Effects of Bicarbonate on the Microbial Dissolution of Meta-Autunite

Injections of a soluble sodium tripolyphosphate amendment into uranium-contaminated groundwater and soil have been shown to effectively sequester uranium through the formation of insoluble uranyl phosphate minerals. Polyphosphate undergoes hydrolysis in aqueous solutions to orthophosphate forms, which serve as readily available nutrients for the various micro-organisms that thrive under these specific conditions and may even lead to an increase in their growth. Microbial activities in many environmental systems are additional layers of complexity that affect U(VI) mobility. The presence of rapidly adapting bacterial populations in sediment could strongly influence the migration/dissolution of uranium by dissolution and desorption due to the secretion of protons and various ligands. Therefore, understanding the role of bacteria in phosphate remediation technology and the interactions between meta-autunite and the microbes is very important. Of particular concern, however, is the long-term stability of the sequestered uranium in the subsurface that may undergo subsequent remobilization.