Characteristics And Source Analysis Of 56 Photochemical Reactants In Zhengzhou City

Volatile Organic Compounds（VOCs）are important precursors of tropospheric ozone（O₃）and secondary organic aerosol（SOA）,which has an important effect on environment and human health.As the primary pollutant,ozone in Zhengzhou City has also increased,so in-depth research on the ozone pollution in Zhengzhou City is very necessary,and study on the pollution characteristics and sources of the precursor VOCs is also particularly important.This study selected continuous concentrations of pollutants in ambient air in Zhengzhou from 2013 to 2019 to analyse the bad changes of various components of pollutants in Zhengzhou in recent years;used online GC-MS to study Ambient air at Henan Provincial Monitoring Center,Zhengzhou Municipal Monitoring Station and the sampling points of Zhengzhou University.This study observed the photochemical components of 56 VOCs in the environmental air from June to September in 2019,analyzed the characteristics of VOC concentration and changes of composition,and identified the main active components and their main source.The main conclusions are as follows:（1）The average hourly concentration of TVOCs in the ambient air at Provincial station,Municipal station and Zhengzhou station during the observation period followed the order of Provincial station>Municipal station>Zhengzhou station.The concentration of TVOCs at the Provincial station was higher than that at the other two stations during the whole observation period,mainly because of the high concentration at 07:00-17:00 and 18:00-23:00.（2）During the observation period,all kinds of VOCs in ambient air at Henan Provincial Monitoring Center and Zhengzhou Municipal Monitoring Station followed the order of alkanes>aromatics>alkenes>alkynes,while VOC composition at Zhengzhou University point was slightly different,as all kinds of VOCs followed the order of alkanes>alkenes>aromatics>alkynes,due to high vegetation coverage and more isoprene emissions at Zhengzhou University point.（3）During the observation period,the top 10 VOC species at Henan Provincial Monitoring Center,Zhengzhou Municipal Monitoring Station and Zhengzhou University point all include ethane,propane,isopentane,toluene,and m/p-xylene.Therefore,it is necessary to control the above VOC species to control the atmospheric pollutants in the ambient air of Zhengzhou.（4）During the observation period,the OFP value and SOAP value of VOCs in the ambient air of Zhengzhou were in the order of Zhengzhou University point>Henan Provincial Monitoring Center>Zhengzhou Municipal Monitoring Station.The daily variation trend of OFP of VOCs in the ambient air of Zhengzhou was opposite to that of O₃ during the observation period,while the variation trend of SOAP concentration of VOCs in the ambient air was roughly the same as that of PM_2.5 mass concentration in the same period.（5）During the observation period,aromatic hydrocarbon made the greatest contribution to the formation of OFP and SOAP at the three points.Therefore,the reduction of aromatic hydrocarbons can effectively control the O₃ pollution in the atmospheric environment of Zhengzhou from June to September.