thumbnail

The aqueous geochemistry of uranium in a drainage containing uraniferous organic-rich sediments, Lake Tahoe area, Nevada, USA

Uranium

By:
, , , and

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time
  • Download citation as: RIS

Abstract

Anomalously uraniferous waters occur in a small (4.2 km2) drainage in the west-central Carson Range, Nevada, on the eastern side of Lake Tahoe. The waters transport uranium from local U-rich soils and bedrock to organic-rich valley-fill sediments where it is concentrated, but weakly bound. The dissolved U and the U that is potentially available from coexisting sediments pose a threat to the quality of drinking water that is taken from the drainage. The U concentration in samples of 6 stream, 11 spring and 7 near-surface waters ranged from <1 to 177 ??g l-1 with an average value of 17 ?? 14 ??g l-1 for stream and spring waters. This value significantly exceeds a reported regional average value of ~5 ??g l-1, and is comparable to proposed maximum contaminant levels of U in drinking water. Calculations that utilize chemical compositions of the waters and thermodynamic data indicate that uranyl-carbonate and uranyl-phosphate complexes are the major inorganic species of dissolved U. In addition, dialysis experiments suggest an association of at least some dissolved U with macromolecular organic matter, particularly in near-surface waters that are in contact with organic-rich sediments. Calculations of the saturation index for uranous and uranyl-bearing minerals indicate that all of the waters are undersaturated with uranium minerals as long as ambient Eh is oxidizing (i.e. > 0.1 V). Possible precipitation of U(IV) minerals is predicted under the more reducing conditions that are particularly likely in near-surface waters, but the inhibitory effects of sluggish kinetics or organic complexing are not considered. These combined results suggest that a process such as adsorption or ion exchange, rather than mineral saturation, is the most probable mechanism for uranium fixation in the sediments. -Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The aqueous geochemistry of uranium in a drainage containing uraniferous organic-rich sediments, Lake Tahoe area, Nevada, USA
Series title:
Uranium
Volume
4
Issue:
4
Year Published:
1988
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Uranium
First page:
281
Last page:
305
Number of Pages:
25