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Immobilization of Ро on natural minerals (magnetite, glauconite), rocks (basalt, dunite), and synthesized manganese dioxide of the composition MnO was studied. Basic and ultrabasic rocks (basalts, dunites) widely occurring in the nature can be used for making artificial geochemical barriers for the removal of Po from weakly acidic and neutral liquid radioactive wastes. Dunite ensures the most efficient Ро immobilization from acidic solutions, and basalt, from neutral solutions. The degree of Ро removal upon 48-h interaction with dunite and basalt was 93 and 80% relative to its initial content in solutions with initial pH 3.0 and 7.0, respectively. With all the samples except MnO, the Ро immobilization in the initial step (0-5 h) is more efficient in the initially neutral solutions, but with time the degree of the Ро removal from the initially acidic solutions becomes higher. The rate of the Ро immobilization on MnO does not appreciably depend on pH in the examined acidity range. [ABSTRACT FROM AUTHOR]