Transport pathways of PM10 during the spring in northwest China and its characteristics of potential dust sources

Abstract

Abstract Dust storms that occur frequently during the spring in the arid and semiarid regions of northwest China can significantly increase PM10 loadings in the local area and its surroundings, and impair environmental ecology, human activity and health. Based on the monitoring data of PM10 and backward trajectories of air parcels calculated by the Hybrid Single Particle Lagrangian Integrated Trajectory model in Jiayuguan, Jinchang and Lanzhou during the spring seasons from 2014 to 2017, trajectory cluster analysis was used to identify the major transport pathways of PM10, and concentration-weighted trajectory and trajectory sector analysis were applied to identify the potential sources and quantify regional transported contributions. The results showed that there were major transport pathways coming from three directions: the northwestern pathways (for Jinchang and Lanzhou), the western pathways (for Jiayuguan and Lanzhou), and the northern pathways (for Jiayuguan and Jinchang). The corresponding potential dust sources for these pathways were the northwesterly sources, the westerly sources and the northerly sources, respectively. In addition, the northern Tibetan Plateau was another important source affecting Jiayuguan. There were distinct differences among the regional transport contributions from various directions. The PM10 concentrations (percentages) that exogenous dust sources contributed to Jiayuguan, Jinchang and Lanzhou decreased in a sequence from west to east at 47 μg/m3 (29.8%), 40 μg/m3 (27.1%) and 26 μg/m3 (17.3%), respectively, which were attributed predominantly to the long-range transport of dust sources with the remainder coming from local or nearby emissions. The above decreasing tendency was in accordance with the distance effect from the dust sources to the receptor sites.