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Integrated Field Research Challenge Site

Reports

Quarterly Reports

I.  Overview and Highlights

Initial activities for the Rifle IFRC have focused on conducting preliminary laboratory and field experiments to provide samples that will allow direct linkage between the environmental metagenome and proteome under conditions of acetate-stimulated Fe-reduction. To facilitate this objective, a meeting of the proteomics subgroup was held in Berkeley in December 2006, a backhoe sample to support column experiments was collected in January 2007, and five backhoe samples with installed well points were obtained in May 2007 to define U(VI) concentrations bounding the area proposed for future Rifle IFRC field experiments.  Two of the backhoe samples were collected in the area planned for a desorption experiment in 2008. The well field for the 2007 biostimulation experiment was installed in June 2007 based on an experimental plan developed in the first few months of the project.

The initial field experiment for the Rifle IFRC successfully replicated previous field-scale biostimulation experiments at the Rifle site, producing Fe- and U-reduction, and a planktonic microbial community dominated by a few species of Geobacter. Genomic and proteomic analyses on samples filtered from groundwater collected during the experiment are currently in progress, but initial examination of the data indicates that proteins in the samples are consistent with Geobacter dominance of the planktonic community. In addition, a wide range of other analyses such as complex resistivity, hydraulic conductivity, stable isotope probing, PLFA, metals, electron acceptors, and electron donors were made before, during, and after the experiment.  The experiment, referred to as "F-0" or "Winchester", also provides the Rifle IFRC team with experience needed to establish procedures that will be used for field experiments throughout the life of the project.

Assessment of sedimentological heterogeneity throughout the Rifle IFRC flood plain was initiated via an EM survey at two sensor spacings.  Preliminary data analysis has been completed, showing significant differences near the margin of the flood plain, possibly reflecting geochemical differences associated with recharge to the aquifer from surrounding bedrock terrain.

Phil Long gave an invited presentation on the Rifle IFRC to the Royal Society for Chemistry, Meeting on Radiochemistry and Radioactively Contaminated Lands. The meeting was held November 29, 2006 at the University of Leeds, Leeds, UK. The presentation was entitled "Field-scale removal of U(VI) from groundwater in an alluvial aquifer during and after in situ electron donor amendment."

II.  Significant Changes

The overall scope and experimental approach of the project remains unchanged.  However, based on discussions at the kickoff meeting for the project held in February 2007 in Grand Junction, project participants decided that the initial field experiment needed to 1) provide biomass samples for directly linking genomic and proteomic data, and 2) replicate earlier successful biostimulation experiments in terms of acetate concentration.  This experiment was thus viewed as a prerequisite to the biostimulation experiments described in the original proposal and was referred to initially as F-0, to indicate that it preceded the other experiments.  The experiment was subsequently given the name Winchester for reasons described below.

Periodic sampling for assessing the natural rate of bioreduction of U(VI) (F-1) is just now getting underway because the approach to that hypothesis was refined during the February meeting.  That refinement is to install and sample appropriately spaced wells on a groundwater flow path that includes a known decrease in U(VI) along the flow path.

Initial deployment of in situ incubators has been shifted from background locations to the Winchester experiment.  Once data from deployment under biostimulated conditions has been completed, we will initiate deployment under background conditions.

III.  Management & Operations

Infrastructure Development

DOE-LM successfully negotiated and completed a Letter of Understanding with the City of Rifle that formalizes the agreement to make the site available for use by the Rifle IFRC for the duration of the project and allows installation of a field trailer at the site.

DOE-LM, Grand Junction Office completed the following site upgrades as an "in kind" contribution to the Rifle IFRC:

  • Graveling the road from the Rifle city maintenance facility into the area of the site used for experimental plots.
  • A gate and smooth wire fence was installed separating the part of the site used by the City of Rifle from the part dedicated to the Rifle IFRC.
  • A temporary field trailer for housing analytical equipment was provided for the Winchester Field Experiment.

