Impact of Environmental Conditions on Secondary Organic Aerosol Production from Photosensitized Humic Acid

Recent studies have shown the potential of the photosensitizer chemistry of humic acid, as a proxy for humic-like substances in atmospheric aerosols, to contribute to secondary organic aerosol mass. The mechanism requires particle-phase humic acid to absorb solar radiation and become photoexcited, t...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 2020-05, Vol.54 (9), p.5385-5390
Main Authors: Fankhauser, Alison M, Bourque, Mary, Almazan, John, Marin, Daniela, Fernandez, Lydia, Hutheesing, Remy, Ferdousi, Nahin, Tsui, William G, McNeill, V. Faye
Format: Article
Language:English
Subjects:
Acids
Aerosols
Atmospheric aerosols
Atmospheric chemistry
Environmental conditions
Environmental impact
Humic acids
Irradiation
Limonene
Organic compounds
Particle size
Photochemicals
Solar radiation
Ultraviolet radiation
VOCs
Volatile organic compounds
Volatility
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Recent studies have shown the potential of the photosensitizer chemistry of humic acid, as a proxy for humic-like substances in atmospheric aerosols, to contribute to secondary organic aerosol mass. The mechanism requires particle-phase humic acid to absorb solar radiation and become photoexcited, then directly or indirectly oxidize a volatile organic compound (VOC), resulting in a lower volatility product in the particle phase. We performed experiments in a photochemical chamber, with aerosol-phase humic acid as the photosensitizer and limonene as the VOC. In the presence of 26 ppb limonene and under atmospherically relevant UV–visible irradiation levels, there is no significant change in particle diameter. Calculations show that SOA production via this pathway is highly sensitive to VOC precursor concentrations. Under the assumption that HULIS is equally or less reactive than the humic acid used in these experiments, the results suggest that the photosensitizer chemistry of HULIS in ambient atmospheric aerosols is unlikely to be a significant source of secondary organic aerosol mass.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b07485