Source Analysis And Environmental Impact Of Atmospheric Volatile Organic Compounds In Jincheng

In recent years,atmospheric ozone(O3)has become the primary pollutant that affects the air quality of urban environment in summer.Urban atmospheric O3 is mainly generated by volatile organic compounds(VOCs)and nitrogen oxides(NOx)and other precursors under the condition of light through a series of complex chemical reactions.Research shows that O3 in many regions of China is in the VOCs control area,especially for industrial cities with many VOCs components,large emissions and complex sources,and it is difficult to control.At present,there are few studies on the chemical activity,source analysis and environmental impact of atmospheric VOCs in typical industrial cities.This paper takes Jincheng City,a typical industrial city in northern China,as the research object,and analyzes VOCs concentration and component characteristics by wind direction based on VOCs online monitoring data.The characteristic species ratio method,positive matrix factorization(PMF)model and backward trajectory model were used to study the sources of VOCs,and the formation potential of O3 and secondary organic aerosols(SOA)was calculated.Analyze its environmental impact.1.The average VOCs concentration in Jincheng from March to August 2022 was 29.93μg·m-3,and the VOCs concentration in spring and summer were basically the same,30.46μg·m-3 and 29.62 μg·m-3,respectively.The VOCs concentration in the north wind was higher than that in the south wind.They were 34.07 μg·m-3 and 26.83μg·m-3,respectively.The dominant species are ethane,propane,acetylene,isopentane.n-butane,toluene,benzene and ethylene.The screening results of dominant species show that Jincheng City is affected by industrial sources,motor vehicle source and combustion sources.2.The results of PMF model indicated that the proportion of VOCs sources in spring in Jincheng from large to small were industrial sources(30.53%),motor vehicle sources(30.15%).combustion sources(27.88%),plant sources(7.81%)and solvent use sources(3.64%).The proportion of VOCs sources in summer from large to small were motor vehicle source(29.27%),industrial source(27.13%),combustion source(23.31%),plant source(11.90%)and solvent use source(8.40%).Under the southerly wind direction,the proportion of VOCs sources from large to small were motor vehicle source(29.66%),combustion source(25.81%),industrial source(24.70%),plant source(12.65%)and solvent use source(7.81%).The proportion of VOCs sources in the north wind direction from large to small were industrial sources(33.33%),combustion sources(27.25%),motor vehicle sources(21.83%),plant sources(9.81%)and solvent use source(7.77%).3.Motor vehicle source and industrial source are the largest sources of atmospheric VOCs in Jincheng City,industrial source is the largest VOCs source in spring,and motor vehicle source is the largest VOCs source in summer.Industrial sources,motor vehicle sources and combustion sources are the key sources of VOCs control in Jincheng City,especially in the north wind,it is necessary to focus on strengthening the emissions of industrial enterprises in the north and the control of motor vehicle sources in the north.The aging degree of Jincheng air mass is higher,which is more obvious in summer and south wind direction.The main transmission source of VOCs in Jincheng in spring is in the southwest direction of Jincheng,and the main transmission source of VOCs in summer is in the south direction of Jincheng.4.The ozone formation potential(OFP)and SOA formation potential were used to estimate the environmental impact of atmospheric VOCs in Jincheng City.In spring and summer,the consumption rates of total VOCs(TVOCs)on OH free radicals were 1.46 S-1,1.88 S-1,1.54 S-1 and 1.96 S-1,under north and south wind directions.The average OFP of TVOCs were 72.50 μg·m-3,77.03 μg·m-3,64.88 μg·m-3 and 89.28μg·m-3.The average SOA generation potential of TVOCs was 0.39 μg·m-3,0.39 μg·m3,0.34 μg·m-3,and 0.46 μg·m-3.In spring and northern wind direction,the contribution of industrial sources to the environmental impact is obvious,and in summer and southern wind direction,the contribution of plant sources to the environmental impact is significantly increased.