Eight backhoe samples (5 with temporary well points) and 26 new wells for the Winchester experimental plot were completed as of September 30, 2007.

A permanent field trailer has been procured and upgraded to meet project requirements.  The trailer will be delivered to the site in late October or early November 2007.

Subcontract Status

All Co-PI subcontracts for FY-07 have been established. No-cost extensions have or will be completed as necessary to allow Co-PI's to continue work with carryover funds while FY-08 subcontracts are placed.  Co-PI's have expended funds to varying levels depending on when subcontracts were placed and other factors.  A few Co-PI's have fully expended their FY-07 allocations and they will be provided with additional funds via contract extensions using overall project carryover.  We anticipate that all Co-PI's will be on a normal fiscal year spending pattern by the end of FY-08.

Team Meetings

Telephone conference calls have been held monthly since the inception of the project, typically on the 2nd Thursday of the month at 10:30 AM Pacific Time.  Agendas and conference call summaries are sent to all project participants including post-docs, students, and collaborators.  Agendas and conference call summaries are available to others on an as-needed basis.

As described above, a major team meeting was held in Grand Junction in February 2007 to plan the first-year course of action.  Part of the organizational aspect of the team meeting was to establish working groups for the project as follows:

Field and Laboratory Experimental Working Groups:
  • Biostimulation working group (Ken Williams, Lead)
  • Sorption and Post-biostimulation Working Group (Jim Davis, Peter Jaffe,Co-Leads)
  • Natural Bioreduction Working Group  (Aaron Peacock, Lead)
Topical Working Groups:
  • Proteomics (and metagenomics) (Jill Banfield, Mary Lipton, Bob Hettich, Co-Leads)
  • Stable Isotope Probing, Lipid Analysis, Chip arrays (Lee Kerkof, Darrell Chandler, Co-leads)
  • Geochemistry (Carl Steefel, Jim Davis, Co-leads)
  • Geohydrology/Hydrogeophysics (Susan Hubbard, Lead)
  • Well drilling, sediment sampling, well completion, and groundwater sampling (Dick Dayvault, Lead)
  • Reactive Transport Modeling (Steve Yabusaki, Lead)
  • Data Management and Web Page Development (TBD)

A team meeting is being scheduled for February 2008 at an airport hub, most likely Salt Lake City.  The purpose of the meeting is to discuss results from analysis of data from the Winchester field experiment, finalize and coordinate publications on the experiment that have not yet been submitted and work out details for the 2008 field experiments.

IV.  Quarterly Highlights

For the purposes of this quarterly report and subsequent reporting activities we establish the following as reportable project tasks: 1) Project Management, 2) Field and laboratory experiments (with subtasks for each active experiment), 3) Web Site and Data Management, 4) Modeling and Interpretation, and 5) ERSD Outreach.

Task 1.  Project Management

Final versions of the Project Management Plan (PMP) and the Health and Safety Plan have been completed and approved.  The Rifle IFRC Quality Assurance Project Plan is complete and has been provided to Co-PI's.  Once changes suggested by Co-PI's are received, it will be routed for final approval.  The Rifle Site Management Plan is still under development.  A detailed schedule was developed and implemented for FY-07 and is under development for FY-08.

We have also created a series of field experiment names to help avoid confusion engendered by using the year of the experiment or the unimaginative "F-#" designation.  Names are based on local Rifle Motels with the first five field experiments named as follows:

2007 - Winchester (F-0); La Quinta (F-1, F-2)

2008 - Big Rusty (F-3, F-5), Little Rusty (F-4)

2009 - Buckskin (F-6)

2010 - River Rouge (F-7), TBD (F-8)

2011 - TBD (F-9)

Task 2.  Field and Laboratory Experiments

Subtask Winchester (F-0).  As described in the experimental plan for the Winchester experiment, acetate was amended to the subsurface in a new experimental plot starting on August 8th for a period approximately 1.5 weeks, after which acetate injection was intentionally halted with fresh groundwater replacing acetate-amended groundwater as the injectate for a period of approximately a week.  Acetate injection was then restarted for approximately 1.5 weeks and then halted on September 8th.  Groundwater, sampling, hydrologic testing, and geophysical monitoring continue at appropriate intervals.  In total, 4200-L of acetate amended groundwater was added to the aquifer over a period of 30-days.

