Measurement of Peroxides and Elucidation of Their Behavior in Subtropical Atmosphere

Peroxides include hydrogen peroxide and organic peroxides. Peroxides oxidize sulfur dioxide in cloud water, and the reaction produces sulfuric acid that causes acid rain and enhances aerosol formation. Thus, understanding behavior of atmospheric peroxides can help understand sources and behavior of aerosols. However, measurement of atmospheric peroxides is still scarce in Japan. We have tried to elucidate the behavior of peroxides in Okinawa Island, Japan. Okinawa Island is located in subtropical climate and close to East Asian countries such as China and Korea. In this study, concentrations of peroxides were determined by p-hydroxyphenyl acetic acid (POHPAA) dimmer technique. Hydrogen peroxide and organic peroxides were separated by a high performance liquid chromatography (HPLC). Atmospheric peroxides were collected by the scrubbing coil method by using phosphoric acid (pH=3.5) as an absorbing solution. We have observed clear diurnal pattern for hydrogen peroxide concentrations; lowest at night and highest at solar noon time. Hydrogen peroxide concentrations ranged from 1.5 to 3.0 ppbv. For organic peroxides, the concentrations were almost constant at 0.5 ppbv all day long. Concentrations of peroxides found in Okinawa Island appeared to be higher than those found in other parts of Japan.