Enhanced Gas Uptake during α-Pinene Ozonolysis Points to a Burying Mechanism
Enhanced Gas Uptake during α-Pinene Ozonolysis Points to a Burying Mechanism
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α-蒎烯臭氧分解过程中气体吸收的增强表明了埋藏机制
DOI：
10.1021/acsearthspacechem.0c00163
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发表时间：
2020
影响因子：
3.4
通讯作者：
Finlayson-Pitts, Barbara J.
中科院分区：
文献类型：
--
作者：
Vander Wall, Allison C.;Wingen, Lisa M.;Perraud, Véronique;Zhao, Yue;Finlayson-Pitts, Barbara J.
了解气体如何与大气中的二次有机气溶胶粒子相互作用并被其吸收，对于预测粒子对气候和人类健康的影响至关重要。这项工作研究了三种气态有机硝酸盐（ON）是如何被吸收成由臭氧分解α-蒎烯（AP）形成的粘性颗粒的。实验在室温下的流动反应器中进行，干燥条件下，有或没有OH清除剂存在，恒定的臭氧和可变的AP浓度。每个ON都被独立地引入流动反应器，并在颗粒形成/生长过程中存在。ON气相浓度采用气相色谱-质谱法测定，颗粒相浓度采用高分辨率飞行时间气溶胶质谱法测定。除2-乙基己基硝酸酯（2-乙基己基硝酸酯）在最低AP浓度时未检出外，各ON的分配系数（KSOA）与初始AP浓度无关。测量到的ksov值大于之前平衡分配所确定的值，这表明在颗粒生长过程中，ON的掺入可能存在掩埋机制。估计的有效净吸收系数（γΟΝ）随着初始AP浓度的增加而增加。使用更新的主化学机制预测的气相氧化产物（包括二聚体和自氧化产物）浓度随着AP浓度的增加而增加，总体物种分布变化不大，这与颗粒生长过程中氮的捕获/掩埋增加从而增加γΟΝ值一致。这些结果进一步证明，如果进入的气相分子在颗粒表面有足够的停留时间，从而在随后的气表面碰撞中被掩埋，那么动力学控制的掩埋可以显著地促进颗粒的生长。
Understanding how gases interact with and are incorporated into atmospheric secondary organic aerosol particles is crucial for predicting particle effects on climate and human health. This work examined how three gaseous organic nitrates (ON) are taken up into viscous particles formed from the ozonolysis of α-pinene (AP). Experiments were performed in a flow reactor at room temperature under dry conditions, either with or without an OH scavenger present, with constant ozone and variable AP concentrations. Each ON was introduced independently into the flow reactor and was present during particle formation/growth. ON gas-phase concentrations were determined by gas chromatography–mass spectrometry, and particle phase concentrations were measured by high-resolution time-of-flight aerosol mass spectrometry. Partition coefficients (KSOA) for each ON were independent of the initial AP concentration, except for 2-ethylhexyl nitrate which was undetectable in the particles at the lowest AP concentration. MeasuredKSOAvalues were larger than those previously determined for equilibrium partitioning, which points to a potential burying mechanism for incorporation of ON during particle growth. Estimated effective net uptake coefficients (γΟΝ) were found to increase with initial AP concentration. Concentrations of gas-phase oxidation products (including dimers and autoxidation products) predicted using an updated master chemical mechanism increased with AP concentration, with little change in the overall species distribution, consistent with increased trapping/burying of ON during particle growth and thus increased values of γΟΝ. These results provide further evidence that kinetically controlled burying can contribute significantly to particle growth, provided that the incoming gas-phase molecules have sufficient residence time on the particle surface to become buriedviasubsequent gas–surface collisions.
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DOI：
--
发表时间：
2014
影响因子：
11.1
作者：
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DOI：
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