Microscale Metabolic, Redox and Abiotic Reactions in Hanford 300 Area Subsurface Sediments
EMSL Project ID
34942
Abstract
This proposal is the NMR component of a funded DOE/ERSP program project in which we proposed to use the Hanford 300 Area as a site for identifying microscale metabolic, abiotic and redox reactions in the subsurface and in the microbial communities. We plan to measure metabolites, redox chemicals and uranyl concentrations at the microscale using nuclear magnetic resonance (NMR) spectroscopy and various microelectrodes (UO22+, H2S, O2, SO4-, NO3-, Eh and pH). In practice, uranium transformation from the liquid phase to the solid phase occurs in established communities of cells growing on mineral surfaces. Development of bacterial communities on surfaces results in dense, highly metabolically active cells along with extracellular polymeric substances (EPS). It was recently shown that precipitated uranium nanoparticles can associate with EPS, which supports the importance of community processes in uranium reduction and immobilization. Hence, microbial processes and redox and abiotic reactions operating at the microscale are critical to understanding factors controlling the macroscopic fate and transport of contaminants in the subsurface.
This proposal addresses the development and implementation of biofilm based methods to understand uranium mobility in subsurface biofilms. EMSL's unique NMR-compatible biofilm reactor will be used to characterize metabolite concentrations (lactate, acetate and pyruvate), alternative electron acceptor concentration (fumarate) with/without uranium. Additionally, NMR diffusion imaging techniques will be used to measure depth-resolved mass transport. NMR data will be combined with microsensor data produced at Washington State University to determine microscale factors affecting uranium mobility and the data will be used further for biofilm modeling. Our preliminary biofilm studies have shown a profound biofilm-age / starvation dependence in the depth-resolved diffusion profiles, thus a long range goal of this project is to determine the endpoint effects of biofilm aging and starvation upon uranium reduction / retention / remobilization. Extended studies will include the effects of subsequent electron-acceptor presence such as the periodic exposure to molecular oxygen similar to Hanford 300 A vadose zone.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2009-10-01
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Ahmed B, B Cao, JS McLean, T Ica, A Dohnalkova, O Istanbullu, A Paksoy, JK Fredrickson, and H Beyenal. 2012. "Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A, Isolated from Hanford 300A Subsurface Sediments." Applied and Environmental Microbiology 78(22):8001-8009. doi:10.1128/AEM.01844-12
Cao B, B Ahmed, DW Kennedy, Z Wang, L Shi, MJ Marshall, JK Fredrickson, NG Isern, PD Majors, and H Beyenal. 2011. "Contribution of Extracellular Polymeric Substances from Shewanella sp. HRCR-1 biofilms in U(VI) Immobilization." Environmental Science & Technology.
Cao B, L Shi, RN Brown, Y Xiong, JK Fredrickson, MF Romine, MJ Marshall, MS Lipton, and H Beyenal. 2011. "Extracellular Polymeric Substances from Shewanella sp. HRCR-1 Biofilms: Characterization by Infrared Spectroscopy and Proteomics." Environmental Microbiology 13(4):1018-1031. doi:10.1111/j.1462-2920.2010.02407.x
Renslow R.S., B. Ahmed, J. Nunez, B. Cao, P.D. Majors, J.K. Fredrickson, and H. Beyenal. 2017. "Modeling substrate utilization, metabolite production, and uranium immobilization in Shewanella oneidensis biofilms." Frontiers in Environmental Science 5. PNNL-SA-123748. doi:10.3389/fenvs.2017.00030
Renslow RS, PD Majors, JS McLean, JK Fredrickson, B Ahmed, and H Beyenal. 2010. "In Situ Effective Diffusion Coefficient Profiles in Live Biofilms Using Pulsed-Field Gradient Nuclear Magnetic Resonance." Biotechnology and Bioengineering 106(6):928-937.