Pollution Characteristics And Source Analysis Of Fine Particulate Matter In Liaocheng City

From the"13th Five-Year Plan"to the blue sky defense war to carbon peak,carbon neutrality,China has launched a series of policies,regulations,standards,programs and prevention measures for atmospheric environmental pollution,but Liaocheng’s ambient air quality is still in the bottom 20 among 339 cities in the country,the air pollution problem is relatively severe,in order to explore its pollution mechanism and main sources of pollution to explore pollution prevention and control measures,this study analyzed air pollutants in Liaocheng City from 2019 to 2021,and collected PM_2.5 samples during the pollution process in December 2021.Combined with principal component analysis（PCA）,potential source analysis model（PSCF）,pollution concentration model（CWT）and other methods to explore the pollution characteristics and sources of PM_2.5and its components in Liaocheng City,the main conclusions are as follows:from 2019 to 2021,the concentration of PM_2.5 in Liaocheng City was high in winter and low in summer,with the highest value distributed in January,the highest hourly concentration was concentrated from 21 am to 1 am and 19 am to 0 am the next day,which was negatively correlated with wind speed,the positive correlation between CO and coal emission in winter was the strongest.Pollution process 1 has the highest WSIIs concentration in PM_2.5（34.65%）,pollution process 3 has the highest SNA fraction in WSIIs（89.00%）,but pollution process2 has higher SOR and NOR than other pollution processes.Due to the local environmental differences around the stations,NO₃^-,NH₄⁺,and SO₄^2-concentrations in customs stations are all higher than those in regional government stations,so targeted control schemes should be formulated according to the local environmental differences around different stations.NO₃^-,NH₄⁺,and SO₄^2-in WSIIs mainly exist in the form of（NH₄）₂SO₄ and NH₄NO₃.When RH is greater than 60%,SOR growth rate increases significantly and is greater than NOR growth rate.The proportion of OC concentration in PM_2.5（19.00%～25.56%）in different pollution processes is much higher than that of EC concentration（4.76%～7.10%）.The ratio of OC/EC and K⁺/EC indicates that the air pollution in Liaocheng is mainly caused by motor vehicle exhaust and combustion sources.The total concentration of 10 inorganic elements accounted for 14.30%～38.04%of PM_2.5,and Al,Fe,Ca,K,Mn and Zn were the main elements.The PCA analysis results of the three pollution processes are industrial sources,secondary sources,combustion sources,dust sources and traffic sources in order from the largest to the smallest contribution rate of pollution sources.At the same time,there are mixed sources of multiple pollution sources.It is necessary to continue to strengthen the pollutant emission control work of local industrial enterprises,strictly control the burning of loose coal,straw burning,garbage burning and other behaviors,establish a dynamic management list of construction sites,deepen the work of road dust control,strengthen the drainage and dredging of road vehicles,and demarcate the section of heavy transport vehicles prohibited.The backward trajectory clustering,PSCF and CWT simulation results show that the atmospheric PM_2.5in Liaocheng in winter is continuously affected by the northwest air mass,and the air mass transport in due west,southwest（Zhengzhou,Anyang,Hebi,Xinxiang,etc.）and northwest（central and southern cities of Hebei）through heavy industry and resource-based cities intensifies the atmospheric PM_2.5 pollution in Liaocheng.