General discussion: Aerosol formation and growth; VOC sources and secondary organic aerosols.
General discussion: Aerosol formation and growth; VOC sources and secondary organic aerosols.
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一般性讨论：气溶胶的形成和增长；
DOI：
10.1039/d1fd90011k
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发表时间：
2021
影响因子：
3.4
通讯作者：
Alam MS
中科院分区：
文献类型：
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作者：
Alam MS
罗伊·哈里森 (Roy Harrison) 开始对 Markku Kulmala 的论文进行讨论：感谢您非常有趣的演讲。我对这项工作有一个问题；您提出的机制看起来完全合理，但它取决于二甲胺的排放，您得出的结论是二甲胺主要来自道路交通。如果是这样的话，我预计这种机制在北京这座交通密集的城市比周围的乡村更为普遍，但二次气溶胶浓度差异很小。因此，我认为它不能完全一致地解释我们在北京看到的由二次成分造成的高浓度雾霾。您对二甲胺的重要性有什么看法吗？除了道路交通之外还有其他来源吗？Markku Kulmala 回复： 谢谢 Roy 提出的非常好的评论和问题。看起来，对于最初的聚类，DMA 和硫酸是城市环境中的关键分子。然而，氨在许多环境中也发挥着至关重要的作用，这两条路线（硫酸+ DMA 或硫酸+氨）中哪一条更重要取决于这些蒸气的相对浓度。一方面，DMA 是一种非常有效的碱，只需要相当小的大气浓度。另一方面，除了流量之外，肯定还有其他 DMA 来源，例如土壤和农业。不幸的是，目前 DMA 源的特性还没有得到很好的描述。
Roy Harrison opened the discussion of the paper by Markku Kulmala: Thanks for the extremely interesting presentation. I have one issue with the work; the mechanism you propose looks entirely plausible, but it depends on emissions of dimethylamine, which you conclude come mainly from road traffic. If that’s the case, I would expect this mechanism to be much more prevalent in the city in Beijing, where there is dense traffic, than in the surrounding countryside, yet there’s very little difference in secondary aerosol concentrations. Therefore, I don’t think it holds together so well as a totally coherent explanation for the high levels of haze we see in Beijing due to secondary components. Do you have any thoughts on, essentially, how crucial dimethylamine is? Are there other sources than road traffic?Markku Kulmala responded: Thank you, Roy, for the very good comment and question. It seems that for the initial clustering, DMA and sulphuric acid are the key molecules in urban environments. However, ammonia also plays a crucial role in many environments, and which of these two routes (sulphuric acid+ DMA or sulphuric acid+ ammonia) is more important depends on the relative concentrations of these vapours. On the one hand, DMA is a very effective base and only pretty minor atmospheric concentrations are needed. On the other hand, there are certainly other DMA sources than traffic, such as soils and agriculture. Unfortunately, the DMA sources are not well characterized at the moment.