台灣北部地區大氣氣膠有機酸特性; The characteristic of aerosol organic acid in North Taiwan

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Title:	台灣北部地區大氣氣膠有機酸特性;The characteristic of aerosol organic acid in North Taiwan
Authors:	黃秋華;Chiu-hua Huang
Contributors:	環境工程研究所碩士在職專班
Keywords:	PM2.5 氣膠有機酸黃沙期間;長程輸送;低分子量一元酸;低分子量二元酸;PM2.5 organic acids;Low-molecular-weight dicarboxylic acids;Yellow Dust period;Low-molecular-weight monocarboxylic acids;Long-range transport
Date:	2010-01-27
Issue Date:	2010-06-10 16:57:22 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	大氣氣膠在全球氣候變遷影響上扮演了重要的角色。針對大氣氣膠特性的探討，雖然很多研究已經轉移到氣膠有機物，但目前對於氣膠有機物中有機酸的瞭解仍然相當有限，因為氣膠有機酸來源廣泛。本文建立低分子量氣膠一元酸和二元酸的分析技術，並分別在台北北部地區中的偏遠站(石門鄉)及都會區(新莊市)進行冷高壓期間(石門鄉)、一般期間(新莊市)、黃沙期間(石門鄉、新莊市)的氣膠樣本採集，採集後帶回實驗室以離子層析儀進行氣膠有機酸，以探討不同地區、時間，不同污染來源對氣膠有機酸濃度變化的影響。研究結果發現，三個觀測期間都顯示，都會區及偏遠地區二元酸以Oxalic acid (C2)濃度最高，其次依照濃度高低順序分別為Succinic acid (C4)、Malonic acid (C3)、及Glutaric acid (C5)。在一般期間，都會區氣膠有機酸來源以光化學反應及上下班尖峰時段機動車輛排放為主。當光化學反應明顯時，一元酸Acetic/Formic acid (A/F)比值大約為0.7，二元酸Malonic/Succinic acid (C3/C4)比值有大於1的現象；但在非光化時段，A/F比值為0.86，C3/C4比值則為0.7，說明光化時段C3較C4有更多的產出。在冷高壓期間，偏遠地區有機酸的產生以長程傳輸過程污染物反應為主，但是一元酸中Formic acid主要受到傳輸光化學反應的影響，Acetic acid的生成則是受到傳輸一次污染排放及類似化石燃料燃燒後發生二次反應的混合影響，A/F比值在1.95左右，在觀測中還發現，一元酸濃度的差異與溫度有相關。類似地，二元酸主要來源是來自於傳輸過程如同化石燃料燃燒後發生的二次反應程序，C3/C4比值大約在0.95附近，兩物種間很高的線性相關指出兩者可能有相同的來源。黃沙期間有機酸來源以長程傳輸的一次污染排放及二次光化學反應為主，都會區與偏遠地區一元酸都以Acetic acid為優勢物種，主要來源為長程傳輸的二次光化學反應，A/F比值分別為1.2及1.9；二元酸在都會區和偏遠地區來源都是長程傳輸一次污染排放及二次光化學反應的混合，C3/C4比值分別為0.96及1。 Atmospheric aerosol plays a significant role in global climate change. Up to now, many studies on atmospheric aerosol characteristics already shifted to focus on aerosol organics; however, the understanding of aerosol organic acids is still limited because aerosol organic acids are diversified. In this study, the analytical method for measuring low molecular weight monocarboxylic acids (MAs) and dicarboxylic acids (DAs) of atmospheric aerosols is established. Atmospheric aerosols were collected at a remote site (Cape Fuquay at Shimen village in Taipei County) and an urban site (the North Aerosol Supersite of Taiwan Environmental Administration at Hsinchuan City) during cold high-pressure period (Shimen), normal period (Hsinchuan), and Yellow Dust period (Shimen and Hsinchuan). The collected aerosols were taken back to the laboratory for organic acids analyses using ion chromatograph. The goal is to investigate the characteristics of aerosol organic acids contributed from different sources at different areas and times. The results show that Oxalic acid (C2) was the most abundant species in DAs, followed by Succinic acid (C4), Malonic acid (C3), and Glutaric acid (C5) in both urban and remote areas during all three periods. Aerosol organic acids are mainly contributed from photochemical reactions and mobile vehicle emissions. When photochemical reactions were dominated, the ratio of Acetic/Formic acid (A/F) in MAs was around 0.7, while that of Malonic/Succinic acid (C3/C4) in DAs was above 1. In contrast, A/F was at 0.86 and C3/C4 was at 0.7 during non-photochemical reactions period. It implies that C3 is produced more than C4 when in photochemical reactions period. The source contributions of organic acids were dominated by long-range transport of pollution in the remote area during cold high-pressure period. Formic acid was mainly affected by photochemical reactions during transport, while Acetic acid was influenced by a combination of transported primary emissions and secondary reactions similar to the processing of fossil fuel burning. The A/F values are around 1.95 during this period. In addition, concentration variations of MAs are found affected by ambient temperature. Analogously, the DAs were mainly produced by a process related to secondary reactions of fossil fuel burning. The ratio of C3/C4 was around 0.95. High linear correlation between C3 and C4 indicates their source contributions are similar. During Yellow Dust period, aerosol organic acids were found related to sources from primary emissions and secondary photochemical reactions of long-range transport. Acetic acid is the preferable MAs in both urban and remote areas. The ratios of A/F were 1.2 and 1.9 in urban and remote areas, respectively. The source inferences in both urban and remote areas of DAs are a combination of primary emissions and secondary photochemical reaction during transport. The C3/C4 values were 0.96 and 1.0 in urban and remote areas, respectively.
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