COMPONENTS CHARACTERISTICS AND SOURCE APPORTIONMENT OF PM2.5 IN AUTUMN AND WINTER IN JINCHENG
Jincheng is an important coal chemical industry base in China,and its industrial economic structure is dominated by heavy industry.In recent years,PM2.5 pollution has become prominent in Jincheng.Atmospheric PM2.5 samples were collected from three sites in Jincheng in the autumn and winter from 2018 to 2019.This study analyzed the component concentrations(ions,elements,and carbon)and secondary transformation characteristics under different conditions.Backward trajectory was used to investigate the impact of regional transport on ambient air,and a chemical mass balance model was used to analyze the source of PM2.5.The results showed that:1)the concentration of PM2.5 in Jincheng was 86.1 μg/m3 during the sampling period.The PM2.5 concentration in the polluted period(131.1 μg/m3)was 2.3 times higher than that in the clean period(58.2 μg/m3),which maybe related to the high humidity and static stability conditions.2)secondary inorganic ions were the main component(83.4%)of water-soluble ions in PM2.5 in Jincheng,which had a higher concentration in the polluted period(71.2 μg/m3)than clean period(24.6 μg/m3).The conversion of SO2 to SO42-in autumn and winter in Jincheng was mainly dominated by heterogeneous reactions,while the formation of NO3 was influenced by both oxidation and heterogeneous hydrolysis.Compared with the clean period,the concentrations of OC and EC in polluted days increased by 88.5%and 83.0%,respectively.The backward trajectory results showed that under the influence of adverse meteorological conditions,the short-distance air mass from the southeast of Jincheng in January aggravated the pollution process,which reflected the importance of regional joint prevention and control.The results of source apportionment showed that dust source(18.4%),secondary nitrates(16.5%),coal combustion(15.9%)source,and vehicle source(12.0%)were the main source of PM2.5.Therefore,to further reduce the concentration of PM2.5 in Jincheng,it is necessary to strengthen the control of vehicle and coal combustion in autumn and winter to reduce the emissions of the primary pollutants(SO2 and NO2).