| Gongzhuling City is an important city in the special planning of"one main,six double"industrial space layout,and the speed of economic and social development is accelerating.In order to alleviate the environmental problems caused by economic and social development and control the pollution of fine particles in Gongzhuling City,PM2.5 sampling is conducted in four seasons of the year in 2019,and the temporal and spatial variation characteristics of PM2.5 and the component characteristics of PM2.5 are analyzed in this article,and the impact of regional transmission on PM2.5 is analyzed using clustering and backward trajectory.Use PMF to analyze the source of PM2.5 in Gongzhuling City.The conclusions of this study are as follows:（1）Annual average PM2.5 mass concentration of Gongzhuling City in 2019 was36.7μg/m3.The PM2.5concentrations in winter is the highest showing 47.8μg/m3,and the PM2.5 concentrations in summer is the lowest showing 22.2μg/m3.The monthly average has the highest concentration in February,and the lowest concentration in August.In 2019,the peak hourly concentration of PM2.5 in Gongzhuling City was from10:00 to 14:00 and from 20:00 to 1:00 the next day,and the trough was from 16:00 to18:00.（2）The concentration of PM2.5 in Gongzhuling City showed a trend of gradually increasing from southwest to northeast,and the difference between the concentration in the northeast and the southwest was larger.The denser the population and traffic,the greater the concentration of PM2.5.（3）The analysis results of inorganic elements show that the concentrations of Ca,Si,Al,Fe,K,Mg,and Na are significantly greater in spring and summer than in autumn and winter;the concentrations of As and Pb are significantly greater in winter than in spring and summer;the remaining industrial elements such as,Hg,Se,Cu,Cr,V,etc.seasonal changes are relatively insignificant.（4）The analysis results of water-soluble ions in PM2.5 in Gongzhuling City show that in spring,summer and autumn,the highest proportions of water-soluble ions are Ca2+,Cl-,SO42-,and the three ions account for more than 75%of the total ion concentration.The concentrations are 1.4μg/m3,0.7μg/m3,0.7μg/m3 in spring,0.9μg/m3,0.9μg/m3,0.7μg/m3 in summer,0.8μg/m3,0.9μg/m3,0.6μg/in autumn.The PM2.5 in Gongzhuling City is generally alkaline,and fixed sources have a greater impact on PM2.5.（5）Gongzhuling City has higher concentrations of OC and EC in PM2.5 in autumn and winter,lower in spring and summer.Concentrations of OC and EC in PM2.5 in winter are 21.0μg/m3,2.8μg/m3,14.2μg/m3and 1.6μg/m3 in autumn,11.8μg/m3,1.4μg/m3 in summer,1.3μg/m3 in spring respectively.The results of OC/EC in Gongzhuling City indicate that the carbon component mainly comes from coal-burning emissions and biomass combustion.The correlation between OC and EC indicates that the OC and EC in spring and summer are strongly correlated and have similar primary emission sources;the correlation between OC and EC in autumn and winter is weak,indicating that the emission sources of OC and EC in autumn and winter are quite different,and there is a greater possibility of secondary sources of OC.（6）The major components of PM2.5 in the four seasons are MIN（mineral dust）and OM（organic matter）.In winter,due to the influence of heating and coal,OM accounts for the largest proportion.In spring,due to the influence of wind speed and other meteorological factors,MIN accounts for the largest proportion.（7）The enrichment factor results show that Fe,K,Na,Al,Mn and Si come from natural emission sources;As,Co,Cr,V and Mg are slightly enriched,and the sources are affected by both natural and anthropogenic emissions;Se,Cu,Mo,Ni,Pb,Zn,Ca,and Sn are moderately enriched and are mainly affected by anthropogenic emissions;the enrichment index of Hg and Cd is greater than 100,indicating that these elements are highly enriched and are greatly affected by anthropogenic emissions.（8）The source of PM2.5 in Gongzhuling City is mainly from coal-fired sources,with a contribution rate of 32.9%,followed by dust sources accounting for 22.7%,industrial sources accounting for 17.1%,biomass combustion sources accounting for10.6%,secondary aerosols accounting for 8.7%and motor vehicle source accounted for8.0%.（9）The backward trajectory results show that Gongzhuling City has the largest proportion of trajectories in the northwest in 2019,and the main impact is concentrated in autumn and winter.The air transport path in the northwest direction is the main path that affects the air quality during the heating period in Gongzhuling City;the air transport path in the east direction is the main path that affects the air quality during the non-heating period in Gongzhuling City. |
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