ИСТИНА

This study is devoted to radioecological problem of long living radionuclides in the highest migration oxidation state. Uranium and technetium are highly migrable and hazardous metals, that can induce high risk of toxic effect for more than 104 years after water pollution itself. Natural microbial processes in subsurface water are described by the main mechanisms of U and Tc immobilization on host rock due to processes of bioprecipitation, bioreduction and biotransformation. This influence may be both positive (for example, due to an increase in cation exchange capacity because of microbial interaction with clay minerals) of negative (like raise of porosity of the rocks etc). However the biogeochemical processes that occur in this environment, and the extent they impact on radionuclide migration, are currently barely understood. New information concerning that can be used as basis for in situ sand aquifers remediation. The aim of this study is to make general biogeochemical model of U and Tc migration in sand aquifers. Here we use water samples from aquifers, contaminated with Tc, U and nitrate from 10-20, 180-200 and 350-380 depth (Tomsk region, Russia). The focus of the work is microbial metal bioreduction capacity, mineral phase formation and biofilms growth on sand, clays and host rocks as well as its role in sorption/precipitation.