| 摘要: | 本文於2011年3月在越南山羅(海拔682公尺)及台灣鹿林山(海拔2,862公尺)以採集PM10及PM2.5濾紙氣膠進行化學分析，目的是瞭解近生質燃燒源及生質燃燒氣團經過長程傳輸後氣膠特性。。結果發現越南山羅觀測前期(3月18至21日)同時受到生質燃燒和傳輸沙塵影響，PM10-2.5及PM2.5氣膠成分以碳成分為主，且PM10-2.5及PM2.5氣膠質量濃度高於PM2.5；觀測後期(3月22至31日)則同時受到生質燃燒和中國南方污染傳輸影響，水溶性離子比例上升並主導氣膠質量，特別是SO42-佔PM2.5質量的改變最為明顯。觀測後期C3/C4比值(0.40)略高於觀測前期(0.34)，顯示中國南方氣膠成分較溶於水且受到光化氧化程度較高。觀測期間，生質燃燒指標物nss-K+與levoglucosan、Char-EC/Soot-EC相關性(R2>0.5)良好，印證受到生質燃燒的影響。 受到生質燃燒傳輸氣流影響時，鹿林山PM2.5氣膠質量濃度增加為4.1倍，PM2.5總碳濃度增加為3.8倍，左旋葡萄糖增加為4.3倍，PM2.5水溶性離子增加3.1倍，其中以nss-K+增加5.4倍最多，顯示左旋葡萄糖及nss-K+都是生質燃燒氣膠指標物。越南山羅及鹿林山受生質燃燒影響時，有氨氣不足的現象，鹿林山未受生質燃燒傳影響時，則是趨近完全中和，顯示生質燃燒煙團氣膠較偏酸性。 越南山羅觀測前期PM2.5氣膠在大氣相對濕度60%以上主要的固體結合型態是Oxalic‧2H2O(s)，觀測後期則是(NH4)2SO4和(NH4)3(H)(SO4)2，鹿林山PM2.5氣膠無論是否受到生質燃燒傳輸氣流影響，在大氣相對濕度60%以上主要的固體結合型態都是(NH4)2SO4。這些不同化合物對太陽輻射衰減程度也會有所差別，在評估環境效應有重要的意義。 氣膠含水量可表示在高濕度大氣下氣膠吸濕粒徑增大能力，因而對太陽輻射衰減程度評估也是重要因子。本文彙整2008年至2011年在鹿林山量測的氣膠含水量，多元迴歸分析顯示PM10氣膠含水量無論在BB及NBB時期都選SO42-及WSOC-HULIS_C (代表WSOC扣減掉重要疏水性成分)為重要預測因子，PM2.5氣膠含水量則無論在任何時期最主要的影響因子都是NH4+，顯示氣膠成分對對氣膠含水量的貢獻取決於物種和濃度。This work collected filter-based PM10 and PM2.5 samples at Son La (682 m a.s.l., Vietnam) in March 2011 and Mt. Lulin (2,862 m a.s.l., Taiwan) from March to April 2011 for analyzing their chemical compositions. The aim of this work is to understand aerosol characteristics from near-source biomass burning (BB) and BB plume after long-range transport. The results showed that Son La aerosol was simultaneously influenced by BB and transported dust in the front observation period to result in the dominance of carbonaceous content both in PM10-2.5 and PM2.5 as well as higher PM10-2.5 mass than PM2.5 from March 18 to 21, 2011. In contrast, the proportion of water-soluble ions was increased to dominate aerosol chemical speciation in the rear observation period from March 22 to 31, 2011, especially for the apparent change of SO42- over PM2.5 mass, which was due to the influence of BB coupling with the pollution transported from the southern China. The slight greater C3/C4 ratio (0.4) in rear than front (0.34) periods implies aerosol component is inclined to be more water-soluble and with greater degree of photochemical oxidation. The moderate high correlations (R2>0.5) for nss-K+ vs. levoglucosan and Char-EC/Soot-EC, respectively, validate the influence of BB activities during the observation period. The enhancements of Mt. Lulin PM2.5 mass, total carbon, total ion, levoglucosan, and K+ were 4.1, 3.8, 3.1, 4.3, and 5.4 folds when under the influence of BB plume transport. This fact identifies aerosol BB tracers from transported airmasses. Ammonia deficient was found for Son La and Mt. Lulin aerosols under the influence of BB; however, aerosol was almost completely neutralized when Mt. Lulin was not affected by the transported BB plume. This indicates that BB plume aerosol tends to be acidic. For Son La aerosol, PM2.5 copound form was Oxalic‧2H2O(s) when atmospheric relative humidity (RH) exceeded 60% in the front period and were (NH4)2SO4 and (NH4)3(H)(SO4)2 in the rear period. For comparison, the copound form of Mt. Luin PM2.5 was always (NH4)2SO4 regardless of the influences of BB. Different compound forms of aerosol exert deviations in the degradation of solar radiation and thus important in the assessment of environmental effect. Aerosol water content is capable of representlin hygroscopic growth under high atmospheric RH and consequently plays an important role for evaluating solar radiation attenuation. This work compiled aerosol water content measured at Mt. Luin from 2008 to 2011. Linear regression analyses show that SO42- and WSOC-HULIS_C are chosen as significant predictors for BB and NBB periods in PM10, while NH4+ is considered as the important predictor for all time. The results imply aerosol water content is determined by speciation and concentration. |
