TY - JOUR
T1 - Impact of wildfires on regional ozone and PM2.5
T2 - Considering the light absorption of Brown carbon
AU - Choi, Minsu
AU - Zhang, Jie
AU - Zhang, Yuwei
AU - Fan, Jiwen
AU - Li, Xinghua
AU - Ying, Qi
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2024/1/1
Y1 - 2024/1/1
N2 - The influence of wildfire brown carbon (BrC) in moderating the formation of O3 and fine particulate matter (PM2.5) due to its absorption of ultraviolet (UV) radiation is, for the first time, investigated using a modified community multiscale air quality (CMAQ) model. The wavelength-dependent imaginary refractive index of the organic carbon from wildfires, which are needed by the CMAQ model for its inline photolysis rate calculation, are generated experimentally from wood burning aerosols from a combustion chamber. On high emission days of the Bastrop County Complex fire in Texas in early September 2011, BrC UV absorption reduces the daytime average NO2 photolysis rate by up to 38% in the core region of the wildfire plume compared to the base scenario that does not consider BrC absorption. Consequently, O3 production in the smoke plume is suppressed compared to the base scenario due to reduced HOx radical concentrations. In the core region, the predicted O3 increase due to wildfire reaches as high as 47–123 ppb without considering BrC absorption, the predicted increase of O3 is 5–15% lower when BrC absorption is considered. Similarly, considering the BrC UV absorption leads to approximately 1% (or ∼2–3 μg m−3) lower estimation of the wildfire emissions’ impact on total PM2.5. This change is small because secondary aerosols, which are the components affected by BrC absorption, only account for a small fraction of the total PM2.5 in wildfire impacted regions in this study. In addition, our study shows that assumptions about aerosol mixing state (core-shell vs. homogeneous) in the inline photolysis rate calculation would not significantly affect out assessment of the impact of wildfire BrC light absorption on O3 and PM2.5.
AB - The influence of wildfire brown carbon (BrC) in moderating the formation of O3 and fine particulate matter (PM2.5) due to its absorption of ultraviolet (UV) radiation is, for the first time, investigated using a modified community multiscale air quality (CMAQ) model. The wavelength-dependent imaginary refractive index of the organic carbon from wildfires, which are needed by the CMAQ model for its inline photolysis rate calculation, are generated experimentally from wood burning aerosols from a combustion chamber. On high emission days of the Bastrop County Complex fire in Texas in early September 2011, BrC UV absorption reduces the daytime average NO2 photolysis rate by up to 38% in the core region of the wildfire plume compared to the base scenario that does not consider BrC absorption. Consequently, O3 production in the smoke plume is suppressed compared to the base scenario due to reduced HOx radical concentrations. In the core region, the predicted O3 increase due to wildfire reaches as high as 47–123 ppb without considering BrC absorption, the predicted increase of O3 is 5–15% lower when BrC absorption is considered. Similarly, considering the BrC UV absorption leads to approximately 1% (or ∼2–3 μg m−3) lower estimation of the wildfire emissions’ impact on total PM2.5. This change is small because secondary aerosols, which are the components affected by BrC absorption, only account for a small fraction of the total PM2.5 in wildfire impacted regions in this study. In addition, our study shows that assumptions about aerosol mixing state (core-shell vs. homogeneous) in the inline photolysis rate calculation would not significantly affect out assessment of the impact of wildfire BrC light absorption on O3 and PM2.5.
UR - https://www.scopus.com/pages/publications/85177032982
U2 - 10.1016/j.atmosenv.2023.120196
DO - 10.1016/j.atmosenv.2023.120196
M3 - 文章
AN - SCOPUS:85177032982
SN - 1352-2310
VL - 316
JO - Atmospheric Environment
JF - Atmospheric Environment
M1 - 120196
ER -