| Title: | Characterization of products formed from the oxidation of toluene and m-xylene with varying NO(x) and OH exposure |
| Author(s): | Srivastava D; Li W; Tong S; Shi Z; Harrison RM; |
| Address: | "School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, United Kingdom. State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, United Kingdom. Electronic address: r.m.harrison@bham.ac.uk" |
| DOI: | 10.1016/j.chemosphere.2023.139002 |
| ISSN/ISBN: | 1879-1298 (Electronic) 0045-6535 (Linking) |
| Abstract: | "Aromatic volatile organic compounds (VOCs) are an important precursor of secondary organic aerosol (SOA) in the urban environment. SOA formed from the oxidation of anthropogenic VOCs can be substantially more abundant than biogenic SOA and has been shown to account for a significant fraction of fine particulate matter in urban areas. A potential aerosol mass (PAM) chamber was used to investigate the oxidised products from the photo-oxidation of m-xylene and toluene. The experiments were carried out with OH radical as oxidant in both high- and low-NO(x) conditions and the resultant aerosol samples were collected using quartz filters and analysed by GC x GC-TOFMS. Results show the oxidation products derived from both precursors included ring-retaining and -opening compounds (unsaturated aldehydes, unsaturated ketones and organic acids) with a high number of ring-opening compounds observed from toluene oxidation. Glyoxal and methyl glyoxal were the major ring-cleavage products from both oxidation systems, indicating that a bicyclic route plays an important role in their formation. SOA yields were higher for both precursors under high-NO(x) (toluene: 0.111; m-xylene: 0.124) than at low-NO(x) (toluene: 0.089; m-xylene: 0.052), likely linked to higher OH concentrations during low-NO(x) experiments which may lead to higher degree of fragmentation. DHOPA (2,3-dihydroxy-4-oxo-pentanoic acid), a known tracer of toluene oxidation, was observed in both oxidation systems. The mass fraction of DHOPA in SOA from toluene oxidation was about double the value reported previously, but it should not be regarded as a tracer solely for oxidation of toluene as m-xylene oxidation gave a similar relative yield" |
| Keywords: | Toluene/analysis Xylenes/analysis Particulate Matter/analysis Aerosols/analysis *Volatile Organic Compounds/analysis *Air Pollutants/analysis OH radicals Oxidation SOA yields Toluene m-Xylene; |
| Notes: | "MedlineSrivastava, Deepchandra Li, Weiran Tong, Shengrui Shi, Zongbo Harrison, Roy M eng England 2023/05/24 Chemosphere. 2023 Sep; 334:139002. doi: 10.1016/j.chemosphere.2023.139002. Epub 2023 May 21" |
