State Key Laboratory of Severe Weather & Key Laboratory of Atmospheric Chemistry of CMA, Chinese Academy of Meteorological Sciences, Beijing 100081, China.
State Key Laboratory of Severe Weather & Key Laboratory of Atmospheric Chemistry of CMA, Chinese Academy of Meteorological Sciences, Beijing 100081, China; State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, 730000 Lanzhou, China.
Sci Total Environ. 2019 Nov 25;693:133521. doi: 10.1016/j.scitotenv.2019.07.327. Epub 2019 Jul 20.
The aerosol liquid water content (ALWC) of submicron particles (PM) was calculated in this work by three methods based on the aerosol physical and chemical properties measurement campaigns in winter in Beijing, including (a) the PM volume difference between the ambient and dry states by applying the particle number size distribution and particle hygroscopicity measurement; (b) the thermodynamic equilibrium model (ISORROPIA II) based on the chemical composition; and (c) the κ-Köhler theory of chemical composition with a volume mixing scheme. The three methods agreed well with reasonable uncertainties. The ALWC showed an exponential trend depending on the relative humidity (RH), and an abundant ALWC was also favored by the high PM mass loading. The contribution of different chemical component to the ALWC was evaluated by the κ-Köhler method, which revealed that during the measurement, the inorganics and organics could contribute to ~80% and ~20%, respectively, under ambient RH conditions, with the largest contributor of ammonium nitrate. When the RH was above 85%, the mass concentration of ALWC was comparable to, or even larger than, that of the dry PM.
本工作通过三种方法计算了冬季北京大气颗粒物（PM）亚微米粒子的气溶胶液水含量（ALWC），这三种方法基于气溶胶物理化学性质测量实验，包括：（a）应用粒子数浓度粒径分布和粒子吸湿性测量，计算环境态和干燥态下 PM 体积差；（b）基于化学成分的热力学平衡模型（ISORROPIA II）；以及（c）具有体积混合方案的化学成分 κ-Köhler 理论。这三种方法的结果差异合理，一致性较好。ALWC 随相对湿度（RH）呈指数趋势，且 PM 质量浓度较高时也有利于形成丰富的 ALWC。κ-Köhler 方法评估了不同化学成分对 ALWC 的贡献，结果表明，在测量期间，无机物和有机物在环境 RH 条件下分别可贡献约 80%和 20%左右，其中最大的贡献者是硝酸铵。当 RH 高于 85%时，ALWC 的质量浓度可与干燥态 PM 的质量浓度相当，甚至更大。
