Evaluation of the chemical composition of gas- and particle-phase products of aromatic oxidation

• DOI: 10.5194/acp-20-9783-2020
• Publication Date: 2020-08-21T06:12:16Z
• Authors: Archit Mehra; Yuwei Wang; Jordan E. Krechmer; Andrew Lambe; Francesca Majluf; Melissa A. Morris; Michael Priestley; Thomas J. Bannan; Daniel J. Bryant; Kelly L. Pereira; Jacqueline F. Ham...; Andrew R. Rickard; Mike J. Newland; Harald Stark; Philip Croteau; John T. Jayne; Douglas R. Worsnop; Manjula R. Canaga...; Lin Wang; Hugh Coe
• Keywords: Particle (ecology)

Abstract. Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and important for both ozone secondary aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation can lead of highly oxidised products. In this study we evaluate gas- particle-phase ions measured by online mass spectrometry during hydroxyl radical substituted C9-aromatic isomers (1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, propylbenzene isopropylbenzene) a polyaromatic hydrocarbon (1-methylnaphthalene) under low- medium-NOx conditions. A time-of-flight chemical ionisation spectrometer (ToF-CIMS) with iodide–anion was used filter inlet gases aerosols (FIGAERO) detection products particle phase, while Vocus proton-transfer-reaction (Vocus-PTR-MS) gas phase. The signal product observed spectra were compared different precursors experimental majority spectral phases comes from which common all precursors, though distributions distinct VOCs. Gas- composition one another. Ions corresponding contained near-explicit phase Master Chemical Mechanism (MCM version 3.3.1) utilised as benchmark current scientific understanding, comparison these observations shows MCM is missing range its mechanism. bulk ring scission ions, large proportion more than reported undergone further form oxygenated molecules (HOMs). Under perturbation OH increased NOx, contribution HOM-ion signals remains elevated precursors. Up 43 % ring-retaining HOMs; most aromatics. Unique minor component systems, many dominant ion formulae concurrent other highlighting challenges utilising marker SOA.