In-Well Sediment Incubators to Evaluate Microbial Community Stability and Dynamics Following Bioimmobilization of Uranium

摘要

An in-well sediment incubator (ISI) was developed to investigate the stability and dynamics of sediment-associated microbial communities to prevailing subsurface oxidizing or reducing conditions. Herein we describe the use of these devices at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site. During a seven-month period in which oxidized Rifle Aquifer background sediment (RABS) were deployed in previously biostimulated wells under iron-reducing conditions, cell densities of known iron-reducing bacteria, including Geobacteraceae, increased significantly, showing the microbial community response to local subsurface conditions. Phospholipid fatty acid (PLFA) profiles of RABS following in situ deployment were strikingly similar to those of adjacent sediment cores, suggesting ISI results could be extrapolated to the native material of the test plots. Results for ISI deployment with laboratory-reduced sediments showed only slight changes in community composition and pointed toward the ability of the ISI to monitor microbial community stability and response to subsurface conditions.