Issue 8, 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%).

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

Supplementary files

Article information

Article type
Paper
Submitted
19 apr 2024
Accepted
14 jun 2024
First published
18 jun 2024
This article is Open Access
Creative Commons BY license

Environ. Sci.: Atmos., 2024,4, 839-847

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

K. Sartelet, Z. Wang, V. Lannuque, S. Iyer, F. Couvidat and T. Sarica, Environ. Sci.: Atmos., 2024, 4, 839 DOI: 10.1039/D4EA00049H

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