Spatial And Temporal Distribution Characteristics Of Air Quality In Typical Cities Of China And Relevance Analysis Of The Influencing Factors

Objectives:Understand the air pollution in typical cities of China,explore the meteorological factors and economic and social development factors that mainly affect the urban air quality in China,identify the source of air pollution,and provide constructive opinions and targeted measures for air pollution prevention and control for national and local decision-making departments.Methods:Using EXCEL for data entry and collation,using SPSS22.0 software to perform Spearman rank correlation analysis of air quality index?AQI?,atmospheric pollutants and meteorological factors,using MATLAB software to carry out urban air quality index?AQI?and economic and social development factors by Gray correlation analysis.Results:1.In 2014-2018,the spatial and temporal distribution of air quality in eight cities?Harbin,Jinan,Taiyuan,Lanzhou,Hefei,Hangzhou,Fuzhou,Guiyang?was noteworthy.According to the annual distribution,the annual average value of AQI in each city was decreasing year by year or growing as“inverted N”.Except for Taiyuan,the air quality of each city has been improved to different entent.According to the seasonal distribution,for inland cities,the air quality was best in summer and autumn,second in spring and worst in winter.While for the coastal cities,best in summer,second in autumn and winter,and worst in spring.According to the monthly distribution,the monthly average value of AQI in each city was showed as“U”-shaped curve distribution.Air pollution was getting worse from north to south,from east to west,and from coast to inland.2.The air pollutions of PM_2.5,PM₁₀,SO₂ and CO in 8 cities was slightly improved,and the pollution situation of O₃ continued to increase.The pollution of NO₂ in some cities increased slightly.The seasonal distribution of PM_2.5,PM₁₀,SO₂,CO and NO₂ in each city showed“the best in summer and the worst in winter”and“U”curve for monthly distribution,while the seasonal distribution of O₃concentration was“best in winter and worst in summer”and the monthly distribution shaped like“inverted U”curve.Except for O₃,the concentration of atmospheric pollutants in northern cities of China was higher than that in southern cities.At present,PM₁₀0 and PM_2.5.5 are still the main pollutants of air quality in different cities,and the type of air pollution has changed from the traditional“soot type”to“composite type”.3.The influence of various factors on urban ambient air quality was relatively concentrated:a.Among meteorological factors,temperature and precipitation had the most significant impacts on cities'ambient air quality;b.Among the urban development factors,urban green coverage,urban population density and urbanization rate had the most significant impacts on cities'ambient air quality;c.Among the economic development factors,the added value of the primary industry and the secondary industry had the most significant impacts on cities'ambient air quality;d.In the energy consumption of industrial enterprises above designated size,the consumption of raw coal,diesel oil and electricity had the most significant impacts on cities'ambient air quality;e.Among urban pollutant emissions,the discharge of three types of domestic exhaust gas had the most significant impacts on cities'ambient air quality;f.Among the vehicle ownership,motorcycle ownership had the most significant impacts on the ambient air quality of cities;among the number of civilian vehicles,the number of trucks had the most significant impacts on cities'ambient air quality.Through comprehensive analysis,among the five types of economic and social development factors,urban population density and urban green coverage had the most significant impact on the ambient air quality of each city.Conclusions:1.The air pollution situation in China has been improved obviously.Although the characteristics of“compound”pollution were remarkable,particulate matter was still the main pollutant affecting air quality.2.The spatial and temporal characteristics of air quality in China were remarkable.Based on time dimension,the seasonal distribution of air quality was“the best in summer and the worst in winter”and“U”curve for monthly distribution.Based on the spatial dimension,the air quality showed“best in the south,worst in the north”,“best in the east and worst in the west”and“best in the inland areas and worst in the coastal areas”.3.The air quality of China was not only affected by temperature and precipitation of meteorological factors,but also influenced by those economic and social development factors,including urban development,population growth,industrial structure,energy consumption,domestic exhaust emissions,and threats from motorcycles and trucks.Urban population density and urban green coverage were the main factors affecting ambient air quality.