Chemical composition of dust storms in Beijing and implications for the mixing of mineral aerosol with pollution aerosol on the pathway

Abstract

Aerosol particle samples collected in spring 2002 in Beijing were analyzed to investigate the impact of transport pathways on chemical composition of Asian dust storms (DSs). The dust storms were divided into two episodes (i.e., DS I and DS II), which were transported along different pathways identified by back‐trajectory and PM10 concentrations. The transport pathway from the westerly direction could be seen as the “polluted” pathway and the north‐northwesterly direction as the relatively “less‐polluted” one. Dust storms not only delivered large amounts of mineral elements but also carried significant quantities of pollutants. The source regions and transport pathways were two vital factors affecting chemical composition of dust storms. Ca/Al could be used as elemental tracer to identify the sources of Asian dust storms owing to the difference in Ca content in different source regions. DS I of the “polluted” pathway carried more pollution elements than DS II of the “less‐polluted” one, and the pollution elements were either from dust soil (such as Zn), the mixing of dust soil with pollution aerosol on the pathway (such as As and Pb in DS I), the “pollution” dust resuspended on the pathway and Beijing local area (such as S in DS I, As and Pb in DS II), or the reactions on the surface of dust particles.