School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
J Environ Sci (China). 2019 May;79:297-310. doi: 10.1016/j.jes.2018.12.002. Epub 2018 Dec 17.
A continuous online observation of ozone and its precursors (NOx, VOCs) was carried out in central urban Wuhan from September 2016 to August 2017. The concentration levels of ozone, NOx, VOCs and their variations in urban Wuhan were analyzed, as well as effects of VOCs on ozone photochemical generation and the main controlling factors for ozone production. During the observation period, the average concentrations of ozone and NOx in Wuhan was 22.63 and 30.14 ppbv, respectively, and the average concentration of VOCs was 32.61 ppbv (42.3% alkanes, 13.0% alkenes, 10.0% aromatics, 7.3% acetylene, 9.9% OVOCs, and 10.5% halohydrocarbons). Ozone concentration was higher in spring and summer as compared with autumn and winter, wheras VOCs and NOx concentratios were lower in spring and summer but higher in autumn and winter. Aromatics and alkenes, two of VOCs species, showed the highest contributions to ozone formation potential in Wuhan (35.7% alkenes, 35.4 aromatics, 17.5% alkanes, 8.6% OVOCs, 1.6% halogenated hydrocarbons, and 1.4% acetylene). Among all VOCs species, those with the highest contribution were ethylene, m-xylene, toluene, propylene and o-xylene. The contribution of these five compounds to the total ozone formation potential concentration was 43.90%. Ozone-controlling factors in Wuhan changed within one day; during the early morning hours (6:00-9:00), VOCs/NOx was low, and ozone generation followed a VOCs-limited regime. However, during the peak time of ozone concentration (12:00-16:00), the ratio of VOCs/NOx was relatively high, suggesting that ozone generation followed a NOx-limited regime.
从 2016 年 9 月到 2017 年 8 月，在武汉市中心进行了臭氧及其前体物（NOx、VOCs）的连续在线观测。分析了武汉市臭氧、NOx、VOCs 的浓度水平及其变化情况，以及 VOCs 对臭氧光化学反应生成的影响和臭氧生成的主要控制因素。观测期间，武汉臭氧和 NOx 的平均浓度分别为 22.63 和 30.14 ppbv，VOCs 的平均浓度为 32.61 ppbv（42.3%烷烃、13.0%烯烃、10.0%芳烃、7.3%乙炔、9.9%OVOCs 和 10.5%卤代烃）。与秋冬季相比，春夏季臭氧浓度较高，而春夏季 VOCs 和 NOx 浓度较低，秋冬季较高。在武汉，VOCs 物种中的芳烃和烯烃对臭氧形成潜力的贡献最大（烯烃 35.7%、芳烃 35.4%、烷烃 17.5%、OVOCs 8.6%、卤代烃 1.6%、乙炔 1.4%）。在所有 VOCs 物种中，乙烯、间二甲苯、甲苯、丙烯和对二甲苯的贡献最大。这五种化合物对总臭氧形成潜力浓度的贡献为 43.90%。武汉臭氧控制因素在一天内发生变化；清晨（6:00-9:00）时，VOCs/NOx 较低，臭氧生成遵循 VOCs 限制机制。然而，在臭氧浓度峰值时段（12:00-16:00），VOCs/NOx 的比值相对较高，表明臭氧生成遵循 NOx 限制机制。
