| 南京冬季气溶胶光学特性及黑碳光吸收增强效应 |
| 摘要点击 2140 全文点击 733 投稿时间：2017-11-24 修订日期：2018-01-10 |
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| 中文关键词 气溶胶 光学特性 黑碳 覆盖物 光吸收增强 |
| 英文关键词 aerosol optical properties element carbon coating materials light absorption enhancement |
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| 中文摘要 |
| 2016年1月1~19日在南京北郊利用三波长光声黑碳光度仪（PASS-3）对气溶胶的光学性质进行了实时在线观测，同时结合气溶胶化学组成分析了黑碳气溶胶的光吸收增强效应.结果表明，观测期间气溶胶在532 nm下的吸收系数、散射系数、单散射反照率的平均值为（64.19±35.28） Mm-1、（454.68±238.71） Mm-1、0.87±0.03，受边界层高度及颗粒物浓度的影响，呈现出明显的日变化特征.黑碳气溶胶的质量吸收截面（MAC）在观测期间的变化趋势为前期低，后期高，与非EC组分相对EC比值的变化趋势一致，受不同污染条件下二次物质的占比及覆盖物厚度变化的影响.基于MAC计算得到的405、532、781nm下的光吸收增强（EMAC）平均值分别为1.53±0.56、1.34±0.47、1.14±0.40，随着波长增加而降低，存在棕色碳（BrC）的贡献.各非EC组分相对EC的比值与EMAC均有一定相关性，其中OC/EC与EMAC相关性最高，说明有机物的积累是导致黑碳光吸收增强的主要原因.K+/EC与EMAC的高相关性表明生物质燃烧过程对光吸收增强也有一定影响. |
| 英文摘要 |
| A three-wavelength photoacoustic soot spectrometer (PASS-3) was employed for real-time online measurement of aerosol optical properties and light absorption enhancement of EC together with chemical composition analysis in the northern suburb of Nanjing during January 1-19, 2016. The average aerosol absorption coefficient, scattering coefficient, and single scattering albedo at 532 nm during the observation period were (64.19±35.28) Mm-1, (454.68±238.71) Mm-1, and 0.87±0.03, respectively, and showed clear diurnal variation, mainly affected by planetary boundary layer height and PM2.5 mass concentration. The mass absorption cross section (MAC) showed an increasing trend during the observation period, consistent with the trend of variation in ratios between non-EC and EC components, resulting from the difference in relative percentage of secondary materials and coating thickness under different pollution conditions. The estimated light absorption enhancement, denoted EMAC, was calculated based on the change in MAC. The campaign-averaged EMAC at 405, 532, and 781 nm were 1.53±0.56, 1.34±0.47, and 1.14±0.40, respectively, showing a decrease with increasing wavelength, suggesting the contribution of brown carbon (BrC). All non-EC components showed linear correlation with EMAC, with the most significant correlation between OC/EC and EMAC, indicating that an increase in organics was likely the main contributor to light absorption enhancement in our study. In addition, the high correlation of K+/EC and EMAC revealed the contribution of biomass burning. |
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