The features of self-purification of the Baltic Sea waters from 137Cs radionuclide

Abstract

The variations of 137Cs concentrations in the southeastern part of the Baltic Sea in 1997–2000, i.e., after 11–14 years from the accident at the Chernobyl nuclear power plant were studied. The rate of the water self-purification appeared to be rather low. The series of data obtained in 1999 was quite the same as that gained after the accident in 1986. The results of theoretical calculations showed that the Baltic Sea would not be puri- fied from the “Chernobyl” cesium-137 until 2020–2022. It was found that the average concentration of this radi- onuclide must be about 50–60 Bq/m3. In some cases, these concentrations were actually observed; meanwhile, higher values of 137Cs concentrations were frequently registered in the southeastern part of the Baltic Sea. In particular, in 1999, the average values ranged from 67 to 80 Bq/m3. In individual samples, relatively high 137Cs concentrations were found, varying from 110 to 212 Bq/m3. No stable correlation was observed between the 137Cs concentration, salinity, and temperature in the surface waters of the aquatic area considered. It was found that the distribution of radionuclide concentrations sometimes depends on the direction of the transfer of water masses. We suppose that the abnormally high 137Cs concentrations in the southeastern part of the Baltic Sea might be caused by an additional supply of radioactive wastes.