Fukushima radionuclides in Vilnius/Lithuania aerosols: modelling of aerosol transport.

Measurements of activity concentrations of (131)I; (129 m)Te, (132)Te, (134)Cs and; (136)Cs, (137)Cs in aerosol were carried out in daily samples after the Fukushima accident during the period of March-April, 2011 in Vilnius. The maximum activity concentrations of (131)I and (137)Cs were found to be 3,700 μBq m(-3) and 1,040 μBq m(-3), respectively. Variations in activity ratios of (132)Te/(129 m)Te and (137)Cs/(136)Cs observed after the accident were explained by the decay of the short-lived isotopes, while those in (134)Cs/(137)Cs by the dilution effect of the Chernobyl-derived (137)Cs. It was found that different behaviours of highly volatile (131)I and (137)Cs resulted in enrichment of ground level aerosol particles by (131)I with respect to (137)Cs. Simulated activity concentrations of (137)Cs attached to aerosol particles for the Vilnius site reasonably agreed with measured activities in aerosol samples during the Fukushima accident.