| 摘要: | 二元酸是大氣環境中氣膠的重要組成之一，二元酸的存在會改變氣膠在大氣中的尺寸及雲凝結的成核反應，進而影響氣候。本研究採集針葉林中PM2.5大氣氣膠微粒探討其二元酸及水溶性組成特性，結果發現無機鹽類合佔41.81%，水溶性總有機酸成分佔1.47%。二元酸是生物污染源排放中PM2.5氣膠微粒之有機酸最主要成分，oxalic acid是最主要的物種佔總有機雖百分比43.17%，其次為 trataric acid、maleic acid 以及微量的 succinic acid 、glutaric acid (1.18%、0.32%)，其中 oxalic acid 豐富的含量與代表針葉林中的五葉松含量呈現一致性的高濃度。此外，針葉林地大氣PM2.5氣膠所含的 formic acid、oxalic acid、mailc acid、 trataric acid、maleic acid、fumaric acid 皆與自然界的生物排放量有關。Formic acid與 acetic acid 分別佔有機酸成分的0.53%、28.7%，acetic acid/ formic acid比值為54.2，遠大於10以上，顯示此地環境中有生質燃燒的產生包括木材燃燒或其他農業燃燒之人為排放，同時大氣PM2.5氣膠的 malonic acid 及 succinic acid 之濃度比值為4.13，顯示此針葉林中未明顯受人為交通排放影響。
Dicarboxylic acids, which change the size and chemical reactions of cloud condensation nuclei (CCN) to influence climate, are one of the important components of atmospheric aerosols. Ambient PM2.5 aerosol in a coniferous forest was collected to analyze its compositions. Total determined water-soluble inorganic species accounted for 41.81% of PM2.5 mass.Total determined water-soluble organic acids, including monocarboxylic acids, dicarboxylic acids and tricarboxylic acids, accounted for 1.47% of PM2.5 mass. Dicarbonxylic acid was the dominant organic acids. Oxalic acid (43.17% by total determined organic acids in forest PM2.5) was the dominant dicarboxylic acid species, followed by tartaric acid (7.21%), maleic acid (7.14%), repectively and, in insignificant succinic acid and glutaric acid (1.18%、0.32%). The abundant concentration of oxalic acid in aerosol was associated with that in Pinus morrisonicola Hayata,. The abundant emission of tartaric and maleic acids existed in the pine forest aerosol. However, formic acid, oxalic acid, malic acid, tartaric acid, maleic acid and fumaric acid in the forest stmospheric aerosol were associated with emissions from biosources. Fomic acid and acetic acid (0.53% and 28.7%, respectively, by the total determined organic acids in the forest PM2.5) were the dominant monocarboxylic acid species and the mass ratio of acetic acid/formic acid was 54.2, indicating the wood and agricultural burning in the pine forest area. Moreover, the mass ratio of malonic acid to succinic acid being 4.13 demonstrated no sognificant traffic emission in the pine forest. |
