The impact of reducing industrial emissions of volatile organic compounds(VOCs)on ozone(O3)pollution is of wide concern particularly in highly industrialized megacities.In this study,O3,nitrogen oxides(NOx)and VOCs were measured at an urban site in the Pearl River Delta region during the 2018 Chinese National Day Holidays and two after-holiday periods(one with ozone pollution and another without).O3 pollution occurred throughout the 7-day holidays even industrial emissions of VOCs were passively reduced due to temporary factory shutdowns,and the toluene to benzene ratios dropped from～10 during non-holidays to～5 during the holidays.Box model(AtChem2-MCM)simulations with the input of observation data revealed that O3 formation was all VOC-limited,and alkenes had the highest relative incremental reactivity(RIR)during the holiday and non-holiday O3 episodes while aromat-ics had the highest RIR during the non-pollution period.Box model also demonstrated that even aromatics decreased proportionally to levels with near-zero contributions of indus-trial aromatic solvents,O3 concentrations would only decrease by less than 20％during the holiday and non-holiday O3 episodes and ozone pollution in the periods could not be elim-inated.The results imply that controlling emissions of industrial aromatic solvents might be not enough to eliminate O3 pollution in the region,and more attention should be paid to anthropogenic reactive alkenes.Isoprene and formaldehyde were among the top 3 species by RIRs in all the three pollution and non-pollution periods,suggesting substantial contri-bution to O3 formation from biogenic VOCs.

Jun Wang;Yanli Zhang;Zhenfeng Wu;Shilu Luo;Wei Song;Xinming Wang

State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;CAS Center for Excellence in Regional Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,China

环境科学学报（英文版）

[1]Jun Wang;Yanli Zhang;Zhenfeng Wu;Shilu Luo;Wei Song;Xinming Wang-.Ozone episodes during and after the 2018 Chinese National Day holidays in Guangzhou:Implications for the control of precursor VOCs)[J].环境科学学报（英文版）,2022(04):322-333

shutdowns,AtChem2,aromat,Isoprene,RIRs

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