Modelling molecular composition of SOA from toluene photo-oxidation at urban and street scales - Centre d'Enseignement et de Recherche en Environnement Atmosphérique
Journal Articles Environmental Science : Atmospheres Year : 2024

Modelling molecular composition of SOA from toluene photo-oxidation at urban and street scales

Abstract

Near-explicit chemical mechanisms representing toluene SOA formation are reduced using the GENOA algorithm and used in 3D simulations of air quality over Greater Paris and in the streets of a district near Paris. The SOA concentrations formed by the toluene photo-oxidation are found to mostly originate from molecular rearrangement with ring opening of a bicyclic peroxy radical (BPR) with an O–O bridge (45%), followed by OH-addition on the aromatic ring (22%), Highly Oxygenated organic Molecules (HOM) formation without ring opening (13%), condensation of methylnitrocatechol (8%), irreversible formation of SOA from methylglyoxal (6%), and ring-opening pathway (3%). The concentrations simulated using the most comprehensive reduced chemical scheme (rdc. Mech. 3) are also compared to those simulated with a SOA scheme based on chamber measurements, and one reduced from the Master Chemical Mechanism. Using rdc. Mech 3 leads to between 50% and 75% more toluene SOA concentrations than the other schemes, mostly because of molecular rearrangement. The SOA compounds from rdc. Mech. 3 are more oxidized and less volatile, with molecules of different functional groups. Concentrations of methylbenzoquinones, which may be of particular health interest, represent about 0.5% of the toluene SOA concentrations. Those are slightly higher in streets than in the urban background (by 2%).
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hal-04673657 , version 1 (20-08-2024)

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Karine Sartelet, Zhizhao Wang, Victor Lannuque, Siddharth Iyer, Florian Couvidat, et al.. Modelling molecular composition of SOA from toluene photo-oxidation at urban and street scales. Environmental Science : Atmospheres , 2024, 4 (8), pp.839-847. ⟨10.1039/D4EA00049H⟩. ⟨hal-04673657⟩
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