Atmospheric Hydrogen Peroxide (H<sub>2</sub>O<sub>2</sub>) at the Foot and Summit of Mt. Tai: Variations, Sources and Sinks, and Implications for Ozone Formation Chemistry
Can Ye, Chaoyang Xue, Chenglong Zhang, Zhuobiao Ma, Pengfei Liu, Yuanyuan Zhang, Chengtang Liu, Xiaoxi Zhao, Wenjin Zhang, Xiaowei He, Yifei Song, Junfeng Liu, Weihao Wang, Benhui Sui, Ran Cui, Xue Yang, Rubo Mei, Jianmin Chen, Yujing Mu
Abstract
Abstract Hydrogen peroxide (H 2 O 2 ) acts as a terminal sink for atmospheric HO x radicals (OH and HO 2 ), playing a key role in tropospheric O 3 formation. However, there are few field measurements of atmospheric H 2 O 2 to assess its role in O 3 formation, especially for the seriously polluted region of the North China Plain. In this study, H 2 O 2 concentrations were measured at the foot of Mt. Tai from May to July 2018 and the summit of Mt. Tai from May to June 2019, with average values of 0.93 ± 1.01 and 2.05 ± 1.20 ppb, respectively. H 2 O 2 exhibited a pronounced diurnal variation with a noon‐peak at the foot of Mt. Tai, which could be well reproduced by a gas‐phase box model with H 2 O 2 dry deposition velocity of 3 cm s −1 included, indicating H 2 O 2 was mainly photochemically produced. Modeling analysis showed H 2 O 2 production at the foot was most sensitive to alkenes and aromatics, while the source and sink for H 2 O 2 were dominated by HO 2 recombination and dry deposition, respectively. Compared with the summer‐measurement in 2007, the remarkable elevation of H 2 O 2 at the summit might be ascribed to volatile organic compounds (VOCs) increase and SO 2 decline. Both H 2 O 2 ‐O 3 correlation and H 2 O 2 /NO z ratio suggested O 3 formation at the foot of Mt. Tai was mainly VOC‐sensitive in the early morning and shifted to NO x ‐sensitive thereafter. Therefore, reduction of VOCs emission especially for the reactive species of alkenes and aromatics in the morning as well as NO x emission around noontime will be effective for mitigating the serious O 3 (as well as H 2 O 2 ) pollution in Tai'an city.