The primary goals of the experiment were accomplished as follows:

  1. Three environmental proteomic samples were obtained.  Samples were collected from two wells (D-07 and D-05) during acetate injection by pumping and filtering approximately 500-L of groundwater per sample.  Given the lag time in the onset of significant iron-reduction across the flow cell, a sample was obtained from D-05 under very similar geochemical conditions to those at the time of the first D-07 sampling, thereby acting as a replicate time-point.  Initial analysis of the first two samples - albeit from different wells - indicates similar dominance by Geobacter sp. (90 to 95% of sequences) at the time of sampling.  The final sample was again taken from D-05 under conditions where pronounced uranium removal was observed.
  2. Successful retention of cellular material by the tangential flow filter during each of the proteomic sampling events yielded sufficient material to allow for sequencing and reconstruction of temporal metagenomic information.  This was an unexpected outcome, as we initially expected insufficient recovery to allow for such analysis.  Discussion is currently underway on which of the three samples will be used for this purpose. 
  3. A comprehensive set of geochemical data was obtained across the flow cell; acetate and bromide were detected in all downgradient wells, with the exception of D-12.  As of this update, significant uranium removal has been observed in most of the first and second row of downgradient wells (D-01 through D-07), with only D-08 showing little evidence of removal.  Of particular interest is that uranium removal has occurred to a more substantial degree than observed during previous experiments, with the lowest values reaching 0.04 to 0.08-uM after just 25-days; these values are 40 to 60% lower than observed in previous experiments.
  4. A temporally extensive set of RNA samples was obtained from numerous downgradient wells during three key stages: the initial period of acetate delivery; the period of acetate depletion accompanying the groundwater flush; and the period of acetate rebound following resumption of injection.  These data are expected to provide field validation of laboratory gene expression studies during conditions of acetate limitation being undertaken by UMass.
  5. For the first time at Old Rifle, we have tracked the cycling of ammonium during biostimulation.  Initial indications are that the pre-existing region of natural bioreduction exerts a strong influence on nitrogen cycling following biostimulation, and the possibility exists for a tie between available ammonium and uranium reduction rates.  This work is very exciting and provides an important piece of biogeochemical information needed for the ongoing in silico modeling activities.
  6. Successful testing of a novel microbe-modified, acetate-sensitive biosensor has been accomplished.  Temporal fluctuations in current density closely track the appearance, disappearance, and reappearance of acetate during the experiment.  Preliminary analysis of the recovered biosensor at UMass has revealed an extensive biofilm coating the sensor, in agreement with our conceptual model involving direct electron transfer by the biofilm community to the sensor during acetate oxidation.
  7. Multi-frequency (0.125, 1, and 4-Hz) complex resistivity data were acquired along two transects oriented perpendicular to groundwater flow at several time points after acetate injection.  The transects were sufficiently offset in the downgradient direction (~6-m) to allow testing of our ability to non-invasively discriminate between areas of iron- and sulfate-reduction using the differential response at specific (e.g. high vs. low) frequencies.  Furthermore, analysis of the baseline complex resistivity data suggests that it is sensitive to the presence of the naturally bioreduced sediments.  This fact, coupled with our initial observations that such zones exert an important influence on natural uranium dynamics in the aquifer, suggest the method to be an excellent tool for characterizing the site-wide distribution of such features.
  8. Hydrologic tests have been conducted before and after biostimulation, enabling us to directly assess the possible impact of biostimulation on the hydraulic properties of the experimental plot. Tests conducted include slug tests in almost all wells and a pumping test in D-01.  Borehole flow meter tests were conducted in selected wells before acetate injection but have not yet been done post-injection.  Initial results indicate that permeability commonly increases by a factor of two between before and after slug test.  We are continuing to analyze the data to determine if cause of the shift is dissolution of Fe oxyhydroxides during bioreduction or the dissipation of air bubbles entrained in the sand pack or formation during rotary sonic drilling.
  9. A comprehensive set of borehole (neutron, gamma, and formation conductivity) and cross-borehole (radar) geophysical data was acquired in advance of acetate injection, which when combined with hydrologic testing data should allow for creation of a hydrogeophysical model of the flow cell.  Recall that there is a discrepancy between Br arrivals predicted from hydraulic conductivities derived from slug tests and those actually observed in the experiment.  Ultimately these data will allow us to understand the heterogeneity in the flow and its impact on acetate delivery and uranium bioreduction.
  10. Dissolved gas samples were obtained from a variety of wells at multiple time points during the experiment.  This is the first time such data have been obtained during acetate injection at the site and initial indications suggest the zone of natural bioreduction exerts a strong influence on gas composition both before and after acetate amendment.
  11. In-field testing of a novel, antibody-based uranium sensor was undertaken with the goal of relating values obtained using the new sensor with those determined via more traditional KPA analysis.

