Vol.:(0123456789) 1 3 Journal of Radioanalytical and Nuclear Chemistry (2020) 326:1467–1476 https://doi.org/10.1007/s10967-020-07429-6 Pre‑Chernobyl deposition dynamics of anthropogenic radionuclides at Cluj‑Napoca, Romania C. Dovlete 1,3  · O. Sima 2,4  · S. Sonoc 1,5  · I. Osvath 1,6 Received: 13 July 2020 / Accepted: 26 September 2020 / Published online: 11 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020 Abstract The  137 Cs bulk deposition samples measured in samples collected at Cluj-Napoca in 1965–1985 are analysed and compared with published  137 Cs deposition data from New-York, St. Petersburg, Helsinki and Bratislava covering partially/totally the period 1955–1985. A total  137 Cs deposition of 4.2 ± 0.9 kBq/m 2  at Cluj-Napoca is estimated for 1955–1985 based on the comparison of available data. The signature of the atmospheric nuclear tests performed in 1977–1980 is presented using the monthly measured bulk depositions of  106 Ru,  125 Sb,  137 Cs and  144 Ce (1978–1982) and 95 Zr,  103 Ru,  141 Ce for the year 1981, following the last atmospheric nuclear test of October 16, 1980. Keywords Environmental radioactivity · Nuclear-weapons tests · Cluj-Napoca deposition · 137 Cs · 125 Sb · 106 Ru Introduction The contamination of the atmosphere with anthropogenic radionuclides was produced predominantly by atmospheric nuclear tests that began in 1945 and ceased in 1980. Con- cerns over the radioactive fallout from the atmospheric tests led some countries (USA, Great Britain, USSR, Denmark, Japan, New Zeeland, France etc.) in the nineteen ffties and the beginning of the sixties to initiate the systematic meas- urements of atmospheric radioactivity and to collect and analyse the depositions or/and aerosol samples. After the peak of atmospheric nuclear weapons tests, at the beginning of sixties, many other countries became interested to moni- tor the global fallout. Since 1962, the environmental samples were systemati- cally collected and measured in Romania at the sampling stations of the National Environmental Radioactivity Sur- veillance Network (NERSN) as part of the national radioac- tivity monitoring programme. The monitoring programme was carried out through a central laboratory and several sta- tions distributed across the country in the framework of the meteorological service. It evolved from 4 stations in 1962 [1] to 24 stations in 1975 and 47 stations in the 1990s. All stations followed a unitary programme and methodology to collect and prepare samples, and to perform gross beta measurements for surveillance purposes [2, 3]. The Environ- mental Radioactivity Laboratory (ERL) Bucharest-Afumati, the central laboratory coordinating the NERSN, performed radionuclide analyses on the samples collected at the sta- tions and carried out studies of atmospheric radioactivity in Romania [4–6]. Until 1990, ERL was afliated to the Institute of Meteor- ology and Hydrology (IMH) and was located at the Atmos- pheric Physics Observatory, Bucharest-Afumati, integrating meteorological information available on site, including wind profle and temperature gradient for the studies using radon and thoron daughters as tracers in the boundary layer of the atmosphere [7, 8]. This paper expresses strictly the views of the authors and doesn’t engage their current institutions. * C. Dovlete cdovlete@yahoo.fr 1 Environmental Radioactivity Laboratory, Bucharest-Afumati 72400, Romania 2 Faculty of Physics, University of Bucharest, Strada Atomiștilor 405, Magurele 077125, Romania 3 Present Address: Eze-Bord de Mer, France 4 Present Address: Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, Str. Reactorului No. 30, P.O.BOX MG-6, Bucharest, Magurele, Romania 5 Present Address: University of Toronto, 27 King’s College Cir, Toronto, ON M5S, Canada 6 Present Address: IAEA-Environment Laboratories, 4 Quai Antoine 1er, 98000 Monaco, Monaco