The impacts of acidic in-situ recovery of uranium in southern Kazakhstan on geochemistry and microbial community structure

Acidic in situ recovery (ISR) of uranium is utilized because of its potential to be much cleaner than traditional physical mining techniques. Instead of spreading uranium-laden waste rock across soil, ISR circulates acid below the surface of the Earth within a closed loop recovery system. Once mining operations cease in Kazakhstan, the acid remains in the aquifer and is left for natural remediation, with the hope that, over time, the native Fe and SO¬4 reducing bacteria will raise the pH and precipitate the mobile metals. The risks of ISR coupled with natural attenuation are groundwater contamination and a long timeframe of pH recovery. Some estimates state that recovery can take up to tens of thousands of years. In order to evaluate the ability of natural attenuation to increase pH and the rate of such ‘natural processes’, first the effect of the acid on both geochemistry and the native microbial communities must be understood. The initial sampling mission from this collaboration, revealed that the acid not only liberates metals and salts, as predicted, but also has an affect on the indigenous microbes. These results will be presented along with future plans to compare natural attenuation vs. biostimulation in situ.