Discussion continues on how best to manage the analysis and release of the extensive data obtained during the experiment.  A list of several publications likely to result from both the Winchester field experiment, and from lab experiments conducted as part of the Rifle IFRC, has been completed.  The list includes tentative authorship list and data sets to be used for each paper.  Undoubtedly, there will be some overlap in the data used (e.g. acetate, Fe(II), and uranium concentrations); however, by identifying the planned manuscripts and authorships at an early stage, we hope to avoid issues concerning dual publication and ensure that initial publication of key data sets makes that data available (via citation) for further discussion or analysis in subsequent papers.

Subtask L-1-A Characterizing the transition from iron- to sulfate-reduction under ambient conditions. This subtask was modified to include creation of biostimulated sediments to test proteomics analytical capabilities.  The work has been shared among LBNL, UC Berkeley, and Princeton University and has been extended over a longer time period than originally planned in order to capture some key ratios of biomass vs. maintenance energy needed for reactive transport modeling.  Results show consistent transition to sulfate reduction at about 30 to 40 days as is seen both in under field and in previous column experiments.  However, a decrease in apparent U(VI) reduction rate after the onset of sulfate reduction observed under field conditions has not been observed in column experiments, indicating a fundamental difference in field vs. column behavior that is currently being assessed.  One possibility is that, under field conditions, fast pathways allow preferential breakthrough of background U(VI) as additional biomass created during sulfate reduction decreases permeability in less permeable zones.  Fast pathways still intersect most wells somewhere over the thickness of the aquifer and thus the observed increase in U(VI) in most wells.  Analogous fast pathways are not available in column experiments, explaining the ongoing removal of U(VI) by reduction to U(IV) in those experiments.

Subtask L-2-A U(VI) sorption under baseline Rifle conditions. Limited U(VI) sorption data were available for Rifle sediments prior to the initiation of the Rifle IFRC.  The initial background sample (Rifle Aquifer Background Sample, RABS) turned out to have considerable sorbed uranium and therefore was unsuitable for developing accurate sorption isotherms.  Collection of a true background sediment required a backhoe sampling effort off site at the adjacent flood plain upriver.  Collection of this sample occurred in August 2007 and therefore initial sorption isotherms are still being developed.  However, samples from the Winchester experimental plot have been analyzed via bicarbonate and nitric acid extractions and these data show that the greatest uranium concentrations on sediments occur in the naturally bioreduced samples.  Peroxide extractions have been performed on RABS.  RABS normally produces a long desorption tail, but with the addition of peroxide the bulk of the uranium is released rapidly indicating that RABS either contains U(IV) that is oxidized by the peroxide or that the peroxide modifies mineral surfaces in a way that releases otherwise strongly sorbed U(VI).

