dc.description.abstract | The tremendous amounts of aerosols and gas pollutants produced in Indo China will affect the downwind region as they are transported in a long distance. Taiwan is one of the best places to observe these transported pollutants as it is located in the downwind region. To circumbent the interference from ground level pollution, this study observed atmospheric aerosols at Mt. Lulin (2,862 m above sea level) from July 2007 to April 2008. The goal is to resolve the differences of aerosol property between biomass burning (BB) and non-biomass burning (NBB) periods. The PM2.5 level is three-fold during BB period as compared to that of NBB period. The PM2.5 ammonium ion, sulfate, and nitrate levels are 1.50 µg m-3, 4.06 µg m-3, and 0.50 µg m-3, respectively. Notably, the PM2.5 potassium ion as one of the markers for BB was four-fold as high as that during NBB period. As for the levels of the resolved carbonaceous fractions, organic carbons (OC) were increased significantly, while only EC1-OP was increased for elemental carbon (EC). Moreover, the mean values of water-soluble OC, levoglucosan, and low molecular-weight diacids during BB period were 3.2, 3, and 4.5 times, respecticely, in contrast to those during NBB period. Trajectory analysis for the air masses during observation period shows that the levels of aerosol components were the lowest for oceanic origin. It also shows that PM10-2.5 and calcium ion from China continent were apparently higher than those from other transport paths probably due to the influence of Asian dust. For the air masses from BB source region via southern China, PM2.5, potassion ion, oxalic acid, and levoglucosan were all higher during BB period than that of NBB period. For the aerosol morphology during BB period, the analysis of scanning electron microscopy reveals that rectangular crystal type is around 70-80% in the number of the observed aerosol particles followed by tar ball type and grape chain aggregrate takes the least. Different size cut samplers were adopted at Mt. Lulin to collect aerosols when in the uprising convective cloud, little difference was found for PM1 and PM2.5 aerosol components; however, a difference was exist for PM1 and TSP. Among aerosol components, the scavenging ratio was highest at 0.41 for nitrate followed by ammonium ion and sulfate. The scavenging ratio for OC and EC were 0.20 and 0.22, respectively. During cloud affecting period, the levels of PM2.5 ammonium ion, sulfate, and nitrate were significantly increased, which indicates anthropogenic pollutants were entrained in the cloud.
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