Characteristics And Sources Of Particulate Matter Pollution In Typical Industrial Cities In North China

High concentration of particulate matter causes reduced visibility in the atmosphere.High concentrations of fine particulate matter have significant impacts on air quality,public health,radiative forcing and climate change.In this thesis,Handan and Yuncheng in North China were selected as the research objects to explore the change characteristics of chemical components of atmospheric particles under different pollution levels,and to obtain the physical and chemical characteristics and sources of fine particles in North China combined with meteorological factors.The main contents of the study are as follows:In the winter of 2021,offline collection of atmospheric particulate matter samples(PM₁ and PM_2.5)was conducted in Handan City and Yuncheng City.During the observation period,the average mass concentrations of PM₁ and PM_2.5 in Handan City were 117.03±38.16μg/m³ and 133.07±38.37μg/m³;The average mass concentration of PM₁ and PM_2.5 in Yuncheng City were 108.47±44.95μg/m³ and 126.24±45.99μg/m³,respectively.Atmospheric particulate matter mass concentration changed little,follow the change rule of high night and day low.In general,the concentration of particulate matter increases with the increase of particle size,and the change of particle mass concentration in the two places is consistent in time series.The data analysis results show that with the increase of particle size,the mass concentration of chemical components of atmospheric particles also increases,among which the growth rate of NO₃^-and SO₄^2-is the most significant.NO₃^-,NH₄⁺,SO₄^2-and Cl^-are the main four kinds of WSIIs,and they are more easily enriched in particles with particle size less than 1μm,indicating that SNA(NO₃^-,NH₄⁺,SO₄^2-)contributes more to the concentration of ultrafine particles.Organic Carbon（OC）/Elemental Carbon（EC）analysis shows that the sources of urban carbon components in North China are complex,mainly concentrated in mobile sources,coal sources and biomass burning sources.The concentration analysis of inorganic elements shows that inorganic elements are more likely to be enriched in particles with larger particle size.Cl,S,Ca,K and Fe are the five main inorganic elements in atmospheric particulate matter in Handan City and Yuncheng City.The source analysis of PMF（Positive Matrix Factorization）draws the following conclusions:Handan City and Yuncheng City have the same source of particulate pollution,which can be divided into five categories:industrial source,combustion source,traffic source,dust source and secondary conversion source;Combustion source and secondary conversion source are the main sources of pollution,contributing more than60%to the mass concentration of particulate matter in both places.The potential source analysis results show that Handan city is greatly affected by the northeast and northwest air flow track transmission,and its atmospheric environment quality is mainly affected by the medium-long air flow track transmission.The areas with high contribution of particulate matter concentration in Yuncheng City are mainly concentrated in the southern part of Shaanxi Province,central part of Henan Province and southern part of Hebei Province.In the heavy pollution process in winter,NO₃^-,NH₄⁺and SO₄^2-were the main components of water-soluble ions,and SNA accounted for the largest proportion of water-soluble ions in heavy pollution days.SO₄^2-and NO₃^-in each stage mainly came from the secondary transformation of SO₂and NO₂,and the secondary transformation was the strongest in heavily polluted days.The clean day OC mainly comes from the direct emission of combustion sources,while the combined correlation analysis of polluted and heavily polluted days shows that the contribution of indirect sources（secondary conversion）to OC increases significantly.