Observational evidence for Criegee intermediate oligomerization reactions relevant to aerosol formation in the troposphere

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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.

• Tipo de documento: Artigo Científico
• Fonte: NATURE GEOSCIENCE; v. 17, n. 3, p. 20-pg., 2024-03-05.

Resumo

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. Measurements of Criegee intermediate oligomerization signatures in the Amazon rainforest indicate that the role of Criegee intermediate chemistry in the composition of Earth's troposphere has been underestimated. (AU)

• Processo FAPESP: 23/04358-9 - Interações entre gases traços, aerossóis e nuvens na Amazônia: da emissão de bioaerossóis aos impactos em larga escala
• Beneficiário: Paulo Eduardo Artaxo Netto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 17/17047-0 - O ciclo de vida de aerossóis e nuvens na Amazônia: emissões biogênicas, emissões de queimadas e impactos no ecossistema
• Beneficiário: Paulo Eduardo Artaxo Netto
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático