Advanced Chemical process Modelling of aqSOA (ACoMa)
Final Report Abstract
The ACoMa project yielded in novel multiphase chemical mechanism modules and a more advanced process model framework that enabled detailed simulations on chemical aerosol cloud interactions and multiphase processing of organic compounds. In ACoMa, various model studies were performed investigating the importance of different radical and non-radical oxidation processes and non-oxidative processes for aqSOA as well as the importance organic-inorganic complexes for aerosol chemistry. Finally, the impact of non-ideal solution effects on different aerosol chemistry subsystems including aqSOA has been examined. The performed studies have shown that non-radical oxidations can play an important role in the aqueous oxidation of organic compounds besides known key radical oxidants. Model simulations demonstrated that O3 can be an important oxidant for soluble unsaturated organic compounds particularly under cloud conditions and H2O2 can be an important oxidant particularly for substituted organic acids under both cloud and deliquesced particle conditions. Another highlight was that ACoMa studies indicated that oligomer formation processes of very soluble dicarbonyls in cloud evaporation zones and their subsequent oxidations can be an important aqSOA formation pathway. This result has strong implications for future field and laboratory experiments investigating chemical processes related to CCN condensation-evaporation cycles. Furthermore, model studies with an advanced epoxide chemistry module demonstrated for the first time that their processing is not only restricted to deliquesced aerosols, and their chemical processing in clouds and their aqueous radical processing can represent an important additional source of aqSOA. Moreover, developed multiphase reaction mechanisms for very soluble hydroperoxides (e.g., ISO- POOH, …), formed from gas-phase oxidation of isoprene and terpenes, revealed that such larger oxidized organic compounds can contribute to the aqSOA formation but also substantially increase the aqueous-phase oxidants budget of particles and clouds. Finally, the performed model developments and accompanied model investigations significantly improved the knowledge on effects of non-ideality on multiphase chemical processing in concentrated aqueous aerosols. Simulation results highlight that a non-ideality treatment strongly affects the chemical multiphase processing of TMIs, oxidants, and organic aerosol constituents in deliquesced particles. Overall, the further developed SPACCIM- SpactMod and the developed mechanism modules enabled advanced model studies and are useful tool further aqSOA related studies. Finally, the ACoMa studies imply that more kinetic and mechanistic investigations are necessary to improve and extend current aqSOA mechanisms and that further interaction parameters for activity models are needed.
Publications
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SPACCIM modelling of the non-radical aqueous-phase chemistry of organic compounds in clouds and deliquesced aerosols, 17th International Conference on Clouds and Precipitation (ICCP), Manchester, UK, 25-29 July 2016, 2016
Tilgner, A., Hoffmann, E. H., Schöne, L., and Wolke, R.
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Tropospheric aqueous-phase OH oxidation chemistry: Current understanding, uptake of highly oxidized organics and its effects. Hunt, S. W., Laskin, A., Nizkorodov, S. A. (Ed.), In: Multiphase environmental chemistry in the atmosphere, American Chemical Society, Washington, DC, p. 49-85 (Chapter 4), (ACS Symposium Series; Vol. 1299), eISBN: 9780841233621
Tilgner, A., and Herrmann, H.
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Modeling the non-ideal chemical processing in aqueous aerosol particles with SPACCIM-SpactMod. IFDA2019-169 P-7-23, 8th International Conference on Fog, Fog Collection and Dew, Taipei, Taiwan, July 2019, 2019
Tilgner, A., Rusumdar, A. J., Wolke, R., Herrmann H.
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Treatment of non-ideality in the multiphase model SPACCIM-Part2: Impacts on the multiphase chemical processing in deliquesced aerosol particles, Atmos. Chem. Phys.
Rusumdar, A. J., Tilgner, A., Wolke, R., and Herrmann, H.
