Abstract The vertical structure of volatile organic compounds (VOCs) is important to understanding the formation mechanisms of O3 and secondary organic aerosol (SOA). To explore the vertical evolution characteristics of VOCs, an observational field campaign using a tethered balloon was carried out in Yuanshi County, Shijiazhuang, from January 8 to 16, 2019. Meteorological variables of the planetary boundary layer (PBL) were measured, and 83 VOC samples were collected. The concentrations of 87 compounds and a total of 10 vertical profiles were obtained. The VOC concentration gradually decreased from the surface to 1000 m, decreasing by 34.8% from the surface to 400 m and 11.4% from 400 m to 1000 m. The proportion of alkanes increased from 60.2% to 79.0%; the proportions of alkenes, halohydrocarbons, and acetylene decreased from 11.8%, 12.3%, and 4.2% to 4.5%, 2.8%, and 1.8%, respectively; and the proportion of aromatics changed very little. The vertical evolution of VOCs had responses to different meteorological conditions in the PBL. The concentration decreased slower in a strong convection state than in a stable state. The VOC concentration at night was higher in the stable boundary layer (SBL) (235 ± 135 ppbv) than in the residual layer (RL) (181 ± 135 ppbv). The concentration and NO3 loss rate of alkenes decreased in the RL at night, implying that the nighttime SOA formation potential may be weaker in the RL.

中文翻译：

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冬季华北平原行星边界层VOC浓度和反应性垂直下降

摘要 挥发性有机化合物 (VOCs) 的垂直结构对于理解 O3 和二次有机气溶胶 (SOA) 的形成机制具有重要意义。为探究VOCs的垂直演化特征，2019年1月8日至16日在石家庄元始县开展了系留气球实地观测活动，测量了行星边界层（PBL）的气象变量，测得83个VOCs收集了样品。获得了 87 种化合物的浓度和总共 10 个垂直分布图。VOC浓度从地表到1000 m逐渐降低，从地表到400 m下降34.8%，从400 m到1000 m下降11.4%。烷烃比例从60.2%提高到79.0%；烯烃、卤代烃和乙炔的比例分别从 11.8%、12.3% 和 4 下降。分别为 2% 至 4.5%、2.8% 和 1.8%；芳香剂的比例变化很小。VOCs 的垂直演化对 PBL 中不同的气象条件有响应。强对流状态下的浓度下降比稳定状态下的要慢。夜间 VOC 浓度在稳定边界层 (SBL) (235 ± 135 ppbv) 中高于残留层 (RL) (181 ± 135 ppbv)。夜间RL 中烯烃的浓度和NO3 损失率降低，表明RL 夜间SOA 形成潜力可能较弱。夜间 VOC 浓度在稳定边界层 (SBL) (235 ± 135 ppbv) 中高于残留层 (RL) (181 ± 135 ppbv)。夜间RL 中烯烃的浓度和NO3 损失率降低，表明RL 夜间SOA 形成潜力可能较弱。夜间 VOC 浓度在稳定边界层 (SBL) (235 ± 135 ppbv) 中高于残留层 (RL) (181 ± 135 ppbv)。夜间RL 中烯烃的浓度和NO3 损失率降低，表明RL 夜间SOA 形成潜力可能较弱。