Photoformation of OH radical in water-extract of atmospheric aerosols and aqueous solution of water-soluble gases collected in Higashi-Hiroshima, Japan

concentration was highest (9.4 ± 4.0 nmol m ‐3 ), followed by NO3 ‐ and Cl ‐ , while the mean concentration of SO4 2‐ in the WEA fraction was 81 ± 33 nmol m ‐3 . The initial concentrations of H 2 O 2 were 0.2 ± 0.3 and 0.9 ± 2.3 nmol m ‐3 in the WSG and WEA, respectively. The extracted sample was irradiated using a solar simulator, after which the ROH was determined and normalized against the sun-light intensity of a clear sky midday on May 1 at 34°N, which revealed values of 1.4 and