Reactive Oxygen Species Formation and Peroxide and Carbonyl Decomposition in Aqueous Photolysis of Secondary Organic Aerosols.
Environ Sci Technol
; 58(10): 4716-4726, 2024 Mar 12.
Article
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| ID: mdl-38412378
ABSTRACT
The mechanism and kinetics of reactive oxygen species (ROS) formation when atmospheric secondary organic aerosol (SOA) is exposed to solar radiation are poorly understood. In this study, we combined an in situ UV-vis irradiation system with electron paramagnetic resonance (EPR) spectroscopy to characterize the photolytic formation of ROS in aqueous extracts of SOA formed by the oxidation of isoprene, α-pinene, α-terpineol, and toluene. We observed substantial formation of free radicals, including â¢OH, superoxide (HO2â¢), and organic radicals (Râ¢/ROâ¢) upon irradiation. Compared to dark conditions, the radical yield was enhanced by a factor of â¼30 for â¢OH and by a factor of 2-10 for superoxide radicals, and we observed the emergence of organic radicals. Total peroxide measurements showed substantial decreases of peroxide contents after photoirradiation, indicating that organic peroxides can be an important source of the observed radicals. A liquid chromatography interfaced with high-resolution mass spectrometry was used to detect a number of organic radicals in the form of adducts with a spin trap, BMPO. The types of detected radicals and aqueous photolysis of model compounds indicated that photolysis of carbonyls by Norrish type I mechanisms plays an important role in the organic radical formation. The photolytic ROS formation serves as the driving force for cloud and fog processing of SOA.
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Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Peróxidos
/
Contaminantes Atmosféricos
Idioma:
En
Revista:
Environ Sci Technol
Año:
2024
Tipo del documento:
Article
País de afiliación:
Estados Unidos