Investigation of variations, causes and component distributions of PM2.5mass in China using a coupled regional climate-chemistry model

Özet

China experiences severe particulate matter (PM) pollution. Although a monitoring network for PM2.5(diameter < 2.5 μm) has been set up in more than 100 major Chinese cities, insufficient spatial coverage ofobservations limits the study of the temporal and spatial characteristics, influencing factors, and component ofPM2.5. In this study, we conducted a one year air quality simulation using a regional climate–chemistry modeland evaluated the simulation's performance based on in situ observations concerning meteorological elementsand PM2.5concentrations. The simulated results showed that, higher PM2.5concentrations appeared in northernChina and the Sichuan Basin, and the maximal value occurred in winter. Furthermore, Vertical PM2.5con-centrations presented a gradual decreasing trend from the surface, whereas in southern coastal cities the profileswere unsteady with a secondary peak in the lower layer. Meteorological conditions were conducive to bothpollutant diffusion and removal in summer, whereas stagnant conditions appeared in winter, characterized byhigh sea level pressure (SLP), the lowest planetary boundary layer height (PBLH), and 2-m temperature (T2). Inprovincial capital cities, PM2.5was positively correlated with residential emissions but negatively correlatedwith precipitation, 10-m wind speed, T2, PBLH, and industrial emissions. Finally, we utilized the simulationresults to investigate the component variations of PM2.5. Results indicated that primary PM2.5components hadsignificantly higher concentrations in northern China where residential heating is the major source of PM2.5emissions, whereas they had lower concentrations in southern China. Secondary components played a crucialrole in PM2.5mass in eastern China. This study provided a clear perspective of seasonal variations, horizontaland vertical distributions of PM2.5and its components and influence factors, which could be used in subsequentstudies to investigate the formation mechanism and emission sources of PM2.5