| 气溶胶中不同类型碳组分粒径分布特征 |
| 摘要点击 2027 全文点击 776 投稿时间：2019-03-06 修订日期：2019-04-02 |
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| 中文关键词 北京 气溶胶 碳组分 粒径分布 OC/EC |
| 英文关键词 Beijing aerosol carbonaceous component size distribution OC/EC |
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| 中文摘要 |
| 了解气溶胶碳组分粒径分布特征对于研究区域气溶胶生成转化机制、辐射特性等非常重要，但北京地区针对气溶胶碳组分粒径分布特征的相关研究非常少.本研究利用MOUDI-120采样器在北京地区3个季节开展气溶胶分级样品的采集，并分析其中不同类型的碳组分的含量，进而系统研究不同季节及污染状况下，各碳组分的粒径分布特征、来源及相互关系.结果表明，碳组分主要富集在细粒子中，秋冬季细粒子中碳组分的比重高于夏季.碳组分主要分布在两个模态，即积聚模态和粗模态.OC1和OC2主要分布在积聚模态，在0.056~0.56 μm范围内有较高比例，OC3+OC4在粗模态的分布较为明显.Soot-EC浓度较低，没有明显的粒径分布特征，在0.10~0.18 μm粒径段浓度较高，表明高温燃烧排放的EC主要分布在超细粒径段.Char-EC浓度远高于Soot-EC，在EC中占绝大部分比重.各主要碳组分在白天和夜晚的分布形态基本一致.夏季和冬季较有利于SOC的形成，OC/EC比值明显高于秋季.OC/EC值在不同粒径区间中差异很大，由于水溶性有机物（WSOC）主要分布在0.056~0.10 μm，OC/EC值明显高于其他粒径段.白天及高温有利于气态有机物氧化生成SOC，致使夏季白天的OC/EC比值明显高于夜晚.各碳组分之间，EC1和OC1相关性最强，此外EC1和K+也有很强的相关性. |
| 英文摘要 |
| It is important to obtain the size distribution of carbonaceous components in aerosols for studying the formation and transformation mechanisms and radiation characteristics of regional aerosols. However, only a few studies on the size distribution of aerosol carbonaceous fractions have been conducted in Beijing. In this study, a Micro-Orifice Uniform Deposit Impactor (MOUDI)-120 sampler was used to collect size-resolved aerosol samples in three seasons in Beijing, and the concentrations of different types of carbonaceous fractions were analyzed. Furthermore, the size distribution, characteristics, sources, and interrelationship of each carbonaceous component in different seasons and under different pollution levels were systematically studied. The results show that the carbonaceous components were concentrated mainly in fine particles, and the proportion of carbonaceous components in fine particles in autumn and winter was higher than that in summer. The carbonaceous components are distributed in two main modes:accumulation mode and coarse mode. Organic carbon fraction 1 (OC1) and OC2 were distributed mainly in the accumulated mode, with a higher proportion in the range of 0.056-0.56 μm, and OC3+OC4 was more abundant in the coarse mode. The concentration of Soot-elemental carbon (EC) was low but was highest in the 0.10-0.18 μm size range, which indicates that the EC emitted by high temperature combustion was distributed mainly in the ultra-fine particle size range. The Char-EC concentration was much higher, accounting for the majority of EC. The distribution appearances of the main carbonaceous components were essentially the same in the daytime and at night. Summer and winter were more conducive to the formation of SOC, and the OC/EC ratio was significantly higher than that in autumn. The OC/EC values varied greatly in different particle sizes because the water-soluble organic compounds (WSOC) were distributed mainly in the range of 0.056-0.10 μm, with significantly higher OC/EC values than other particle sizes. Sunlight and high temperature were beneficial to the oxidation of gaseous organic matter to SOC, resulting in the OC/EC ratio in summer in daytime to be significantly higher than that at night. Among the carbonaceous components, EC1 and OC1 had the strongest interrelation. In addition, EC1 also had stronger interrelation with potassium. |
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