Long term ⁷Be deposition in Romania

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.