Changes in Uranium Speciation through a Depth Sequence of Contaminated Hanford Sediments

Journal Article · Sun Apr 16 04:00:00 EDT 2006 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es0520969· OSTI ID:882379

Catalano, Jeffrey G; McKinley, James P; Zachara, John M; Heald, Steve M; Smith, Steven C; Brown, Gordon E

The disposal of basic sodium-aluminate and acidic U(VI)-Cu(II) wastes into the now-dry North and South 300 A Process Ponds at the Hanford site resulted in U(VI) groundwater plume. To gain insight into the geochemical processes that occurred during waste disposal and that will affect the future fate and transport of this uranium plume, the solid-phase speciation of uranium in a depth sequence from the base of the North Process Pond through the vadose zone to the water table was investigated using electron microprobe measurements and x-ray absorption fine structure spectroscopy. Uranium in sediments from the base of the pond was predominantly coprecipitated with calcite. From {approx}2 m below the pond base to the water table uranium occurred dominantly in a sorbed form, likely on the surface aluminosilicate clay minerals. The presence of a U(VI)-phosphate phase was also observed in this region, but it only occurred as a major uranium species at one depth. The initial sequestration of U(VI) in these sediments likely occurred through coprecipitation with calcite as conditions did not favor adsorption. As the calcite-bearing pond sediments have been removed as part of a remediation effort, future uranium fate and transport will likely be controlled primarily by adsorption/desorption phenomena.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 882379
• Report Number(s): PNNL-SA-46734; KP1302000
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 8 Vol. 40; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CALCITE
CLAYS
COPRECIPITATION
GEOCHEMISTRY
GROUND WATER
HANFORD RESERVATION
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
SEDIMENTS
SETTLING PONDS
URANIUM COMPOUNDS