Evolution in physiochemical and cloud condensation nuclei activation properties of crop residue burning particles during photochemical aging
Evolution in physiochemical and cloud condensation nuclei activation properties of crop residue burning particles during photochemical aging
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光化学老化过程中作物残茬燃烧颗粒的理化和云凝结核活化特性的演变
DOI：
10.1016/j.jes.2018.06.004
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Jun Zheng
中科院分区：
文献类型：
--
作者：
Yan Ma;Chao Chen;Junfeng Wang;Youling Jiang;Zewen Zheng;Hui Chen;Jun Zheng
农作物秸秆焚烧作为农业国家生物质燃烧的主要形式，是大气细颗粒物的重要来源。在烟雾箱中对我国四种主要农作物秸秆燃烧排放的颗粒物进行了老化研究。同时测量了云的粒径分布、化学成分和云凝结核（CCN）活动。不同燃料类型的秸秆燃烧颗粒物的性质有很大差异。在老化过程中，颗粒的大小和质量浓度大幅增加，这表明通过形成二次气溶胶冷凝增长。颗粒组成以有机物为主。老化导致有机物和无机物的显著增强，增强比分别为1.24-1.44和1.33-1.76，以及有机物的氧化水平的持续增加。在老化过程中观察到CCN活性升高，新鲜颗粒的吸湿性参数κ在0.16至0.34之间变化，老化颗粒的吸湿性参数κ在0.19至0.40之间变化。根据体积混合规则，推导出了有机组分的吸湿系数（κorg）。随老化时间的延长，κ Og值呈增加趋势，这与O：C比值的变化趋势基本一致，表明秸秆焚烧有机气溶胶的氧化程度与吸湿性和CCN活性有关。结果表明，光化学老化不仅通过产生二次气溶胶，而且通过增强有机组分的吸湿性，对农作物燃烧气溶胶的CCN活化有显著影响，从而对气溶胶的间接气候强迫有贡献。
As a main form of biomass burning in agricultural countries, crop residue burning is a significant source of atmospheric fine particles. In this study, the aging of particles emitted from the burning of four major crop residues in China was investigated in a smog chamber. The particle size distribution, chemical composition and cloud condensation nuclei (CCN) activity were simultaneously measured. The properties of crop residue burning particles varied substantially among different fuel types. During aging, the particle size and mass concentration increased substantially, suggesting condensational growth by formation of secondary aerosols. The particle composition was dominated by organics. Aging resulted in considerable enhancement of organics and inorganics, with enhancement ratios of 1.24–1.44 and 1.33–1.76 respectively, as well as a continuous increase in the oxidation level of organics. Elevated CCN activity was observed during aging, with the hygroscopicity parameter κ varying from 0.16 to 0.34 for fresh particles and 0.19 to 0.40 for aged particles. Based on the volume mixing rule, the hygroscopicity parameter of organic components (κorg) was derived. κorgexhibited an increasing tendency with aging, which was generally consistent with the tendency of the O:C ratio, indicating that the oxidation level was related to the hygroscopicity and CCN activity of organic aerosols from crop residue burning. Our results indicated that photochemical aging could significantly impact the CCN activation of crop burning aerosols, not only by the production of secondary aerosols, but also by enhancing the hygroscopicity of organic components, thereby contributing to the aerosol indirect climate forcing.