Research On Spatio-Temporal Differentiation And Goverance Of PM_2.5 Pollution In Chengdu-Chongqing Urban Agglomeration

Since the 21st century,rapid improvement of industry and fast development of urbanization in China have consumed great amounts of fossil fuels,causing increasingly serious air pollution.Chengdu-Chongqing Urban agglomeration?CCUA?which is the fourth urban agglomeration officially approved by the State Council of China experienced gradually deteriorated regional air proplems,especially the PM_2.5 pollution.In 2017,CCUA's annual average of PM_2.5 concentration is 47.56?g/8)³,which is 1.11times of the average level of China and 1.36 times of China's target limit.At present,CCUA's air pollution is not restricted in single cities,as regional air quality is influenced by not only local pollution sources and also neighbouring areas.Therefore,deepening an insight into sptio-temporal differentiation and its influence factors is the basis of regional joint prevention and control for PM_2.5 pollution in CCUA.The article conducted the following aspects of research:Firstly,the article combined qualitative and quantitative methods such as literature analysis method,frequency statistics method,expert scoring method,correlation analysis and collinearity analysis to build the influence factors system for CCUA's PM_2.5 pollution including eight factors,among which include elevation,vegeration coverage,wind speed,precipitation,urbanization rate,motor vehicle ownership,rate of industrial added value and unit industry energy consumption.Secondly,annual,quarterly,monthly and daily distribution characteristics of PM_2.5 concentrations were explored,based on CCUA's hourly PM_2.5 concentration data from 2015 to 2017.Thirdly,global and local auto-correlations of CCUA's PM_2.5 concentrations were analyzed using Moran's I,General G and LISA index,and then the impacts of natural and socio-economic factors on PM_2.5 concentrations were studied based on spatial regression model.Fourly,after reviewing air pollution goverance policies and regulations,the article proposed some goverance measures for CCUA's PM_2.5 pollution.The article's results show as follow.Firstly,CCUA's PM_2.5 pollution presents significant spatio-temporal characteristics.In time dimension,CCUA's PM_2.5.5 pollution has generally improved year by year from 2015 to 2017;in addition,CCUA's PM_2.5problem shows obvious quarterly and monthly characteristics:CCUA's winter has the strictest PM_2.5 pollution,and the air quality in CCUA's spring and autumn have no obvious difference and are better than that in winter,and CCUA's summer is the least polluted season all year around.In spatial dimension,CCUA's PM_2.5 pollution have significant regional differences:there is more serious PM_2.5 pollution in southern CCUA including Luzhou,Yibin,Zigong and other cities.Secondly,CCUA's PM_2.5concentrations distribute with obvious spatial auto-correlation.At the global level,CCUA's PM_2.5 presents significant global auto-correlation and obvious spatial agglomeration.At the local level,PM_2.5 concentration in part CCUA also shows local spatial auto-correlation,and its agglomeration is more obvious than its dispersibility,especially southern CCUA's high-high agglomeration region and northern CCUA's low-low agglomeration region.Thirdly,spatial lag model?SLM?results demonstrate that urbanization rate,motor vehicle ownership,rate of industrial added value and precipitation have large impacts on regional PM_2.5 concentration.In detail,urbanization rate and precipitation have negative impacts on CCUA's PM_2.5 concentration,while motor vechile ownership and rate of industrial added value have positive impacts on PM_2.5 concentration.Fourthly,the article proposes to take specific action for heavily polluted weather,optimize industrial structure,control motor vechicles emission,implement joint prevention and control policies and build urban information technology management platform for air pollutants.