Robust quantification of the burst of OH radicals generated by ambient particles in nascent cloud droplets using a direct-to-reagent approach
Robust quantification of the burst of OH radicals generated by ambient particles in nascent cloud droplets using a direct-to-reagent approach
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DOI：
10.1016/j.scitotenv.2023.165736
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发表时间：
2023-07-29
影响因子：
9.8
通讯作者：
Paulson，Suzanne E.
中科院分区：
文献类型：
--
作者：
Taghvaee，Sina;Shen，Jiaqi;Paulson，Suzanne E.
活性氧 (ROS) 在云水化学以及肺液等其他水相和废水处理中发挥着核心作用。最近，模拟新生云滴的工作表明，气溶胶颗粒在第一次吸收水时会产生大量的 OH 自由基。此活动在两分钟内突然停止。 OH自由基的来源尚不清楚，但它可能包括ROS和/或有机氢过氧化物以及氧化还原活性金属（例如铁和铜）的水相化学。 ROS 及其前体通常具有高反应性和不稳定性，因此在传统采样方法中可能无法存活，传统采样方法通常需要在过滤器上进行数小时收集或直接采样到水或其他收集液体中。此外，这些物质可能在储存过程中进一步腐烂。在这里，我们开发了一种技术，将气溶胶颗粒生长成小液滴，并将液滴直接捕获到装有对苯二甲酸酯探针的水中的小瓶中，该小瓶立即清除气溶胶颗粒产生的 OH 自由基。该方法使用液体点样取样器。该方法的广泛表征表明，收集液体从气相中吸收了大量的 OH/OH 前体。通过添加活性炭去除器可以有效解决这个问题。然后，我们比较了直接试剂法与过滤器收集法测量的 OH 形成。我们发现，在对收集液体中形成的 OH 进行适度校正后，收集到试剂中的样品产生的 PM2.5 和总悬浮颗粒物产量约为过滤器上收集的样品的六倍。这突出表明需要采用直接试剂测量方法来准确量化环境气溶胶颗粒产生的 OH。
Reactive oxygen species (ROS) play a central role in chemistry in cloud water, as well as in other aqueous phases such as lung fluid and in wastewater treatment. Recently, work simulating nascent cloud droplets showed that aerosol particles produce a large burst of OH radicals when they first take up water. This activity stops abruptly, within two minutes. The source of the OH radicals is not well understood, but it likely includes the aqueous phase chemistry of ROS and/or organic hydroperoxides and redox active metals such as iron and copper. ROS and their precursors are in general highly reactive and labile, and thus may not survive during traditional sampling methods, which typically involve multi-hour collection on a filter or direct sampling into water or another collection liquid. Further, these species may further decay during storage. Here, we develop a technique to grow aerosol particles into small droplets and capture the droplets directly into a vial containing the terephthalate probe in water, which immediately scavenges OH radicals produced by aerosol particles. The method uses a Liquid Spot Sampler. Extensive characterization of the approach reveals that the collection liquid picks up substantial OH/OH precursors from the gas phase. This issue is effectively addressed by adding an activated carbon denuder. We then compared OH formation measured with the direct-to-reagent approach vs. filter collection. We find that after a modest correction for OH formed in the collection liquid, the samples collected into the reagent produce about six times those collected on filters, for both PM2.5and total suspended particulate. This highlights the need for direct-to-reagent measurement approaches to accurately quantify OH production from ambient aerosol particles.