| dc.description.abstract | Biomass burning (BB) causes significant impacts on air quality, public health, and climate change. This study collected and analyzed aerosol trace organic components at the Mt. Lulin atmospheric background station (2,862 meters above sea level) from March to April and October 2020, and in Taichung City in April 2020.
Water-soluble organic carbon (WSOC) had similar concentrations at Mt. Lulin and Taichung City in spring. The values of the WSOC/OC in BB and weak BB-free troposphere trajectory types (70-75%) were higher than that of weak BB-anthropogenic trajectory type (50-62%). In Taichung City, the values of the WSOC/OC were 62-64%, indicating that anthropogenic pollution emissions contributed less proportion of water-soluble organic matter than BB. For the formation processes of PM2.5 WSOC, Mt. Lulin and Taichung City are both affected by the liquid phase reactions. The proportion of levoglucosan in total monosaccharide anhydrosugars was higher in PM2.5 than PM10-2.5 at Mt. Lulin in spring. On the contrary, mannitol was higher in PM10-2.5 than PM2.5, which showed that BB aerosol with smaller and bioaerosol with larger particle sizes. The concentration of mannitol and arabitol decreased with the increase in wind speed at Taichung City, which represented local emissions but that of Mt. Lulin was not related to wind speed. Diacids and their salts include oxalic acid (C2), malonic acid (C3), and succinic acid (C4). The concentration of C2 at Mt. Lulin in spring was higher than that in Taichung City regardless of particle size, indicating that BB contributed more C2 than anthropogenic pollution. The C3/C4 values of PM2.5 and PM10-2.5 in Taichung City were 0.98 and 15.53, respectively, which were higher than those of Mt. Lulin. According to the observation of the O3 trend, Taichung City was more strongly affected by photochemical reactions than Mt. Lulin. In addition to photochemical reactions, Taichung PM10-2.5 C3 was also affected by marine aerosols. The proportion of humic-like substances (HULIS) in PM10 is the highest for the BB among all trajectory types at Mt. Lulin, indicating the dominance of BB. The values of HULIS/WSOC in PM2.5 at Taichung City were slightly varied inversely to the relative humidity, implying that the photochemical reaction was important for the formation of HULIS at Taichung City.
In summary, the trace organic components of the spring aerosol at Mt. Lulin are mainly contributed by biomass burning but also influenced by anthropogenic pollution sources and secondary reactions in the liquid phase. The trace organic components of aerosols at Taichung City are mainly affected by traffic emissions and photochemical reactions. | en_US |