Evolution in Chemical Composition of Secondary Organic Aerosol from Heated-Cooking Oil Emissions
Abstract
Food cooking emissions represent one of the most important sources of primary organic aerosol in urban areas. However, like many organic emissions, the physical and chemical evolution of food cooking aerosol in the atmosphere is poorly understood. Previous studies have shown significant production of secondary organic aerosol (SOA) formation, but lack the understanding of composition of SOA at the molecular level. Therefore, in this work, we investigate the formation of SOA from gas-phase organics of cooking oils using a flow tube reactor. The chemical composition of cooking SOA is analyzed using a thermal desorption-gas chromatography-mass spectrometry (TD-GC/MS), and shows that particle-bound composition of SOA exists as unresolved complex mixture (UCM). Our results highlight that detailed speciation of UCM can be achieved, and all the GC elutable material can be classified into different functional groups. Furthermore, we use average carbon oxidation state (OSc), and carbon number (nc) framework to describe the oxidative evolution of cooking emissions undergoing dynamic oxidation processes. Our results demonstrate an increase in OSc (from -0.77 to ~-0.1), and decrease in nc (from 7 to 5) with increasing atmospheric oxidation for cooking oils suggesting that fragmentation reactions are key processes in the oxidative ageing of cooking emissions. The measurement and identification of compounds forming the UCM helps constrain the bulk value of OSc and, in addition, these individual compounds span a range in carbon number, oxidation state, and volatility. Overall, our results provide insights into the atmospheric evolution of cooking SOA.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A51T2735T
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE