Hourly monitoring datasets of PM2.5 mass concentration and associated chemical compositions were used to investigate the variations in their mass concentrations before, during, and after the 7th Military World Games held in Wuhan. Furthermore, the source analysis was conducted through PMF combined with the backward trajectory and concentration weighted trajectory cluster analysis. The study revealed the variations in PM2.5 compositions and sources around the Wuhan Military Games period and their response to local and surrounding regional control measures. This can provide a reference for regional precise prevention and control of PM2.5. Under the influence of emission reduction measures, PM2.5 mass concentration during the control period [(31.3±12.0) μg·m-3] decreased by 14.7% compared with that before the control period, whereas the secondary components were obviously formed, in which sulfate, nitrate, and ammonium(SNA) increased by 25.6% in total. After the control period, owing to the decrease in humidity and the influence of the northwest air mass, the mass concentration of SNA decreased by 36.9%, whereas the mass concentration of mineral elements increased by 4.7 times. The source apportionment results indicated that there was no significant difference between the vehicle emissions before and after the control(P<0.05). Compared with that in the non-control period, the contributions of industrial emission and coal burning decreased by 68.1% and 43.7%, respectively, whereas the contribution of secondary inorganic aerosol increased by 89.5%. With the lack of large-scale control of vehicle emissions, the mass concentrations of NO3- and NOx increased by 6.13 μg·m-3 and 3.56 μg·m-3, respectively. The vehicle emissions peaked at 21:00 [(10.9±3.67) μg·m-3], reflecting the emissions of cargo vehicles, which were only allowed to pass at night during the control period. With the banning of ship navigation, the ship emission in the middle and lower reaches of the Yangtze River significantly decreased(48.8%). There were also high values of fugitive dust and industrial emissions near the Anhui section of the Yangtze River waterway, which reflected the dense distribution of industrial activities and road transportation along the Yangtze River. After the control period, the fugitive dust increased by 6.6 times, and the source areas were mainly distributed in Xiangyang and Jingmen.
Keywords: Wuhan Military World Games; concentration weighted trajectory; control measure; fine particulate matter; real-time source apportionment; regional transportation.