Loading in 2 Seconds...
Loading in 2 Seconds...
Synchrotron-based investigations of biogeochemical transformations of priority contaminants in soils at DOE sties. July 18, 2006 Presented by Jeff Fitts Environmental Research & Technology Division. DOE Environmental Management Sites. http://web.em.doe.gov/em94/sitesum.html.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
July 18, 2006
Presented by Jeff Fitts
Environmental Research & Technology Division
Environmental Remediation Sciences Program mission is to advance our understanding of the fundamental biological, chemical, and physical processes that control contaminant behavior in the environment in ways that help solve DOE’s intractable problems in environmental remediation and stewardship.
ERSP Field Research Center at ORNL
Manipulate Uranium oxidation state to control U solubility
Will introduction of nickel resistance into indigenous microbial community have a positive effect on nitrate reducers and stimulate iron and sulfate reducers?
Goal:Immobilize uranium in contaminated sediments via microbial reduction and precipitation
Problem: Active uranium reducers are inhibited by co-contaminants in complex waste streams (e.g., heavy metals)
S3 ponds at ORNL
Major project objectives
Demonstrate application of natural gene transfer to improve community function under increased levels of toxic metal stress (Dr. Daniel van der Lelie, BNL Biology Dept.)
Demonstrate ability to enhance uranium immobilization in ORNL sediments by indigenous microorganisms that have adopted the toxic metal resistance marker(Fitts)
1. Community structure
2. Improved nitrate red.
Horizontal gene transfer (in vivo) – soil columns
Isolated from FRC fluidized bed reactor
1. S and Fe reduction
2. Uranium reduction and precipitation
Contaminant speciation in complex real-world systems
Speciation on model soil particles
and in pure bacterial cultures
Improve predictions of contaminant behavior
Single-crystal oxide/water interfaces
1. Growth media
2. Common soil bacteria, Pseudomonas
w/ and w/o gene for Ni resistance
3. As a function of Ni concentration
2-5 ml sample
1. Monitor bacterial growth (UV-Vis)
2. Measure Ni uptake by bacteria
X-ray transparent window
Optical Density at 290eV
Ni resistance mechanisms
Scanning Transmission X-ray Microscope imaging at the carbon K-edge
Washed cells exposed to Ni for 2 hrs
Rinsed cells are dried on microscope window
Pseudomonas DMY2::ncc-nre exposed to 2 mM NiCl2
Carbonates not observed
O K-edge will be sensitive to NiO formation
Carbonate in organic matrix
NSLS Beamline X1A
U(VI) reduction by Fe(II)-containing minerals
Green rust after
Rxn w/ U(VI)-containing aqueous solution
After initial rxn with Green rust
Reduced U, sequestered as U(IV)
After exposure to oxygen
Mixture of U(VI) & U(IV)
How stable is U(IV) that is associated with Fe-oxide?
What is the role of aqueous Fe(II)?
2,6 - FRC community
3,7 - FRC community + Pseudomonas wild type
4,8 - FRC community + Pseudomonas pMol222
5,9 - FRC community + Pseudomonas::ncc-nre
1 mM NiCl2
no Nickel added
S speciation and redox state
U oxidation state at M5 edge
Area 2 FRC soil
Area 2 FRC soil
reduced organic S species
NSLS beamlines X27A & X15B
Column effluent indicators
Ni distribution in Column 2
Soil indicators by x-ray absorption spectroscopy
Summary: Applications of synchrotron-based studies in nuclear waste management
BNL Environmental Sciences Dept.
BNL Biology Department
Niels van der Lelie
David Moreels, Safiyh Taghavi, Craig Garafola
Paul Northrup (BNL Environmental Sci. Dep.) – XAS & Microprobe
Bjorg Larson, Sue Wirick (Stony Brook University) – STXM
James Ablett (BNL NSLS) – Microprobe beamline X27A
Oak Ridge FRC
Dave Watson (ORNL)