Characteristics, Sources And Contribution Of Atmospheric Volatile Organic Compounds To Ozone Generation In Shenyang Cit

Volatile organic compounds（VOCs）pollution has become a major environmental issue in industrialized cities in recent years,adversely impacting human health and the ecosystem.The components of VOCs,with a wide range of sources and complex composition,will involve complex secondary chemical reactions in the process of staying and transporting in the atmosphere,leading to the frequent occurrence of atmospheric pollution events such as excessive ozone and photochemical smog,and constantly expanding the scope of pollution.In this study,to provide some suggestions and a basis for atmospheric control in Shenyang,the Online observation data of three stations in the different functional zone from 2019 to 2021will be used to analyze VOCs concentration variation and components.What’s more,to further understand the relationship between ozone（O₃）and VOCs,the nitrogen dioxide（NO₂）and the meteorological data will be used to analyze O₃during the period exceeded the national air-quality standard of annual mean concentrations,and the relative contribution of VOCs to O₃formations also estimated by the maximum incremental reactivity（MIR）method.The potential source contribution method（PSCF）and concentration weight analysis（CWT）are used to identify the potential source areas of contribution of atmospheric VOCs and OFP in Shenyang.The atmospheric VOCs’emission source is analyzed using the orthogonal matrix factor（PMF）model.The conclusion is that:（1）During the study period in 2019,the average total atmospheric VOC concentration in Shenyang was（82.19±54.99）μg·m^-3,in the middle to upper range of domestic cities,and the component ratio was alkanes（53.83%）>aromatic hydrocarbons（23.82%）>olefins（14.84%）>alkynes（7.51%）.VOC concentrations were respectively（69.05±43.84）μg·m^-3and（95.33±86.94）μg·m^-3in the non-heating and heating period,and were twice as high in the industrial area as in the mixed commercial-residential areas and the mixed cultural-educational areas.More aging air masses are found in the mixed commercial-residential areas and the mixed cultural-educational areas,and the traffic source affects the daily variation of VOCs with double peaks.The factory emissions in the industrial area produce fresh air mass,which affects the diurnal variation of VOCs with multiple peaks.（2）From 2019 to 2021,the O₃concentration in Shenyang will continue to decline,with the number of days exceeding the O₃standard at 40,28 and 10 days respectively,while the NO₂concentration will first decline and then rise slightly,and the VOCs concentration will first rise and then decline.During O₃pollution,the alkyne component of the VOCs showed irregular and sudden increases,while indicating that acetylene combustion has a fixed emission point.In 2019,the mean value of OFP contribution was 231.89μg·m^-3during the heating and non-heating periods,and 321.67μg·m^-3,204.43μg·m^-3and 172.58μg·m^-3in the industrial,mixed cultural and educational and mixed commercial-residential areas,respectively.The most significant contribution to ozone generation is made by olefin components,mainly ethylene and propylene,with a maximum contribution of 81.63%during ozone pollution.（3）The main emission sources can be classified into four types.Combustion sources（29.87%）and motor vehicle exhaust（29.57%）are the most important emission sources of atmospheric VOCs in Shenyang,followed by solvent volatilization（20.68%）and industrial sources（19.88%）.Since the contribution of ozone generation from combustion sources（48.01%）is much larger than other emission sources,to prevent ozone pollution from occurring in Shenyang,emissions from combustion sources should be controlled as much as possible.The potential source areas of high VOCs concentrations are in the coastal areas of the Shandong Peninsula and the Liaodong Peninsula,and the range of potential source areas of high OFP contribution extends to the interior of the land,and there is also some potential contribution of OFP within large urban areas such as Tianjin and Qingdao.