Spatial clustering and spillover pathways analysis of O, NO, and CO in eastern China during 2017-2021.

The eastern China presented the most serious O pollution and increasingly prominent regional characteristics. To understand the transport characteristics of O and its precursors and identify their potential relationships are of great guiding significance for interregional joint prevention and control. In this study, the annual and seasonal transport networks of O and its precursors (NO and CO) during 2017-2021 were constructed by applying the complex network method to air quality observations. And the key spatial clusters, the spillover paths and the potential links among pollutants were comprehensively analyzed based on the topological characteristic analysis of the established air pollutant transport networks. As the results showed, O pollution in the eastern China was affected by active regional transports of O and its precursors. Regional transports of O, NO, and CO were more prominent in autumn and showed high synchronization. The regional transport of precursors, especially NO, was an important cause of regional O pollution. Air pollutant transport characteristics varied with seasons and regions, which demonstrating the importance of regulating seasonal and regional differentiated joint prevention and control strategies, especially for NO. The results of this study can provide science-based guidance for the regional cooperative control of O pollution in the eastern China, and the application of complex networks can also provide a new methodological perspective for the study of air pollution transmission.