Seasonal Variation And Source Analysis Of Inorganic And Polar Organic Components In Fine Particulate Matter In Jina

To understand the pollution characteristics and seasonal characteristics of atmospheric PM_2.5 in Jinan PM_2.5 samples were collected on the roof of the Science and Technology Building of Shandong Jianzhu University from 2020.12 to 2021.12.A total of 264 valid samples were collected.The average concentration of PM_2.5 during the sampling period was 41.7μg m^-3,with a seasonal pattern of winter>spring>autumn>summer throughout the year.In this study,8 kinds of water-soluble ions and 19 kinds of heavy metal elements in samples were determined and analyzed by ion chromatography and inductively coupled plasma mass spectrometry.A total of 24 polar organic compounds（including 17 secondary organic aerosol tracers（SOAT）and 7 sugars and sugar alcohols）were determined by gas chromatography-mass spectrometer.The average mass concentration of water-soluble ions in PM_2.5 was 38.8μg m^-3,accounting for 93.0%of the mass concentration of PM_2.5.The order of each ion from high to low was NO₃^->SO₄^2->NH₄⁺>Ca²⁺>Na⁺>Cl^->K⁺>Mg²⁺,and the seasonal variation followed winter>spring>autumn>spring.The concentration of heavy metal elements followed Fe>Al>Se>V>Zn>Mn>Ti>Sb>Tl>Pb>Cr>Cu>Ba>Ni>Li>Cd>Mo>Co>Ag,and the seasonal variation was as follows:spring>winter>summer>autumn.The heavy metal elements in Jinan was at a high level compared with other studies at home and abroad.The annual concentration of SOAT from natural sources was 37.1 ng m^-3,and the concentration of SOAT from natural sources had significant seasonal differences,with the highest concentration in summer and the lowest concentration in winter.The seasonal concentrations of DHOPA,which was considered as SOAT from anthropogenic source,were spring>winter>autumn>summer from high to low.The annual concentration of sugar and sugar alcohols was 266.5 ng m^-3.From the aspect of seasonal variation,the trends of sugars and sugar alcohols were higher in spring and summer than in autumn and winter.According to the measured results of chemical compositions in PM_2.5,positive matrix factorization method was then applied to analyze the specific pollution sources and contribution rates of PM_2.5 in Jinan.The identified seven sources including industrial sources,mobile sources,secondary conversion of inorganic ions,biomass combustion,secondary generation of organic aerosol,plants emission,and crust source.The three sources with the largest contribution rate were secondary conversion of inorganic ions,biomass combustion and crustal sources.Prevention and control of the secondary conversion of SO₂ and NO_x emission sources and reduction of the use of biomass fuels would effectively decrease the PM_2.5 pollution degree in Jinan.This study provided a basis data for exploring the chemical process of PM_2.5 in the atmosphere,and has reference value for the prevention and control of atmospheric PM_2.5 pollution in Jinan and even the surrounding areas like Beijing-Tianjin-Hebei.