芜湖市大气挥发性有机物污染特征、大气反应活性及源解析

Characteristics, Atmospheric Reactivity, and Source Apportionment of Ambient Volatile Organic Compounds in Wuhu

2018年9月至2019年8月对芜湖市城区大气中挥发性有机物(VOCs)进行观测,探讨其污染特征、光化学影响和来源.结果表明,芜湖市大气中VOCs全年平均体积分数为27.86×10^-9,季节变化规律为:秋季(31.16×10^-9)>夏季(28.70×10^-9)>冬季(24.75×10^-9)>春季(24.04×10^-9),日变化规律呈双峰型,峰值在08:00~09:00时与18:00~19:00时出现,与交通流量的变化有关.芜湖市大气VOCs的平均臭氧生成潜势(OFP)为255.29μg·m-3,不同组分对平均OFP的贡献率排序为:芳香烃(48.83%)>烷烃(21.04%)>烯烃(18.32%)>OVOCs(11.47%)>卤代烃(0.35%).总气溶胶生成潜势(AFP)为1.84μg·m-3,芳香烃贡献率最高(87.69%),其次为烷烃(12.31%).苯/甲苯/乙苯(B/T/E)比值表明,芜湖市大气中苯系物的主要贡献源为机动车排放源和工业排放及溶剂使用源.源解析显示:油气挥发源、机动车排放源、溶剂挥发源、LPG排放源、植物排放源和二次生成源对采样期内的VOCs贡献率分别为11.57%、34.53%、16.63%、20.76%、3.54%和12.97%.

In this study,the pollution characteristics,photochemical effects,and sources of atmospheric volatile organic compounds(VOCs)in the urban areas of Wuhu were investigated from September 2018 to August 2019.The results showed that the annual average mixing ratio of ambient VOCs in Wuhu was 27.86×10^-9,with the highest values in fall(31.16×10^-9),followed by summer(28.70×10^-9),winter(24.75×10^-9),and spring(24.04×10^-9).The diurnal patterns showed two VOC peaks,due to traffic exhaust,at 08:00-09:00 and 18:00-19:00.The estimated total OFP of VOCs was 255.29μg·m-3,and aromatics,olefins,alkanes,OVOCs,and halocarbons contributed 48.83%,21.04%,18.32%,11.47%,and 0.35%to the average OFP,respectively.The total AFP was 1.84μg·m-3,among which aromatics and alkanes accounted for 87.69%and 12.31%,respectively.The ratios of B/T/E indicated that atmospheric aromatic hydrocarbons were mainly derived from vehicle exhaust,as well as industry emission and solvent usage.Source apportionment indicated that petroleum evaporation,vehicle exhaust,solvent evaporation,liquefied petroleum gas(LPG),biogenic source,and secondary source shared 11.57%,34.53%,16.63%,20.76%,3.54%,and 12.97%of ambient VOCs during the sampling period,respectively.