Long term 7Be deposition in Romania

Abstract

This study is based on monthly 7Be deposition data at 29 of the stations of Romania's National Environmental Radioactivity Surveillance Network (NERSN), with different geographical and climatological conditions, extending over periods up to 17 years (1979–1995). The 7Be activity in each monthly sample from each station was determined using high-resolution gamma-ray spectrometry performed at the Environmental Radioactivity Laboratory, Bucharest-Afumati.The annual dynamics of atmospheric deposition of 7Be at each NERSN station showed a strong seasonal trend, very similar to the precipitation regime, with the highest values being observed in spring/summer and the lowest in winter. But the annual 7Be deposition fluxes varied broadly from station to station and year to year, from a minimum of 164 Bq/m2/y (Bechet, 1989) to a maximum of 1388 Bq/m2/y (Baia Mare, 1988). This large space-time variability of deposition was mainly due to the variability of the precipitation regime.The analysis of experimental data confirms the strong correlation of 7Be deposition data with precipitation, air temperature and the number of sunspots.Wet and dry deposition data are presented and discussed for four stations where separate dry and wet 7Be deposition measurements were performed.