TY - JOUR
T1 - An overlooked oxidation mechanism of toluene
T2 - computational predictions and experimental validations
AU - Fu, Zihao
AU - Ma, Fangfang
AU - Liu, Yuliang
AU - Yan, Chao
AU - Huang, Dandan
AU - Chen, Jingwen
AU - Elm, Jonas
AU - Li, Yuanyuan
AU - Ding, Aijun
AU - Pichelstorfer, Lukas
AU - Xie, Hong Bin
AU - Nie, Wei
AU - Francisco, Joseph S.
AU - Zhou, Putian
PY - 2023/10
Y1 - 2023/10
N2 - Secondary organic aerosols (SOAs) influence the Earth's climate and threaten human health. Aromatic hydrocarbons (AHs) are major precursors for SOA formation in the urban atmosphere. However, the revealed oxidation mechanism dramatically underestimates the contribution of AHs to SOA formation, strongly suggesting the importance of seeking additional oxidation pathways for SOA formation. Using toluene, the most abundant AHs, as a model system and the combination of quantum chemical method and field observations based on advanced mass spectrometry, we herein demonstrate that the second-generation oxidation of AHs can form novel epoxides (TEPOX) with high yield. Such TEPOX can further react with H2SO4 or HNO3 in the aerosol phase to form less-volatile compounds including novel non-aromatic and ring-retaining organosulfates or organonitrates through reactive uptakes, providing new candidates of AH-derived organosulfates or organonitrates for future ambient observation. With the newly revealed mechanism, the chemistry-aerosol box modeling revealed that the SOA yield of toluene oxidation can reach up to 0.35, much higher than 0.088 based on the original mechanism under the conditions of pH = 2 and 0.1 ppbv NO. This study opens a route for the formation of reactive uptake SOA precursors from AHs and significantly fills the current knowledge gap for SOA formation in the urban atmosphere.
AB - Secondary organic aerosols (SOAs) influence the Earth's climate and threaten human health. Aromatic hydrocarbons (AHs) are major precursors for SOA formation in the urban atmosphere. However, the revealed oxidation mechanism dramatically underestimates the contribution of AHs to SOA formation, strongly suggesting the importance of seeking additional oxidation pathways for SOA formation. Using toluene, the most abundant AHs, as a model system and the combination of quantum chemical method and field observations based on advanced mass spectrometry, we herein demonstrate that the second-generation oxidation of AHs can form novel epoxides (TEPOX) with high yield. Such TEPOX can further react with H2SO4 or HNO3 in the aerosol phase to form less-volatile compounds including novel non-aromatic and ring-retaining organosulfates or organonitrates through reactive uptakes, providing new candidates of AH-derived organosulfates or organonitrates for future ambient observation. With the newly revealed mechanism, the chemistry-aerosol box modeling revealed that the SOA yield of toluene oxidation can reach up to 0.35, much higher than 0.088 based on the original mechanism under the conditions of pH = 2 and 0.1 ppbv NO. This study opens a route for the formation of reactive uptake SOA precursors from AHs and significantly fills the current knowledge gap for SOA formation in the urban atmosphere.
UR - http://www.scopus.com/inward/record.url?scp=85176087506&partnerID=8YFLogxK
U2 - 10.1039/d3sc03638c
DO - 10.1039/d3sc03638c
M3 - Journal article
C2 - 38023500
AN - SCOPUS:85176087506
SN - 2041-6520
VL - 14
SP - 13050
EP - 13059
JO - Chemical Science
JF - Chemical Science
IS - 45
ER -