Chia Nan University of Pharmacy & Science Institutional Repository:Item 310902800/9091
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    標題: 背景與郊區大氣氣膠無機鹽類及二元有機酸之化學特性及其粒徑變異研究
    Characterization of Compositions and Size Distributions of Inorganic Salts and Dicarboxylic Acids in Background and Suburban Aerosols
    作者: 翁子翔
    Tzu-hsiang Weng
    貢獻者: 蔡瀛逸
    嘉南藥理科技大學：環境工程與科學系碩士班
    關鍵字: 大氣氣膠
    二元有機酸
    日期: 2006
    上傳時間: 2008-11-24 17:01:24 (UTC+8)
    摘要: 本研究探討阿里山背景地區及台南郊區於夏季、秋季非高污染時期、高污染時期及農廢燃燒時期之大氣氣膠無機鹽類及二元有機酸(low-molecular-weight dicarboxylic acids)之組成變異，並探討氣膠之無機鹽類及二元有機酸組成粒徑分布特性。
    氣膠SO42-之前趨物SO2之日夜濃度變化，於高污染時期日夜間之SO2濃度均較其他時期為高，濃度分別為32.8±7.6 ug m-3、20.3±7.7 ug m-3，而阿里山背景環境之SO2日夜平均濃度最低，分別為0.15±0.04 ug m-3、0.12±0.06 ug m-3，顯示背景環境之SO2濃度遠低於郊區所受之人為污染排放。
    阿里山背景地區之PM2.5氣膠之SO42-、NO3-、NH4+濃度日間比夜間為高，且SO42-濃度最高，再者為NH4+，由於在阿里山區NH4+的前趨物NH3來源豐富，在光化反應下有較高之NH4+濃度表現。而台南郊區夏季及秋季無機鹽類濃度均以SO42-、NO3-及NH4+光化產物為最大量，且秋季非高污染時期SO42-、NO3-及NH4+濃度均高於夏季，又以SO42-的9.67±2.29 ug m-3濃度為最高。而高污染時期氣膠NO3-＞SO42-，與在夏季與秋季非高污染時期為SO42-＞NO3-不同，且NO3-濃度表現在農廢燃燒時期與高污染時期，佔PM2.5質量比例在白天分別為19.6%及18.0%，所佔PM2.5 mass的比例最大，顯示高污染及農廢燃燒時期，NO3-對PM2.5 mass的貢獻有明顯增加。此外農廢燃燒污染時期NH4+濃度較高污染時期更高出0.95 ug m-3。
    而在阿里山背景地區二元有機酸，以oxalic acid為最大量，succinic acid次之，再者為malonic acid，而二元有機酸均與NH4+具有高度相關性，顯示阿里山之氣膠二元有機酸之生成主要來自自然排放後經光化反應所形成。而台南郊區高污染時期氣膠二元有機酸日夜間濃度有明顯增量，而濃度以oxalic acid＞succinic acid＞maleic acid，其二元有機酸組成濃度多寡順序與夏季相同，而六種二元有機酸之濃度在日間較夏季及秋季非高污染時高出約2-3倍，農廢燃燒時期，二元有機酸之日夜趨勢與高污染時非常相似，由濃度相關矩陣發現oxalic acid與NH4+、K+相關性為0.72、0.69，這三者的關係比其它大氣時期為高，顯示農廢燃燒氣膠含有大量oxalic acid。
    在大氣氣膠濃度粒徑分布上，阿里山背景地區無機鹽類主要波峰分布在0.46-2.4 um的droplet mode、5.7-11.3 um的coarse mode及4-90 nm 的nuclei mode，二元有機酸最主要則是在0.46-2.4 um的droplet mode，且4 nm有最初始二元有機酸微粒之生成，而在台南郊區之氣膠無機鹽類與二元有機酸組成之濃度粒徑分布，由夏季的單峰或雙峰，轉變成秋季的三峰及更多波峰的形態，高污染時的二元有機酸最大濃度波峰集中於0.19-0.32 um的condensation mode，顯示高污染時期氣膠有更明顯的二元有機酸膠凝及光化產物生成貢獻。此外，氣膠succinic acid (C4)及malonic acid (C3)之最大濃度波峰與oxalic acid (C2)不同，秋季非高污染時期及高污染時期之oxalic acid最大濃度波峰往奈米粒徑位移，顯示秋季氣膠oxalic acid是經由C4和C3二元有機酸光化反應後之最後產物。
    In this research, variations of characteristic composition as well as size distributions of the atmospheric inorganic salts and low-molecular-weight dicarboxylic acids (low-Mw DCAs) in aerosol for the background Ali Mountain and Tainan suburban regions during summer season, the autumn non-serious pollution period, the autumn high pollution period and the agricultural burning period were studied.
