The mineral aerosol and its impact on urban pollution aerosols over Beijing, China

Abstract

A campaign of sampling total suspended particles (TSP) and fine particles ( PM 2.5 ) in Beijing from 2001 to 2004 were carried out to investigate the mineral aerosol and its impact on urban pollution aerosols, mainly sulfate, nitrate, and ammonium. In urban Beijing, mineral aerosol accounted for 32–67% of TSP, 10–70% of PM 2.5 in normal four seasons, and as high as 74% of TSP and 90% of PM 2.5 in dust storm period. The sources from outside Beijing accounted for 62% of the total mineral aerosols in TSP, and 76% in PM 2.5 in spring, 69% and 45% in TSP and PM 2.5 , respectively, in winter, ∼ 20 % of both TSP and PM 2.5 in summer and autumn; and it reached as high as 97% of TSP in dust storm days. Mineral aerosol has an important positive influence on formations of sulfate, nitrate, and ammonium, as there was a positive correlation between sulfate/nitrate/ammonium and mineral aerosol under appropriate meteorological conditions. Sulfate, and ammonium mainly existed in fine particles, PM 2.5 . Sulfate might mostly derive from the formation on the pathways of the long-range transport by the reactions of their precursors SO 2 on the surfaces of dust particles, while nitrate was mostly derived by the homogeneous reaction and the neutralization of their precursors NO 2 on surfaces of mineral aerosol. Nitrate and ammonium mostly derived from the local pollution sources.