Influence of an Asian Dust Storm and Southeast Asian Biomass Burning on the Characteristics of Seashore Atmospheric Aerosols in Southern Taiwan

This study explores the effects of an Asian dust storm (ADS) and Southeast Asian biomass burning on the composition of atmospheric aerosols in the coastal area of southern Taiwan in spring 2010. Coarse and fine particles were collected using two manual dichotomous samplers (Dichots) that were equipped with Teflon and Quartz filters. The results reveal that the concentrations of PM10 and PM2.5 in the ADS period were about twice those before and after this. More than half of water-soluble ions in coarse particles (PM2.5-10) were Cl-and Na+ (sea salt), while 70% of water-soluble ions of fine particles were SO42- and NH4+ (secondary aerosols). The OC/EC ratios of PM2.5 and PM2.5-10 were all above 2.0. Over 98% of the metals in coarse and fine particles were crustal elements (98.1-99.1%), and over 60% of the metals in PM10 were in coarse particles (PM2.5-10). The water-soluble ion, EC, OC, and metal contents in PM2.5 all exceeded those in PM2.5-10. The ADS was associated with higher concentrations of water-soluble ions in PM2.5 and PM2.5-10 than was the non-ADS period, except for K+ in PM2.5-10. ADS most increased the Ca2+ content and concentration, causing a rise in the average concentrations of Ca2+ in coarse and fine particles by factors of 3.0 and 3.2, respectively. In the ADS period, although the OC and EC concentrations of coarse and fine particles increased, the OC and EC contents in these particles decreased. The ADS period was associated with higher metal contents in coarse and fine particles than the non-ADS period, and the increase in PM2.5-10 (more than 2%) exceeded that in PM2.5. In PM2.5-10 and PM2.5, the Ca and Ni contents increased the most, respectively. In addition, the concentrations of the water-soluble ions, EC, OC, and metals in PM2.5-10 and PM2.5 increased, but their contents decreased, while the contents of the other constituents (= total - (water-soluble ions + EC + OC + metals)) in PM2.5-10 and PM2.5 increased. It is also found that Southeast Asian biomass burning is related to the deterioration of the air quality of southern Taiwan.