| 摘要: | 有機氣膠對大氣輻射、氣候變化、人體健康有重大影響。本文於2021年春、秋季在鹿林山大氣背景觀測站(海拔2,862 m)採集氣膠，比較鹿林山生質燃燒傳輸煙流和大氣背景氣膠水可溶有機碳(Water-Soluble Organic Carbon, WSOC)、類腐植質物質(HUmic-LIke Substances, HULIS)、二元酸及其鹽類(Dicarboxylic acids and their salts, DCAs C2-C5)、單醣脫水醣類氣膠特性。本文另於 2021年12月在臺中市採樣，比較高山和都市地區氣膠微量有機成分異同。
鹿林山春季及臺中市採樣期間氣膠微量有機成分以WSOC為主，各占PM2.5有機碳濃度70 ± 20% 和57 ± 30%，其次為HULIS，鹿林山春季平均濃度都高於臺中市。由生質燃燒指標成分比值推論：2021年鹿林山長程傳輸生質氣膠的燃燒狀態以明火為主，燃燒硬木數量多於軟木。鹿林山春季及臺中市採樣期間DCAs以C2為主，臺中市觀測期間C3/C4比值高於鹿林山，但受光化學影響都不大。鹿林山及臺中市於採樣期間生質燃燒指標左旋葡聚糖在總醣占比PM2.5較PM2.5-10高，生物氣膠指標葡萄糖則相反，顯示生質燃燒氣膠粒徑較小，生物氣膠則較大。為了較周延地瞭解鹿林山有機氣膠污染源貢獻，本文彙整2019-2021年鹿林山相關數據，使用正矩陣因子法受體模式推估春季鹿林山PM10有機氣膠污染源貢獻，分別為生質燃燒 32.5%、生物來源 30.1%、原生排放與光化學反應23.6 %、海鹽12.8%。
總結來說，鹿林山受生質燃燒煙團長程傳輸影響時，微量有機氣膠濃度高於臺中市，來源以生質燃燒為主，生物源貢獻相近；臺中市微量有機氣膠來源則以交通源為主，生質燃燒為次。
;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. |
