[Transport Pathways and Potential Sources of PM_2.5 During the Winter in Zhengzhou]

In this study, meteorological and air mass concentration data of Zhengzhou from December 2017 to February 2018 (winter) were used to quantify the influence of meteorological factors on the PM. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to analyze the 48-hour backward trajectories and the cluster method was applied to classify the airflow backward trajectory. Moreover, the potential source contribution function and concentration-weighted trajectory analysis were applied to evaluate the transport pathways and sources of PM_2.5 in Zhengzhou. The results show that the heavy pollution in Zhengzhou during winter is mainly due to the low wind speed, high relative humidity, and low precipitation. The cluster analysis revealed that up to 60% of the back trajectories came from the northwest and 25.56% of the back trajectories came from the Beijing-Tianjin area. The airflow trajectories from the south and east account for 7.5% and 6.1% with higher PM_2.5 concentrations. The main potential sources of PM_2.5 in Zhengzhou during winter are located in Beijing-Tianjin-Hebei air pollution transmission channel cities including Jiaozuo, Kaifeng, Xinxiang, Hebi, Puyang, Anyang, Handan, and Xingtai. The adjacent provinces, including Shanxi, Hubei, and Anhui, also have great influence on the PM_2.5 in Zhengzhou.