Estimation Of Volatile Organic Compounds Emissions And Ozone Formation Potential In Xi'an City Of Northwest University

With the rapid economic development in urban areas,the content of volatile organic compounds?VOCs?in the atmosphere continues to increase,prompting urban areas to face complex air pollution problems.VOCs in Xi'an city can provide some data support and theoretical basis for effectively formulating VOCs pollution control measures,and improving Xi'an air quality.In this study,the VOCs Xi'an city were divided into anthropogenic volatile organic compounds?AVOCs?and biogenic volatile organic compounds?BVOCs?from their sources.According to the system of pollution source classification,the anthropogenic sources were divided into 7 categories,and the emission factor method was used to estimate the emissions of AVOCs in Xi'an city in 2016;The vegetation types were interpreted by remote sensing images in Xi'an city,and then the emission factors of typical trees were obtained through experimental analysis of thermal desorption-gas chromatography-mass spectrometry?TD-GC-MS?,and finally the G95 light temperature model was used to calculate the emissions of BVOCs in Xi'an city in 2016;Based on the emission inventory of VOCs in Xi'an,the ozone formation potential?OFP?of each every VOCs component was estimated by using the maximum incremental reactivity?MIR?.According to the above methods,the emissions of AVOCs and BVOCs and their OFP in Xi'an city in 2016 were obtained.The main conclusions drawn form this study are as follows:?1?In 2016,the total emission of AVOCs in Xi'an city was 119.19 kt.Compared with other sources,the sources of solvent,mobile sources and process sources were larger,50.68,29.41 and 24.43 kt respectively;Among the districts and counties,the total emission of AVOCs of Chang'an District,Yanta District,Weiyang District and Beilin District was relatively larger.Comparing the emission intensity per unit area of AVOCs in other parts of China,it is found that the emission intensity per unit area of AVOCs Xi'an city was at in medium level.?2?In 2016,the total emission of BVOCs in Xi'an city was 74.10 kt.Among them,the emissions of isoprene,monoterpene and inactive OVOCs accounted for 44.91%,24.16%and 30.93%,respectively.Among the various vegetation types,broad-leaved forests have the largest BVOCs emissions.Among the districts and counties,the total emission of BVOCs of Zhouzhi county,Lantian county,Chang'an district and Huxian county were relatively larger.The emission of isoprene of Zhouzhi county and Lantian county were larger.In each district and county,the distribution of monoterpene emissions was similar with isoprene.?3?Based on the emission list of VOCs,the total OFP produced by AVOCs was estimated to be 222.087kt.Among them,the emission of OFP of solvent use source,biomass combustion source,process source,fossil fuel combustion source and waste disposal source accounted for 79.95%,8.37%,7.89%,2.99%and 0.80%of the total OFP,respectively;Among the districts and counties,the total emission OFP of Chang'an District,Yanta District,Beilin District,Weiyang District and Lianhu District were relatively larger.The total emission of OFP emitted by BVOCs in Xi'an city was 425.44 kt,of which the OFP produced by isoprene and monoterpene account for 83%and 17%of the total OFP,respectively;Through comparison,it was found that the spatial distribution of OFP produced by AVOCs was basically consistent with the spatial distribution of the concentration of O₃ at existing stations;The pollution control measures of VOCs in Xi'an city are mainly active head classification control,total control and high chemical reaction active components priority control.