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Distribution of uranium contamination in weathered fractured saprolite/shale and ground water.
Phillips, D H; Watson, D B; Roh, Y; Mehlhorn, T L; Moon, J-W; Jardine, P M.
Afiliação
  • Phillips DH; Environmental Engineering Research Centre, School of Planning, Architecture, and Civil Engineering, Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland, UK.
J Environ Qual ; 35(5): 1715-30, 2006.
Article em En | MEDLINE | ID: mdl-16899743
The objective of this study was to determine how structure, stratigraphy, and weathering influence fate and transport of contaminants (particularly U) in the ground water and geologic material at the Department of Energy (DOE) Environmental Remediation Sciences Department (ERSD) Field Research Center (FRC). Several cores were collected near four former unlined adjoining waste disposal ponds. The cores were collected, described, analyzed for U, and compared with ground water geochemistry from surrounding multilevel wells. At some locations, acidic U-contaminated ground water was found to preferentially flow in small remnant fractures weathering the surrounding shale (nitric acid extractable U [U(NA)] usually < 50 mg kg(-1)) into thin (<25 cm) Fe oxide-rich clayey seams that retain U (U(NA) 239 to 375 mg kg(-1)). However, greatest contaminant transport occurs in a 2 to 3 m thick more permeable stratigraphic transition zone located between two less permeable, and generally less contaminated zones consisting of (i) overlying unconsolidated saprolite (U(NA) < 0.01 to 200 mg kg(-1)) and (ii) underlying less-weathered bedrock (U(NA) generally < 0.01 to 7 mg kg(-1)). In this transition zone, acidic (pH < 4) U-enriched ground water (U of 38 mg L(-1)) has weathered away calcite veins resulting in greater porosity, higher hydraulic conductivity, and higher U contamination (U(NA) 106 to 745 mg kg(-1)) of the weathered interbedded shale and sandstone. These characteristics of the transition zone produce an interval with a high flux of contaminants that could be targeted for remediation.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Poluentes Radioativos da Água / Monitoramento Ambiental / Urânio / Sedimentos Geológicos País/Região como assunto: America do norte Idioma: En Revista: J Environ Qual Ano de publicação: 2006 Tipo de documento: Article País de publicação: Estados Unidos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Poluentes Radioativos da Água / Monitoramento Ambiental / Urânio / Sedimentos Geológicos País/Região como assunto: America do norte Idioma: En Revista: J Environ Qual Ano de publicação: 2006 Tipo de documento: Article País de publicação: Estados Unidos