Analysis Of Spatio-temporal Distribution Characteristics Of Atmospheric Pollutants And Their Correlation With Meteorological Factors In Typical Areas Of Beijing

Recently,air quality in Beijing has greatly improved as a result of a series of measures that enacted by the State Council and the Beijing Municipal Government to control air pollution.However,some pollutants are not yet compliance with the air quality standard,and heavy pollution events still occur frequently.Fundenmental knowledge of the temporal and spatial distribution characteristics of air pollution and its relationship to meteorological factors in Beijing can provide a guideline for the development of air pollution control policies.Using the hourly data of major air pollutants(i.e.PM_2.5,PM₁₀,NO₂,SO₂,CO,O₃)in Changping District,Chaoyang District and Daxing District in Beijing from 2018 to 2020,respectively,this study analyzed the temporal variation of air pollutants,and subsequently investigated the influence of atmospheric pollutants and meteorological factors on selected pollutants(PM_2.5 and O₃)by coupling air pollution data with meteorological observations.Annual average concentrations of PM_2.5,PM₁₀,NO₂,SO₂ and CO decrease significantly from 2018 to 2020 in Changping District,Chaoyang District,and Daxing District,respectively,and SO₂ and CO in the districts have met the national secondary standard.The annual average concentration of O₃ drops slightly and is still incompliance with the limit.Air quality in Changping District is generally better than other two districts.Monthly concentrations of air pollutant presented a marked seasonal pattern.O₃concentrations were high in summer but become low in winter,while the reverse trends were observed for other five pollutants.Hourly concentrations of air pollutant showed a significant diurnal feature.The peak time of the daily variation curves of PM_2.5,PM₁₀,NO₂,SO₂ and CO is consistent with the morning and evening traffic peaks,while the peak of O₃appeared in the midnoon with the strongest photon flux due to photochemcial reactions.The correlation coefficient matrix shows a positive relationship for pollutants investigated except for O₃,O₃ and NO₂ are negatively correlated as expected,since the depletion of NO₂ leads to the formation of oxygen radical and,thus,O₃.According to the univariate linear regression model,there was no significant relationship between PM_2.5/O₃ concentrations and most of factors in the study areas.According to the generalized additive model,CO,NO₂,PM₁₀,O₃,relative humidity,temperature,and air pressure have significant effects on PM_2.5 concentrations.PM_2.5 production will be promoted under the conditions of"low temperature+high humidity+abnormal air pressure+high CO/NO₂/PM₁₀/O₃ concentration".O₃ varies with NO₂,PM_2.5,sunshine hours,temperature,and relative humidity.High O₃ concentrations are likely appeared under conditions of high temperature,long sunshine periods,and low relative humidity.Our results suggested that,to achieve scientific governance and precise efforts,stakeholders should fully consider the temporal and spatial distributions of atmospheric pollutants and their correlations with meteorological factors for the development of region-time-specific air pollution control and manage policies.