[en] The concentration data of artificial radionuclides in the Baltic Sea were averaged for the every year in the period of time 1986-2001. The averaged data consist of the measured results in the Baltic Sea proper, in the southeastern area and in the coastal waters. A slow decrease of the average concentration of ¹³⁷Cs in 1991-1995 and swift decrease in 1996 is defined. The measured and calculated average concentration of ¹³⁷Cs values were in a good agreement in 1997-1998 and in 2000. The discrepancy of mentioned results in another period of time is possible because of an extra radioactive contamination penetrating from the Bothnian Sea and the local effects. The discrepancy of measured and calculated results of average concentration of ⁹⁰Sr in the waters of the Baltic Sea is found out. The theoretic results show the tendency of the self-cleaning process of this radionuclide, however the measured data don't indicate this tendency. The measured results are higher of the theoretic one in 1991-2000. The ratio of ¹³⁷Cs/⁹⁰Sr concentration changed in 1986-2000: the maximum number is 6.5 and minimum is 2.8. The slow self-cleaning of the Baltic Sea waters is possible because of the penetration an extra amount of artificial radionuclides. (author)

[en] The sup(137)Cs radionuclide spreading scheme in the south-eastern part of the Baltic sea is presented. Calculations were carried out on the basis of the equation of contaminant transport in sea water within a certain synoptical situation in early September and late October 1977. The experimental data on sup(137)Cs radionuclide concentration was obtained during the Oceanograph expeditions in the autumn of 1977. Theoretical calculations and experimental data coincide satisfactorily

[en] The article presents the measurement results of the volumetric activity (VA) of artificial radionuclides ⁹⁰Sr and ¹³⁷Cs in the coastal waters of the Baltic Sea near the Curonian Peninsula in 2005-2009. The annual average values for this period of time were 12 Bq/m³ (⁹⁰Sr) and 40 Bq/m³ (¹³⁷Cs). Considerable variations in the VA of the radionuclide in individual measurements compared to the average results were observed. The extreme values were 6 and 16 Bq/m³ for ⁹⁰Sr and for ¹³⁷Cs-27 and 75 Bq/m³. It is proposed to allow such variations under the influence of a variety of external factors such as hydro meteorological situations, inflowing rivers and bays, storm activity and etc. Besides, a possibility of penetration of radionuclides into the sea waters from the additional radioactive sources is not excluded. (author)

[en] On the basis of data of the radionuclide ¹³⁷Cs volume activity in the Baltic Sea after Chernobyl accident the coefficient of the vertical turbulent diffusion (K_z) was calculated. Calculations were carried out for the deepest area of the Baltic Sea. The obtained K_z values were are in the interval from 0.63 to 1.63 cm²/s what can be attributed to different spreading conditions of penetration of radionuclide ¹³⁷Cs into a deep water in different regions of the Baltic Sea. This value of the vertical turbulent diffusion coefficient for the Gotland Depth is two times higher than result obtained by means of radionuclide ⁹⁰Sr. (author)

[en] Autocorrelation function computational method according to the artificial radionuclides volume activity measurements results in the Baltic Sea waters is presented. The algorithm of volume activity of radionuclides interpolation in the chosen points of the Baltic Sea surface waters according to the known values of autocorrelation functions and Monte-Carlo method is suggested. (author)

[en] The radionuclide ¹³⁷ Cs sorption rate from the Baltic Sea coastal waters depending on sorption condition and sorbent chemical composition is investigated. It is found out that according to sorbent turbulent admixture condition in capsule the sorption of radionuclide ¹³⁷ Cs from sea water by cobalt-ferrocyanide sorbent is 19% and by nickel-ferrocyanide sorbent is 34%. Using radiochemical and sorption methods the volume activity of radionuclides ¹³⁷ Cs, ⁹⁰ Sr and ¹⁴⁴ Ce in the coastal waters of the Baltic Sea (settlement Juodkrante) in 1990 was measured. The average values of these radionuclides volume activity are 117,25 and 6 Bq/m³ correspondingly. (author)

[en] Long - term observation results of radionuclides and volume activity (VA) in the Baltic Sea water were analysed. Radiological situations in the coastal zone and the open area of the south-eastern Baltic were observed. The objective analysis method was used to define the radionuclide VA field structure. Thee measured and calculated results of and VA field comparison in the south-eastern Baltic was satisfactory. According to the nuclear hydrophysical model an imitated situation of a 'passive' admixture spreading calculation in the south-eastern Baltic was carried out. In the case of the 'pollution' source concentration 10⁶ times exceeding the 'natural' background at the western wind velocity 10 m/s, the whole coastal area of Lithuania would be contaminated in three days. (author). 7 figs., 2 tabs., 8 refs