Uranium sequestration and release by framboidal pyrite in bioreduced sediments
EMSL Project ID
47507
Abstract
Exploratory research is proposed to gain insight into interactions between microbes, framboidal pyrite (FeS2), and uranium (U) in organic-matter rich, naturally bioreduced zones at an Integrated Field Research Center (IFRC) Uranium Mill Tailings Remedial Action (UMTRA) field site located at Old Rifle, CO (Rifle). U-containing framboidal pyrite was recently discovered in both IFRC/SFA sites at Rifle and Hanford. Results from a recent study by members of our collaboration demonstrate that U interacted with framboidal pyrite suggesting that pyrite-U interactions may play a significant role in controlling the fate and transport of groundwater U(VI) at DOE sites. Furthermore, biofilms present on some framboidal pyrite surfaces, indicate potential synergistic framboidal pyrite-microbe interactions that drive U sequestration in the subsurface. Our overall working hypothesis is that framboidal pyrite-associated microbes play an integral role in governing U bioreduction by catalyzing initial formation of framboidal pyrite and subsequently engaging in electron transfer processes with the pyrite surface that drive U reduction and sequestration through adsorption and precipitation.In this proposal, we suggest using Mössbauer spectroscopy for characterizing synthetic framboidal pyrite that will be used in biostimulated microcosm experiments. The goal is to characterize the framboidal pyrite before and after the experiment. This will help gain insight into (1) the phase characteristics of framboidal pyrite and (2) determine potential phase transformations that occur to the pyrite during biostimulation.
Mössbauer spectroscopy in conjunction with other advanced imaging and surface-sensitive spectroscopic techniques will be applied, including ESEM, aS/TEM, photoelectron microprobe, etc. The ultimate outcome will be a conceptual model of microbe-framboidal pyrite interactions, including key electron transfer processes that help determine U fate and transport at the Rifle site, including uptake, release, adsorption, and precipitation. Thus, the overall project vision will support DOE’s Subsurface Biogeochemical Research (SBR) mission by providing a fundamental scientific understanding of framboidal pyrite-microbial interactions, which are largely uninvestigated, despite representing a potentially key process governing long term U fate and transport at DOE sites. Further, the ability to stimulate these interactions may offer a new remediation strategy for DOE sites. This project will take advantage of the scientific expertise and resources offered at the Environmental Molecular Sciences Laboratory (EMSL). Two publications and a full proposal is envisioned to follow this exploratory research effort that would provide a detailed examination of the role of biological, hydrological and chemical processes impacting framboidal pyrite, microbial, and U interactions to predict the rate and extent of U(VI) attenuation in bioreduced sediments.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2012-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Qafoku N, BN Gartman, RK Kukkadapu, BW Arey, KH Williams, PJ Mouser, SM Heald, JR Bargar, N Janot, SB Yabusaki, and PE Long. 2014. "Geochemical and Mineralogical Investigation of Uranium in Multi–element Contaminated, Organic–rich Subsurface Sediment ." Applied Geochemistry. doi:10.1016/j.apgeochem.2013.12.001
Veeramani H, A Scheinost, N Monsegue, N Qafoku, RK Kukkadapu, M Newville, A Lanzirotti, A Pruden, M Murayama, and MF Hochella. 2013. "Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite." Environmental Science & Technology 47(5):2361-2369. doi:10.1021/es304025x