Abstract View
Volatility Distributions and Solubility of Monoterpene-derived Organic Nitrates
MASAYUKI TAKEUCHI, Yuchen Wang, Gamze Eris, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 257
Working Group: Aerosol Chemistry
Abstract
Organic nitrates (ON) in the atmosphere contribute to a major fraction of the oxidized reactive nitrogen (NOy) budget; however, their complex interaction in the cycling of NOy via the formation, evolution, and decay remains largely unelucidated. Key parameters to understand the dynamics of this NOy cycling include volatility distribution and solubility because these two properties affect gas/particle partitioning of ON and subsequent chemical pathways and physical processes. Monoterpenes are a large source of atmospheric gaseous and particulate ON and serve as good candidates to investigate the partitioning behaviors. In this study, we perform a series of chamber experiments to estimate volatility distributions of bulk ON formed from hydroxyl and nitrate radical oxidation of α-pinene and β-pinene. To estimate volatility distributions, four independent methods are employed: yield-based approach using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Scanning Mobility Particle Sizer (SMPS), thermogram-based approach, molecular formulae approach, and partitioning approach using a Filter Inlet for Gases and AEROsols coupled to a High Resolution Time-of-Flight Iodide Chemical Ionization Mass Spectrometer (FIGAERO-HR-ToF-I-CIMS). We do not observe a good agreement in the ON mass concentration between HR-ToF-AMS and FIGAERO-HR-ToF-I-CIMS, pointing towards the critical needs to understand potential causes of such discrepancy. Solubility is studied by investigating partitioning behaviors of synthesized, atmospherically relevant hydroxyl nitrates in the presence of deliquesced ammonium sulfate aerosols. Our results regarding ON volatility and solubility values would provide fundamental constraints in chemical transport models and help better understand the role of ON in NOx cycling, ozone and SOA formation.