TY - JOUR
T1 - Sulfate formation via aerosol-phase SO2 oxidation by model biomass burning photosensitizers: 3,4-dimethoxybenzaldehyde, vanillin andsyringaldehyde using single-particle mixing-state analysis
AU - Zhou, Liyuan
AU - Liang, Zhancong
AU - Mabato, Beatrix Rosette Go
AU - Cuevas, Rosemarie Ann Infante
AU - Tang, Rongzhi
AU - Li, Mei
AU - Cheng, Chunlei
N1 - KAUST Repository Item: Exported on 2023-05-29
Acknowledgements: This research has been supported by the Hong Kong Research Grants Council (grant nos. 11304121, 11314222, and R1016-20F) and the National Natural Science Foundation of China (grant no. 42275104).
PY - 2023/5/10
Y1 - 2023/5/10
N2 - Atmospheric oxidation of sulfur dioxide (SO2) to sulfate has been widely investigated by means of gas-phase and in-cloud chemistry studies. Recent field measurements have shown significant sulfate formation in cloud-free environments with high aerosol loadings. As an important fraction of biomass burning aerosol components, particulate phenolic and non-phenolic aromatic carbonyls may initiate photosensitized multiphase oxidation of SO2 in aerosols, of which our knowledge however is still in its nascent stage. In this study, on the basis of single-particle aerosol mass spectrometry (SPAMS) measurements, we find evident sulfate formation in the biomass-burning-derived photosensitizer particles under UV and SO2 exposure, attributable to photosensitized oxidation of S(IV), while almost no sulfate was observed under dark conditions. The efficiency of sulfate production by photosensitizer particles under UV irradiation, represented by the number percentage of sulfate-containing particles (99 %–43 %) and the relative peak area (RPA) of sulfate (0.67–0.12) in single-particle spectra, in descending order, were 3,4-dimethoxybenzaldehyde (DMB), vanillin (VL) and syringaldehyde (SyrAld). Internal mixtures of VL and potassium nitrate (KNO3) gave a slightly lower number percentage and RPA of sulfate than VL particles alone. In externally mixed VL and KNO3 particles, sulfate was predominantly formed on the former, confirming that sulfate formation via photosensitization prevails over that via nitrate photolysis. Our results suggest that photosensitized oxidation of S(IV) could make an important contribution to aerosol sulfate formation, especially in areas influenced by biomass burning.
AB - Atmospheric oxidation of sulfur dioxide (SO2) to sulfate has been widely investigated by means of gas-phase and in-cloud chemistry studies. Recent field measurements have shown significant sulfate formation in cloud-free environments with high aerosol loadings. As an important fraction of biomass burning aerosol components, particulate phenolic and non-phenolic aromatic carbonyls may initiate photosensitized multiphase oxidation of SO2 in aerosols, of which our knowledge however is still in its nascent stage. In this study, on the basis of single-particle aerosol mass spectrometry (SPAMS) measurements, we find evident sulfate formation in the biomass-burning-derived photosensitizer particles under UV and SO2 exposure, attributable to photosensitized oxidation of S(IV), while almost no sulfate was observed under dark conditions. The efficiency of sulfate production by photosensitizer particles under UV irradiation, represented by the number percentage of sulfate-containing particles (99 %–43 %) and the relative peak area (RPA) of sulfate (0.67–0.12) in single-particle spectra, in descending order, were 3,4-dimethoxybenzaldehyde (DMB), vanillin (VL) and syringaldehyde (SyrAld). Internal mixtures of VL and potassium nitrate (KNO3) gave a slightly lower number percentage and RPA of sulfate than VL particles alone. In externally mixed VL and KNO3 particles, sulfate was predominantly formed on the former, confirming that sulfate formation via photosensitization prevails over that via nitrate photolysis. Our results suggest that photosensitized oxidation of S(IV) could make an important contribution to aerosol sulfate formation, especially in areas influenced by biomass burning.
UR - http://hdl.handle.net/10754/692103
UR - https://acp.copernicus.org/articles/23/5251/2023/
U2 - 10.5194/acp-23-5251-2023
DO - 10.5194/acp-23-5251-2023
M3 - Article
SN - 1680-7324
VL - 23
SP - 5251
EP - 5261
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 9
ER -