CCN activity of secondary aerosols from terpene ozonolysis under atmospheric relevant conditions

Abstract

Gas‐phase ozonolysis of terpenes is an important source of atmospheric secondary organic aerosol. The contribution of terpene‐derived aerosols to the atmospheric cloud condensation nucleus (CCN) burden under atmospheric conditions, however, remains highly uncertain. The results obtained in previous studies under simple laboratory conditions may not be applicable to atmospheric relevant conditions. Here we present that CCN activities of aerosols from terpene ozonolysis can be significantly affected by atmospheric relevant species that can act as stabilized Criegee intermediate (SCI) or OH scavengers. Ozonolysis reactions of α‐pinene, limonene, α‐cedrene, and α‐humulene were conducted in a 4.5 m3 collapsible fluoropolymer chamber at near‐atmospheric concentrations in the presence of different OH scavengers (cyclohexane, 2‐butanol, or CO) and SCI scavengers (CH3COOH, H2O, or SO2). The number size distribution and CCN activity of aerosol particles formed during ozonolysis were simultaneously determined. Additionally, particulate products were chemically analyzed by using a Filter Inlet for Gases and AEROsols High‐Resolution Time‐of‐Flight Chemical‐Ionization Mass Spectrometer. Results showed that aerosol CCN activity following monoterpene ozonolysis was more sensitive to the choice of OH scavengers, while that from sesquiterpene ozonolysis was significantly affected by SCI scavengers. Combined with chemical analysis results, it was concluded that the unimolecular decomposition of CIs giving hygroscopic organic products can be largely suppressed by bimolecular reactions during sesquiterpene ozonolysis but was not significantly impacted in monoterpene ozonolysis. Our study underscores the key role of CIs in the CCN activity of terpene ozonolysis‐derived aerosols. The effects of atmospheric relevant species (e.g., SO2, H2O, and CO) need to be considered when assessing the contribution of biogenic terpenes to the atmospheric CCN burden under ambient conditions.

Sensitivity of a Q-ACSM to chamber generated SOA with different oxidation states

“…1) was used to generate organic aerosols under atmospheric relevant conditions. The chamber was essentially the same as the one used in our earlier work (Yao et al, 2014;Yuan et al, 2017) and has been described in details previously. Before each set of the experiments, the chamber was thoroughly cleaned by irradiation with black light UV-lamps and exposure to a high concentration (a few ppmv) of O 3 for more than 6 hours.…”

Hygroscopicity of internally mixed ammonium sulfate and secondary organic aerosol particles formed at low and high relative humidity

“…41 Additionally, Emanuelsson et al (2013) showed that humidity during SOA formation increased aerosol volatility. 42 In addition, the work of Yuan et al (2017) suggests that the formation of SOA in the presence of water-vapor may form more stable Criegee-intermediates that could lead to the formation of more hygroscopic materials for monoterpene SOA systems. 43 In this study, we focus our efforts towards understanding the differences in measured hygroscopicity that could result from modifying the initial water-vapor concentration in the reaction chamber.…”

“…42 In addition, the work of Yuan et al (2017) suggests that the formation of SOA in the presence of water-vapor may form more stable Criegee-intermediates that could lead to the formation of more hygroscopic materials for monoterpene SOA systems. 43 In this study, we focus our efforts towards understanding the differences in measured hygroscopicity that could result from modifying the initial water-vapor concentration in the reaction chamber. The difference in the extent to which SOA inorganic mixtures uptake water formed during wet conditions is unknown.…”

Accurate Prediction of Organic Aerosol Evaporation Using Kinetic Multilayer Modeling and the Stokes–Einstein Equation

“…Current research at the interface of climate science and aerosol science is multifaceted, because the impacts of aerosol can be wide ranging, influencing for instance cloud cover, , pollution in cities, and the radiative balance of the atmosphere . The incorporation of the fundamental physicochemical properties of aerosol as more accurate measurements become available, including evaporation rates, into the prediction of weather and climate, is challenging.…”