Speciation of radionuclides in water and bottom sediments of some industrial basins at the Mayak Production Association

A study was made of speciation of radionuclides in samples of water and bot tom sediments taken from the industrial basins B-10 and B-11 at the Mayak P roduction Association. It was established that radiostrontium, calcium, and magnesium are primarily present in the aqueous phase in the cationic form whereas for transuranium elements and iron anionic forms prevail. The fract ion of the mobile form of the radionuclides in bottom sediments increases a s follows: Cs-137 < Pu-239 < Am-241 < Sr-90. Distribution of radionuclides between groups and fractions of the organic matter of bottom sediments was studied. It was shown that humus acids and nonspecific low-molecular-weight organic acids and their compounds with metals contribute significantly to formation of the mobile forms of radionuclides in aquatic ecosystems.