TY - JOUR
T1 - Rapid sulfate formation from synergetic oxidation of SO2 by O3 and NO2 under ammonia-rich conditions
T2 - Implications for the explosive growth of atmospheric PM2.5 during haze events in China
AU - Zhang, Si
AU - Li, Dapeng
AU - Ge, Shuangshuang
AU - Liu, Shijie
AU - Wu, Can
AU - Wang, Yiqian
AU - Chen, Yubao
AU - Lv, Shaojun
AU - Wang, Fanglin
AU - Meng, Jingjing
AU - Wang, Gehui
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/6/10
Y1 - 2021/6/10
N2 - Extremely high levels of atmospheric sulfate aerosols have still frequently occurred in China especially in winter haze periods and often been underestimated by models due to some missing formation mechanisms. Here we investigated the heterogeneous reaction dynamics of SO2 oxidation by the abundantly co-existing O3 and NO2 in the urban atmosphere of China by using a laboratory smog chamber simulation technique. Our results showed that with an increase of NH3 concentrations from 0.05 ppm to 1.5 ppm, SO2 oxidation by O3 can be greatly promoted and lead to an exponential increase of diameter growth factor (GF) of particles in the chamber from 1.29 to 1.98 for NaCl seeds and from 1.20 to 1.60 for (NH4)2SO4 seeds, along with an increasing uptake coefficient (γ) of SO2 from 4.47 × 10−5 to 1.52 × 10−4 on NaCl seeds and from 2.32 × 10−5 to 5.74 × 10−5 on (NH4)2SO4 seeds, respectively. The heterogeneous production of sulfate from oxidation of SO2 under NH3-rich conditions by O3 and NO2 mixture in the chamber was 2.0–3.5 times the sum of sulfate from SO2 oxidations by O3 and NO2, suggesting a strongly synergetic effect of the mixed oxidants on the heterogeneous oxidation of SO2, which can cause rapid formation of (NH4)2SO4 and NH4NO3 and is responsible for the explosive growth of PM2.5 in the winter haze period of China. Our chamber results further showed that such synergetic process is only efficient under NH3-rich conditions, clearly indicating that the combined controls on O3, NOx and NH3 are necessary for further mitigating the PM2.5 pollution in China.
AB - Extremely high levels of atmospheric sulfate aerosols have still frequently occurred in China especially in winter haze periods and often been underestimated by models due to some missing formation mechanisms. Here we investigated the heterogeneous reaction dynamics of SO2 oxidation by the abundantly co-existing O3 and NO2 in the urban atmosphere of China by using a laboratory smog chamber simulation technique. Our results showed that with an increase of NH3 concentrations from 0.05 ppm to 1.5 ppm, SO2 oxidation by O3 can be greatly promoted and lead to an exponential increase of diameter growth factor (GF) of particles in the chamber from 1.29 to 1.98 for NaCl seeds and from 1.20 to 1.60 for (NH4)2SO4 seeds, along with an increasing uptake coefficient (γ) of SO2 from 4.47 × 10−5 to 1.52 × 10−4 on NaCl seeds and from 2.32 × 10−5 to 5.74 × 10−5 on (NH4)2SO4 seeds, respectively. The heterogeneous production of sulfate from oxidation of SO2 under NH3-rich conditions by O3 and NO2 mixture in the chamber was 2.0–3.5 times the sum of sulfate from SO2 oxidations by O3 and NO2, suggesting a strongly synergetic effect of the mixed oxidants on the heterogeneous oxidation of SO2, which can cause rapid formation of (NH4)2SO4 and NH4NO3 and is responsible for the explosive growth of PM2.5 in the winter haze period of China. Our chamber results further showed that such synergetic process is only efficient under NH3-rich conditions, clearly indicating that the combined controls on O3, NOx and NH3 are necessary for further mitigating the PM2.5 pollution in China.
KW - Ammonia neutralization
KW - Heterogeneous reaction
KW - Hygroscopic growth
KW - Smog chamber simulation
KW - Sulfate and nitrate
UR - https://www.scopus.com/pages/publications/85101812365
U2 - 10.1016/j.scitotenv.2020.144897
DO - 10.1016/j.scitotenv.2020.144897
M3 - 文章
C2 - 33770894
AN - SCOPUS:85101812365
SN - 0048-9697
VL - 772
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 144897
ER -
