武汉市城区PM2.5重金属元素源解析变化

Source Apportionment Variations of Heavy Metals in PM2.5 in Urban Wuhan

为识别武汉市城区大气细颗粒物(PM2.5)的季节特征,比较其重金属元素在不同年份源解析的变化,于2016年4月-2017年4月和2019年1月-2019年9月,在城区共采集240份样品,对其PM2.5及重金属元素(Na、Mg、Al、K、Ca、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Sr、Cd、Cs、Ce、Pb)的质量浓度进行测定。结果表明,PM2.5的质量浓度有明显的季节特征,冬季浓度最高,春季、秋季次之,夏季最低。采用正定矩阵因子(PMF)模型对武汉市城区大气细颗粒物(PM2.5)进行了来源解析。结果表明:两段采样时期(2016年4月-2017年4月和2019年1月-2019年9月)均识别了5个相同的因子,分别是化石燃料燃烧、金属生产、土壤粉尘、道路扬尘和生物质燃烧,对PM2.5的贡献率分别为19.7%、20.0%、19.3%、20.2%、20.7%和19.0%、20.9%、13.5%、20.5%、26.1%。由此可见,部分因子的贡献率发生了明显变化,其中生物质燃烧的贡献率显著上升,而土壤粉尘的贡献率则有所下降。

To investigate the seasonal characteristics of PM2.5 and the sources of heavy metals in the differ-ent years in Wuhan,the mass concentration of PM2.5 and heavy metals were determined in the 240 aerosolsamples collected at an urban site from April 2016 to April 2017 and from January 2019 to September 2019.Our results show a strong seasonal variation of PM2.5 with the highest concentration in winter followed byspring and autumn,and the lowest in summer.The positive Matrix Factorization(PMF)model revealedfive causal factors of pollution in both of sampling years,namely fossil fuel combustion,metal production,soil dust,road dust and biomass burning.They contributed 19.7%,20.0%,19.3%,20.2%,20.7%and19.0%,20.9%,13.5%,20,5%,26.1%to PM2.5 respectively in the two years,which shows a remarkablerise of biomass burning and a significant drop of soil dust.