、Pb、Pb,除了主导痕量金属,对于单个金属,其空间分布及季节分布都存在差异;利用分歧系数法分析了城市间颗粒物中痕量金属的组成,洛阳与其他城市颗粒物中痕量金属的CD值在0.4左右,表明洛阳与各城市颗粒物中痕量金属的组成有很大差异,而西安与乌鲁木齐、兰州两个城市的CD值几乎都小于0.2,则他们组成相似;健康风险评结果显示,颗粒物PM_(2.5)中的痕量金属Cr对成年人有着显著的致癌和非致癌风险,而且Cd、As对4个城市居民的致癌风险是显著的,Ni对其致癌风险不显著.长期处于该研究环境,对人体健康存在一定健康威胁.此外痕量金属对人体的健康风险也具有季节性,所有痕量金属ILCR值都高于10-6,尤其是As、Cd、Cr的致癌风险超过了安全水平(10-4),尤其是Cr和As春冬季的致癌风险最高.

To investigate the regional distribution,seasonal variation and health effects of trace metals in atmospheric fine particles,PM2.5 samples were collected from four central-western cities in China(Xi'an,Urumqi,Luoyang and Lanzhou).The concentrations of nine trace metals(V,Cr,Cd,Mn,Ni,Cu,Zn,As and Pb)in PM2.5 was measured by ICP-AES(inductively coupled plasma atomic emission spectrometry).The predominant trace metals during sampling campaigns were Mn,Zn,Pb,and Pb in Xi'an,Urumqi,Luoyang,and Lanzhou,respectively.The spatial-temporal variations of these predominant trace metals were varied with cities.In addition,the other trace metals presented different spatial distributions and seasonal variation patterns.The spatial difference of the particulate trace metals was further explored by using the coefficient of divergence analysis.The composition of trace metals in Luoyang and various urban particles was very different.Because the CD value of trace metals in Luoyang and other urban particles was about 0.4.But the CD values of Xi'an and Urumqi and Lanzhou were almost less than 0.2.The composition was similar.Health risk assessment showed that Cr had both significant carcinogenic and non-carcinogenic risk effects to adults.The carcinogenic risks of Cd and As to residents of the four cities were more significant than other metals,while Ni had no obvious effects.There was a certain threat to human health in the research environment for a long-term.Moreover,the health risks of trace metals to the public showed seasonal variation patterns.The ILCR values of all trace metals were higher than 10^-6,As,Cd and Cr had a cancer risk that exceeded the safety level(10^-4),with the highest cancer risks of Cr and As occurred in the spring and winter.The results highlighted that there is a certain threat to the residents in the case of subjecting to a long-term exposure.