Potential sources and transport pathways of PM2.5 in Shanghai, China

This study investigates the potential sources and transport pathways of PM_2.5 in Shanghai, China from January 2013 to December 2014 by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling, K-means clustering, and concentration-weighted trajectory (CWT) analysis methods. Six transportation pathways that contribute to PM_2.5 in Shanghai were identified by trajectory clustering. The primary potential pathway originated from the nearby northwestern regions, including Hebei, Henan, Shandong, Jiangsu, and Anhui, which mainly affect PM_2.5 in winter and spring. The second primary potential pathway originated from northern and north-western regions, such as Mongolia. The lowest PM_2.5 concentrations were found in the southern pathway with clean marine air masses from the South China Sea and Pacific Ocean in summer. The CWT method also identified the primary potential sources on the basis of the trajectory clustering results.