Uranium geochemistry in groundwater from tertiary sediments

Spalding, Roy F.; Druliner, A.D.; Whiteside, Lowell S.; Struempler, Arthur W.

doi:10.1016/0016-7037(84)90316-8

Cited by 13 publications

(5 citation statements)

References 10 publications

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“…Emission of an α particle from the radioactive decay of 238 U results in the recoil of the daughter atom, 234 Th . This recoil sometimes causes the occluded atoms to spring out from the mineral phase, which then can be easily acted upon by environmental forces . Self-oxidation can also be promoted by electron stripping during 234 Th and 234 Pa β decay. , Additionally, radiolysis of water molecules can occur because of radioactive decay, resulting in the formation of oxidants ( • OH, • H, H 2 O 2 ), which can subsequently convert U(IV) to U(VI). , …”

Section: Resultsmentioning

confidence: 99%

“…Emission of an α particle from the radioactive decay of 238 U results in the recoil of the daughter atom, 234 Th. 10 This recoil sometimes causes the occluded atoms to spring out from the mineral phase, which then can be easily acted upon by environmental forces. 10 Self-oxidation can also be promoted by electron stripping during 234 Th and 234 Pa β decay.…”

Section: Environmentalmentioning

confidence: 99%

“…10 Self-oxidation can also be promoted by electron stripping during 234 Th and 234 Pa β decay. 10,12 Additionally, radiolysis of water molecules can occur because of radioactive decay, resulting in the formation of oxidants ( • OH, • H, H 2 O 2 ), which can subsequently convert U(IV) to U(VI). 9,11 Organic Matter Analysis.…”

Section: Environmentalmentioning

confidence: 99%

“…Exposure to oxidizing conditions may convert U(IV) to the more mobile U(VI) . Apart from redox-driven changes, U(IV) minerals can also undergo self-oxidation to form U(VI) through radioactive decay. − Uranium(VI) could then form secondary minerals based on solution–sediment chemistry . Dissolved inorganic carbon in groundwater is crucial for U geochemistry as it enhances the dissolution of uranyl minerals. , The mobilized U is known to sorb to minerals, such as Fe oxides, − manganese dioxide (MnO 2 ), calcite, , and clay. , Dissolved organic matter (DOM), native to an aquifer zone or infiltrated from the topsoil, can also affect the fate and transport of U.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Sujathan

Singh

2023

Environ. Sci. Technol.

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Elevated uranium (U) (>WHO limit of 30 μg L −1 ) in Indian groundwaters is primarily considered geogenic, but the specific mineralogical sources and mechanisms for U mobilization are poorly understood. In this contribution, statistical and geochemical analyses of well-constrained metadata of Indian groundwater quality (n = 342 of 8543) were performed to identify key parameters and processes that influence U concentrations. For geochemical predictions, a unified speciation model was developed from a carefully compiled and updated thermodynamic database of inorganic, organic (Stockholm Humic model), and surface complexation reactions and associated constants. Critical U contamination was found at shallow depths (<100 m) within the Indo-Gangetic plain, as determined by bivariate nonparametric Kendall's Tau b and probability-based association tests. Analysis of aquifer redox states, multivariate hierarchical clusters, and principal components indicated that U contamination was predominant not just in oxic but mixed (oxic−anoxic) aquifers under high Fe, Mn, and SO 4 concentrations, presumably due to U release from dissolution of Fe/Mn oxides or Fe sulfides and silicate weathering. Most groundwaters were undersaturated with respect to relevant U-bearing solids despite being supersaturated with respect to atmospheric CO 2 (average pCO 2 of reported dissolved inorganic carbonate (DIC) data = 10 −1.57 atm). Yet, dissolved U did not appear to be mass limited, as predicted solubilities from reported sediment concentrations of U were ∼3 orders of magnitude higher. Integration of surface complexation models of U on typical aquifer adsorbents, ferrihydrite, goethite, and manganese dioxide, was necessary to explain dissolved U concentrations. Uranium contamination probabilities with increasing dissolved Ca and Mn exhibited minima at equilibrium solubilities of calcite [∼50 mg L −1 ] and rhodochrosite [∼0.14 mg L −1 ], respectively, at an average groundwater pH of ∼7.5. A potential indirect control of such U-free carbonate solids on U mobilization was suggested. For locations (n = 37) where dissolved organic carbon was also reported, organic complexes of U contributed negligibly to dominant U speciation at the groundwater pH. Overall, the unified model suggested competitive dissolution−precipitation and adsorption−desorption controls on U speciation. The model provides a quantitative framework that can be extended to understand dominant mobilization mechanisms of geogenic U in aquifers worldwide after suitable modifications to the relevant aquifer parameters.

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Section: Resultsmentioning

confidence: 99%

Section: Environmentalmentioning

confidence: 99%

Section: Environmentalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Sujathan

Singh

2023

Environ. Sci. Technol.

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“…The elevated Na values are likely due in part to cation exchange of Ca in solution for Na on clay minerals originating in the Pierre (Cerling et al 1989). Additionally, University of Nebraska groundwater researchers hypothesize that high levels of SO 4 and Na in a Tertiary age aquifer in northwestern Nebraska may reflect upward migration of highly mineralized Na-SO 4 groundwater from the underlying Pierre Shale (Spalding et al 1984).…”

Section: Resultsmentioning

confidence: 99%

Baseline evaluation of legacy hydrochemical data for the Republican River watershed, southcentral Nebraska, USA

Atkinson

2021

Environ Earth Sci

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The objective of this study was to comprehensively evaluate and interpret hydrogeochemically the extensive legacy surfacewater data for the expansive Republican River watershed in southcentral Nebraska. Historical (1968-1991 hydrochemistry data [major cations and anions, total salinity [specific conductance (SC)] and pH supplied by the Nebraska Department of Environmental Quality and the US Geological Survey were hydrogeochemically and statistically analyzed. Interpretation of this large legacy dataset (315 sample analyses at 12 Republican River sampling stations) revealed that the Republican River's range in SC is relatively low (200-1020 µS/cm), with a river-wide median of 587 µS/cm (~ 380 mg/L). The range in SC for 10 tributaries (204 sample analyses) is 190-2910 µS/cm with a median value of 550 µS/cm (~ 360 mg/L). The Ca-HCO 3 hydrochemical facies dominates throughout the watershed followed by the Na-HCO 3 facies. Hydrochemical equilibrium modeling reveals that most samples occurred in an aqueous environment characterized by gypsum undersaturation but slight calcite and dolomite supersaturation; low supersaturation values comprise a line of evidence for the thermodynamic equilibrium or near equilibrium of the studied surface waters. Scatter plots of meq/L concentrations for selected anions and cations reveal the impact of silicate mineral (e.g., feldspars) weathering on the aqueous hydrochemistry throughout the watershed. These ubiquitous feldspar minerals most likely originated along the eastern slope of the Front Range during Late Cretaceous time (Laramide Orogeny) and were subsequently transported into the study area. The relatively high concentrations of sulfate and sodium in numerous samples collected from the Arikaree River probably originate in the underlying Pierre Shale, rich in S-bearing minerals.

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1994

Drainage Geochemistry

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Uranium geochemistry in groundwater from tertiary sediments

Cited by 13 publications

References 10 publications

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Baseline evaluation of legacy hydrochemical data for the Republican River watershed, southcentral Nebraska, USA

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