亜熱帯太平洋域小笠原諸島母島において測定された大気中の過酸化水素濃度

Abstract

Concentrations of gaseous H 2 O 2 and O 3 have been measured at Ogasawara Hahajima Island located 1000 km south of Tokyo in April and July 1995. In April, when the Ogasawara Islands was covered with the continental air mass, O 3 and H 2 O 2 concentrations were high. Although O 3 concentration in July. was significantly lower than that in April, the mean H 2 O 2 concentration in July was higher than in April. This may be due to a difference in the solar radiation. Hydrogen peroxide concentration was usually higher in daytime than at night. However, the increases of H 2 O 2 concentrations were sometimes observed in the nighttime when the relative humidity was low. The nocturnal decrease of H 2 O 2 concentration was strongly dependent on the relative humidity; in other words, H 2 O 2 concentration is somewhat inversely proportional to the relative humidity. The loss of H 2 O 2 at night is caused by a heterogeneous process in the marine atmosphere. The heterogeneous loss rate was estimated at 0.3 to 6.5 × 10 -5 s -1 and was greatly influenced by the relative humidity. This process may significantly: affect HO x concentrations in the marine atmosphere.