The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State
The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State
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DOI：
10.3390/atmos9040131
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发表时间：
2018-03
期刊：
影响因子：
2.9
通讯作者：
Shashank Jain;Kevin B. Fischer;G. Petrucci
中科院分区：
文献类型：
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作者：
Shashank Jain;Kevin B. Fischer;G. Petrucci
绝对二次有机气溶胶（SOA）质量负荷（CSOA）是决定半挥发性和中等挥发性化合物分配到颗粒相的关键参数。然而，它对SOA阶段状态的影响在很大程度上仍未被探索。在这项研究中，进行了系统的实验室室测量，以阐明CSOA（范围为0.2至160 µg m−3）对臭氧分解各种前体（包括α-蒎烯、柠檬烯、顺式-3-己烯基乙酸酯（CHA）和顺式-3-己烯-1-醇（HXL））形成的SOA相态的影响。利用先前建立的估计SOA反弹因子（BF，颗粒粘度的替代物）的方法来推断作为CSOA的函数的颗粒粘度。结果表明，在名义上相同的条件下，最大BF下降约30%，在更高的CSOA，这表明一个更液相状态。除了HXL-SOA（作为阴性对照），所有研究的SOA前体的相态随CSOA的变化而变化。此外，当SOA颗粒分布达到50-60 nm的几何平均粒径时，BF被发现是最大的。实验结果表明，CSOA是一个重要的参数，影响SOA的相态，加强最近的研究结果，外推实验不进行大气相关的SOA水平可能不会产生结果，是相关的自然环境。
Absolute secondary organic aerosol (SOA) mass loading (CSOA) is a key parameter in determining partitioning of semi- and intermediate volatility compounds to the particle phase. Its impact on the phase state of SOA, however, has remained largely unexplored. In this study, systematic laboratory chamber measurements were performed to elucidate the influence of CSOA, ranging from 0.2 to 160 µg m−3, on the phase state of SOA formed by ozonolysis of various precursors, including α-pinene, limonene, cis-3-hexenyl acetate (CHA) and cis-3-hexen-1-ol (HXL). A previously established method to estimate SOA bounce factor (BF, a surrogate for particle viscosity) was utilized to infer particle viscosity as a function of CSOA. Results show that under nominally identical conditions, the maximum BF decreases by approximately 30% at higher CSOA, suggesting a more liquid phase state. With the exception of HXL-SOA (which acted as the negative control), the phase state for all studied SOA precursors varied as a function of CSOA. Furthermore, the BF was found to be the maximum when SOA particle distributions reached a geometric mean particle diameter of 50–60 nm. Experimental results indicate that CSOA is an important parameter impacting the phase state of SOA, reinforcing recent findings that extrapolation of experiments not conducted at atmospherically relevant SOA levels may not yield results that are relevant to the natural environment.