Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), CNRS , Université Lyon 1 , 69626 Villeurbanne , France.
Department of Chemistry , University of California, Berkeley , Berkeley , California 94720 , United States.
Environ Sci Technol. 2019 Nov 5;53(21):12379-12388. doi: 10.1021/acs.est.9b03386. Epub 2019 Oct 10.
Predicting the activation of submicrometer particles into cloud droplets in the atmosphere remains a challenge. The importance of surface tension, σ (mN m), in these processes has been evidenced by several works, but information on the "surfactants" lowering σ in actual atmospheric particles remains scarce. In this work, PM aerosols from urban, coastal, and remote regions of Europe (Lyon, France, Rogoznica, Croatia, and Pallas, Finland, respectively) were investigated and found to contain amphiphilic surfactants in concentrations up to 2.8 μg m in the air and 1.3 M in the particle dry volume. In Pallas, correlations with the PM chemical composition showed that amphiphilic surfactants were present in the entire range of particle sizes, supporting recent works. This implied that they were present in hundreds to thousands of particles cm and not only in a few large particles, as it has been hypothesized. Their adsorption isotherms and critical micelle concentration (CMC) were also determined. The low CMC obtained (3 × 10-9 × 10 M) implies that surface tension depression should be significant for all the particles containing these compounds, even at activation (growth factor ∼ 10). Amphiphilic surfactants are thus likely to enhance the CCN ability of submicrometer atmospheric particles.
预测大气中亚微米颗粒转化为云滴的过程仍然具有挑战性。表面张力σ（毫牛顿/米）在这些过程中的重要性已被多项研究证明，但有关实际大气颗粒中降低σ的“表面活性剂”的信息仍然很少。在这项工作中，研究了来自欧洲城市、沿海和偏远地区的 PM 气溶胶（分别为法国里昂、克罗地亚罗戈日尼察和芬兰帕拉斯），发现它们在空气中含有浓度高达 2.8 μg m 的两亲性表面活性剂，在颗粒干体积中含有 1.3 M 的表面活性剂。在帕拉斯，与 PM 化学成分的相关性表明，两亲性表面活性剂存在于整个颗粒尺寸范围内，这支持了最近的研究。这意味着它们存在于数以百计到数千个颗粒 cm 中，而不仅仅是在少数几个大颗粒中，如之前假设的那样。还确定了它们的吸附等温线和临界胶束浓度（CMC）。得到的低 CMC（3×10-9×10 M）意味着即使在颗粒激活（生长因子∼10）时，这些化合物也会显著降低表面张力。因此，两亲性表面活性剂很可能会增强亚微米大气颗粒的 CCN 能力。
