| dc.description.abstract | Every spring from March to April, it is the time period for active biomass burning in East Asia. The aerosols produced from biomass burning were lifted 2 to 5 Km above the ground by the rise of a frontal system and a strong convective air mass. They were then transported to the other areas by the air mass in the high altitude. This study chose Lu-Lin Mountain, as the study site for aerosol collection, which situated in the middle Taiwan 2,862 m above sea level. The goal of this study is to observe the aerosol characteristics from biomass burning in East Asia via long range transport in lower free troposphere. The observations included two biomass burning events in April 2003 and March 2004 and a background observation in December 2003.
This study used manual sampler and continuous measuring instrument to obtain the information of aerosol from the two biomass burning events and bacdground. Besides, in order to infer the characteristic of the fresh aerosol near biomass source, we burned wood and hay and used manual sampler to correct fresh aerosol. Comparing the aerosol of fresh-burning biomass and Lu-Lin Mountain, we can tell the differences of long-range transport. The results showed that PM2.5 and PM10 concentrations are 2 and 4 μgm-3 for background observations, respectively. The peak diameter is in the range between 0.1-0.3 μm and major chemical species are sulfate, ammonium ions, nitrate, and carbonaceous materials. For biomass burning events, aerosol mass was increased and specises like sulfate, ammonium ions, nitrate, and carbonaceous materials were all enhanced. In addition, potassium ion was found significantly increased in aerosol fine fraction. Moreover levoglucosan in aerosol was detected high during biomass burning period with an average of 48 ngm-3.
In TOR analysis, OC1 is in majority in background observation and OC3 is predominant in biomass burning events. By using Hysplit backward air trajectory model, we find that aerosol are high in potassium ion, carbonaceous materials, and levoglucosan as the air mass passed biomass-burning sources. Besides, using Marine Enrichment Factor(MEF) and Chlorine Loss Method(CLM), we find that the water-solube ions in fine fraction are contributed from secondary sulfate, secondary nitrate and biomass burning. In contrast, the coarse particles included soil materials and seat-salts. Finally, aerosols from long range transport contain high fraction of sulfate, nitrate, and ammonium ions as compared to high carbonaceous material, potassium, and chloride ions. | en_US |