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Reduction of radiostrontium mobility in acid soils by carbonate treatment

Journal Article · · J. Environ. Qual.; (United States)
OSTI ID:7008852

Development of chemical treatments to immobilize /sup 90/Sr in soil to prevent its leaching from radioactive waste disposed in shallow land burial sites is highly desirable. Six in situ carbonate-precipitating treatments, varying the amounts of carbonate, alkaline earth cation (Ca or Ba as chlorides), and order of addition were examined for their ability to immobilize radiostrontium in laboratory soil columns. The Na/sub 2/CO/sub 3/-followed by CaCl/sub 2/-treatment was most consistently successful at reducing the leachability of radiostrontium by 0.05M CaCl/sub 2/ from three low organic matter-acid soils, immobilizing as much as 53% of added radiostrontium. For the high organic matter-slightly acid soil, Na/sub 2/CO/sub 3/ alone, without supplemental Ca or Ba, resulted in the best immobilization (39%); dissolution of soil organic matter and the alkalinity-induced aggregate dispersion probably interfered with CaCO/sub 3/ and/or BaCO/sub 3/ precipitation. Success of the treatments is based primarily on their ability to generate, in situ, Ca(Sr,Mg)CO/sub 3/ or Ba(Ca,Mg,Sr)CO/sub 3/ precipitates that exchange radiostrontium very slowly with eluting Ca ions. Allied tests with /sup 137/Cs, which is commonly codisposed with /sup 90/Sr, indicated that the treatments describe did not interfere with the natural tendency of the selected soils to fix /sup 137/Cs strongly.

Research Organization:
Oak Ridge National Lab., TN
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
7008852
Journal Information:
J. Environ. Qual.; (United States), Journal Name: J. Environ. Qual.; (United States) Vol. 13:1; ISSN JEVQA
Country of Publication:
United States
Language:
English