| The concentration, speciation and chemical reactivity of ambient volatile organic compounds (VOCs) were analyzed and measured by using online gas chromatography during a typical ozone episode (from July. 28th to August. 2nd, 2010) and 55 kinds of VOCs were detected. The results show that two peaks in the morning and evening were observed in the profile of VOCs, with max mixing ratio of 4010-9 ～ 6010-9. The major components of the VOCs were alkanes 14.310-9(44.8%),aromatics 10.110-9 (31.7%), alkenes 5.310-9 (16.7%) and acetylene 2.0510-9(6.4%). Furthermore, the Maximum Ozone Formation Potential (OFP) is analyzed and also show that two peaks in the morning and evening for the OFP, and one more times in the episode than before the episode. The contributions of OFP for the components were aromatics (44%～66%), alkenes (20%～40%), alkanes (12%～16%) and acetylene (＜1%), respectively. Considering individual compounds, xylenes, toluene, propylene, ethane were the most important contributors (＞70%) to ozone formation in the episode. There were a significantly negative correlation between the O3 and OFP in all the episode day, and exist a different relationships for the different episode day. The least levels of OFP were 0.10 mg/m3 ～ 0.20 mg/m3 and suggest that the reactivity of the atmosphere were very strong, there still a large room for the OFP transformed into ozone. |
