Atmospheric ozone chemistry and control strategies in Hangzhou, China: Application of a 0-D box model

A field campaign was carried out during May–September of 2018 at three sites in Hangzhou, representing residential (ZH), industrial (XS), and natural (HZHP) areas, respectively. The characteristics of precursors to ozone (O3) - volatile organic compounds (VOCs) and nitrogen (NOx) - revealed observably diversities among the three sites. A 0-D atmospheric box model contained the Master Chemical Mechanism (MCMv3.3.1) was implemented to study the O3-precursor sensitivity and O3 in-situ photochemical processing. The discussion of relative incremental reactivity (RIR) showed that O3 production at HZHP was mostly limited by both VOCs and NOx, while ZH and XS were generally identified as VOC-limited regime. More specifically, ethene, m-xylene, and toluene had the largest contributing to O3 production in Hangzhou. The simulated mixing ratios of hydroxyl radical (OH) were within same level among ZH, XS and HZHP, while the simulated mixing ratios of hydroperoxyl radical (HO2) at HZHP were much higher than the other two sites, indicating the different cyclic processes between OH and HO2 among the three sites. Modellings for various emission reduction scenarios were conducted, and the results implied that different strategies were needed for different areas in order to efficiently reduce O3 pollution. For example, the abatement ratio of anthropogenic VOCs (AVOCs) to NOx mixing ratios should be higher than 1.6 and 2.5 at ZH and XS, respectively, while we should target on reducing NOx instead of AVOCs at HZHP. The obtained results provide policy relevant guidance on understanding the photochemical pollution through fundamental chemical mechanism, and can assist local governments (Hangzhou) in taking effective control strategies to deal with O3 pollution.