| Title: | Photolysis Controls Atmospheric Budgets of Biogenic Secondary Organic Aerosol |
| Author(s): | Zawadowicz MA; Lee BH; Shrivastava M; Zelenyuk A; Zaveri RA; Flynn C; Thornton JA; Shilling JE; |
| Address: | "Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States. Department of Atmospheric Science, University of Washington, Seattle, Washington 98195, United States" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "Secondary organic aerosol (SOA) accounts for a large fraction of the tropospheric particulate matter. Although SOA production rates and mechanisms have been extensively investigated, loss pathways remain uncertain. Most large-scale chemistry and transport models account for mechanical deposition of SOA but not chemical losses such as photolysis. There is also a paucity of laboratory measurements of SOA photolysis, which limits how well photolytic losses can be modeled. Here, we show, through a combined experimental and modeling approach, that photolytic loss of SOA mass significantly alters SOA budget predictions. Using environmental chamber experiments at variable relative humidity between 0 and 60%, we find that SOA produced from several biogenic volatile organic compounds undergoes photolysis-induced mass loss at rates between 0 and 2.2 +/- 0.4% of nitrogen dioxide (NO(2)) photolysis, equivalent to average atmospheric lifetimes as short as 10 h. We incorporate our photolysis rates into a regional chemical transport model to test the sensitivity of predicted SOA mass concentrations to photolytic losses. The addition of photolysis causes a approximately 50% reduction in biogenic SOA loadings over the Amazon, indicating that photolysis exerts a substantial control over the atmospheric SOA lifetime, with a likely dependence upon the SOA molecular composition and thus production mechanisms" |
| Keywords: | "Aerosols *Air Pollutants Models, Chemical Particulate Matter Photolysis *Volatile Organic Compounds;" |
| Notes: | "MedlineZawadowicz, Maria A Lee, Ben H Shrivastava, Manish Zelenyuk, Alla Zaveri, Rahul A Flynn, Connor Thornton, Joel A Shilling, John E eng Research Support, U.S. Gov't, Non-P.H.S. 2020/03/11 Environ Sci Technol. 2020 Apr 7; 54(7):3861-3870. doi: 10.1021/acs.est.9b07051. Epub 2020 Mar 19" |
