Spatial-temporal Patternchanges Of Air Quality Innortheast China And Specialperiod Characteristic Analysis

With the rapid development of economy and the increase of industrial and mining enterprises,a large amount of waste gas is discharged in the production process,thus resulting in the poor air quality.According to the atmospheric data of China’s Ecological Environment Bulletin in 2017,the air quality of more than 250cities among 338 prefecture-level cities and above in China exceeds the standard,accounting for 70%of all cities,while northeast China accounts for 11%.Northeast China is an important industrial development base in China,and the industrial production has discharged a large number of pollutants,which affected the regional air quality.Therefore,it is of great significance to discuss the spatial and temporal pattern change characteristics and special time features of air quality in northeast China.Therefore,based on the air quality status of 36 prefecture-level cities in Liaoning,Jilin and Heilongjiang in northeast China and 3 cities and 2 leagues in eastern Inner Mongolia autonomous region from 2015 to 2017,the spatial and temporal pattern changes and special period characteristics were analyzed in this paper,and the following conclusions were drawn:（1）Seeing from the perspective of time change,AQI,PM_2.5,PM₁₀,CO,O₃,SO₂and NO₂ showed a decreasing trend year by year during the three years,indicating that the air quality was improved;The concentration of PM_2.5,PM₁₀,CO,SO₂ and NO₂ was higher in winter and lower in summer,while the concentration of O₃ was the highest in summer and the lowest in winter.In addition,the concentration change in weekends was higher than other time periods.（2）Judging from the perspective of spatial changes,the overall air quality in northeast China presented an aggregated distribution.The high-pollution areas were mainly the first and second tier cities,while the low-pollution areas were the edge cities and the third and fourth tier cities.The barycenter of AQI,PM_2.5.5 and PM₁₀was in Siping City,and it rotated from southwest to northeast,which reflected that air pollutants in northeast China were more densely distributed from southwest to northeast.（3）There was a strong correlation between the change of pollutant concentration in special periods and the influencing factors.During the Spring Festival,around the Qingming Festival,and during the straw burning period,the change of pollutant concentration was correlated with the humanistic factors.The pollutants in blizzard period,rainstorm period,early rain period and early snow period were positively correlated with air temperature,air pressure and sunshine duration,thus aggravating air pollution,but they were negatively correlated with rainfall,relative humidity and wind speed.（4）Seeing from the impact of influencing factors on AQI,industrial smoke powder emissions,proportion of secondary industry,urban population density,total population,air temperature,air pressure and sunshine duration were positively correlated with AQI,while greening rate,spending on energy conservation and environmental protection,rainfall,relative humidity,wind speed of the urban built-up area were negatively correlated with AQI,thus making the air quality better.