人为源减排对长三角臭氧生成敏感性的影响

This study investigated the spatiotemporal variations of ozone (O₃) pollution and O₃ formation sensitivity in the Yangtze River Delta (YRD) with the air quality model CAMx and an optimized photochemical indicator (PH₂O₂/PHNO₃). The critical years of emission reduction strategies (2013, 2017, 2020, and 2030) were selected to simulate and predict changes in ozone concentration and formation sensitivity under different emission scenarios. The results revealed a north-south gradient in O₃ concentrations, with higher levels in northern areas and lower levels in southern areas. The ozone formation sensitivity regimes were divided by an Anqing-Nanjing-Suzhou-Jiaxing line. The northern aeras of the line were governed by a VOCs-limited regime (occupying 43.3% of the total area) and the southern areas were predominantly NO_x-limited (45.3%), with transitional zones covering the remaining area. Under fixed meteorological conditions, continuous reduction in anthropogenic emissions during 2013~2020led to a sustained decline in the daily maximum 8-hour average (MDA8) O₃ concentration, and a shift of the ozone formation regime from VOCs-limited to NO_x-limited. In 2030, O₃ levels in urban hotspots such as Shanghai are likely to increase, despite an overall reduction in regional O₃ levels. The shift towards the NO_x-limited region will continue, increasing by 30.2% from 2013 levels. Only specific cities along the Yangtze River and areas with heavy traffic emissions will remain VOCs-limited. In summary, excluding the impact of climate change, the emission mitigation strategies can effectively decrease the ozone levels in the YRD. Meanwhile it is still necessary to coordinate the reduction rates of NO_x and VOCs in VOCs-limited cities to prevent increases in O₃ levels.