    During the high pollution period, Tainan has higher concentrations of daytime and nighttime concentrations of SO2, a precursor to the formation of SO42-, than other periods; the daytime and nighttime SO2 concentrations are 32.8±7.6 ug m-3, 20.3±7.7 ug m-3, respectively. The background Ali Mountain region has the lowest daytime (0.15±0.04 ug m-3) and nighttime (0.12±0.06 ug m-3) SO2 concentrations indicating that the background environment SO2 concentration is much lower than man-made pollution emission in Tainan suburban region.
    The background daytime concentrations of SO42-, NO3- and NH4+ in PM2.5 aerosols in Ali mountain region are higher than nighttime concentrations. This region is abundant in NH3, which is a precursor of NH4+, leading to relative higher concentrations of NH4+ produced from photochemical reactions. During summer and autumn, Tainan suburban region experiences the maximum quantities of SO42-, NO3- and NH4+ photochemical products while the autumn non-serious polluted season has higher concentrations of SO42-, NO3- and NH4+ than summer with 9.67±2.29 ug m-3 of SO42- being the highest concentration. During the high pollution period, the aerosol has higher NO3- concentration than SO42- that is different from the higher SO42-concentration than NO3- concentration during summer and the autumn non-serious pollution period. The quantity of ratio of NO3- to PM2.5 mass is the highest during high pollution and agricultural waste burning periods; the ratios are 19.6% of the daytime PM2.5 mass during high pollution period and 18.0% of the daytime PM2.5 mass during agricultural waste burning period, respectively. These observations indicate that during the high pollution and the agricultural waste burning periods, the contribution of NO3- to PM2.5 mass apparently increases. Additionally, the NH4+ concentration during the agricultural waste burning period is 0.95 ug m-3 higher than during the high pollution period.
    Oxalic acid is the most abundant low-Mw DCAs in the Ali Mountain region followed by succinic acid and malonic acid. These low-Mw DCAs are highly correlated with NH4+ demonstrating that the aerosol low-Mw DCAs in Ali Mountain are the photochemical products from natural emissions. In Tainan suburban region during high pollution period, concentrations of the daytime and nighttime low-Mw DCAs are obviously higher. Similarly, oxalic acid during summer is the most abundant followed by succinic acid and maleic acid. Additionally, daytime concentrations of the six observed low-Mw DCAs are 2 to 3 times higher than those during summer while during agricultural waste burning period, the diurnal variation tendency is quite similar to that during high pollution period. The concentration matrix reveals that the correlation coefficients are 0.72 between oxalic acid and NH4+ and 0.69 between oxalic acid and K+. Since during the agricultural burning period, these three chemical species are more correlated than other seasons and periods indicating that the sol from agricultural waste burning contains a large quantity of oxalic acid.
    As the atmospheric particle size distribution is concerned, the Ali Mountain background inorganic salts show droplet mode (concentration peaks between 0.46-2.4 um), coarse mode (concentration peaks between 5.7-11.3 um) and nuclei mode (concentration peaks between 4-90 nm). The low-Mw DCAs are principally droplet mode with concentration peaks in 0.46-2.4 um; the 4 nm peaks shows the beginning formation of low-Mw DCA primary particles. For Tainan suburban region, the particle size distributions for both aerosol inorganic salts and low-Mw DCAs change from single peak or double peaks in summer to triple or multiple peaks in autumn. During the high pollution period, the maximum concentration peaks for low-Mw DCAs dominant in the condensation mode of 0.19-0.32 um. This reveals that particle coagulation and photochemical products contribute to the observed aerosols during the high pollution period. Additionally, the aerosol succinic (C4) and malonic acids (C3) have different maximum concentration peaks from oxalic acid (C2). During the autumn non-serious pollution period and high pollution period, the maximum concentration peak for oxalic acid shifts toward the nanometer range indicating that the autumn sol oxalic acid is an end photochemical product from C4 and C3 low-Mw DCAs.
    關聯: 校內外均一年後公開
    顯示於類別:[環境工程與科學系(所)] 博碩士論文

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