Spatial-temporal Evolution Of Air Quality And Its Socio-economic Driving Forces In The Yangtze River Delta Urban Agglomeration

With the celerity development of urbanization and industrialization in Yangtze River Delta,the air quality problem is prominent,leading to frequent haze weather,which seriously affecting the normal production and life of residents.Therefore,the great improvement on resident’s living standards,their demand for clean air are more urgent.With the proposal of“green economy”and“cyclic economy”,and effective improving the city air quality has become a top priority.Based on this,this paper selected the data of air quality index（AQI）,three pollutant concentrations(PM₁₀,NO₂,SO₂)and economic driving factors of 10 major cities in the Yangtze River Delta Urban Agglomeration（YRDUA）from 2016 to 2020.The spatial-temporal evolution characteristics of AQI and pollutants,their correlation are studied by multidisciplinary approach.Furthermore,the environmental Kuznets curve（EKC）model of AQI and economic factors is constructed to analyze the driving forces affecting of air quality,the correlation is analyzed by using grey correlation analysis method.the effective suggestions to decision-making were put forward on this basis.the mainly conclusions of this article are as follows:Firstly,spatial interpolation method,Spearman correlation coefficient and spatial descriptive statistics are used to analyze the annual,seasonal,monthly and spatial evolution characteristics of AQI,PM₁₀,NO₂and SO₂pollutant concentrations in the study area.The results shown that the average value are between 50 and 100 in recent 5 years of the study area.Zhoushan city has good air quality（88.71%of the days with excellent）,and Hefei city has the most serious air pollution（58.80%of the days with excellent）.The monthly AQI and the mean value of pollutants in each city showed“U”type,all of them generally reached the lowest values in July and August,ranged are from 4.32μg/m³to 53.92μg/m³,and reached the peak value from January to March and December,presenting a variation characteristic of“high in spring and winter,low in summer and autumn”.Meanwhile,the air pollution is higher in northwest inland area,lower in eastern coastal area and higher in central area,air pollution in inland areas is more serious than that in coastal areas.It is confirmed that AQI is significantly correlated with the three pollutants,and the primary pollutant was PM₁₀in each city.Secondly,in order to overcome the effects of autocorrelation and heteroscedasticity,the EKC is used to establish an economic driving force model affecting air quality.This paper empirically studies the relationship between economic driving force and air quality in the study area of five years,and that calculates the inflection point of air quality change.The results show that the EKC of air quality in the study area is inverted“N”type but has not reached the theoretical inflection point,and there are driving factors affecting air quality.The regional GDP and secondary industry values have a negative impact on air quality improvement.However,the increase of population density and the rapid growth of vehicle ownership have slightly impact on air quality.Air pollution caused by excessive discharge of industrial waste gas is more serious.The expansion of urban per capita park green area can improve air quality.But the improvement effect is not significant.Then,the correlation between AQI,PM₁₀,NO₂and SO₂concentrations and socioeconomic driving forces is studied by using grey correlation analysis.The research show that population density,secondary industry value and industrial exhaust emissions are the most important factors affecting air quality,secondary industry value is the primary factor affecting the urban agglomeration.the per capita GDP,regional GDP,civil vehicle ownership and per capita park green area have weak impacts on air quality.Finally,the research results of spatial-temporal evolution characteristics and socioeconomicdriving factors of air quality in the YRDUA are summarized.In order to improve the air quality of YRDUA.They are summarized as follows:（1）The main task of air pollution control in the next stage is to prevent seasonal mutations in air pollution of the study area.（2）It is to analyze main economic driving factors affecting air quality in the study area,and the overall consideration should be highly encouraged.（3）We will create a new model of regional win-win governance,carry out joint regional“prevention and control”of air pollution,improve regional air quality,and strengthen coordinated green development.