浙江金华秋季干气溶胶中主要化学组分的消光贡献解析

Analysis of light extinction contributions of major components in dry aerosol in the autumn of Jinhua,China

造成雾霾事件的主要原因是高浓度的大气细颗粒物污染.为了深入研究大气细颗粒物的消光来源,本研究采用高时间分辨率气溶胶观测仪器获得了浙江金华秋季PM1主要化学组分浓度及干气溶胶吸收系数和散射系数演变情况.结合有机气溶胶正矩阵因子解析模型(PMF)和多元线性回归方法,建立了拟合优度很高(R2=0.977)的细颗粒物中主要化学组分与干气溶胶消光系数间的定量关系模型.结果表明,观测期间消光贡献最大的是硫酸铵,贡献率为35.1%;其次是硝酸铵,贡献率为26.7%;二次有机气溶胶(SOA)、生物质燃烧有机气溶胶(BBOA)、黑碳(BC)及氯化铵的消光贡献率分别为14.3%、11.2%、8.7%、4.0%.在一些特定污染时段,BBOA具有最大的消光贡献,是导致此时大气能见度大幅度衰减的首要因子.

The occurrence of haze is mainly due to high concentrations of atmospheric fine particles. In order to further investigate the light extinction sources of fine particles,the mass concentrations of main components in PM1 and light extinction coefficients of dry aerosol in the autumn of Jinhua,China,were obtained using high resolution aerosol observation instruments. A high quality fitting formula was established by the multiple linear regression method based on the obtained data combined with the positive matrix factor analysis（ PMF） model for organic aerosol. The results showed that during the sampling period,ammonium sulfate was the species with the highest light extinction contribution（ ave. 35. 1%） in dry aerosol,followed by ammonium nitrate（ ave. 26.7%）. The average contributions of secondary organic aerosol（ SOA）,biomass burning organic aerosol（ BBOA）,black carbon（ BC）,and ammonium chloride were 14.3%,11.2%,8.7%,and 4.0%,respectively. BBOA was found to contribute mostly in some pollution periods and was the primary factor leading to the quite low atmospheric visibility at that time.