晋城市冬季环境空气中挥发性有机物的污染特征及来源解析

Characteristics and Source Apportionment of Ambient Volatile Organic Compounds in Winter in Jincheng

采集晋城市冬季环境空气样品,利用色谱-质谱仪分析了其挥发性有机物(VOCs)的组份特征,运用PMF、特征比值、后向轨迹模型对其来源进行了研究,并计算了臭氧和二次有机气溶胶的生成潜势,探讨了其环境影响.结果表明,观测期间,晋城市VOCs平均浓度为93.35μg·m^(-3),其中烷烃类化合物浓度为52.91μg·m^(-3),在VOCs中占比较高为56.68%;PMF分析VOCs排放源有工业排放源、燃烧源、机动车源、溶剂使用源和植物源,贡献率分别为33.71%、30.27%、26.28%、9.00%和0.74%;特征比值法分析中,苯/甲苯和异戊烷/正戊烷比值分别为1.58±0.68和2.07±0.43,介于道路来源与燃煤源之间,为两者混合来源.后向轨迹聚类3个代表性气团均来自西北方向,分别占比50%、25%和25%,西北方向的工业污染可能会对晋城市VOCs造成影响;观测期间,晋城市空气质量指数、总VOCs浓度和机动车源贡献率在风速较小时(<3 m·s-1)分别为143、162.48μg·m^(-3)和46.16%,各数值均高于风速较大(3~6.9 m·s-1)时(60、35.72μg·m^(-3)和16.15%);芳香烃类化合物的臭氧和二次有机气溶胶生成潜势分别为98.89μg·m^(-3)和1.21μg·m^(-3),占总生成潜势的37.28%和97.01%,是两种生成潜势最高的VOCs化合物种类.因此,控制工业、机动车和燃烧排放是控制晋城市环境空气中VOCs污染的主要途径.

Air samples were collected and analyzed by GC-MS to investigate the component characteristics of volatile organic compounds（VOCs） in winter in Jincheng. PMF,ratio analysis,and the backward trajectory model were used to investigate sources of VOCs. Ozone formation potential and secondary organic aerosol formation potential were calculated, in order to analyze the environmental implications of detected VOCs. Results showed that the average concentration of VOCs was 93. 35 μg·m^-3 in Jincheng,with the most abundant component being alkane（52. 91 μg·m^-3 and 56. 68% of total VOCs）. Based on PMF analysis,five sources of ambient VOCs in Jincheng were identified,namely industrial emission sources（33. 71%）,fuel combustion sources（30. 27%）,vehicle emissions（26. 28%）,solvent evaporation sources（9. 00%）,and plant emission sources（0. 74%）. Ratios of B/T and i-pentane/n-pentane were 1. 58 ± 0. 68 and 2. 07 ± 0. 43,indicating that VOCs were derived from the mixture of road and coal combustion sources. Clustered analysis of the air mass backward trajectory showed that three air masses cluster,which were accounting for 50%,25% and 25% of the total back trajectories respectively,all came from the northwest,and industrial pollution from the northwest might therefore significantly influence VOCs in Jincheng. With low wind speed（ 3 m·s-1）,the air quality index,concentration of total VOCs,and contribution rate of vehicle emissions were 143,162. 48 μg·m^-3,and 46. 16%,respectively,higher than values at faster wind speeds（3-6. 9 m·s^-1）. Ozone formation potential and secondary organic aerosol formation potential of aromatic hydrocarbons,which had the highest formation potential,were 98. 89 μg·m^-3 and 1. 21 μg·m^-3,respectively,accounting for 37. 28% and 97. 01% of total formation potential. To reduce the pollution of VOCs in Jincheng,it is important to control industrial emissions,vehicle emissions,and fuel combustion emissions.