Аннотация:Sorption of technetium, plutonium, and curium by natural and sterilized bottom sediments sampled from Lake Beloe Kosino of the Moscow region was studied. Natural bottom sediments sorb 98% of technetium within 4.5 months. Technetium sorption is due to sulfate reduction process generating hydrogen sulfide, which converts initial readily soluble sodium pertechnetate to insoluble Tc(VII) and Tc(IV) sulfides. For actinides the degree of sorption by natural and sterilized bottom sediments is 98 and 36%, respectively. The ratio between solid and liquid phases in the bottom sediments was 2.3 x 10(-2) g ml(-1).