The Pollution Characteristics And Source Apportionment Of VOSs In Guangzhou City

Atmospheric volatile organic compounds（VOCs）are the key precursors for the formation of secondary pollution in the atmosphere.Study the changes in the concentration composition of atmospheric VOCs in urban areas,identify key active components that affect urban air quality,and explore the main sources of atmospheric VOCs,explore the chemical behavior of VOCs in the atmosphere,it helps people understand the formation mechanism of atmospheric combined pollution in China and is conducive to the development of effective control strategies.In this paper,an atmospheric volatile organic matter monitoring system-gas chromatography-mass spectrometer was used in Guangzhou city.The representative month was selected for online monitoring of atmospheric VOCs for one year.The concentration variation characteristics and species composition characteristics of VOCs in each season of the four seasons were analyzed,and the sources of atmospheric VOCs in four months were analyzed.The chemical consumption of atmospheric VOCs was quantified using the photochemical age-based parameterization method.The differences between the PMF source analysis results before and after the correction were compared.The average volume fractions of TVOCs observed in Guangzhou,China,July,October,January,and April 2016 were 40.07?10^-9,49.16?10^-9,57.49?10^-9,47.51?10^-9,respectively.TVOCs exhibit a high concentration variation in the winter and low in the summer.The dominant species with higher concentrations were propane,n-butane,ethane,toluene,isobutane and the like.In the daily variation analysis,species associated with vehicle exhaust emissions tend to peak in the morning and evening peak hours,while species with complex sources do not have significant diurnal variations,explain that the motor vehicle has obvious influence on the site.Isoprene showed obvious single-peak changes in the July,October and April,but there was no obvious daily variation in January due to lower temperature and smaller emissions.In the activity analysis of atmospheric VOCs,the aromatics have the largest OFP,followed by alkenes and alkanes;the largest species of OFP were m/p-xylene,toluene,ethylene,o-xylene,propylene,etc.They were all related to fuel and vehicle emissions,therefore,prioritizing the control of vehicle emissions was an effective way to control ozone generation.The relationship between atmospheric VOCs and transmission shows that high concentration VOCs mainly come from local emissions around the site,while part of the transmission effect in October.PMF results show that there were six main sources of VOCs at the site,namely vehicle exhaust（45%）,LPG+gasoline volatilization（23%）,fuel combustion source（10%）,paint and coating source（9%）,other solvent source（11%）,plant emission source（2%）.It can be seen from the analysis of the CPF that the fuel combustion source and plant emission source were greatly affected by the emission from the north side of the station,while the vehicle exhaust source,LPG+gasoline volatilization source and solvent source were affected by the emissions from the east and west sides.The quantitative characterization of chemical evolution of atmospheric VOCs indicated that the chemical consumption of volatile organic compounds in the atmosphere resulted in a large difference between the emission concentration and the observed concentration.And this difference was reflected in the source analysis results of VOCs,and the influence of high-activity species was greater.Before and after considering the effects of chemical evolution,the contribution rate of each factor in the source analysis resulted to VOCs in the atmospheric environment was different.