| 2008~2010年北京城区大气BTEX的浓度水平及其O3 生成潜势 |
| 摘要点击 2060 全文点击 1321 投稿时间：2012-09-11 修订日期：2012-12-04 |
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| 中文关键词 大气污染 被动采样法 苯系物 O3生成潜势 北京 |
| 英文关键词 atmospheric pollution passive sampling BTEX ozone formation potentials Beijing |
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| 中文摘要 |
| 苯、甲苯、乙苯及二甲苯是典型的人为排放有机物,不仅危害人体健康还参与对流层的光化学反应,生成O3和二次有机气溶胶. 为认知北京大气中BTEX的浓度水平,评估其O3生成潜势,于2007年12月~2010年11月使用被动采样和化学分析相结合的方法对BTEX和O3浓度进行了连续3 a的同步观测. 结果表明,北京城区大气BTEX中甲苯的浓度高达(8.7±3.1)μg·m-3,其次为苯、乙苯和间对二甲苯,浓度分别为(7.1±3.3)、(4.2±1.4)和(3.4±1.5)μg·m-3. BTEX总浓度在春、夏、秋和冬季的平均值分别为(16.8±1.4)、(24.7±2.8)、(25.9±4.9)和(26.8±12.1)μg·m-3,冬季苯的浓度全年最高,而夏季甲苯浓度高于冬季. 采用最大增量反应活性方法计算了北京城区大气BTEX夏季O3生成潜势,发现间对二甲苯的贡献最大. 北京2008、2009和2010年夏季BTEX的O3生成潜势分别为65.2、60.2和75.7 μg·m-3,与O3实际浓度的年际变化趋势一致(同期浓度分别为80.5、65.0和101.9 μg·m-3). 机动车尾气和溶剂挥发是北京城区大气BTEX的主要来源,冬季苯的浓度可能受取暖燃煤的影响,夏季溶剂挥发对BTEX影响更大,并对O3的生成有一定贡献. |
| 英文摘要 |
| Benzene, toluene, ethylbenzene and dimethylbenzene are typical anthropogenic emitted organics in the atmosphere, which not only endanger human health but also actively participate in photochemical reactions, generating O3 and secondary organic aerosols. In order to investigate the pollution level and its ozone formation potentials, concentrations of BTEX and O3 were parallel measured by the passive sampler and analyzed using GC-MS and ICS-90 during 2008-2010 in urban Beijing. The results show that toluene was the most abundant compound (8.7±3.1) μg·m-3, followed by benzene, ethylbenzene and m/p-xylene, with concentrations of (7.1±3.3), (4.2±1.4) and (3.4±1.5) μg·m-3, respectively. Concentrations of BTEX peaked in winter, followed by autumn, summer, and spring, with values of (26.8±12.1), (25.9±4.9),(24.7±2.8) and (16.8±1.4) μg·m-3, respectively. Benzene concentrations were the highest in winter, while for toluene, the concentration was higher in summer than that in winter. Based on the maximum incremental reactivity scale, m/p-xylene was found to be the dominant contributor to ozone formation among BTEX. The ozone formation potentials of BTEX in Beijing were 65.2, 60.2, and 75.7 μg·m-3 in 2008, 2009, and 2010, respectively, which were consistent with the measured values of 80.5, 65.0, and 101.9 μg·m-3during the corresponding period. Vehicular emission and solvent evaporation were the major sources of BTEX. Concentrations of benzene were affected by coal heating in winter, whereas BTEX concentration was more influenced by solvent evaporation in summer, which had an important contribution to the formation of O3 in urban Beijing. |
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