| Title: | Photodegradation of alpha-Pinene Secondary Organic Aerosol Dominated by Moderately Oxidized Molecules |
| Author(s): | Pospisilova V; Bell DM; Lamkaddam H; Bertrand A; Wang L; Bhattu D; Zhou X; Dommen J; Prevot ASH; Baltensperger U; El Haddad I; Slowik JG; |
| Address: | "Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland. Tofwerk, 3600 Thun, Switzerland. Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, Karwar 342037, India" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "Atmospheric secondary organic aerosol (SOA) undergoes chemical and physical changes when exposed to UV radiation, affecting the atmospheric lifetime of the involved molecules. However, these photolytic processes remain poorly constrained. Here, we present a study aimed at characterizing, at a molecular level and in real time, the chemical composition of alpha-pinene SOA exposed to UV-A light at 50% relative humidity in an atmospheric simulation chamber. Significant SOA mass loss is observed at high loadings ( approximately 100 mug m(-3)), whereas the effect is less prevalent at lower loadings ( approximately 20 mug m(-3)). For the vast majority of molecules measured by the extractive electrospray time-of-flight mass spectrometer, there is a fraction that is photoactive and decays when exposed to UV-A radiation and a fraction that appears photorecalcitrant. The molecules that are most photoactive contain between 4 and 6 oxygen atoms, while the more highly oxygenated compounds and dimers do not exhibit significant decay. Overall, photolysis results in a reduction of the volatility of SOA, which cannot be explained by simple evaporative losses but requires either a change in volatility related to changes in functional groups or a change in physical parameters (i.e., viscosity)" |
| Keywords: | Aerosols *Air Pollutants Bicyclic Monoterpenes Monoterpenes Photolysis; |
| Notes: | "MedlinePospisilova, Veronika Bell, David M Lamkaddam, Houssni Bertrand, Amelie Wang, Liwei Bhattu, Deepika Zhou, Xueqin Dommen, Josef Prevot, Andre S H Baltensperger, Urs El Haddad, Imad Slowik, Jay G eng Research Support, Non-U.S. Gov't 2021/05/08 Environ Sci Technol. 2021 May 18; 55(10):6936-6943. doi: 10.1021/acs.est.0c06752. Epub 2021 May 7" |
