| 摘要: | 生質燃燒(Biomass burning, BB)對空氣品質、民眾健康和氣候變遷具有重大影響。本文於2020年3~4月(春季)及2020年10月(秋季)在鹿林山大氣背景站 (海拔2,862 m )，2020年4月在臺中市採集分析微量有機成分。
水可溶有機碳(Water-soluble Organic Carbon, WSOC)在鹿林山和臺中市春季有類似濃度，WSOC/OC在鹿林山的BB及弱生質燃燒-自由大氣類型(70-75%)比弱生質燃燒-人為排放類型(50-62%)高，臺中市則是62-64%，表示人為污染排放貢獻的氣膠水可溶有機物占比較生質燃燒小。PM2.5 WSOC形成途徑，在臺中市和鹿林山都受到液相反應影響。左旋葡聚醣在總醣占比鹿林山春季PM2.5較PM10-2.5高，甘露醇則是相反，說明BB氣膠粒徑較小，生物氣膠粒徑較大。甘露醇和阿拉伯醣醇在臺中市隨風速增高而濃度降低，代表為本地排放，但在鹿林山則與風速無關。二元酸及其鹽類包括草酸(C2)、丙二酸(C3)、琥珀酸(C4)，春季鹿林山C2濃度不論粒徑都高於臺中市，顯示BB比人為污染貢獻較多C2。臺中市的PM2.5及PM10-2.5的C3/C4分別為0.98及15.53，都高於鹿林山；配合O3趨勢觀察，臺中市受光化學反應影響較鹿林山強烈。除了光化學反應外，臺中市PM10-2.5 C3還受到海洋氣膠影響。鹿林山類腐殖質物質(HUmic-LIke Substances, HULIS)在PM10占比以BB氣流軌跡類型最高，推測鹿林山HULIS主要為BB主導，但其他軌跡類型則有人為污染貢獻。臺中市PM2.5的HULIS/WSOC與相對濕度數值略有相反趨勢，顯示光化學反應對臺中市HULIS形成重要。
總結來說，鹿林山春季氣膠微量有機成分主要受生質燃燒排放貢獻，但也有人為排放源影響以及液相二次反應影響。臺中市氣膠微量有機成分主要受到交通排放及光化學反應影響。
;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. |
