| Air pollution in the border area between Jiangsu,Anhui,Shandong and Henan has become increasingly serious,so this area has become a new key area that needs emission control.Based on the air quality data and meteorological data of 16 cities in the border area between Jiangsu,Anhui,Shandong and Henan from 2015 to 2019,this study analyzed the status of air quality,the characteristics of the changes in air pollutants,and the influences of different meteorological factors on the daily and interannual variations of major air pollutants in winter and summer.The results show that:（1）Air quality at the border of Jiangsu,Anhui,Shandong and Henan from 2015 to 2019showed a spatial pattern of relatively good air quality in the southeast and relatively poor air quality in the northwest.Air pollutants showed large seasonal and monthly variations.O3concentrations were the highest in summer,followed by spring,autumn,and winter,with a monthly variation characteristics of"rising first and then falling".Other air pollutants had opposite seasonal and monthly variations.In the border area of our concern,concentrations of PM2.5 in winter decreased year by year,while concentrations of O3 in summer had a trend of increasing.Our analyses indicated that winter and summer were the key periods for regional air pollution prevention and control.（2）During the studied time period,the regional air pollution was affected by both transport and local accumulation.The air masses that caused high concentrations of PM2.5 were mainly accumulated in local areas and were influenced by transport by northwesterlies or northerlies,while the air masses that caused high concentrations of O3 were mainly transported from the surrounding areas together with the accumulation in local areas.In addition,the regional variations of pollutants were different in winter and summer.（3）T2M had a positive correlation with PM2.5.T2M was the most important meteorological driving factor affecting the daily variations of PM2.5 in winter in the border area between Jiangsu,Anhui,Shandong and Henan,with a relative contribution 71.4%.The second and third most important meteorological factors were PBLH and V850,with relative contributions of 14.7%and 8.9%respectively,which were negatively correlated with PM2.5.The two most important meteorological factors affecting the daily variations of MDA8＿O3（the maximum daily average 8-hour O3）in summer were RH1000 and RH500,with their relative contributions of 60.9%and 16.3%,respectively.The key driving factors were followed by wind850,whose relative contribution was 9.8%.They were all negatively correlated with the concentrations of O3.The two most important meteorological factors influencing the interannual variations in PM2.5 in winter and MDA8＿O3 in summer were both T2M and RH1000.With respect to interannual variations in PM2.5 in winter,their relative contributions were 40.8%and 32.8%,both of which were positively correlated with concentrations.The relative contribution and correlation of the interannual variations in MDA8＿O3 in summer were42.1%and positive,and 38.7%and negative,respectively.The changes of meteorological factors in winter during the studied period resulted in the reduction of PM2.5(-0.84μg m-3 yr-1),which had a smaller impact on the decreases in PM2.5 compared to the role of the changes in anthropogenic emissions(-1.91μg m-3 yr-1).The changes of meteorological conditions in summer led to an increasing trend of O3(5.97μg m-3 yr-1),which together with the role of changes in anthropogenic emissions(1.49μg m-3 yr-1)jointly led to higher regional O3 concentrations. |
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