51ÖØ¿ÚÁÔÆæ

Increased radioactivity in the near-surface atmosphere is virtually an annual occurrence in the Gomel region, Belarus. However, there is no explicit evidence as to what causes these anomalies and whether their origin has a strong seasonal association. To establish any such relations, we have analysed long-term radiation monitoring data recorded in the region over the past 17 years from 2003 to 2020 to find that abnormal levels of atmospheric radioactivity in summer and in winter have different origins. Summer spikes are most likely caused by occasional wildfires blazing in contaminated afforested areas in extreme heat weather, such as the wildfires of 2015 and 2020 in the Chernobyl Exclusion Zone, which is confirmed by backward and forward trajectories of the air mass transport at the time calculated using the HYSPLIT model. By contrast, in winter, when a wildfire cannot occur, a potential source of atmospheric radioactivity in the Gomel region may be the use of wood fuel from contaminated territories in residential woodstoves. Measurements of wood ash sampled from local households across the contaminated area and close to the woods show excessively high concentrations of 137Cs and 90Sr. The Holt-Winters and the Facebook's Prophet models used for the purposes of this study prove their applicability for performing a short-term (5 years) prediction of the weekly index dynamics of the atmospheric radioactivity.