School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States.
Environ Sci Technol. 2012 Mar 20;46(6):3093-100. doi: 10.1021/es203362w. Epub 2012 Mar 2.
Secondary organic aerosol (SOA) resulting from the oxidation of organic species emitted by the Deepwater Horizon oil spill were sampled during two survey flights conducted by a National Oceanic and Atmospheric Administration WP-3D aircraft in June 2010. A new technique for fast measurements of cloud condensation nuclei (CCN) supersaturation spectra called Scanning Flow CCN Analysis was deployed for the first time on an airborne platform. Retrieved CCN spectra show that most particles act as CCN above (0.3 ± 0.05)% supersaturation, which increased to (0.4 ± 0.1)% supersaturation for the most organic-rich aerosol sampled. The aerosol hygroscopicity parameter, κ, was inferred from both measurements of CCN activity and from humidified-particle light extinction, and varied from 0.05 to 0.10 within the emissions plumes. However, κ values were lower than expected from chemical composition measurements, indicating a degree of external mixing or size-dependent chemistry, which was reconciled assuming bimodal, size-dependent composition. The CCN droplet effective water uptake coefficient, γ(cond), was inferred from the data using a comprehensive instrument model, and no significant delay in droplet activation kinetics from the presence of organics was observed, despite a large fraction of hydrocarbon-like SOA present in the aerosol.
次生有机气溶胶（SOA）是由深海地平线石油泄漏所排放的有机物种氧化形成的，在 2010 年 6 月，国家海洋和大气管理局的 WP-3D 飞机进行了两次调查飞行，对其进行了采样。一种新的快速测量云凝结核（CCN）过饱和度谱的技术，称为扫描流动 CCN 分析，首次在机载平台上部署。回收的 CCN 谱表明，大多数颗粒在（0.3±0.05）%过饱和度以上作为 CCN 起作用，对于采样的最富含有机物的气溶胶，这一比例增加到（0.4±0.1）%过饱和度。气溶胶吸湿性参数κ是通过 CCN 活性测量和加湿颗粒光衰减推断得出的，在排放羽流中从 0.05 变化到 0.10。然而，κ 值低于化学成分测量值，表明存在一定程度的外部混合或尺寸相关的化学，通过假设双峰、尺寸相关的组成，可以调和这一点。利用综合仪器模型从数据中推断出 CCN 液滴有效水吸收系数γ（cond），尽管气溶胶中存在大量类似碳氢化合物的 SOA，但没有观察到有机物质存在时液滴活化动力学的明显延迟。
