Radionuclides from the Fukushima accident in the air over Lithuania: measurement and modelling approaches G. Lujanien _ e a, * , S. By  cenkien _ e a , P.P. Povinec b , M. Gera b a Environmental Research Department, SRI Center for Physical Sciences and Technology, Savanoriu 231, 02300 Vilnius, Lithuania b Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia article info Article history: Received 25 August 2011 Received in revised form 30 November 2011 Accepted 5 December 2011 Available online xxx Keywords: Fukushima accident Aerosols Iodine-131 Caesium-134,137 Plutonium-238,239þ240 abstract Analyses of 131 I, 137 Cs and 134 Cs in airborne aerosols were carried out in daily samples in Vilnius, Lith- uania after the Fukushima accident during the period of MarcheApril, 2011. The activity concentrations of 131 I and 137 Cs ranged from 12 mBq/m 3 and 1.4 mBq/m 3 to 3700 mBq/m 3 and 1040 mBq/m 3 , respectively. The activity concentration of 239,240 Pu in one aerosol sample collected from 23 March to 15 April, 2011 was found to be 44.5 nBq/m 3 . The two maxima found in radionuclide concentrations were related to complicated long-range air mass transport from Japan across the Pacific, the North America and the Atlantic Ocean to Central Europe as indicated by modelling. HYSPLIT backward trajectories and meteo- rological data were applied for interpretation of activity variations of measured radionuclides observed at the site of investigation. 7 Be and 212 Pb activity concentrations and their ratios were used as tracers of vertical transport of air masses. Fukushima data were compared with the data obtained during the Chernobyl accident and in the post Chernobyl period. The activity concentrations of 131 I and 137 Cs were found to be by 4 orders of magnitude lower as compared to the Chernobyl accident. The activity ratio of 134 Cs/ 137 Cs was around 1 with small variations only. The activity ratio of 238 Pu/ 239,240 Pu in the aerosol sample was 1.2, indicating a presence of the spent fuel of different origin than that of the Chernobyl accident. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction On March 11, 2011 a strong earthquake followed by high tsunami and fires damaged three reactors and a fuel pond at the Fukushima Dai-ichi Nuclear Power Plant (NPP) in Japan with releases of radionuclides to the atmosphere and the sea. According to the NISA (Nuclear and Industrial Safety Agency) report from 1.3  10 17 Bq to 1.5  10 17 Bq of 131 I and about 6.1  10 15 to 1.3  10 16 Bq of 137 Cs were released to the atmosphere (NISA, 2011; Chino et al., 2011). The consequences of this accident at the beginning estimated as level 4 were raised to the maximum level of 7 on the INES (International Nuclear and Radiological Event Scale) scale (IAEA, 2011), although the amount of discharged radioactive materials comprised approximately 10% of the Chernobyl accident only. Measurements carried out at Tokushima (about 700 km southwest from the Fukushima NPP) indicated the maximum activity concentration of particulate 131 I in the air of w3 mBq/m 3 which was observed on 6 April (Fushimi et al., 2011). Worldwide monitoring activities started immediately after the announcement of large radionuclide releases from the Fukushima NPP. The particulate 131 I activities of 4.4 mBq/m 3 were detected on 19e21 of March in Seattle (USA) (Diaz Leon et al., 2011). According to the CTBTO (Comprehensive Test-Ben Treaty Organization) data the first signs of diluted airborne activities appeared over Europe after 12 days of the Fukushima accident (Wotawa, 2011). The elevated levels of radionuclides on aerosols derived from the Fukushima NPP were detected at several sampling stations in Spain (Lozano et al., 2011), Germany (Pittauerová et al., 2011), Greece (Manolopoulou et al., 2011), Russia (Bolsunovsky and Dementyev, 2011). The most comprehensive radionuclide data over the Europe has been compiled by Masson et al. (2011). Anthropogenic radionuclides were introduced into the terres- trial and marine environments primarily after the atmospheric nuclear weapon tests carried out by the United States and the former Soviet Union from the 1940s to the early 1960s (Livingston and Povinec, 2002). Another source of anthropogenic radionuclides is related to nuclear accidents. The most severe of them was the Chernobyl accident when among other radionuclides about 1760 PBq of 131 I, 47 PBq of 134 Cs and 85 PBq of 137 Cs were released into the environment (IAEA, 2006). The consequences of the * Corresponding author. Tel.: þ370 5 2644856; fax: þ370 5 2602317. E-mail address: lujaniene@ar.fi.lt (G. Lujanien _ e). Contents lists available at SciVerse ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad 0265-931X/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2011.12.004 Journal of Environmental Radioactivity xxx (2012) 1e10 Please cite this article in press as: Lujanien _ e, G., et al., Radionuclides from the Fukushima accident in the air over Lithuania: measurement and modelling approaches, Journal of Environmental Radioactivity (2012), doi:10.1016/j.jenvrad.2011.12.004