Characterization of water-soluble inorganic ions in size-segregated aerosols in coastal city, Xiamen
The samples of water-soluble inorganic ions (WSIs), including anions (F−, Cl−, SO4 2−, NO3−) and cations (NH4+, K+, Na+, Ca2+, Mg2+) in 8 size-segregated particle matter (PM), were collected using a sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) from October 2008 to September 2009 at five sites in both polluted and background regions of a coastal city, Xiamen. The results showed that particulate matters in the finemode (PM2.1, Dpb2.1 μm) comprised large part of mass concentrations of aerosols, which accounted for 45.56–51.27%, 40.04–60.81%, 42.02–60.81%, and 40.46–57.07% of the total particulate mass in spring, summer, autumn, and winter,respectively. The water-soluble ionic species in the fine mode at five sampling sites varied from15.33 to 33.82 (spring), 14.03 to 28.06 (summer), 33.47 to 72.52 (autumn), and 48.39 to69.75 μgm−3 (winter), respectively, which accounted for 57.30±6.51% of the PM2.1 massconcentrations. Secondary pollutants of NH4+, SO4 2− and NO3− were the dominant contributors of WSIs, which suggested that pollutants from anthropogenic activities, such as SO2, NOx were formed in aerosols by photochemical reactions. The size distributions of Na+, Cl−, SO42− and NO3− were bimodal, peaking at 0.43–0.65 μm and 3.3–5.8 μm..