Subtask F-4 Tracer test with accelerated U(VI)desorption.  A draft plan for the field-scale desorption experiment was completed.  In the near term, the plan provides the basis for initial drilling of the experimental site in October 2007.  The plan will be reviewed, discussed at the Rifle IFRC meeting and finalized in March 2008.

Other subtasks either are not scheduled to start yet or have been postponed as noted above.

Task 3.  Website and Data Management

A project web site is currently under development and will be reviewed by Co-PI's and PNNL prior to public release.  Our approach is to have a public web site to ensure that the public and the scientific community are aware of the overall project plan, scientific progress, experimental schedules, and availability of site materials. We are using a share point site internal to PNNL, with external access by Co-PI's as the mechanism for housing and sharing data, posting manuscripts, etc.  The Rifle IFRC share point site will serve as the portal to our data management system which includes 1) real-time data access via SOARS (System Operations and Analysis at Remote Sites), and 2) a database system that will either use DOE-LM's GEMS (Geospatial Environmental Management System) or will use the database under development for the Hanford IFRC.  Currently real-time data from multiparameter probes are managed and stored using SOARS and other field data are managed using spreadsheets posted on the share point site as the data are reviewed and verified.

Task 4.  Modeling and Interpretation

We have made excellent progress on reactive modeling of earlier experiments including a publication on the 2002 and 2003 experiments by Yabusaki et al. (2007.  Tracer inversion modeling and modeling of precipitated phases have been completed by our LBNL collaborators.  Results from both of these activities should enable significant improvement in overall modeling of the Winchester and future field experiments.

We were also able to perform limited premodeling of the Winchester experiment, particularly an assessment and visualization of cross-well mixing that demonstrated that cross-well mixing did not interfere with the overall down-gradient flux in the experimental plot.

Task 5.  ERSD Outreach

Phil Long gave an invited presentation on the Rifle IFRC to the Royal Society for Chemistry, Meeting on Radiochemistry and Radioactively Contaminated Lands.  The meeting was held November 29, 2006 at the University of Leeds, Leeds, UK.  The presentation was entitled "Field-scale removal of U(VI) from groundwater in an alluvial aquifer during and after in situ electron donor amendment.  Other outreach presentations are scheduled for 1)Northwest Geological Society (invited presentation, October 13, 2007), 2) The annual meeting of the Geological Society of America (October 29, 2007), and 3) The American Geophysical Union, Fall Meeting (week of December 14, 2007).

V.  Non-IFRC Project Activities

Key Collaborators

We have two collaborators who are not funded out of the IFRC budget but who are funded by ERSP and play key roles in IFRC field and data analysis activities.   Derek Lovley’s group at the University of Massachusetts provides metagenomic sampling and sample processing/data analysis, gene tracking during field experiments, and field sampling and analytical support.  They are also linked to the Rifle IFRC via a new project that will merge an in silico microbial model of Geobacter with a multicomponent reactive transport model.  The project will use selected Rifle Geobacter gene expression data to calibrate the in silico model and the merged model will ultimately be tested against Rifle field results.

Susan Hubbard’s group at LBNL is a key collaborator in the area of hydrogeophysics, tracer inversion/reactive transport modeling, and geochemistry.  They have been analyzing previous Rifle experiments to assess possible pore clogging and its impact on tracer movement, interpreting geophysical measurements, modeling solids precipitation, and assessing sulfur isotopic changes.

Other Collaborators:

Linda Figueroa, Associate Professor Environmental Science and Engineering and James F. Ranville, Associate Professor, Department of Chemistry & Geochemistry, Colorado School of Mines, Golden, Colorado have an independently funded student, Emily Lesher who is characterizing the dissolved and solid organic carbon fractions in the Winchester experiment before and during biostimulation.  The Colorado School of Mines group has provided significant field support during drilling at the site.

