[Modeling Studies of Source Contributions to PM_2.5 in Chengdu, China]

This study establishes eight emission scenarios in the air pollutant emissions inventory of Chengdu City, China. We use the Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) models and a "zero-out" approach to investigate contributions of air pollution transport and sources to aerosol fine particulate matter (PM_2.5) pollution in Chengdu City during January, April, July, and October 2015. The results showed that PM_2.5 pollution in Chengdu City was serious during these months and reached >130 μg·m^-3 in January. Highest concentrations were measured in the city center. PM_2.5 pollution in Chengdu and the surrounding cities was found to exhibit regional characteristics. Since the air mass was stable during the monitoring periods, the interregional transmission capability of air pollution was poor, and thus local sources were the main contributors (61% of the annual average concentration) to PM_2.5 pollution in Chengdu City. The contributions of local sources in April and July were higher than of those in January and October. We found that the main sources of PM_2.5 pollution in Chengdu City were automobile emission (29% of the total), dust (26%), and domestic pollution (24%), and should be further controlled in the future.