Air Primary Pollutant During 2015-2019 Over 19 Chinese Urban Agglomerations: Spatiotemporal Distribution And Emission Source Impacts

The "comparative attitude" of urban agglomerations (UAs) involves multidimensional perspectives such as infrastructure, ecological protection, and air pollution. Based on monitoring station data, comparative studies of multispatial, multitime scale and multiemission pollution sources of air quality on 19 urban agglomerations (UAs) during the 13th Five-Year Plan period in China were explored by mathematical statistics. The comparison results are all visualized and show that clean air days gradually increased and occurred mainly in summer, especially in South and Southwest China. PM 2.5 , PM 10 and O 3 were still the main primary pollutants. PM 2.5 is mainly concentrated in December, January and February, and PM 10 is mainly concentrated in October-November and March-April. The O 3 pollution in the Pearl River Delta and Beibu Gulf UA located in the south is mainly concentrated from August to November, which is different from others from May to September. Second, the hourly O 3 concentration rates were significantly higher than the particulate matter (PM) pollution rates from 2015 to 2019. Diurnal trends in O 3 concentration in all directions also showed a single peak, with the largest increments that appeared between 13:00 and 16:00, while the spatial distribution of this peak was significantly regional, earlier in the east but later in the west. Third, this analysis indicated that the annual average air quality index (AQI) showed a gradually decreasing trend outward, taking the Central Plains UA as the center. Furthermore, the total amount of PM 2.5 pollution caused by anthropogenic sources is approximately 2.5 times that of PM 10, and industries are the main sources of PM 2.5 , PM 10 and VOCs (volatile organic compounds). VOCs and NO X increased in half of the urban agglomerations, which are the reasons for the increase in ozone pollution. The outcomes of this study will provide targeted insights on pollution prevention in urban agglomerations in the future.