NSRRC Activity Report 2023

080 NSRRC ACTIVITY REPORT 2023 mechanical calculations, and high-resolution liquid chromatography-electrospray ionization-mass spectrometry, to find that water directly intervenes in the ozonolysis of limonene and its Criegee chemistry. On the one hand, water acts as a catalyst by lowering the energy barrier during the formation of hydroperoxide through the isomerization of Criegee intermediates. On the other hand, water, especially water dimers, directly react with Criegee intermediates during limonene ozonolysis, revealing a new pathway for SOA generation. The study revealed that the chemical composition of SOAs generated from ozonolysis of water-containing limonene aerosols differs from SOAs generated by ozonolysis of dry limonene aerosols containing no water, indicating that water alters the reaction mechanisms and final products during ozonolysis. Water is the third most abundant component in air, after nitrogen and oxygen. Traditionally water was considered only as a polar aqueous medium and its function as a catalyst or reactant was not considered. However, mounting studies have demonstrated the importance of water in atmospheric processes in regions with severe air pollution. This issue is both important and non-negligible in Asian countries, where the relative humidity is generally higher than American and European countries. For the first time, this study conducted by the Aerosol Science Research Center research team led by Wang revealed the multifunctional role played by water during the formation of SOAs by the ozonolysis of monoterpenes. Because the influential effects of water were not taken into consideration in most atmospheric chemical reaction modeling simulations, the overall yield of SOA generated in reactions where water plays a role may have been underestimated, contributing to uncertainty in predicting the impact of atmospheric aerosols on climate change. Another important finding of this research is that ozone concentration in the air is a key factor promoting the conversion of limonene aqueous aerosols into SOAs. Environments with high ozone concentrations, such as places where ozone-based air purifiers are frequently used, can experience enhanced production of secondary organic aerosols from ozonolysis of limonene aerosols, with numerous adverse health effects on humans and animals. To fully understand their environmental impact, it is crucially important to pay close attention to possible sources of aerosols, their chemical composition and formation routes, and their physicochemical and biochemical properties. In summary, to fully understand the impact of aerosols on the Earth’s atmosphere, climate, and health, it is crucial to understand the chemical composition, formation and transformation mechanisms, accompanying energetic information, and other physicochemical properties of SOAs, in addition to the key factors affecting them. Water, conventionally considered as an inert aqueous medium, greatly enhances SOA formation in limonene ozonolysis by serving as both a catalyst and a reactant. It is necessary to revise atmospheric and climate modeling to consider the role of water to accurately estimate the influence of atmospheric aerosols on regional and global climates. It is equally important to raise public awareness on potential sources of SOAs, both outdoors and indoors, and possible influential factors in different environmental settings to mitigate the adverse health effects of secondary organic aerosols. (Reported by Chia C. Wang, National Sun Yat-sen University) This report features the work of Chia C. Wang and her coworkers published in J. Phys. Chem. Lett. 14 , 3765 (2023). This paper was selected as a cover of the issue. TLS 21B2 Gas Phase • UPS • Aerosol Physical Chemistry, Environmental Chemistry References 1. W. Steffen, K. Richardson, J. Rockström, S. E. Cornell, I. Fetzer, E. M. Bennett, R. Biggs, S. R. Carpenter, W. de Vries, C. A. de Wit, C. Folke, D. Gerten, J. Heinke, G. M. Mace, L. M. Persson, V. Ramanathan, B. Reyers, S. Sörlin, Science 347 , 1259855 (2015). 2. J.-H. Huang, F. Zhang, Y.-P. Shi, J.-R. Cai, Y.-H. Chuang, W.-P. Hu, Y.-Y. Lee, C. C. Wang, J. Phys. Chem. Lett. 14 , 3765 (2023). Ozonolysis of limonene is considered one of the most important sources of indoor SOAs. [Figure courtesy of Chia C. Wang]