中文摘要 为探究珠江三角洲城区大气甲醛的垂直分布特征，本研究首次在广州塔上3个不同高度点开展了甲醛的同步观测.在2018年秋季连续32 d使用2，4-二硝基苯肼（DNPH）法采集午间1 h甲醛样品，并通过高效液相色谱（HPLC）进行分析.结果表明，广州塔地面、118 m点和488 m点的甲醛浓度均值分别为（5.10±1.93）、（6.61±2.84）和（5.33±2.55）μg·m-3.3个高度观测点的甲醛浓度均与大气氧化剂Ox存在正相关性（R为0.65~0.75），表明光化学过程是广州市城区甲醛的重要来源.甲醛垂直浓度廓线依据分布形状分为3类，出现频率最高的一类为上下低中间高，发生在边界层对流较为温和、光化学反应活跃的状态下，中高层（118 m）可能受到来自较远处的工业高架源传输影响.根据垂直浓度梯度估算出广州塔点的甲醛垂直柱浓度均值为（11.23±4.80）×1015 molecules·cm-2，比同期卫星提供的甲醛柱浓度低19%，和已有报道值数量级一致. 英文摘要 To investigate the vertical distribution of atmospheric formaldehyde in the Pearl River Delta (PRD) urban area, simultaneous measurements were performed at three heights on Canton Tower for the first time. Carbonyls including formaldehyde were sampled with 2,4-dinitrophenylhydrazin (DNPH) at noon for 32 days in autumn of 2018, and then analyzed using high-performance liquid chromatography (HPLC). Average mass concentrations of formaldehyde at ground level, 118 m, and 488 m sites at Canton Tower were (5.10±1.93), (6.61±2.84), and (5.33±2.55) μg·m-3, respectively. The measured formaldehyde was positively correlated with atmospheric oxidant Ox at the three sites (R 0.65-0.75), indicating that photochemical formation is an important source for urban formaldehyde in PRD. Three different profiles were found for formaldehyde vertical distribution during the measurements. The most frequently observed one showed a higher value at 118 m while lower ones at ground level and 488 m, occurring when the boundary layer is in moderate convection state with high photochemical reactivity. The 118 m layer may be also influenced by transported high-chimney emissions from industries in suburban areas. Vertical columns of formaldehyde were also calculated according to its vertical profile. The average value was (11.23±4.80)×1015 molecules·cm-2, 19% lower than that from satellite retrieval, while in the same magnitude as values reported in reference papers.
PDF全文下载地址:
https://www.hjkx.ac.cn/hjkx/ch/reader/create_pdf.aspx?file_no=20201216&flag=1&journal_id=hjkx&year_id=2020
