Laboratory-generated primary marine aerosol via bubble-bursting and atomization
Laboratory-generated primary marine aerosol via bubble-bursting and atomization
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DOI：
10.5194/amt-3-141-2010
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发表时间：
2010-01-01
影响因子：
3.8
通讯作者：
McFiggans, G.
中科院分区：
文献类型：
--
作者：
Fuentes, E.;Coe, H.;McFiggans, G.
一系列气泡和海雾气溶胶发生器已经在实验室进行了测试，并与文献中的海洋测量结果进行了比较。结果表明，气溶胶粒子的生成方法对气溶胶粒子的性质有很大影响。因此，模拟大气气溶胶的生成系统的有效性取决于它以现实的方式生成气泡和颗粒的能力。一种通过水撞击产生气泡的气溶胶发生器被证明最好地再现了海洋气泡的光谱形状，这证实了以前的发现。两个多孔鼓泡器和一个下水喷射系统作为气泡爆发气溶胶发生器进行了测试，并与标准雾化器进行了比较。通过分析气泡爆发系统产生的气泡谱和不同技术产生的气溶胶的亚微米尺寸分布、吸湿性和云凝结核活动，对气溶胶的产生方法进行了评价。当使用不同的气溶胶发生器时，气泡光谱和气溶胶性质有显著差异。当以纯无机盐为母体海水溶液时，不同方法产生的气溶胶具有相似的吸湿性和云凝结核活动行为；但当使用富含生物成因有机物的过滤天然海水样品时，发现气溶胶性质有显著差异。气溶胶中有机物的存在导致相对湿度高于75%时生长因子受到抑制，相对于不含有机物的人造海水的生成，临界过饱和度增加。有机物对气溶胶性质的影响程度因颗粒生产方法而异。这项工作的结果表明，气溶胶的产生机制影响到颗粒的有机浓缩，因此产生的气溶胶的行为强烈地依赖于所采用的实验室气溶胶发生器。几个实验室模拟中的气泡寿命与海洋条件的比较表明，需要对目前使用的气泡爆破实验室系统的尺寸进行相当大的扩展，才能重现典型的海洋气泡寿命。我们分析了比例系统中减少的气泡停留时间对海洋表面活性剂在上升气泡上的吸附的影响，发现达到吸附平衡的时间尺度比小型实验室发电机中的气泡寿命短得多。这意味着海洋表面活性物质的吸附不受表面活性剂向气泡表面输送的限制。
A range of bubble and sea spray aerosol generators has been tested in the laboratory and compared with oceanic measurements from the literature. We have shown that the method of generation has a significant influence on the properties of the aerosol particles produced. Hence, the validity of a generation system to mimic atmospheric aerosol is dependent on its capacity for generating bubbles and particles in a realistic manner. A bubble-bursting aerosol generator which produces bubbles by water impingement was shown to best reproduce the oceanic bubble spectral shapes, which confirms previous findings.Two porous bubblers and a plunging-water jet system were tested as bubble-bursting aerosol generators for comparison with a standard nebulizer. The methods for aerosol production were evaluated by analysing the bubble spectrum generated by the bubble-bursting systems and the submicron size distribution, hygroscopicity and cloud condensation nucleus activity of the aerosols generated by the different techniques. Significant differences in the bubble spectrum and aerosol properties were observed when using different aerosol generators. The aerosols generated by the different methods exhibited similar hygroscopicity and cloud condensation nucleus activity behaviour when a sample of purely inorganic salts was used as a parent seawater solution; however, significant differences in the aerosol properties were found when using samples of filtered natural seawater enriched with biogenic organics. The presence of organics in the aerosol caused suppression of the growth factor at humidities above 75% RH and an increase in the critical supersaturation with respect to the generation from artificial seawater devoid of organics. The extent of the effect of organics on the aerosol properties varied depending on the method of particle production. The results of this work indicate that the aerosol generation mechanism affects the particles organic enrichment, thus the behaviour of the produced aerosols strongly depends on the laboratory aerosol generator employed.Comparison between bubble lifetimes in several laboratory simulations and the oceanic conditions indicated that it would require a considerable extension of the dimensions of the currently used bubble-bursting laboratory systems in order to replicate the characteristic oceanic bubble lifetimes. We analyzed the implications derived from the reduced bubble residence times in scaled systems, regarding marine surfactants adsorption on rising bubbles, and found that adsorption equilibrium is reached on a timescale much shorter than the bubble lifetime in small-scale laboratory generators. This implies that adsorption of marine surface-active material is not limited by surfactant transport to the bubble surface.