2020年长沙市PM2.5组分特征及来源解析OACSTPCD

Based on the online and offline daily monitoring data of seven sites in Changsha City in 2020,the chem-ical component pollution characteristics of PM2.5 were analyzed.The positive matrix factorization(PMF)model was used to analyze the source apportionments of PM2.5.The results show that the water-soluble ions in PM2.5 has the highest mass proportion,accounting for 64.3%,followed by organic matter(OM),accounting for 26.6%,SO2-4,NO-3 and NH+4 are the main components in water-soluble ions.The PMF model identified five sources of PM2.5,vehicle exhaust emission source(36% ),secondary formation source(31% ),industrial emission source(16% ),biomass burning source(9% ),and dust source(8% ).The highest proportion at Changsha Environmen-tal Protection College are secondary formation and motor vehicle emissions,reaching 38% and 37%;the contribu-tion of motor vehicle emissions at Mapoling site is the highest,42%;the sharing rates of secondary formation,mo-tor vehicle emissions,and industrial emissions at Environmental Protection Bureau of the High-tech Zone are rela-tively similar,28%,26%,and 25% .In order to further control PM2.5 pollution,it is recommended that Changsha could focus on controlling vehicle exhaust emissions,accelerating the elimination of old motor vehicles,and pro-moting the electrification of fuel vehicles;meanwhile,differentiated control measures should be implemented for different seasons,with focus on controlling vehicle exhaust emissions in autumn and winter;in summer,it is recom-mended to prioritize controlling oxidants such as ozone to reduce the secondary formation rate of PM2.5.