[Characteristics of Ozone Photochemical Reaction and Emission Reduction Strategies in Summer and Autumn in Shangqiu].

Abstract

Recently, ozone （O₃） pollution in Shangqiu has become increasingly prominent, especially in summer and autumn, crucially affecting the local environmental air quality. Based on the monitoring data of O₃ pollution days from the Environmental Monitoring Station in June and September 2022 （representing summer and autumn） in Shangqiu, an observation-based model （OBM） was used to study the causes and photochemical reaction characteristics of O₃ pollution in the city and precursor emission reduction strategies were studied. The observation results indicated that during summer in Shangqiu, the ρ（O₃） and O₃ daily maximum 8 h moving concentrations [ρ（MDA8-O₃）] were 149.7 μg·m^-3 and 195.4 μg·m^-3, whereas in autumn, ρ（O₃） and ρ（MDA8-O₃） were 119.8 μg·m^-3 and 173.9 μg·m^-3, respectively； the O₃ concentration in summer was significantly higher than that in autumn. Ozone sensitivity research showed that the generation of O₃ in summer and autumn in Shangqiu was controlled by volatile organic compounds （VOCs）. Among them, oxygen-containing volatile organic compounds （OVOCs）, aromatic hydrocarbons, and alkenes contributed the most to the ozone generation potential （OFP） and ·OH reactivity （L_·OH）, and the control must have been strengthened. The OBM simulation results indicated that the maximum O₃ generation rates in summer and autumn were 23.0×10^-9 h^-1 and 13.6×10^-9 h^-1, with maximum net generation rates of 17.4×10^-9 h^-1 and 10.4×10^-9 h^-1 and the maximum and maximum net generation rates of O₃ in summer were 1.68 times higher than those in autumn, indicating that the photochemical reactions in summer were significantly stronger than those in autumn. Compared with that in summer, the generation of O₃ in autumn was greatly influenced by regional inputs from other regions or cities, with a maximum input of 14.2×10^-9 h^-1. The prevention and control of O₃ pollution in the summer and autumn seasons in Shangqiu should mainly focus on controlling VOCs. The reduction ratio of VOCs/nitrogen oxides （NO_x） in autumn should be greater than that in summer and the reduction ratios of 3∶1 in summer and 4∶1 in autumn could be adopted for control.