Gamma spectrometrical analyses of annual deposition samples collected in Romania in 1987-1989

The dynamics of artificial radionuclide concentrations in deposition samples in the years 1987-1989 is presented in this paper. High resolution gamma spectrometrical analyses have been performed on wet and dry deposition samples from the following stations of the National Environmental Radioactivity Surveillance Network: Cluj-Napoca, Satu-Mare, Constanta, Ceahlau-Tosca, lasi and Craiova. In order to determine small concentrations of low level artificial radionuclides (having an appropriate half life) yearly samples obtained by cumulating daily samples were measured. The following gamma emitting radionuclides were identified in these samples: 106Ru, 110mAg, 125Sb, 134Cs, 137Cs, 144Ce. It can be seen that the level of radionuclide activities in deposition samples at any time is dependent on the 'initial' deposition of May 1986. An environmental half life of 137Cs in deposition can be assessed. For a particular case the evolution during 1987-1989 of 137Cs and 7Be specific activities in monthly samples is also presented. (author)