Study On The Spatio-temporal Characteristics And Potential Sources Of Air Pollutants In 29 Cities In Shaanxi-Gansu-Ningxia

In recent years,with the promotion of China's"One Belt And One Road"and"western development"strategic deployment,the regional ambient air quality is increasingly concerned by people,and various air pollutants are closely related to the production and life of human beings.Using historical observation data to explore the fluctuation of air pollutants in a short period of time is helpful to formulate air pollution prevention and control measures,and is of great significance to the coordinated development of regional environmental economy.Based on2016-2018 to several area 29 level cities air quality index?AQI?and six standard of air pollutants(PM_2.5 and PM₁₀,CO,SO₂,NO₂ and O₃)monitoring and real-time data effectively.Using general kriging difference method,backward trajectory clustering analysis method,concentration weight trajectory analysis method and Pearson correlation analysis method,mainly from the overall characteristics of air quality,air quality,space and time distribution,particle contaminant transport ways and characteristics of potential source area,air quality influence factors on the concrete analysis.From 2016 to 2018,the air quality in shaanxi-gansu-ningxia region was generally good,but some areas were seriously polluted,especially some cities in shaanxi province.In the past three years,the main pollutants were PM_2.5,PM₁₀ and O₃,which accounted for a large proportion of the total pollution days.Among the29 cities most affected by PM_2.5 pollution are ankang,longnan and xianyang,the major cities affected by PM₁₀ are jiuquan,baiyin and wuzhong.As a major pollutant,O₃ mainly affects zhangye,gannan Tibetan autonomous prefecture and yulin in shaanxi,gansu and ningxia.The air quality index?AQI?and the 6 standard air pollutant mass concentrations have obvious spatial and temporal distribution differences.In terms of time,the concentrations of PM_2.5,gaseous pollutants NO₂,SO₂ and CO in shaanxi-gansu-ningxia area have been on the decline in the past three years,while the concentrations of PM₁₀ and O₃ have been on the rise.The seasonal average concentrations of PM₁₀,O₃ and PM₁₀ are high,?(PM_2.5)and?(PM₁₀)both exceed the national level 2 standard concentration limits,which indicates that compared with other air pollutants,PM_2.5 and PM₁₀ have a more significant impact on the air pollution in shaanxi-kansu-ningxia region.Except for O₃,the concentration of 5pollutants was the highest in winter,followed by spring and autumn,and the lowest in summer.Spatially,the air quality index is higher in the guanzhong plain of shaanxi province,the northern plain of ningxia hui autonomous region and the jiuquan region of gansu province,while the air quality index is lower and the air quality is better in the southwest of Shaanxi-Gansu-Ningxia region.At the same time,AQI,?(PM_2.5)and?(PM₁₀)are clustered and distributed in space as a whole.The transport routes and potential sources of particulate pollution in Jiuquan city,Lanzhou city,Shizuishan city and xi'an city vary from season to season.Jiuquan city and Lanzhou city on the whole to the northwest airstream,moving speed block,long transport distance.The main transport channel for particulate matter in Shizuishan city is from the east of xinjiang province,and it passes through the northwest of Gansu province.The xi'an flow moves the fastest and has the longest transport distance in spring,which is from the central Henan province.In winter and spring,the average mass concentrations of PM_2.5 and PM₁₀ in most tracks of four typical cities exceeded the standard.In summer and autumn,the average mass concentrations of all kinds of track particles were relatively low,and only some tracks exceeded the standard.In autumn,the average concentrations of PM_2.5 and PM₁₀ and the average concentrations of the tracks exceeded the standard were higher than those in summer.Influence of jiuquan city high concentrations of PM₁₀ and PM_2.5 potential source area mainly concentrated in the northwest of eastern Xinjiang,Gansu,Inner Mongolia and the badain jaran desert in northwestern Qinghai province,Lanzhou PM₁₀ and PM_2.5 concentrations of potential source area are mainly distributed in the badain jaran desert area in Inner Mongolia and southern gansu province,north of sichuan province and shaanxi province in the southwest of shizuishan PM₁₀ and PM_2.5 concentrations potential source rock distribution is relatively concentrated,mainly from the badain jaran desert and tengger desert in Inner Mongolia and northern ningxia,The potential sources of high concentrations of PM₁₀ and PM_2.5 in xi'an are mainly from central henan province,northwest hubei province and northern sichuan province,and the contributions in spring and winter are significantly higher than those in summer and autumn.Average precipitation,average temperature,average pressure,relative humidity and topography are closely related to the air quality index?AQI?.Proper rainwater has the effect of scouring and diluting the pollutants in the air,so the higher the average precipitation,the smaller the AQI value and the better the air quality.When the air temperature of the ground is higher than that of the upper atmosphere,the atmosphere is unstable,and the air pressure near the ground decreases.Under the action of thermal convection,pollutants are diffused upward,thereby reducing the concentration of pollutants on the ground.The spatial difference of topographic fluctuation degree also indirectly affects the spatial change of air quality.The areas with serious air pollution are mainly concentrated in the plain,basin and plateau.Due to the large topographic fluctuation degree,the terrain is conducive to the diffusion of airflow,so the air pollution degree is relatively light.Municipal district population,industrial output,GDP and industrial companies for air quality index?AQI?also has a significant impact,they present significant positive correlation with AQI,among them,the increase of industrial companies increased industrial waste emissions,increased the total amount of air pollution,is one of the main air to several area variation of social and economic factors.