Unexpectedly High Levels of H 2 O 2 Drive Sulfate Formation over the Residual Layer in Beijing

作者：Pengfei Liu, Shuyuan Jia, Shuying Li, Pengkun Ma, Yongjing Ma, Yuan Liu, Zhiheng Liao, Yonghong Wang, Biwu Chu, Qingxin Ma, Jiannong Quan, Yujing Mu, Hong He · 发表于：Environmental Science & Technology · 年份：2025 · DOI：10.1021/acs.est.4c09004 · 被引用次数：14 · 研究领域：Atmospheric and Environmental Gas Dynamics、Atmospheric chemistry and aerosols、Oil Spill Detection and Mitigation

Hydrogen peroxide (H 2 O 2 ) plays a key role in atmospheric chemistry, but knowledge of its variation, sources, and impact on sulfate formation remains incomplete, especially in the urban boundary layer aloft. Here, we conducted a field campaign with measurements of H 2 O 2 and related species at a tower-based site (∼528 m above the ground surface) of Beijing in spring of 2022. The observed hourly H 2 O 2 concentration reached up to 21.2 ppbv with an average value of 3.4 ± 3.7 ppbv during the entire observation period, which was higher than values from previous observations throughout the world. The H 2 O 2 budget revealed that the two known sources (self-reaction of HO 2 radicals and ozonolysis of alkenes) could not account for the significant formation of H 2 O 2, leading to a considerable unknown source strength (∼0.14–0.53 ppbv h –1 ) of H 2 O 2 at noon and after sunset. Based on the levoglucosan signal, distribution of fire points, and backward trajectories, biomass burning emissions from the southwest of Beijing (e.g., North China Plain) were found to contribute greatly to H 2 O 2 formation. Besides, photochemical aging of PM 2.5 might also have a potential impact on H 2 O 2 production at noon. The unexpectedly high concentrations of H 2 O 2 aloft made a vital contribution to sulfate production (0.2–1.1 μg m –3 h –1 ), which could be transported to the ground surface during the turbulent mixing. Our findings provide an improved understanding of the H 2 O 2 chemistry in...