Impact of Microbial Activity on Uranyl Mobility in the subsurface

0001923 Leckie本研究的目的是阐明土壤和地下水环境中重金属归宿的主导过程。 本研究将特别侧重于一个控制良好的模型生物地球化学系统，包括螯合剂（柠檬酸），矿物表面（针铁矿），纯微生物培养（荧光假单胞菌），重金属铀U（VI）作为铀酰离子（UO 22+），和CO2。 首先，将进行四个子系统的实验，以密切评估可能在铀酰命运中发挥作用的机制。 这些子系统包括：（1）不含细菌的铀酰-柠檬酸盐-Geothite系统，以确定柠檬酸盐对铀酰在Geothite上吸附的影响，（2）不含固相的铀酰-柠檬酸盐-微生物系统，以确定微生物与系统组分的相互作用，（3）铀酰-Geothite-微生物系统，以确定在不存在柠檬酸盐的情况下的行为，（4）不含铀酰离子的体系，测定柠檬酸盐吸附对其生物降解的影响。 在第二阶段，将调查整个地球化学系统，以确定影响铀酰总体分配的机制。***

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. ***