Heterogeneous Nucleation Drives Particle Size Segregation in Sequential Ozone and Nitrate Radical Oxidation of Catechol

Secondary organic aerosol formation via condensation of organic vapors onto existing aerosol transforms the chemical composition and size distribution of ambient aerosol, with implications for air quality and Earth’s radiative balance. Gas-to-particle conversion is generally thought to occur on a co...

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Bibliographic Details
Published in:Environmental science & technology 2021-12, Vol.55 (23), p.15637-15645
Main Authors: Garofalo, Lauren A, He, Yicong, Jathar, Shantanu H, Pierce, Jeffrey R, Fredrickson, Carley D, Palm, Brett B, Thornton, Joel A, Mahrt, Fabian, Crescenzo, Giuseppe V, Bertram, Allan K, Draper, Danielle C, Fry, Juliane L, Orlando, John, Zhang, Xuan, Farmer, Delphine K
Format: Article
Language:English
Subjects:
aerosol microphysics
Aerosols
Aerosols - analysis
Air Pollutants - analysis
Air quality
Ammonium sulfate
Anthropogenic Impacts on the Atmosphere
Atmospheric chemistry
Catechol
Catechols
Chemical composition
Condensation
GEOSCIENCES
Microphysics
Nitrates
Nucleation
Outdoor air quality
Oxidation
Ozone
Particle Size
Particle size distribution
secondary organic aerosol
Size determination
Size distribution
Vapors
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Summary:Secondary organic aerosol formation via condensation of organic vapors onto existing aerosol transforms the chemical composition and size distribution of ambient aerosol, with implications for air quality and Earth’s radiative balance. Gas-to-particle conversion is generally thought to occur on a continuum between equilibrium-driven partitioning of semivolatile molecules to the pre-existing mass size distribution and kinetic-driven condensation of low volatility molecules to the pre-existing surface area size distribution. However, we offer experimental evidence in contrast to this framework. When catechol is sequentially oxidized by O3 and NO3 in the presence of (NH4)2SO4 seed particles with a single size mode, we observe a bimodal organic aerosol mass size distribution with two size modes of distinct chemical composition with nitrocatechol from NO3 oxidation preferentially condensing onto the large end of the pre-existing size distribution (∼750 nm). A size-resolved chemistry and microphysics model reproduces the evolution of the two distinct organic aerosol size modesheterogeneous nucleation to an independent, nitrocatechol-rich aerosol phase.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.1c02984