Research On The Temporal And Spatial Effects And Influencing Factors Of PM_2.5 Concentration In China's Eight Comprehensive Economic Zones

Taking the air pollution problem as the research object,the time-space distribution characteristics and influencing factors of PM_2.5 concentration in China’s eight comprehensive economic regions from 2004 to 2018 were analyzed,and the time of PM_2.5concentration change in the eight economic regions was explored through descriptive statistical analysis.Sequence characteristics,and the concentration comparison between regions at the same time,secondly based on the inverse distance square matrix to explore the characteristics of the spatial agglomeration effect of the economic zone,combined with the spatial panel measurement model to analyze the influence and direction of different socio-economic factors in the region on PM_2.5 concentration.First,the descriptive statistical analysis method explored the characteristics of PM_2.5concentration changes in the eight economic zones,and concluded that the percentage of cities with annual average PM_2.5.5 concentration values lower than 10ug/m³ from 2004 to2018 decreased from 3.22%to zero.The proportion of cities with an average annual PM_2.5concentration of 35.00ug/m³ and 50.00ug/m³ increased from 29.03%in 2004 to 54.84%in2018,an increase of nearly 1.89 times.The proportion of cities with a concentration of more than 50.00ug/m³ fell from 16.13%to 9.68%in 2018.The years in which the annual average PM_2.5.5 concentration is higher than the average annual limit of 35.00ug/m³ in China accounted for more than 50%of the total number of cities concentrated in 2006-2010.The number of extremely low-polluting cities with a concentration value lower than 10.00ug/m³decreased,and the number of cities higher than 35.00ug/m³ increased.The comparison of concentration change trends between regions shows that in any year from 2004 to 2018,the northern coastal economic zone has the highest concentration,followed by the eastern coastal economic zone,and the southern coastal economic zone has the lowest concentration.In 2012,the concentration values of the eight major economic regions all had a significant inflection point,and in 2016 there was a second low concentration point.In 2017,the concentration value increased again.Secondly,through spatial autocorrelation analysis to study the regional spatial agglomeration,the results show that the PM_2.5.5 pollution range in the northeast economic zone has an increasing trend;the hot spots in the eastern coastal area have significantly reduced,and the air quality tends to improve;the northern coastal area The hotspot areas with high values are mainly concentrated in Beijing and Tianjin,and the phenomenon has expanded toward Hebei;the concentration value of the entire southern coastal area has increased and the pollution area has increased;the pollution range in the northwestern region has an increasing trend;the concentration in the southwestern region is high The range of values has narrowed;the high-value range of hotspots in the middle reaches of the Yangtze River has been significantly reduced,mainly concentrated in northern Anhui;the high-value range of pollution in the south of the middle reaches of the Yellow River has expanded.Finally,a spatial panel measurement model is used to study the impact of socioeconomic indicators on PM_2.5.5 concentration.There are differences in the influence degree and direction of economic indicators on PM_2.5.5 concentration.In terms of degree of impact,population density has the highest impact on the northeast,southwest,and middle reaches of the Yangtze River,followed by the northern and eastern coastal areas.The proportion of the secondary industry has the highest impact on the northern and southern coastal areas.The proportion of employees in the tertiary industry has a greater influence on the PM_2.5.5 concentration in the eastern coast and the middle reaches of the Yellow River.In terms of impact direction,the proportion of coal consumption has a positive effect on the PM_2.5 concentration,and the increase in the proportion of natural gas consumption helps to suppress the PM_2.5 concentration in the middle reaches of the Yellow River and the middle reaches of the Yangtze River;Concentration has a positive promotion effect;population density has a negative effect on the northeast,eastern coastal,and northwestern regions;green space coverage can improve the atmospheric environment,and the environmental governance investment is only for the southern coastal economic zone PM_2.5The concentration has a positive effect.