2023 Volume 58 Issue 6 Pages 99-108
A daytime highly time-resolved volatile organic compounds (VOCs) survey was conducted in Maebashi, Gunma Prefecture during the high photochemical oxidant concentration episode in the Kanto region in June 2022. During the daytime when the solar radiation increased, the concentrations of alkanes and aromatics decreased and the concentration of aldehydes increased. This was considered to be the result of the consumption of alkanes and aromatics and the formation of aldehydes by photochemical reactions. However, on days when the northwest wind was blowing during the daytime, the daytime Ox concentration did not significantly increase and the concentrations of the alkanes and aromatics from anthropogenic emissions were relatively low. In the evening when the southeasterly wind was blowing, the Ox concentration was the highest and simultaneously, the concentrations of alkanes, aromatics, and aldehydes increased. This result was attributed to the arrival of Ox generated by photochemical reactions during advection processes in the air masses containing high concentrations of anthropogenic VOCs emitted in the southern Kanto region, and the VOCs that remained unconsumed. In order to reduce the high concentration of Ox in the inland Kanto region, it is important to consider countermeasures of VOCs over the wide area of the Kanto region.
