Characteristics of radioactivity in the surface air along the 45°N zonal belt in South-Eastern Europe

This study investigates the beryllium-7, lead-210 and caesium-137 activity concentrations in aerosol filter samples collected monthly along the 45°N zonal belt over 1991–2019. Sampling was performed in three locations, one in Serbia and two in Slovenia, and the Slovenian data records are published here for the first time. The activity concentrations were determined by standard gamma spectrometry. The obtained results are in general agreement with the literature data for Europe. The data sets at different sites display similarities in measurement ranges, overall means and seasonal cycles. Still, statistical tests show significant differences among the radionuclides’ concentrations across the locations. To investigate underlying processes that affect radioactivity in the surface air in this region, multivariate statistical concepts are applied to the radionuclides’ concentrations and local meteorological parameters. Discriminant analysis shows that all three sites are well separated from each other. Principal component analysis gives common pattern of interconnection between the observables: temperature has a stronger influence on the behaviour of beryllium-7 and lead-210 than that of caesium-137, but a negative correlation of the radionuclides’ concentrations with precipitation seems the strongest for caesium-137. Principal component analysis also shows local differences in the degree of relationship between the meteorological parameters and activity concentrations of the investigated radionuclides. This is an important finding for future atmospheric transport studies.