Radical chemistry in the Pearl River Delta: observations and modeling of OH and HO2 radicals in Shenzhen in 2018
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Published:2022-09-26
Issue:18
Volume:22
Page:12525-12542
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ISSN:1680-7324
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Container-title:Atmospheric Chemistry and Physics
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language:en
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Short-container-title:Atmos. Chem. Phys.
Author:
Yang Xinping, Lu KedingORCID, Ma Xuefei, Gao Yue, Tan ZhaofengORCID, Wang HaichaoORCID, Chen Xiaorui, Li XinORCID, Huang Xiaofeng, He Lingyan, Tang Mengxue, Zhu Bo, Chen Shiyi, Dong Huabin, Zeng Limin, Zhang Yuanhang
Abstract
Abstract. The ambient radical concentrations were measured continuously by laser-induced fluorescence during the STORM (STudy of the Ozone foRmation Mechanism) campaign at the Shenzhen site, located in the Pearl River Delta in China, in the autumn of 2018. The diurnal maxima were 4.5×106 cm−3 for OH radicals and 4.2×108 cm−3 for HO2 radicals (including an estimated interference of 23 %–28 % from RO2 radicals during the daytime), respectively. The state-of-the-art chemical mechanism underestimated the observed OH
concentration, similar to the other warm-season campaigns in China. The OH
underestimation was attributable to the missing OH sources, which can be
explained by the X mechanism. Good agreement between the observed and
modeled OH concentrations was achieved when an additional numerical X
equivalent to 0.1 ppb NO concentrations was added into the base model. The
isomerization mechanism of RO2 derived from isoprene contributed
approximately 7 % to the missing OH production rate, and the oxidation of isoprene oxidation products (MACR and MVK) had no significant impact on the missing OH sources, demonstrating further exploration of unknown OH sources is necessary. A significant HO2 heterogeneous uptake was found in this study, with an effective uptake coefficient of 0.3. The model with the
HO2 heterogeneous uptake can simultaneously reproduce the OH and
HO2 concentrations when the amount of X changed from 0.1 to 0.25 ppb.
The ROx primary production rate was dominated by photolysis reactions, in which the HONO, O3, HCHO, and carbonyls photolysis accounted for 29 %, 16 %, 16 %, and 11 % during the daytime, respectively. The ROx
termination rate was dominated by the reaction of OH+NO2 in the morning, and thereafter the radical self-combination gradually became the major sink of ROx in the afternoon. As the sum of the respective oxidation
rates of the pollutants via reactions with oxidants, the atmospheric
oxidation capacity was evaluated, with a peak of 11.8 ppb h−1 around
noontime. The ratio of P(O3)net to AOCVOCs, which indicates
the yield of net ozone production from VOC oxidation, trended to increase
and then decrease as the NO concentration increased. The median ratios
ranged within 1.0–4.5, with the maximum existing when the NO concentration
was approximately 1 ppb. The nonlinear relationship between the yield of net ozone production from VOC oxidation and NO concentrations demonstrated that optimizing the NOx and VOC control strategies is critical to controlling ozone pollution effectively in the future.
Funder
Beijing Municipal Natural Science Foundation National Key Basic Research Program For Youth National Natural Science Foundation of China
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference73 articles.
1. Berndt, T., Chen, J., Kjaergaard, E. R., Moller, K. H., Tilgner, A.,
Hoffmann, E. H., Herrmann, H., Crounse, J. D., Wennberg, P. O., and
Kjaergaard, H. G.: Hydrotrioxide (ROOOH) formation in the atmosphere,
Science, 376, 979–982, https://doi.org/10.1126/science.abn6012, 2022. 2. Brocco, D., Fratarcangeli, R., Lepore, L., Petricca, M., and Ventrone, I.:
Determination of aromatic hydrocarbons in urban air of Rome, Atmos. Environ., 31, 557–566, https://doi.org/10.1016/s1352-2310(96)00226-9, 1997. 3. Chen, X., Wang, H., Liu, Y., Su, R., Wang, H., Lou, S., and Lu, K.: Spatial
characteristics of the nighttime oxidation capacity in the Yangtze River
Delta, China, Atmos. Environ., 208, 150–157, https://doi.org/10.1016/j.atmosenv.2019.04.012, 2019. 4. Ehhalt, D. H.: Photooxidation of trace gases in the troposphere, Phys. Chem. Chem. Phys., 1, 5401–5408, https://doi.org/10.1039/a905097c, 1999. 5. Elshorbany, Y. F., Kurtenbach, R., Wiesen, P., Lissi, E., Rubio, M., Villena, G., Gramsch, E., Rickard, A. R., Pilling, M. J., and Kleffmann, J.: Oxidation capacity of the city air of Santiago, Chile, Atmos. Chem. Phys., 9, 2257–2273, https://doi.org/10.5194/acp-9-2257-2009, 2009.
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