Diane Blake, Professor, Department of Biochemistry, Tulane University, New Orleans, LA, tested her antibody based U analysis systems, including a field-portable version during the Winchester experiment.

Tom Johnson, Assoc. Professor, Craig Lundstrom, Assoc. Professor, and Rob Sanford, Senior Research Scientist, Department of Geology, University Of Illinois At Urbana-Champaign, collaborate on U isotopic measurements.  Preliminary data from previous experiments Rifle indicate that there is a uranium isotopic signature of U bioreduction.  Samples from the Winchester experiment will be analyzed to further assess this possibility.

Sample Requests and Related Activities:

Argonne National Laboratory (Ed O’Loughlin) has made an informal request for Rifle samples for microbiology studies.  We have also had discussions with Ken Kemner and Shelly Kelly regarding X-ray micropobe XANES at the Advanced Photon Source (APS).

Approximately 10 kilograms of RABS was provided to for column experiments to Rizlan Bernier-Latmani, Assistant  Professor, Environmental Microbiology Laboratory, Ecole polytechnique fédérale de Lausanne, Lausanne, Switzerland. Dr. Bernier-Latmani collaborates with Dr. Brad Tebo, Oregon Health Sciences University, Portland, OR; John Bargar, Stanford Synchrotron Radiation Laboratory; and Dan Giammar, Aquatic Chemistry Laboratory at Washington University in St. Louis, MO.  The focus of the ERSP-funded project is to assess the stability of bacteriogenic uraninite (Title: Coupled Biogeochemical Processes Governing the Stability of Bacteriogenic Uraninite and Release of U(VI) in Heterogeneous Media: Molecular to Meter Scales).

The Rifle IFRC project has extensive stores of archived samples, including 100’s of kilograms of RABS, and 0.2 to 1.0 kg amounts of individual frozen or refrigerated samples.  Depth-specific residual samples that have not been environmentally controlled are also available in five-gallon buckets on site.  Availability of these materials will be noted on the web site and at upcoming Geological Society of America, American Geophysical Union, and Northwest Geological Society meetings.

VI.  Funding Issues

Initial funding of $1.75M was received by March 2007. This was supplemented in July 2007 by $250K for the purpose of extending heterogeneity studies at the Rifle site including a flood plain-wide electromagnetic survey, bringing the total funding for FY-07 to $2.0M. Expenditure plus commitments (obligated subcontracts to Co-PI's) through the end of FY-07 total $1.68M. This leaves carryover funding of $0.32M. Carryover funds will enable the project to function effectively under conditions of continuing resolution.

Funding for capital equipment was provided as follows:
  1. $116K for the purchase of a Mossbauer spectrometer with a closed-cycle refrigerant (CCR) cryostat that would allow measurements down to liquid helium temperatures (4.2˚ K).  The new spectrometer is needed because existing EMSL Mossbauer spectrometers are fully subscribed and it will allow samples to be changed while the system is cold and has better temperature control than older EMSL Mossbauer spectrometers. The new system has been received and will be installed as soon as modifications to the EMSL Mossbauer facility allow.
  2. $118K for the purchase of a borehole logging system that includes multiple sondes suitable for characterizing subsurface formations at all three ERSP IFRC's.  Operation of the logging system will be performed by National Laboratory or DOE-LM Grand Junction personnel and will be controlled by an operating procedure developed by Rifle IFRC personnel.  The system will be DOE property under the control of PNNL but will normally housed at DOE-LM Grand Junction until it is needed for use at the ORNL IFRC, The Hanford 300 Area IFRC, or other ERSP field locations.

VII.  Upcoming Plans/Issues

The following bulleted items summarize plans for FY 08.  Plans for the second half of FY 08 will be further refined in the next quarterly report.

