中文关键词
挥发性有机物体积分数化学反应活性·OH消耗速率臭氧生成潜势(OFP) | 英文关键词volatile organic compounds(VOCs)volume fractionchemical reactivity·OH loss rateozone formation potential |
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| 中文摘要 |
| 采用GC-FID自动在线监测系统对南京市2015年环境大气中56种VOCs开展了为期1a的连续观测.结果表明，南京市城区大气VOCs小时平均体积分数为（17.49±11.35）×10-9，其中4月最高（22.21×10-9），7月最低（12.39×10-9），日均体积分数变化特征不明显.烷烃、烯烃、芳香烃和乙炔占比分别为56.51%、11.06%、24.62%和7.81%，丙烷（15.26%）、乙烷（14.14%）、乙炔（7.81%）、甲苯（6.97%）、正丁烷（6.23%）、乙烯（5.23%）、异丁烷（4.34%）、丙烯（4.13%）、异戊烷（4.12%）和间/对-二甲苯（4.06%）是含量最丰富的VOCs物种.T/B（甲苯/苯）均值为2.02，表明南京市城区大气VOCs主要受机动车尤其是汽油车排放的影响.E/E（乙烷/乙炔）均值为2.24，表明观测站点区域大气老化程度较严重.利用·OH消耗速率（L·OH）和臭氧生成潜势（OFP）评估了大气VOCs的反应活性.南京市城区大气VOCs冬春季大气反应活性较夏秋季强.芳香烃和烯烃的活性最高，对L·OH和OFP的贡献依次为46.96%和41.58%、33.73%和39.86%，丙烯、乙烯和二甲苯等苯系物是活性最高的VOCs物种. |
| 英文摘要 |
| Online gas chromatography with flame ionization detection (GC-FID) systems were employed to observe 56 species of volatile organic compounds (VOCs) in the environmental atmosphere in Nanjing in 2015. The results showed that the annual volume fraction of VOCs was (17.49±11.35)×10-9. The highest concentration of VOCs was in April (22.21×10-9), and the lowest in July (12.39×10-9). Diurnal values of VOCs concentration had no obvious variations. Alkanes, alkenes, aromatics, and acetylene accounted for 56.51%, 11.06%, 24.62%, and 7.81%, respectively. Propane (15.26%), ethane (14.14%), acetylene (7.81%), toluene (6.97%), n-butane (6.23%), ethylene (5.23%), isobutane (4.34%), propylene (4.13%), isoprene (4.12%), and m/p-xylene (4.06%) were the most abundant VOCs species. The average ratio of toluene/benzene (T/B) was 2.02, indicating that the atmospheric VOCs were mainly affected by emissions of motor vehicles, especially gasoline vehicles. The average ratio of ethane/ethyne (E/E) was 2.24, showing that the plume had aged. The hydroxyl radical (·OH) loss rate(L·OH) and ozone formation potential(OFP)were applied to assess the chemical reactivity of VOCs. The atmospheric activity of VOCs was higher in the winter and spring than in the summer and autumn. Aromatics and alkenes were the most important contributors to L·OH and OFP. Their contributions to L·OH and OFP were 46.96% and 41.58%, and 33.73% and 39.86%, respectively. Propylene, ethylene, and xylene were the most active species. |
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