Distribution of <sup>137</sup>Cs in the Surface Layer of the Black Sea in Summer, 2017
Purpose. The purpose of the study is to investigate distribution of 137Cs in the coastal and deep-water part of the Black Sea. To achieve this goal, the following scientific problems has to be solved: choosing a method for concentrating 137Cs from seawater samples, seawater sampling and 137Cs concentrating, measurements of the obtained samples, discussion of the obtained results and their comparison with the available scientific literature data. Materials and Results. Distribution of 137Cs activity in the coastal and deep-water part of the Black Sea was studied. The in situ data on spatial-temporal variability of the 137Cs volumetric activity field in the Black Sea surface layer obtained in course of the 95th cruise of the R/V "Professor Vodyanitsky" in June, 14-July 7, 2017 were used. The data on the radionuclide vertical distribution in the sea active layer were obtained at a number of stations. 22 seawater samples were taken and processed at 11 stations. To separate 137Cs from seawater, a ferrocyanide sorbent of the FCC brand was first applied; it was intentionally developed for selective recovery and separation of 134Cs and 137Cs radionuclides from the technological processing solutions and radioactive waste water. Conclusions. According to the results, the volumetric activity of 137Cs varied spatially in the range 5.7-8.8 Bq/m3 and amounted on average 6.9 ± 0.2 Bq/m3. Within the active layer boundaries, vertical distribution of 137Cs was found to be uniform.