What is it about?
Biogenic Factors make the most important increments to Radionuclide Immobilization in many Environments and especially on Sandy Rock surfaces of Upper Aquifers.Geochemical simulation being based o experimentally collected factors shows us that microbial processes can lead to the formation of U(IV) and Tc(IV) precipitates in a mixture with biogenic sulfide. Fouling of the surface of aquifer rock particles with microbial polysaccharide biofilms worsens the sorption of Cs and Sr but improves the efficiency of the uranium immobilization.
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Why is it important?
More than 20 years ago we have discovered that Biogenic Factors make the most important increments to Radionuclide Immobilization in many Natural Environments. So are also the Sandy Rock surfaces exposed to different types of Upper Aquifers. The factors that ride the behaviour of redionuclides are investigated here.The effect of microorganisms on immobilization of Cs, Sr, U, and Tc on sandy rocks from upper aquifers was studied. Aquifer water samples taken from observation boreholes in the region of the suspended liquid radioactive waste (LRW) repository, B-2 basin of the Siberian Chemical Combine, were studied in a laboratory, and computer geochemical simulation was performed to estimate the diversity of radionuclide species taking into account the physicochemical conditions in upper aquifers. Analysis showed that the activity of microorganisms could give rise to reducing conditions in this zone, favoring immobilization of radionuclides with variable oxidation state.
Perspectives
The results of this study provide us with the options for the prediction of radionuclide sorption\desorption in bioenvironments.when studying the radionuclide migration in aquifers, along with abiotic processes it is necessary to take into account the effect of microorganisms. The formation of polysaccharide biofilms can worsen the sorption capacity of rocks for Cs and Sr because of shielding of chemical sorption sites of the surrounding rock. On the other hand, the U and Tc immobilization can be expected to increase owing to the formation of additional sorption sites for U and biogenic reduction of Tc as a result of changes in the redox conditions in the medium and direct enzymatic reduction. The results of geochemical simulation suggest the possibility of the Tc immobilization in the form of a new mineral phase, Tc(IV) oxide with biogenic sulfide.
Prof Konstantin Ed. German
Frumkin Institute of Physical Chemistry and Electrochemistry RAS
Read the Original
This page is a summary of: Biogenic Factors of Radionuclide Immobilization on Sandy Rocks of Upper Aquifers, Radiochemistry, January 2019, Pleiades Publishing Ltd,
DOI: 10.1134/s1066362219010156.
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