The Role of Microorganisms in Uranium Behavior in the Water–Rock System

Abstract

Geochemical processes involving redox reactions and leading to either formation or transformation of geochemical barriers may be largely induced or enhanced by microbial activity. The microbial reduction of uranium is studied as a strategy for rehabilitation of uranium-containing groundwater. The bioremediation mechanism converts dissolved uranium(VI) into low-solubility U(IV). The processes involving dissimilatory reducing bacteria, which facilitate the reduction and retention of U(VI) in soils and rocks, are considered. The diversity of microorganisms involved in anaerobic reduction of uranium is shown. The geochemical conditions that may affect the rate of microbial reduction of U(VI) are specified, i.e., the presence of nitrate ions, phosphate ions, calcium ions, and iron oxides. The mechanisms of their action are examined. Geochemical barriers with the participation of microorganisms are proposed for the rehabilitation of groundwater with uranium removed from groundwater and deposited locally as a result of microbial reduction of U(VI).