TY - JOUR
T1 - Heterogeneous SO 2 Oxidation in Sulfate Formation by Photolysis of Particulate Nitrate
AU - Gen, Masao
AU - Zhang, Ruifeng
AU - Huang, Dan Dan
AU - Li, Yongjie
AU - Chan, Chak K.
N1 - Funding Information:
Support from the National Natural Science Foundation of China (41675120 and 41875142) and the Science and Technology Development Fund of Macau (136/2016/A3) is gratefully acknowledged.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/2/12
Y1 - 2019/2/12
N2 - Heterogeneous oxidation of sulfur dioxide (SO 2 ) is suggested to be one of the most important pathways for sulfate formation during extreme haze events in China, yet the exact mechanism remains highly uncertain. We propose a much less explored pathway for aqueous-phase SO 2 oxidation for the formation of particulate sulfate by NO 2 and OH radicals produced from photolysis of particulate nitrate. Reactive uptake experiments with SO 2 and ammonium nitrate particles under ultraviolet irradiation show measured SO 2 uptake coefficients of 10 -5 . Model calculations of sulfate production rates, comparing known mechanisms of oxidation by O 3 , NO 2 , H 2 O 2 , and transition metal ions, and the nitrate photolysis mechanism suggest that the nitrate photolysis pathway could contribute significantly to the overall sulfate production at pH 4-6. This study provides new insight into the current debate about sulfate production pathways under typical haze conditions in China.
AB - Heterogeneous oxidation of sulfur dioxide (SO 2 ) is suggested to be one of the most important pathways for sulfate formation during extreme haze events in China, yet the exact mechanism remains highly uncertain. We propose a much less explored pathway for aqueous-phase SO 2 oxidation for the formation of particulate sulfate by NO 2 and OH radicals produced from photolysis of particulate nitrate. Reactive uptake experiments with SO 2 and ammonium nitrate particles under ultraviolet irradiation show measured SO 2 uptake coefficients of 10 -5 . Model calculations of sulfate production rates, comparing known mechanisms of oxidation by O 3 , NO 2 , H 2 O 2 , and transition metal ions, and the nitrate photolysis mechanism suggest that the nitrate photolysis pathway could contribute significantly to the overall sulfate production at pH 4-6. This study provides new insight into the current debate about sulfate production pathways under typical haze conditions in China.
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U2 - 10.1021/acs.estlett.8b00681
DO - 10.1021/acs.estlett.8b00681
M3 - Article
AN - SCOPUS:85061626450
SN - 2328-8930
VL - 6
SP - 86
EP - 91
JO - Environmental Science and Technology Letters
JF - Environmental Science and Technology Letters
IS - 2
ER -