| 北京市BTEX的污染现状及变化规律分析 |
| 摘要点击 2816 全文点击 1682 投稿时间：2011-05-25 修订日期：2011-07-23 |
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| 中文关键词 北京 BTEX 预浓缩-GC-MS 季节变化 日变化 |
| 英文关键词 Beijing BTEX CCD-GC-MS seasonal variation diurnal variation |
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| 中文摘要 |
| 2008年10～2009年10月,利用前级浓缩-气相色谱/质谱法,对北京市大气中5种苯系物BTEX(苯、甲苯、乙苯、间、对二甲苯、邻二甲苯)的组成及浓度变化进行了采样分析研究.结果表明,北京市大气BTEX平均浓度为13.9～44.0 μg·cm-3,其中甲苯的含量最高,苯次之,邻二甲苯含量最低,与国外城市和地区相比北京大气中BTEX浓度较低,研究发现北京市BTEX主要来自机动车排放,城市燃煤和工业溶剂挥发也是BTEX的重要来源.一年的观测结果表明,BTEX春、夏季节浓度较高,秋季浓度较低,季节性排放源的变化是BTEX季节变化的主要原因,同时也不能忽视温度和大风等天气因素对BTEX浓度的影响.受交通排放和边界层高度的影响,BTEX类化合物的日变化形式为夜晚高于白天,呈双峰形,日最低浓度出现在14:00前后. |
| 英文摘要 |
| In order to study the pollution status and the seasonal and diurnal variations, ambient concentrations of BTEX were analyzed at Beijing from 2008-10 to 2009-10, by using the method of two-step-concentration-gas spectrometry/mass (CCD-GC/MS). The average concentration of BTEX in Beijing was 13.9-44.0 μg·cm-3. The dominant compound components were toluene, benzene, followed by ethyl benzene, m/p-xylene, o-xylene. Compared with foreign cities and regions, the level of BTEX at Beijing atmosphere was relatively lower. The study found that BTEX in Beijing mainly came from vehicle emissions, coal and solvent evaporation were also important sources of BTEX. No significantly obvious seasonal variation was observed, with the highest concentrations observed in spring and summer and the lowest concentrations generally found in autumn. Seasonal variations of emission sources were the main reason for seasonal changes of BTEX. However, the impact of weather factors on the BTEX can not be ignored, such as temperature and strong winds. Significant diurnal variations in BTEX were observed. The BTEX concentrations displayed a bimodal pattern, with peak between 08:00 and 10:00. and between 16:00 and 08:00. The minimum concentration generally appeared around 14:00. |
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