重污染天气情况下市区和市郊居民社区空气PM2.5的昼夜污染特征与来源贡献

Study on pollution characterization and source apportionment of day and night samples of PM2.5 in residential community of urban and suburb on heavy pollution weather conditions

目的了解在重污染天气(AQI>200)情况下市区和市郊区域居民社区空气PM2.5的昼夜污染特征和来源差异。方法采集天津市市区和市郊社区2015—2016年间昼夜两时段的PM2.5样品,分别检测PM2.5样品的质量浓度,金属元素,多环芳烃和无机水溶性离子浓度,并运用正矩阵因子分解模型分析社区空气PM2.5昼夜的不同来源。结果在重污染天气情况下市郊居民社区部分金属元素日间浓度高于夜间,且市郊昼夜PM2.5中的部分成分均高于同期市区的浓度水平。市区社区空气PM2.5昼夜的主要来源均为二次气溶胶,来源贡献率均在30.00%以上,市郊居民社区空气PM2.5日间的主要来源为燃煤排放,来源贡献率为55.20%,夜间的主要来源分别为二次气溶胶和汽、柴油车燃料燃烧排放,来源贡献率分别为39.70%和38.00%。结论市区和市郊区域居民社区空气PM2.5的污染状况均较为严重,重污染天气情况下市区和市郊PM2.5的昼夜污染来源差异均有统计学意义(P<0.05)。

Objective To study the pollution characteristics and source apportionment of PM2.5in residential community of urban and suburb during daytime and nighttime with AQI greater than200weather conditions.Methods From2015to2016,day and night PM2.5samples were collected at two typical communities in urban and suburb of Tianjin respectively.Major chemical components in PM2.5,including metal elements,polycyclic aromatic hydrocarbons(PAHs)and inorganic water-soluble ions,were monitored.Positive matrix factorization(PMF)model was employed to apportion potential sources of PM2.5in daytime and nighttime respectively.Results In the case of AQI above than200weather condition.the concentrations of some metal elements in the daytime of suburban residential community were higher than during the nighttime.Some components of PM2.5in the suburb are higher than urban in the same period.When the AQI is greater than200,the main source of PM2.5in the urban residential community is secondary aerosol both daytime and nighttime,and the source apportionments are both above30.00%.The main source of air PM2.5in the suburban residential community is coal combustion during daytime,while secondary aerosol and fuel combustion emissions of gasoline and diesel vehicles were the mainly sources during nighttime and the source apportionments of them are55.20%,39.70%and38.00%.Conclusion The pollution status of PM2.5in residential communities of urban and suburban is serious,and the source apportionments of day and night PM2.5samples of urban and suburban are differences on heavy pollution weather conditions.