| dc.description.abstract | Aerosol organic components have significant impacts on atmospheric radiation, climate change, and human health. In this study, aerosols were collected during the spring and autumn of 2021 at the Lulin Atmospheric Background Station (elevation 2,862 m a.s.l.). The study compares the characteristics of water-soluble organic carbon (WSOC), humic-like substances (HULIS), dicarboxylic acids and their salts (DCAs C2-C5), and anhydrosugar aerosols in the transported biomass burning (BB) plumes and atmospheric background aerosols at Lulin Mountain. This study also conducted sampling in Taichung City in December 2021 to compare the differences in aerosol trace organic components between mountainous and urban areas.
During the sampling periods in the spring season at Lulin Mountain and in Taichung City, the primary aerosol trace organic component was WSOC, accounting for 70 ± 20% and 57 ± 30% of the organic carbon concentration in PM2.5, respectively. The next most abundant component was HULIS, with the average concentration at Lulin Mountain in the spring being higher than that in Taichung City. Based on the ratios of BB marker components, it is inferred that the BB aerosols transported over long distances to Lulin Mountain in 2021 were primarily from open burning, with a higher quantity of hardwood being burned compared to softwood. During the sampling periods in the spring at Lulin Mountain and in Taichung City, DCAs were primarily composed of C2. The C3/C4 ratio observed in Taichung City was higher than that at Lulin Mountain, but both locations showed minimal influence from photochemical effects. The BB marker, levoglucosan, accounted for a higher proportion of PM2.5 than PM10-2.5 during the sampling periods at both Lulin Mountain and Taichung City. In contrast, the bioaerosol marker, glucose, showed the opposite trend, indicating that BB aerosols are smaller in size, while bioaerosol is larger. To gain a more comprehensive understanding of the sources contributing to organic aerosol at Lulin Mountain, this study compiled relevant data from 2019 to 2021. Using the Positive Matrix Factorization (PMF) receptor model, the contributions to PM10 organic aerosol pollution at Lulin Mountain in the spring were estimated to be: BB 32.5%, biological sources 30.1%, primary emissions and photochemical reactions 23.6%, and sea salt 12.8%.
In summary, when Lulin Mountain is affected by long-range transported BB plumes, the concentration of trace organic aerosols is higher than in Taichung City, with BB being the primary source and biological contributions being similar. In Taichung City, the primary source of trace organic aerosols is traffic emissions, followed by BB. | en_US |