In Situ Microbial Community Control of the Stability of Bio-reduced Uranium

Baldwin, Brett, R. ; Peacock, Aaron, D. ; Resch, Charles, T. ; Arntzen, Evan ; Smithgall, Amanda, N. ; Pfiffner, Susan ; Gan, M. ; McKinley, James, P. ; Long, Philip, E. ; White, David, C.

关键词: AQUIFERS;    BINDING ENERGY;    DISSOLUTION;    ELECTRONS;    MAINTENANCE;    REMOVAL;    SEDIMENTS;    SORPTION;    STABILITY;    URANIUM;    URANIUM 228;    VALENCE;    WASTES uranium reduction;    in situ bioremediation;    in well sediment incubators;    in situ microcosms;    iron reduction;    sulfate reduction;   

DOI  :  10.2172/926154
RP-ID  :  DOE/ER/63939-1
PID  :  OSTI ID: 926154
Others  :  TRN: US1002174

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

In aerobic aquifers typical of many Department of Energy (DOE) legacy waste sites, uranium is present in the oxidized U(VI) form which is more soluble and thus more mobile. Field experiments at the Old Rifle UMTRA site have demonstrated that biostimulation by electron donor addition (acetate) promotes biological U(VI) reduction (2). However, U(VI) reduction is reversible and oxidative dissolution of precipitated U(IV) after the cessation of electron donor addition remains a critical issue for the application of biostimulation as a treatment technology. Despite the potential for oxidative dissolution, field experiments at the Old Rifle site have shown that rapid reoxidation of bio-reduced uranium does not occur and U(VI) concentrations can remain at approximately 20% of background levels for more than one year. The extent of post-amendment U(VI) removal and the maintenance of bioreduced uranium may result from many factors including U(VI) sorption to iron-containing mineral phases, generation of H2S or FeS0.9, or the preferential sorption of U(VI) by microbial cells or biopolymers, but the processes controlling the reduction and in situ reoxidation rates are not known. To investigate the role of microbial community composition in the maintenance of bioreduced uranium, in-well sediment incubators (ISIs) were developed allowing field deployment of amended and native sediments during on-going experiments at the site. Field deployment of the ISIs allows expedient interrogation of microbial community response to field environmental perturbations and varying geochemical conditions.