Study On The Regional Demarcation For PM_2.5 Joint Prevention And Control Based On Air Resource Endowment

Under the background of increasing regional and complex air pollution characteristics of China,the implementation of the Joint Prevention and Control of Atmospheric Pollution(JPCAP)is an effective way to improve regional air quality,and the accurate understanding and scientific quantification of the regional scope is the primary question to be answered for JPCAP.Nevertheless,there are still no mature theories and technical methods for how to scientifically define the regional scope till now.If the scope for implementing JPCAP is too small,the effectiveness of pollution control will be reduced,and if the scope is too large,it may increase the difficulty of inter-regional coordination.Based on a multidisciplinary fusion method of air pollution meteorology,numerical simulation technology and complex network theory,etc.,this study aims to develop a technical method that can efficiently and accurately identify the regions with highly similar or convergent characteristics of pollution and air basins,so as to provide theoretical and technical supports for regional scope optimization and pollution control decisions of the JPCAP.In this study,PM_2.5 was selected as the indicator representing the air pollution characteristics in China.Hourly PM_2.5 monitoring data from 2013 to 2017 were collected.The arithmetic average method and percentile method were used for contrastively analyzing the spatiotemporal distribution characteristics of PM_2.5 in Chinese cities.The results show that air quality of cities has shown a significant improvement trend,and the cumulative annual average annual PM_2.5 concentrations in the three major regions of China have declined by more than 30%since the implementation of the Air Pollution Prevention Action Plan.PM_2.5 pollution in China still presents strong regional characteristics.The most polluted regions for PM_2.5 are mainly distributed in the Beijing-Tianjin-Hebei regions and their surrounding areas;the distribution pattern of the pollution degree is centered in the southern area of Hebei and gradually alleviated outwardly.From the perspective of time changes,the overall PM_2.5 concentration across China shows seasonal changes of high in winter and low in summer,and monthly distribution characteristics of U-shape.In view of the complexity of atmospheric flow,the Air Resource Endowment(ARE)and ARE indices were proposed and constructed as comprehensive indicators representing the distinct spatiotemporal differentiation characteristics of air basins.On this basis,ARE and its sub-indices calculation modules suitable for different spatiotemporal scales have been developed and applied for analyzing the spatiotemporal distribution characteristics of ARE in China.The results indicate that the ARE indices'calculation model constructed in this study could better represent the correlation between meteorological pollution conditions and PM_2.5 concentration.The correlation coefficient between them was as high as-0.632(P<0.01).The ARE distribution has significant spatiotemporal differences all over China.As for the spatial distribution of ARE,about 15%of Chinese land areas were high-value areas of ARE indices.The regions with higher and lower ARE indices account for 20%and25%,respectively,while the proportion of the regions with the lowest ARE indices was about 40%.From the point of view of time distribution,the monthly average changes of ARE and its sub-indices in China and the three key regions showed an M-shape change as a whole,and the M-shape change characteristics in Beijing-Tianjin-Hebei were the most significant.Considering all above,the network correlation model of the ARE and the PM_2.5were constructed,and the regional network correlation model was integrated.Through the analysis of the topological characteristics of complex networks,the critical threshold W corresponding to the construction of the optimal community structure in complex network was determined.Finally,the network correlation model developed was applied to the regional delineation of China's provincial-level JPCAP from the aspects of the similarity of air basins and the convergence of pollution characteristics,and the feasibility and validity of the ARE index for the delineation of the JPCAP areas were compared and analyzed.The results showed that there were nine regions with similar air basins as well as pollution characteristics in China.Among them,the five regions,namely Beijing-Tianjin-Hebei,Beijing-Tianjin-Hebei and their surrounding areas,Yangtze River Delta,East China,and three provinces in Northeast China,were all the overlap regions of the ARE network and the PM_2.5network;while the other four regions,namely Chengdu-Chongqing,Northwest China,Southwest China,and South China,have significant regional characteristics of the ARE network characteristics.