南京市秋季大气中VOCs污染特征及来源解析

Pollution Characteristics and Source Analysis of VOCs in Autumn in Nanjing

挥发性有机物(VOCs)是形成光化学烟雾的前体物,其在大气中的浓度水平直接影响光化学污染物臭氧(O_(3))的污染特征。2020年9月1日~10月15日,运用大气挥发性有机物快速连续自动监测系统对南京市区大气中116种VOCs进行监测。监测结果表明:南京市秋季大气中VOCs质量浓度在19.91~136.12μg/m^(3),平均质量浓度为45.65μg/m^(3)。烷烃、卤代烃、OVOCs等组分对VOCs贡献较大,烯烃、OVOCs、芳香烃、烷烃等组分对O3生成潜势(OFP)贡献较大。O3平均质量浓度为121μg/m^(3),其前体物NO_(2)和VOCs浓度变化趋势基本一致,与O3浓度变化呈明显的负相关性;秋季的南京市总体处于VOCs控制区。用PMF模型对VOCs进行来源解析,分析结果表明:秋季南京市大气中VOCs的来源主要为汽车尾气排放(占比为24.7%)、工业排放(占比为23.4%)、汽油类挥发(占比为21.8%)、溶剂使用(占比为21.0%)和植物排放(占比为9.1%)。

Volatile organic compounds(VOCs)were precursors that form photochemical smog,and their concentration in theatmosphere directly affected the pollution characteristics of photochemical pollution ozone(O_(3)).From September 1st to October 15th,2020,a rapid and continuous automatic monitoring system for atmospheric volatile organic compounds was used tomonitor 116 types of VOCs in the atmosphere of Nanjing.The monitoring results showed that the mass concentration of VOCsin the atmosphere of Nanjing in autumn was 19.91~136.12 μg/m^(3),and the average mass concentration was 45.65 μg/m^(3).Alkanes,halogenated hydrocarbons,OVOCs and other components maked greater contributions to VOCs,while olefins,OVOCs,aromatic hydrocarbons,and alkanes maked greater contributions to O_(3) generation potential(OFP).The average massconcentration of O_(3) was 121 μg/m^(3),and the change trend of its precursors NO_(2) and VOCs was basically the same,showing anobvious negative correlation with the change of O_(3);Nanjing in autumn was generally in the VOCs control area.The PMF model was used to analyze the sources of VOCs,and the analysis results showed that the main sources of VOCs in theatmosphere of Nanjing in autumn were automobile exhaust emissions(24.7%),industrial emissions(23.4%),gasolinevolatilization(21.8%),solvent use(21.0%),and plant emissions(9.1%).