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    Please use this identifier to cite or link to this item: http://ir.cnu.edu.tw/handle/310902800/23257


    標題: Size Distributions of Nano/micron Dicarboxylic Acids and Inorganic Ions in Suburban PM Episode and Non-episodic Aerosol
    作者: Li-Ying Hsieh
    Su-Ching Kuo
    Chien-Lung Chen
    Ying I. Tsai
    貢獻者: 環境工程與科學系
    關鍵字: Organic compounds
    Size-resolved PM
    Nanoparticles
    Episode
    Suburban aerosol
    In-cloud processes
    日期: 2009-09
    上傳時間: 2010-11-18 11:46:11 (UTC+8)
    摘要: The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16–17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5–100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2–82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution period to 28.08% during the PM episode, favoring dicarboxylic acid formation in the nuclei mode. The evidence suggests stronger formation strength and contribution potential exists for dicarboxylic acids than for inorganic salts in nanoscale particles, especially in PM episode aerosol.
    Appears in Collections:[環境工程與科學系(所)] 期刊論文
    [醫藥化學系 ] 期刊論文

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