银川市城区大气PM_(2.5)中金属元素污染特征及来源分析

Characteristics and source of metal elements in ambient PM_(2.5) in urban area of Yinchuan

目的探讨银川市大气PM_(2.5)中金属元素来源及各来源所占比例,为金属元素污染控制提供科学依据。方法在银川市城区设置2个监测点,2015年每月定期采集大气PM_(2.5)样品,共采集样品164份,分析锑(Sb)、铝(Al)、砷(As)、镉(Cd)、铬(Cr)、汞(Hg)、铅(Pb)、锰(Mn)、镍(Ni)、硒(Se)、铊(Tl)11种金属元素含量及来源。结果 PM_(2.5)质量浓度及部分金属元素含量具有明显的季节变化特征,夏秋低、冬春高。PM_(2.5)中金属元素平均质量浓度顺序:Al>Pb>Mn>As>Tb>Cd>Cr>Se>Tl>Ni>Hg,环境空气中Pb年均浓度和季平均浓度均未超标。Pb、Tl、Cd、Mn、Se、As主要来源为人为源,主要受到交通源、工业源及燃烧源等人为污染影响。结论银川市大气PM_(2.5)重金属元素的污染特征和来源有其自身的地域性特征。PM_(2.5)质量浓度及金属元素含量受供暖期影响,主要来源于人为污染。

Objective To explore the source and the proportion of metal elements in ambient PM2.5 in Yinchuan, in order to provide scientific basis for pollution control for PM2.5 and metal elements. Methods A total of 164 PM2.5 samples were collected monthly in 2015 from two monitoring points set randomly in Yinchuan, contents and source of Sb, Al, As, Cd, Cr, Hg, Pb, Mn,Ni, Ni, Se, Tl were analyzed. Results PM2.5 mass concentration and some metal elements contents presented obvious seasonal variation characteristics, higher in winter and spring,lower in summer and autumn.The average mass concentrations of metal elements in PM2.5 ranked as the following order, Al〉Pb〉Mn〉As〉Tb〉Cd〉Cr〉Se〉Tl〉Ni〉Hg. The average annual and seasonal concentration of ambient lead were all qualified. The main source of Pb, Tl, Cd, Mn, Se and As were artificial pollution,mainly by traffic,industry and combustion. Conclusion Pollution and source of metal element in ambient PM2.5 has regional characteristics in Yinchuan.The mass concentration of ambient PM2.5 and metal element mainly from man-made pollution are affected by heating period.