Influence of Ozone and Radical Chemistry on Limonene Organic Aerosol Production and Thermal Characteristics

• Published in: Environmental science & technology Vol. 46; no. 21; pp. 11660 - 11669
• Main Authors: Pathak, Ravi K, Salo, Kent, Emanuelsson, Eva U, Cai, Cilan, Lutz, Anna, Hallquist, Åsa M, Hallquist, Mattias
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.11.2012
• Subjects: Aerosols; Analytical Chemistry; Analytisk kemi; Analyzers; Applied sciences; Atmospheric aerosols; Atmospheric pollution; Butanols - chemistry; Chemical Sciences; Chemistry; Climate Research; Computer Simulation; Cyclohexenes - chemistry; Earth and Related Environmental Sciences; Environmental Sciences; Exact sciences and technology; Fysikalisk kemi; Geovetenskap och miljövetenskap; Hydroxyl Radical - chemistry; Kemi; Klimatforskning; Miljövetenskap; Models, Chemical; Organic Chemistry; Organisk kemi; Oxidants - chemistry; Oxidation; Ozone; Ozone - chemistry; Physical Chemistry; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Reaction kinetics; Temperature; Terpenes - chemistry; Volatility; Volatilization; Water - chemistry; 1,8-p-Menthadiene; Photochemical oxidants; Pollutant formation; Ozone; Secondary pollutant; Free radical reaction; Terpene; Atmospheric chemistry; Aerosols; Hydroxyl radicals; Air pollution; Oxidation; Organic compounds
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es301750r

Limonene has a strong tendency to form secondary organic aerosol (SOA) in the atmosphere and in indoor environments. Initial oxidation occurs mainly via ozone or OH radical chemistry. We studied the effect of O3 concentrations with or without a OH radical scavenger (2-butanol) on the SOA mass and thermal characteristics using the Gothenburg Flow Reactor for Oxidation Studies at Low Temperatures and a volatility tandem differential mobility analyzer. The SOA mass using 15 ppb limonene was strongly dependent on O3 concentrations and the presence of a scavenger. The SOA volatility in the presence of a scavenger decreased with increasing levels of O3, whereas without a scavenger, there was no significant change. A chemical kinetic model was developed to simulate the observations using vapor pressure estimates for compounds that potentially contributed to SOA. The model showed that the product distribution was affected by changes in both OH and ozone concentrations, which partly explained the observed changes in volatility, but was strongly dependent on accurate vapor pressure estimation methods. The model–experiment comparison indicated a need to consider organic peroxides as important SOA constituents. The experimental findings could be explained by secondary condensed-phase ozone chemistry, which competes with OH radicals for the oxidation of primary unsaturated products.