Source Apportionment Of PM_2.5 In Winter In Airport New City Of Xixian New Area

Airport New City,located in Xi Xian New Area to the north of Xi’an,is committed to giving full play to the advantages of air transportation hub and vigorously developing three economies relying on Xi’an Xianyang International Airport.In recent years,with the development and construction of the city,the problem of air pollution has become increasingly serious.In this paper,the air pollution characteristics of Airport New City in recent three years were researched by using the monitoring data and meteorological data from the national control station of Beidu Street Office.By carrying out PM_2.5observation in winter at the regular stations（Beidu Street Office and Cultural Management Station）of Airport New City,the composition of 19 elements,organic carbon,elemental carbon components and 8 water-soluble inorganic ions in samples were analyzed.Based on the PMF model,PM_2.5source analysis was carried out.On this basis,the control countermeasures of PM_2.5in Airport New City are put forward.The specific conclusions are as follows:（1）The air pollution situation of the Airport New City is still serious.From 2017 to2019,the number of excellent days in Airport New City increased year by year,accounting for 7.2%to 10.0%,while the"good"days decrease first and then increase,but the number of polluted days in 2019 increased compared with the past two years.Compared with 2018,the number of days of severe pollution or above in 2019 has increased from 17 days to 35 days,accounting for an increase of 5%.The situation of particulate matter pollution in 2019 is still not optimistic.Compared with 2018,the concentrations of PM₁₀and PM_2.5in January and February in 2019 show a large upward and downward trend,resulting in a continuous upward trend of particulate matter concentration.（2）During the observation period,the air quality of the Airport New City was slightly better than the average level of Xi’an.Among them,the number of good days is one day more than that in Xi’an,the number of light pollution days is two days more than that in Xi’an,but the number of moderate pollution days is three days less than that in Xi’an.The average concentration of PM_2.5was 74.3%±41μg/m³,which is close to the daily average concentration of PM_2.5class II standard of ambient air quality standard.（3）The observation and analysis of PM_2.5show that the correlation coefficient between OC and EC is high,which indicates that the combustion source of primary emission has a higher contribution to PM_2.5in Airport New City.The ratios of NO₃^-/SO₄^2-in Beidu Street office and Wenguan office were 1.57 and 1.62,which were all greater than 1,indicating that the mobile source of PM_2.5emitted more than the fixed sources.The contribution of inorganic aerosols generated by the secondary reaction to PM_2.5in winter is the highest and more than40%,which is mainly related to the higher levels of NO₃^-,SO₄^2-and SO₂and NO₂ in the atmosphere of the Airport New City.The contribution of coal-fired sources to Beidu and wenguansuo stations is as high as 24.6%and 20.9%respectively.The contribution of biomass combustion sources to the two stations is relatively consistent and close to 10%.The contribution of motor vehicle sources is quite different between Beidu and wenguansuo stations（7.1%）and the contribution of dust sources to Beidu and wenguansuo stations is 8.6%and 12.5%respectively.（4）Air pollution prevention and control practice of Airport New City with PM_2.5as the focus.According to the PM_2.5source analysis,it can be concluded that coal burning pollution,vehicle exhaust pollution,biomass combustion pollution emissions and dust pollution are the main sources of pollution particles,and targeted measures should be taken to control them.The pollution from coal burning is the second largest source of PM_2.5in Airport New City.Therefore,the management of coal burning should be strengthened,and the energy structure policy of"coal free zone"in the new district should be actively implemented,publicity should be strengthened,strict control should be carried out,and the pollution emission from coal burning in the district should be eliminated.Pollution caused by biomass combustion,and is widely used in the local rural branches,straw and other biomass burning kitchen,hotan markings over clean combustion of straw,so want to continue to strengthen the clean energy into the village door,at the same time promote the recycle of field straw technology,reduce field burning,completes the propaganda of environmental protection,reduce the pollution caused by biomass burning.Motor vehicle sources should reduce exhaust emissions through road testing,emission testing,improving the quality of oil,reducing vehicle idling and other ways,non-road mobile machinery must carry out smoke testing,qualified before entering the field to use.The dust source in the area is mainly from construction dust and road dust.For construction dust,"six hundred percent"dust suppression measures should be implemented on construction sites.Road dust should continue to strengthen wet cleaning of the road,strengthen repair and maintenance of damaged roads,muck cars are prohibited from loading,strictly do a good job in and out of the washing,reduce road dust pollution emissions.