Impact of Microbial Activity on Uranyl Mobility in the subsurface

Stanford University, Stanford CA

Investigators

Abstract

0001923 Leckie The objective of this research is to elucidate the dominant processes governing the fate of heavy metals in soil and groundwater environments. This research will focus specifically on a well-controlled model biogeochemical system consisting of a chelator (citric acid), a mineral surface (goethite), a pure microbial culture (Pseudomonas fluorescens), the heavy metal uranium U(VI) as the uranyl ion (UO22+), and CO2. First, experiments with four sub-systems will be performed to closely evaluate the mechanisms which may play a role in the fate of uranyl. These sub-systems include: (1) a system of uranyl-citrate-geothite, without bacteria, to determine the effect of citrate on the sorption of uranyl on geothite, (2) a uranyl-citrate-microbe system, without the solid phase, to determine the microbial interactions with the system components, (3) a uranyl-geothite-microbe system to determine behavior in the absence of citrate, (4) a system without the uranyl ion to determine the effect of citrate sorption on its biodegradation. In the second phase, the overall biogeochemical system will be investigated to determine the mechanisms affecting the overall partitioning of uranyl. ***