α-Pinene, Limonene, and Cyclohexene Secondary Organic Aerosol Hygroscopicity and Oxidation Level as a Function of Volatility

Abstract

The hygroscopicity and oxidation level of secondary organic aerosol (SOA) produced in an atmospheric simulation chamber were measured as a function of volatility. The experimental setup combines thermodenuding, isothermal dilution, aerosol mass spectroscopy, and sizeresolved cloud condensation nuclei measurements to separate the SOA by volatility and then measure its physical (hygroscopicity via the hygroscopicity parameter, κ) and chemical (oxidation level via the oxygen-to-carbon ratio, O:C) properties. The technique was applied to SOA from the ozonolysis of α-pinene, limonene, and cyclohexene. The O:C and κ of the α-pinene ozonolysis SOA decreased as volatility decreased. The semi-volatile and the low volatility organic compounds produced during limonene ozonolysis have similar O:C and κ values, but the corresponding extremely low volatility organic compounds have significantly lower oxygen content and hygroscopicity. The average O:C of the cyclohexene ozonolysis SOA increased, but the average κ decreased as volatility decreased. These results suggest that some organic aerosol (OA) systems have a more complex relationship between hygroscopicity, oxidation level, and

Contrasting Influence of Nitrogen Oxides on the Cloud Condensation Nuclei Activity of Monoterpene‐Derived Secondary Organic Aerosol in Daytime and Nighttime Oxidation

“…Therefore, we used average κ at all supersaturations. The observed ranges of κ Org were in agreement with the results of previous studies (Cain et al., 2021; Frosch et al., 2011; Lambe, Onasch, et al., 2011; Massoli et al., 2010; Zhao et al., 2016). At low NO x , the CCN activity of SOA formed by OH oxidation of α‐pinene and limonene showed an increasing trend with time at some supersaturations (Figure S1 in Supporting Information ).…”

Impacts of Fuel Stage Ratio on the Morphological and Nanostructural Characteristics of Soot Emissions from a Twin Annular Premixing Swirler Combustor

“…24,25 Nanostructure characteristic features, such as fringe length, fringe tortuosity, and separation distance, are indicative of soot particles oxidative reactivity under certain conditions, influencing their ability to produce secondary aerosols. 26 Such secondary aerosols derived from soot particles are often characterized by increased hygroscopicity 27 and enhanced light absorption. 28 The oxidative behaviors of soot particles notably amplify their impacts on air quality and climate forcing.…”

“…Studying the morphology and nanostructure of aero-engine emitted carbonaceous particles can enhance our understanding of their environmental and human health impacts. , The thickness of organic coatings on aerosol particles significantly influences their ice nucleation capabilities, which is crucial for cloud formation in the atmosphere. , Nanostructure characteristic features, such as fringe length, fringe tortuosity, and separation distance, are indicative of soot particles oxidative reactivity under certain conditions, influencing their ability to produce secondary aerosols . Such secondary aerosols derived from soot particles are often characterized by increased hygroscopicity and enhanced light absorption . The oxidative behaviors of soot particles notably amplify their impacts on air quality and climate forcing.…”

Volatility of Cl-Initiated C12–C14 n-Alkylcyclohexane Secondary Organic Aerosol: Effects of NOx and Photoaging

“…Volatility is a crucial physical property of aerosol since it determines the partitioning of the components between gas and particle phases and influences their atmospheric fates . Currently, the thermodenuder (TD) is one of the most common devices to assist in measuring aerosol volatility, and its downstream instruments are usually a scanning mobility particle sizer (SMPS) or a mass spectrometer. − SOA volatilities of aromatic hydrocarbons (e.g., toluene, o-xylene, o-cresol, and 1,3,5-trimethylbenzene), − isoprene, − monoterpenes (e.g., α-pinene, β-pinene, and limonene), ,− ,− sesquiterpene (e.g., β-caryophyllene), , and other alkenes (e.g., cyclohexene, 1,3-butadiene, and 2,3-dimethyl-1,3-butadiene) , were widely studied, but the volatilities of alkane SOA were rarely reported, especially for those initiated by Cl atoms. ,, …”

“…46 Currently, the thermodenuder (TD) is one of the most common devices to assist in measuring aerosol volatility, and its downstream instruments are usually a scanning mobility particle sizer (SMPS) or a mass spectrometer. 47−49 SOA volatilities of aromatic hydrocarbons (e.g., toluene, o-xylene, ocresol, and 1,3,5-trimethylbenzene), 50−54 isoprene, 55−57 monoterpenes (e.g., α-pinene, β-pinene, and limonene), 49,51−54,58−68 sesquiterpene (e.g., β-caryophyllene), 51,69 and other alkenes (e.g., cyclohexene, 1,3-butadiene, and 2,3-dimethyl-1,3-butadiene) 62,68 were widely studied, but the volatilities of alkane SOA were rarely reported, especially for those initiated by Cl atoms. 47,51,70 In this study, we propose a homemade TD to investigate the SOA volatility of Cl-initiated C 12 −C 14 n-alkylcyclohexane reactions and focus on the influences of NO x , aging time, precursors, and SOA mass concentrations.…”