Source Analysis And Environmental Impact Of Ambient Volatile Organic Compounds In Basin City

In order to study the pollution characteristics,sources and environmental impact of VOCs in small basin cities,this study selected Xinzhou as the research object,collected the air samples from three sites in Xinzhou during summer and winter from 2018 to 2019 with SUMMA canister,and detected 60 kinds of VOCs concentration using a method of pre-concentrator-GC-MS.The emission sources of VOCs were analyzed by characteristic species ratio method and PMF model;HYSPLIT model combined with WPSCF method was used to analyze the spatial transportation of VOCs;The ozone formation potential(OFP)and secondary organic aerosol formation potential(SOAp)were calculated by MIR coefficient method and FAC coefficient method respectively to evaluate the impact of VOCs on the formation of O3 and SOA.The main conclusions are as follows:1.The value of benzene/toluene was 1.34 and 1.92 in summer and winter,indicating benzene and toluene mainly came from coal combustion.The value of isopentane/n-pentane were 3.27 and 1.61 in summer and winter,respectively,indicating that pentane in summer were mainly affected by vehicle exhaust and gasoline evaporation,while those in winter were mainly affected by coal combustion and vehicle exhaust.The results of source apportionment by PMF showed that VOCs in summer were contributed by vehicle exhaust(32.7%),industrial emissions(22.8%)and coal combustion(19.8%).In winter,coal combustion(47.5%)contributed the most,followed by vehicle exhaust(24.8%);during the whole observation period,coal combustion and vehicle exhaust contributed the most.2.Cluster analysis of backward trajectory shows that the average concentrations of VOCs in Xinzhou City are significantly higher than that in the north when they are controlled by air masses from Shanxi(south)and Hebei(southeast)cities along the east side of Taihang Mountain in summer.In winter,the concentrations of VOCs are the highest under the control of the air mass from Shanxi(south).In winter,VOCs are transported more from Shanxi Province.The analysis results of PSCF are consistent with the cluster trajectory results.During the summer observation period,the potential source areas are mainly Shanxi Province and the junction of Shandong,Henan and Hebei provinces.During the winter observation period,the potential source areas of VOCs are cities along the line from Taiyuan to Zhengzhou.3.In summer and winter,the contribution to OFP and SOAp was mainly from industrial source,coal combustion and vehicle exhaust.The contribution of VOCs emission sources to OFP in summer and winter is as follows:industrial emission(27.7%,24.0%),coal combustion(26.7%,45.0%),vehicle exhaust(21.8%,19.0%),nature source(14.9%,4.0%),gasoline evaporation(8.9%,8.0%),and the contribution to SOAp is as follows:industrial emission(44.4%,36.6%),coal combustion(25.3%,29.7%),vehicle exhaust(12.1%,17.8%),nature source(9.1%,7.9%),gasoline evaporation(9.1%,7.9%).Strengthening the control of local major VOCs emission sources such as coal combustion,vehicle exhaust and industrial sources and the joint prevention and control with surrounding areas are conducive to reducing the concentration of VOCs and relieve ozone and particulate pollution in basin cities indirectly.