Abstract

Characterization of sediments from Old Rifle, CO, a former uranium mill

More than 34 million gallons (~129 million liters) of groundwater are contaminated with uranium at Old Rifle, Colorado – a former uranium-processing site that operated until 1958. The original Department of Energy strategy for remediation, involving natural flushing of U from the groundwater through mixing with surface water, has not been as successful as predicted. The uranium plume is replenished when insoluble U(IV) is oxidized to the more mobile U(VI). Relatively thin pockets of silt-, clay-, and organic-rich sediments contain reduced uranium, iron and sulfur and are referred to as naturally reduced zones (NRZs). There is a correlation between organic carbon (OC) and U concentrations; thus it can be inferred that OC is controlling U distribution and speciation.

Sediment samples representing five different depths from the JB-02 well at Old Rifle were collected; two depths are above the NRZ, two are within the NRZ and one is below the NRZ. Sub-samples were then extracted using deionized water, NaCl and NaOH. The extractions were analyzed for non-purgeable organic carbon (NPOC) concentrations. Base extractions produced the highest concentrations of dissolved organic carbon (DOC) at all depths. Sediments within the NRZ produced more DOC than sediments above or below the NRZ. Further analysis by X-ray absorption spectroscopy (XAS) is expected to give key information on which organic functional groups are present within the sediments and their extractable carbon fractions, which will inform uranium management strategies. Additionally the amount of permanganate oxidizable carbon will be determined to further compare the carbon pools in and out of the NRZ.

Disciplines

Environmental Chemistry

Mentor

Morris Jones, Sharon Bone, Michael Schaefer

Lab site

SLAC National Accelerator Laboratory (SLAC)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU)., This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013 and Grant No. 0833353. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU)., This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013 and Grant No. 0934931. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU)., This material is based upon work supported by the Howard Hughes Medical Institute (HHMI). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of HHMI. This work was administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESAME) and the Fresno State Science and Mathematics Education Center (SMEC) on behalf of the California State University.

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URL: http://digitalcommons.calpoly.edu/star/268

 

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