Hydrogen Peroxide Measured in the Tokyo Metropolitan Area, Japan: Case Studies during Summer Campaigns in 2022 and 2023

抄録

Atmospheric hydrogen peroxide (H₂O₂) was intensively measured in the Tokyo metropolitan area (Kazo City, Saitama Prefecture and Shinjuku-ku, Tokyo), Japan in the summer of 2022 and 2023. In particular, the temperatures in the summer of 2023 were very high. H₂O₂ and ozone (O₃) concentrations were generally higher in Kazo City than in Shinjuku-ku, and the concentrations were particularly higher during the period of typical summer atmospheric pressure pattern when Photochemical Oxidant Warning was issued in Saitama Prefecture. Sufficiently high concentrations of H₂O₂ exceeding 3-4 ppb (30-minute values) were occasionally measured, which have hardly been seen in Toyama Prefecture, where the air environment is relatively clean in Japan. The oxidation capacity of SO₂ seems to be high in summer in the Tokyo metropolitan area. In Kazo City, H₂O₂ was highly positively correlated with O₃. When the atmospheric pressure pattern was typical for summer, both O₃ and H₂O₂ reached their maximums at around 15 JST in Kazo City; however, in Shinjuku-ku, the peak time of O₃ was in the early afternoon (around 13 JST), while the highest concentration of H₂O₂ was seen at around 15 JST when NO_X became significantly low.