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The study investigated the sorption behaviour of 99Tc and 125I on bottom sediments from the Japan Sea, Khanka Lake and commercially available sapropel. It was determined that organic matter can have an impact on the iodine sorption process. After a 20-day period, sapropel reached an equilibrium state with a sorption value of up to 100%. In real systems of bottom sediment–water in the Far East region, iodine sorption was found to be superior on marine bottom sediments with a sorption value reaching 85% within 20 days, as opposed to freshwater sediments which only reached up to 35% within the same period. Tc(VII) in the form of pertechnetate anion exhibits no sorption under either aerobic or anaerobic conditions in the pH range of 4–11. Under aerobic conditions at pH 11 Tc(IV) is sorbed up to 15% only on sapropel; under anaerobic conditions at pH 7 the sorption reaches 25% for lake sediments, 10% for marine sediments and when the pH is 11, the sorption value of Tc by sapropel is as high as 100%. [ABSTRACT FROM AUTHOR]

Monitoring of radionuclide concentration in natural samples is important for assessing environmental safety. The low concentration of long-lived radionuclides require concentration from large volumes of natural water samples. This paper presents a method for sequential separation and simultaneous determination of radioisotopes of U, Pu, Am and Tc in water samples. Actinides and technetium were pre-concentrated by coprecipitation with iron hydroxides from the aqueous sample. Separation of actinides and Tc was achieved by extraction chromatography. The developed method allows separation of actinide and technetium from 100 L water with chemical yields between 40 and 70%. [ABSTRACT FROM AUTHOR]