近日，美国阿贡国家实验室Caravan, R. L.和英国曼彻斯特大学Percival, C. J.及其课题组成员的研究，揭示了与对流层气溶胶形成有关的克里基中间低聚反应的观测证据。相关论文于2024年3月5日发表在《自然—地球科学》杂志上。
从亚马逊雨林的颗粒和气相质谱测量中，研究人员确定了与预期的CH2OO克里基中间体低聚化特征一致的质量序列，这一过程涉及臭氧分解驱动的气溶胶形成。研究人员使用实验室臭氧分解实验、克里基中间反应的直接动力学研究，和高水平的理论计算来评估低聚化的潜在贡献。基于这些动力学结果建立的全球大气模型表明，特别是在高湿地区，克里基中间化学可能在改变地球对流层组成方面，发挥比当前大气模型所捕获的更大的作用。
然而，这些模型仍然只捕获到相对小部分的观测到的信号，相当低估了克里基中间体浓度和反应性，和/或其他目前尚未表征的氧化机制的主导作用。研究结果强调，要明确评估克里基中间体低聚反应的作用，需要解决排放清单中剩余的不确定性以及大气水蒸气对关键化学反应的影响，以明确评价克里基中间寡聚化反应的作用。
据介绍，克里基中间体是活性中间体，与改变地球对流层的组成和二次有机气溶胶的形成有关，影响地球的辐射平衡、空气质量和人类健康。然而，在现场直接识别它们的痕迹仍然是不可能的。
附：英文原文
Title: Observational evidence for Criegee intermediate oligomerization reactions relevant to aerosol formation in the troposphere
Author: Caravan, R. L., Bannan, T. J., Winiberg, F. A. F., Khan, M. A. H., Rousso, A. C., Jasper, A. W., Worrall, S. D., Bacak, A., Artaxo, P., Brito, J., Priestley, M., Allan, J. D., Coe, H., Ju, Y., Osborn, D. L., Hansen, N., Klippenstein, S. J., Shallcross, D. E., Taatjes, C. A., Percival, C. J.
Issue&Volume: 2024-03-05
Abstract: Criegee intermediates are reactive intermediates that are implicated in transforming the composition of Earth’s troposphere and in the formation of secondary organic aerosol, impacting Earth’s radiation balance, air quality and human health. Yet, direct identification of their signatures in the field remains elusive. Here, from particulate and gas-phase mass-spectrometric measurements in the Amazon rainforest, we identify sequences of masses consistent with the expected signatures of oligomerization of the CH2OO Criegee intermediate, a process implicated in ozonolysis-driven aerosol formation. We assess the potential contributions of oligomerization through laboratory ozonolysis experiments, direct kinetic studies of Criegee intermediate reactions, and high-level theoretical calculations. Global atmospheric models built on these kinetics results indicate that Criegee intermediate chemistry may play a larger role in altering the composition of Earth’s troposphere than is captured in current atmospheric models, especially in areas of high humidity. However, the models still capture only a relatively small fraction of the observed signatures, suggesting considerable underestimates of Criegee intermediate concentrations and reactivity and/or the dominance of other, presently uncharacterized, oxidation mechanisms. Resolving the remaining uncertainties in emission inventories and the effects of atmospheric water vapour on key chemical reactions will be required to definitively assess the role of Criegee intermediate oligomerization reactions.
DOI: 10.1038/s41561-023-01361-6
Source: https://www.nature.com/articles/s41561-023-01361-6