Always Lost but Never Forgotten: Gas-Phase Wall Losses Are Important in All Teflon Environmental Chambers
Always Lost but Never Forgotten: Gas-Phase Wall Losses Are Important in All Teflon Environmental Chambers
复制标题
总是丢失但永远不会忘记：气相壁损失在所有特氟龙环境室中都很重要
DOI：
10.1021/acs.est.0c0338
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Jimenez, Jose L.
中科院分区：
文献类型：
--
作者：
Krechmer, Jordan E.;Day, Douglas A.;Jimenez, Jose L.
在实验室室中测量挥发性有机化合物氧化形成的二次有机气溶胶（SOA）的产量，然后应用于区域和全球模型。气相损失到大型聚四氟乙烯壁的环境室最近已被证明，以减少SOA的产量。历史上，大多数腔室以批处理模式运行。然而，越来越多地使用连续流（CF）模式，其中反应物和产物被连续地引入腔室和从腔室排出。最近的文献报告表明，在CF室中测量的SOA产率不受气相壁损失（GWL）的影响。在这里，我们使用一个实验约束箱模型来表明，气相壁损失影响两种类型的腔室在类似的条件下运行时。我们发现CF实验在长时间（>2天）实验运行后确实减轻了气相壁损失的一些影响，但对于1天的典型文献实验时间，它们具有显著的损失。然而，这种缓解现象是一个实验和机制依赖性，GWL仍然影响SOA的绝对产量。最后，我们表明，在冷凝汇值高于壁损失率的产量与种子表面积的变化缺乏并不一定表明GWL是否影响实验，并没有建议的幅度。
Yields of secondary organic aerosol (SOA) formation from oxidation of volatile organic compounds are measured in laboratory chambers and then applied in regional and global models. Gas-phase losses to large Teflon-walled environmental chambers have been recently shown to reduce SOA yields. Historically, most chambers have operated in batch mode. Increasingly, however, continuous flow (CF) mode is being used, in which reactants and products are continuously introduced and exhausted from the chamber. Recent literature reports indicate a belief that SOA yields measured in CF chambers are not affected by gas-phase wall losses (GWL). Here, we use an experimentally-constrained box model to show that gas-phase wall losses impact both types of chambers when run under similar conditions. We find CF experiments do mitigate some effects of gas-phase wall losses after long (>2 days) experiment run times, but they have significant losses for typical literature experiment times of 1 day. However, this mitigation phenomenon is an experiment- and mechanism-dependent, and GWL still affects the absolute SOA yield. Finally, we show that at condensation sink values higher than the wall loss rate a lack of change in yield vs seed surface area does not necessarily indicate whether GWL affects the experiment and does not suggest the magnitude.