| In recent years,with the rapid development of industry and agriculture,stable growth of national economy and the promotion of urbanization,people's living standards have gradually improved,however,the following is the increasingly frequent air pollution events represented by haze,which seriously affect people's normal life and production.Jilin is an important old industrial base and chemical city in the northeast of China with the energy structure dominated by coal,in recent years,with the rapid development of economy,the scale of the city continues to expand,the number of people,industrial enterprises and motor vehicles is increasing,and affected by the geographical location,Jilin city is surrounded by mountains,air pollution is increasing and difficult to spread,resulting in serious air pollution problems.Therefore,it has important theoretical and practical significance for Jilin region sustainable development to make clear the temporal and spatial distribution characteristics of main air pollutants,to carry out the cause analysis of heavy pollution period,and to explore the influencing factors of air quality.This paper is based on the global assimilation system data(GDAS)provided by the National Environmental Prediction Center of the United States(NCEP),meteorological data,ground monitoring data of ambient air quality and other multi-source data,combined with the HYSPLIT backward trajectory meteorological model,the temporal variation trend and spatial distribution characteristics of the concentrations of PM10,PM2.5,O3,CO,NO2,SO2 and other major air pollutants in Jilin area during the period from January 1,2017 to December 31,2017 are analyzed.On this basis,the paper analyzes the pollution formation mechanism of a typical pollution event,the temporal and spatial variation characteristics of pollutants,and the influencing factors of air quality in Jilin City,from a scientific point of view,it provides theoretical support for the relevant departments to control air pollution and formulate air pollution control measures.The main conclusions of this paper are as follows:(1)The monthly variation and seasonal distribution of PM2.5,PM10,O3 were analyzed.In spring,PM10 pollution and O3 pollution are mainly seen;In summer,only appearing O3 pollution;In autumn and winter,the mass concentration of particulate matter increases sharply,and O3 concentration is relatively low.According to the monthly change curve of the ratio of PM2.5 to PM10,the impact of sand dust weather on PM10 in spring is greater than that of PM2.5;the impact of heating period in winter on PM2.5 is greater than that of PM10.(2)The time-by-time characteristics of the main influencing factors in each season were analyzed.In spring,the pollution of particulate matter from evening to night is more serious than that in the day,the O3 concentration is higher in the day and lower in the night;In summer,only appearing O3 pollution;In autumn,the maximum mass concentration of particulate matter appear around 22:00,the pollution at night is significantly higher than that in the day,the mass concentration of O3 is obviously lower than that in summer;In winter,there are two obvious small wave peaks in the hourly variation of particle mass concentration,the first is near 9:00,the second is near 20:00.(3)Compare and analyze the daily average concentration of pollutants on working days,weekends and the whole year in 2017,the average concentration of particulate matter on weekends was significantly higher than that on weekdays and the whole year,showing a significant "weekend effect" phenomenon.Compare and analyze the daily average concentration of pollutants in 2017 holidays and the whole year,during the legal holidays,there is a "holiday effect" phenomenon that the concentration of pollutants in holidays is higher than the average daily concentration of the whole year.During the Spring Festival,the phenomenon of "holiday effect" is more serious.(4)The HYSPLIT backward trajectory analysis model is used to analyze the transport path of foreign pollutants and determine the potential source distribution of pollutants.The distribution characteristics of air pollutants are obvious in Jilin City.PM2.5,PM10 and O3 all have obvious main channel directions.The results of potential source analysis show that the main potential source areas of PM2.5 in Jilin City are located in the north of Heilongjiang Province,around Jilin City and near Shanghai,the main potential source areas of PM10 in Jilin City are located in the east of Inner Mongolia and the southeast of Russia,and the main potential source areas of O3 in Jilin City are located in the areas near Jilin City,ocean and Shandong Peninsula.(5)A typical heavy pollution event from November 1 to November 3,2017 is analyzed.The combined pollution of coal,dust and straw burning in the open air is the main cause of this typical heavy pollution event,and adverse meteorological conditions such as wind speed,wind direction and relative humidity also provide the basis for the formation of this pollution.The pollutants in the area near Jilin can be transported to Jilin in a long distance.The air masses from Russia,Heilongjiang Province and Changchun,Siping and other places in Jilin province carry serious pollution,which promotes the formation of this heavy pollution phenomenon.(6)To explore the influencing factors of urban air quality.In the analysis of meteorological factors,according to the Pearson correlation coefficients of PM2.5,PM 10 and 03 with temperature,relative humidity and wind speed,the correlation analysis was carried out.In addition,geographical location,industrial layout,vehicle exhaust,coal-fired heating,straw burning and other factors are also the main factors affecting the air quality of Jilin City. |
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