Effects of the VACES particle concentrator on secondary organic aerosol and ambient particle composition
Effects of the VACES particle concentrator on secondary organic aerosol and ambient particle composition
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DOI：
10.1080/02786826.2022.2081065
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发表时间：
2022-05-28
影响因子：
5.2
通讯作者：
Kleinman，M. T.
中科院分区：
文献类型：
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作者：
Wingen，L. M.;Herman，D. A.;Kleinman，M. T.
对多功能气溶胶浓缩系统(VACES)浓缩颗粒物的效果进行了研究，重点考察了有机颗粒物的组成。VACES使用水冷凝来生长颗粒，并通过虚拟撞击来浓缩颗粒浓度，然后通过扩散干燥来去除多余的液态水。用气溶胶-质谱仪比较了实验室臭氧分解α-Pinene二次有机气溶胶及其周围颗粒物在真空气相化学气相沉积前后的亚微米有机成分。在VACES后，两种类型的样品的尺寸分布都保持不变。SOA颗粒在浓缩后形成了高分子量化合物，这表明在水的冷凝和/或蒸发阶段会发生一些齐聚反应，但元素组成只有轻微的变化。环境中的颗粒物也观察到了齐聚现象，尤其是积聚模式下O/C值较高的颗粒物。环境中O/C较低的超细颗粒物没有得到有效的浓缩。有机部分的这种组成变化可能与其他方法有关，在这些方法中，颗粒通过吸水生长，然后干燥，以及涉及吸水和蒸发的大气过程。在颗粒质量的背景下，齐聚程度较小。然而，鉴于颗粒浓缩器在健康效应和颗粒组成研究中的广泛使用，这是否会影响使用颗粒浓缩器时对健康效应和颗粒组成数据的解释，还需要进一步探讨。版权所有©2022美国气溶胶研究协会
The effects of concentrating particles using the Versatile Aerosol Concentration Enrichment System (VACES) were investigated with a focus on the organic particle composition. The VACES uses water condensation to grow particles and allow enrichment in particle concentrations by virtual impaction, followed by diffusion drying to remove excess liquid water. Aerosol mass spectrometry was used to compare the submicron organic composition before and after the VACES for laboratory-generated secondary organic aerosol (SOA) from ozonolysis of α-pinene as well as ambient particles. Size distributions were retained after the VACES for both types of samples. SOA particles showed evidence of high molecular weight compounds forming after enrichment, suggesting that some oligomerization occurs during the water condensation and/or evaporation stages, but with only slight changes in the elemental composition. Oligomerization was also observed for ambient particles, especially those with higher O/C in the accumulation mode. Ambient ultrafine particles with low O/C were not as efficiently enriched. Such composition changes in the organic fraction may be relevant to other methodologies where particles are grown through water uptake and then dried, as well as to atmospheric processes involving water uptake and evaporation. In the context of particle mass, the extent of oligomerization is small. However, given the widespread use of particle concentrators in health effects and particle composition studies, whether this impacts interpretation of health effects and particle composition data when using particle concentrators needs further exploration.Copyright © 2022 American Association for Aerosol Research