[Photochemical Mechanism and Control Strategy Optimization for Summertime Ozone Pollution in an Industrial City in the North China Plain].

To investigate the characteristics and formation mechanism of ozone (O) pollution in an industrial city, an extensive one-month field campaign focusing on O and its precursors (e.g., volatile organic compounds[VOC] and nitrogen oxides[NO]) was conducted in Zibo City, a highly industrializd city in the North China Plain, in June 2021. The 0-D box model incorporating the latest explicit chemical mechanism (MCMv3.3.1) was applied using an observation dataset (e.g., VOC, NO, HONO, and PAN) as model contraints to explore the optimal reduction strategy for O and its precursors. The results showed that ① during high-O episodes, stagnant weather conditions with high temperature and solar radiation as well as low relative humidity were observed, and oxygenated VOCs and alkenes from anthropogenic VOCs contributed the most to the total ozone formation potential and OH reactivity (). ② The in-situ O variation was primarily affected by local photochemical production and export process horizontal to downwind areas or vertical to the upper layer. The reduction in local emissions was essential to alleviate O pollution in this region. ③ During high-O episodes, high concentrations of ·OH (10×10 cm) and HO· (14×10 cm) radical drove and generated a high O production rate (daytime peak value reached 36×10 h). The reaction pathways of HO·+NO and ·OH+NO contributed the most to the in-situ gross O photochemical production (63%) and photochemical destruction (50%), respectively. ④ Compared to those during low-O episodes, the photochemical regimes during high-O episodes were more inclined to be considered as the NO-limited regime. Detailed mechanism modeling based on multiple scenarios further suggested that the synergic emission reduction strategy of NO and VOC, while focusing on NO emission alleviation, would be practical options for controlling local O pollutions. This method could also provide policy-related guidance for the precise O pollution prevention and control in other industrialized Chinese cities.