Pollution Characteristics And Sources Of Atmospheric VOCs In Nanchang In 2021

From February to December 2021（except May）,115 kinds of volatile organic compounds（VOCs）in the atmosphere of Nanchang Economic and Technological Development Zone were observed online by using AQMS-900VCM online monitoring system.The VOCs concentration level,composition characteristics,diurnal,monthly and seasonal variation characteristics of atmospheric VOCs in Nanchang city in 2021 were analyzed.The ozone formation potential（OFP）of various VOCs was estimated,and the source of VOCs was discussed based on the ratio of characteristic substances and PMF model.The main results show that:（1）The volume concentration of VOCs in Nanchang Economic and Technological Development Zone from February to December,2021（except May）was（106.53±85.64）×10^-9,which was more serious than other cities in China.Alkane was the main contributor of VOCs,accounting for 50.87%of TVOCs,followed by oxygen-containing volatile organic compounds（OVOCs）and halogenated hydrocarbons,accounting for 18.68%and 15.49%of TVOCs respectively.（2）In the seasonal analysis of VOCs species,the VOCs concentration in spring,summer,autumn and winter of 2021 in Nanchang is（147.34±40.16）×10^-9,（167.37±68.08）×10^-9,respectively.（81.35±83.71）×10^-9and（30.05±12.29）×10^-9,TVOCs showed high in spring and summer,low in autumn and winter,which may be related to the climatic conditions and the effective implementation of atmospheric VOCs control measures in Nanchang.（3）In species classification analysis,low carbon alkanes such as isopentane are the main alkane,alkynes are mainly ethylene and acetylene,aromatic hydrocarbons are mainly naphthalene,toluene and m/p-xylene,halogenated hydrocarbons are mainly chloromethane and dichloromethane,and OVOCs are mainly acetone and acetaldehyde.（4）The diurnal variation trend of alkanes is consistent with that of TVOCs.Influenced by such factors as morning and evening peak,boundary layer change and nocturnal emission of photochemical reaction,the diurnal variation trend is obvious.The concentration of TVOCs is higher in the daytime than in the evening,which may be related to human activities in the daytime.（5）OFP showed summer>spring>autumn>winter,and was mainly affected by alkanes in spring and summer,and OVOCs in autumn and winter.（6）In the ratio of characteristic substances,T/B value indicates that VOCs in spring and winter are mainly affected by motor vehicles,and in summer and autumn,in addition to motor vehicle emissions,they are also affected by the use of organic solvents,and E/E value indicates the existence of atmospheric aging phenomenon in Nanchang.（7）PMF results show that the main sources of atmospheric VOCs in Nanchang in2021 are combustion sources,natural sources,oil and gas volatilization sources,motor vehicle emission sources,solvent use and industrial sources.