Temporal And Spatial Evolution Of The Relationship Between PM_2.5 Concentration And Urbanization In The Yangtze River Delta Urban Agglomeration From 2001 To 2016

The problem of PM_2.5 pollution hasbeen paid more and more attention by the government,academics and the public.In the past decade or so,China has experienced rapid urbanization,but the problem of PM_2.5 pollution and the public health burden associated with it are particularly serious.This paper selects the Yangtze River Delta urban agglomeration as the research area,the environmental Kuznets Curve（EKC）hypothesis of the Yangtze River Delta urban agglomeration is proposed.Based on the2001-2016 remote sensing inversion of PM_2.5 data and urbanization data（premium GDP,urbanization rate,new construction land,night lighting,industrial soot）.Based on the bivariate spatial correlation analysis and the construction of the spatial Dubin model,The temporal and spatial variation characteristics of PM_2.5 concentration and the spatial and temporal changes of urbanization are analyzed.Characteristics,explored the relationship between PM_2.5 and urbanization,and examined the relationship between possible PM_2.5 and urbanization EKC.Research indicates:（1）From 2001 to 2016,the concentration of PM_2.5 in Nanjing,Hangzhou and Hefei,the central cities of the Yangtze River Delta urban agglomeration,showed an upward trend.Refer to the"AQI Technical Regulations（Trial）"to re-divide the air quality level by the annual average value of PM_2.5 concentration.The average annual limit of PM_2.5concentration in 26 cities in the Yangtze River Delta urban agglomeration reaches"excellent"or"good"The number of cities in the grade dropped from 65%in 2001 to19%in 2016,and PM_2.5 pollution has intensified.（2）Using the Mann-Kendall test,the trend of urbanization and PM_2.5 concentration fluctuating between 2001 and 2016 was obtained.Through the spatial correlation analysis,it is concluded that the concentration of PM_2.5 in the Nanjing metropolitan area and the Suzhou-Cities metropolitan area in Jiangsu Province has a“high-high”aggregation relationship with urbanization.The urbanization of Ningbo city circle and the concentration of PM_2.5 in Zhejiang Province are“low-low"aggregation relationship";the urbanization of Hefei metropolitan area in Anhui Province has a"low-high"aggregation relationship with PM_2.5 concentration;the urbanization of Shanghai and other places has a"high-low"aggregation relationship with PM_2.5 concentration growth trend.（3）The PM_2.5 concentration and its growth trend in the 26 cities of the Yangtze River Delta urban agglomeration have obvious regional differences in space.The level of urbanization,pollution sources and emission intensity are different,and the differences in environmental regulation,technological innovation,pollution control and other capabilities are the main reasons for this difference.In addition,polluting companies show signs of shifting from developed coastal areas to the interior,which will have a new impact on PM_2.5 concentration patterns and trends.（4）The concentration of PM_2.5 showed a trend of“U”type change with the development of urbanization.By analyzing the temporal and spatial dynamics of PM_2.5concentration in the region and the correlation between urbanization and PM_2.5concentration and its changing trend,it is concluded that PM_2.5 concentration is positively correlated with the initial stage of urbanization,and negatively correlated with the late urbanization.The hypothesis of this study was verified,that is,the relationship between PM_2.5 concentration in the Yangtze River Delta urban agglomeration and urbanization has relationship of EKC.The results of the study interpret the relationship between PM_2.5 concentration and urbanization,and provide reference for the development of PM_2.5.5 pollution control and governance policies from the perspective of urbanization.