October, 07 - March, 08

  • Finalize all project management documentation (Nov).
  • Complete review of external web site and release for public access (Nov).
  • Complete field trailer installation (Nov).
  • Procure field trailer equipment and install (Nov - March)
  • Continue monthly sampling of the Winchester experimental plot to track concentration trends in U(VI) and other key constituents.
  • Continue analysis of data and samples from Winchester, with priority on publication of basic experimental, gene expression, and metagenomic/proteomic data.
  • Initiate routine sampling of background wells, particularly MNA-1 (Nov).
  • Initiate installation of ISI's in background wells (Nov).
  • Complete detailed schedule for FY-08 (end-Oct).
  • Request regulatory approval for bicarbonate and additional tracers for injection at the Rifle IFRC. Include approval for insertion of U(VI) amended ISI's. (End-Nov).
  • Draft plan for Big Rusty (F-3 and F-5) (end Jan)
  • Full Rifle IFRC investigator meeting (Late Feb).
  • Finalize experimental plans for Big Rusty and Little Rusty (F-4) (end March)

April, 08 - September, 08

  • Complete coring and well installation for Big and Little Rusty (late April to early May).
  • Complete submittal of manuscripts for Winchester publications.
  • Conduct Big Rusty and Little Rusty experiments simultaneously after spring runoff peaks (July - Sept).

VIII.  Peer Reviewed Publications, Abstracts, and Presentations

Several publications are planned based on the Winchester experiment and laboratory experiments completed to date.  However, no Rifle IFRC manuscripts have yet been submitted.  The following are recent submittals or publications that resulted from prior ERSD-supported research at the Rifle site.

Publications

Yabusaki, S.B., Fang, Y., Long, P.E., Resch, C.T., Peacock, A.D., Komlos, J., Jaffe, P.R., Morrison, S.J., Dayvault, R.D., White, D.C., and Anderson, R.T., 2007. Uranium Removal from Groundwater via In Situ Biostimulation: Field-Scale Modeling of Transport and Biological Processes: Journal of Contaminant Hydrology, 93 (2007) 216–235.

R.A. O’Neil, D.E. Holmes, M.V. Coppi, L.A.Adams, M.J. Larrahondo, J.E. Ward, K.P. Nevin, T.L. Woodard, H.A. Vrionis, A.L.N’Guessan and D. R. Lovley. Gene transcript analysis of assimilatory iron limitation in Geobacteraceae during groundwater bioremediation. Environmental Microbiology. 2007 accepted.

D.E. Holmes, R.A. O’Neil, H.A.Vrionis, L.A. N’Guessan, I. Ortiz-Bernad, M.J. Larrahando, L.A. Adams, J.E. Ward, J.S. Nicoll, K.P. Nevin, M.A. Chavan, J.P. Johnson, P.E. Long, and D.R. Lovley. Subsurface Clade of Geobacteraceae that Predominates in a Diversity of Fe(III)-Reducing Subsurface Environments. ISME Journal, 2007 submitted.

Abstracts

Long, P.E. 2007. Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado. GSA Abstracts with Program, Vol. 39, Number 6 (Sept. 2007) 259.

Lesher, E., Figueroa, L., and Ranville, J. 2007. Characterization of Dissolved Organic Carbon in a Biostimulated Aquifer. GSA Abstracts with Program, Vol. 39, Number 6 (Sept. 2007) 259.

Presentations

Long, P.E. 2006. Field-scale removal of U(VI) from groundwater in an alluvial aquifer during and after in situ electron donor amendment. Royal Society for Chemistry, Meeting on Radiochemistry and Radioactively Contaminated Lands. University of Leeds, Leeds, UK, November 29, 2006.

Rifle IFC Team. 2007. Breakout Session on the Rifle IFC at the ERSD Annual Program Meeting. April 16-19, 2007; National Conference Center, Lansdowne, VA.

Rifle Colorado Site

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