Radionuclides in the ground-level atmosphere in Vilnius, Lithuania, in March 2011, detected by gamma-ray spectrometry

This study presents the ground-level air monitoring results obtained in Vilnius, the capital of Lithuania, on 14 March–14 April 2011 after the recent earthquake and subsequent Tsunami having a crucial impact on Japanese nuclear reactors at the Fukushima Daiichi Nuclear Power Plant (NPP) on 11 March 2011. To collect representative diurnal aerosol samples a powerful sampling system ensuring the air filtration rate of 5500 m3 h−1 was used. The following artificial gamma-ray emitting radionuclides have been determined: 129mTe, 132Te (in equilibrium with its daughter 132I), 131I, 134Cs, 136Cs and 137Cs. Activity concentration of the globally distributed fission product 137Cs has increased from a background value of 1.6 μBq m−3 to the value of 0.9 mBq m−3 at the beginning of April. The activity ratio 134Cs/137Cs was found to be close to 1, with a slightly higher activity of 134Cs. The maximum aerosol-associated 131I activity concentration of 3.45 mBq m−3 was by four orders of magnitude lower than that measured at the same location in April–May 1986 as a consequence of the Chernobyl NPP accident. The estimated gaseous fraction of iodine-131 constituted about 70% of the total 131I activity.

► We present results on artificial gamma-emitting nuclides in ground-level air in Vilnius.
► New fission products occurred after the earthquake at Japanese site on 11 March 2011.
► Activity concentrations of Te-129m as high as (594 ± 58) μBq m−3 have been measured in aerosol filters.
► Effects are by 4 orders of magnitude lower than after the Chernobyl accident in 1986.