南京市南部地区O3污染特征、生成敏感性及传输影响分析

作为中国最重要的城市群之一，近年来长江三角洲(YRD)地区大气臭氧(O₃)污染问题突出.于2020年7～9月和2021年4～5月在南京市南部地区溧水站点开展了大气O₃、氮氧化物(NO_x)和挥发性有机物(VOCs)等污染物的在线观测.在此基础上分析了溧水站点O₃的污染特征并与城区站点进行比较，发现溧水站点O₃污染较城区站点更加严重.在观测期间选择了3次典型的O₃污染过程，分别为2020年8月16～27日、 2020年9月3～11日和2021年5月17～25日.利用基于观测的模型(OBM)分析了这3次污染过程的O₃-VOCs-NO_x敏感性.基于OBM所模拟的O₃前体物相对增量反应性(RIR)和NO_x和VOCs削减情景下O₃生成等值线(EKMA曲线)结果显示，3次污染过程中O₃-VOCs-NO_x敏感性分别处于N...

Analysis of O3 Pollution Characteristics, Formation Sensitivity, and Transport Impact in Southern Nanjing

As one of the most important city clusters in China, surface ozone (O₃) pollution in the Yangtze River Delta (YRD) Region has become a prominent air quality problem in recent years. Online observations of ambient O₃, nitrogen oxides (NO_x), and volatile organic compounds (VOCs) were conducted in southern Nanjing from July-September 2020 and April-May 2021. On this basis, the pollution characteristics of O₃ were analyzed. The O₃-VOCs-NO_x sensitivity and the transport influence of its precursors were further discussed using models. The frequency statistics of the daily maximum 8-hour moving average (DMA-8h O₃) and hourly concentration (O₃-1h) showed that O₃ pollution in southern Nanjing was more serious than that in urban areas. Three typical O₃ pollution episodes were selected during the whole observation period, which included August 16^th-27^th, 2020; September 3^rd-11^th, 2020; and May 17^th-25^th, 2021. The O₃-VOCs-NO_x sensitivities in these three pollution episodes were analyzed using the observation-based model (OBM). The results of the relative incremental reactivity (RIR) and empirical kinetics modeling approach (EKMA) showed that the sensitivities of O₃ formation in the three pollution episodes were in the NO_x-limited regime, the transition regime, and the VOCs-limited regime, respectively. This difference in O₃-VOCs-NO_x sensitivity reflects that the site may have been influenced by transport. Therefore, the potential source contribution function (PSCF) and the concentration weighted trajectory (CWT) method were further used to analyze the potential source areas of NO_x, VOCs, and O₃ in these three pollution episodes. The results showed that there were obvious regional transport effects of NO_x, VOCs, and O₃ in these three pollution episodes. The location of potential sources differed in these three pollution episodes, which were affected by the eastern cities of the Lishui site; the urban area of Nanjing and eastern area of Anhui Province; and the urban area of Nanjing and the middle of the YRD Region, respectively. The impact of transport on O₃ and its precursors also indicated the necessity of regional joint prevention and control of O₃ pollution in the YRD Region.