Reactive Uptake of an Isoprene-Derived Epoxydiol to Submicron Aerosol Particles

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• 作者：Cassandra J. Gaston ; Theran P. Riedel ; Zhenfa Zhang ; Avram Gold ; Jason D. Surratt ; Joel A. Thornton
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：October 7, 2014
• 年：2014
• 卷：48
• 期：19
• 页码：11178-11186
• 全文大小：382K
• ISSN：1520-5851

文摘

The reactive uptake of isoprene-derived epoxydiols (IEPOX) is thought to be a significant source of atmospheric secondary organic aerosol (SOA). However, the IEPOX reaction probability (纬_IEPOX) and its dependence upon particle composition remain poorly constrained. We report measurements of 纬_IEPOX for trans-尾-IEPOX, the predominant IEPOX isomer, on submicron particles as a function of composition, acidity, and relative humidity (RH). Particle acidity had the strongest effect. 纬_IEPOX is more than 500 times greater on ammonium bisulfate (纬 鈭?0.05) than on ammonium sulfate (纬 鈮?1 脳 10^鈥?). We could accurately predict 纬_IEPOX using an acid-catalyzed, epoxide ring-opening mechanism and a high Henry鈥檚 law coefficient (1.7 脳 10⁸ M/atm). Suppression of 纬_IEPOX was observed on particles containing both ammonium bisulfate and poly(ethylene glycol) (PEG-300), likely due to diffusion and solubility limitations within a PEG-300 coating, suggesting that IEPOX uptake could be self-limiting. Using the measured uptake kinetics, the predicted atmospheric lifetime of IEPOX is a few hours in the presence of highly acidic particles (pH < 0) but is greater than 25 h on less acidic particles (pH > 3). This work highlights the importance of aerosol acidity for accurately predicting the fate of IEPOX and anthropogenically influenced biogenic SOA formation.