U isotopic fractionation — a process characterising groundwater systems

Suksi, Juhani; Rasilainen, Kari; Marcos, Nuria

doi:10.1007/3-540-28367-6_69

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…For pit lakes in Morocco with alkaline water, the 234 U-to- 238 U concentration ratio was 4.3–5.4 [ 12 ], and in acidic pit lakes in Spain the ratio was 1.6–4.5 [ 11 ]. Ratios higher than unity is commonly found in groundwater [ 28 ] and has been reported to be as high as ten [ 29 ].…”

Section: Resultsmentioning

confidence: 99%

Natural radioactivity and element characterization in pit lakes in Northern Sweden

et al. 2022

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Northern Sweden has been the object of intense metal mining in the last decades producing several water-filled open-pits, or pit lakes. Most of these pit lakes have been limed to maintain a good water quality and to prevent generation of acidic water that could leach the exposed rocks and release metals into water. The aim of this work was to examine the concentration of stable elements and naturally occurring radionuclides in water and sediment samples from pit lakes originating from non-uranium mining activities in Northern Sweden. Surface water and surface sediments were collected from 27 pit lakes in Northern Sweden. Water quality parameters, concentration of stable elements and radionuclides were measured by a water probe, ICP-MS and XRF, and alpha and gamma spectrometry, respectively. Furthermore, a multivariate statistical analysis (PCA) was performed on the water samples and sediments. In general, the quality of the surface water was good, but some lakes had low pH values (2.5–5.7), and high concentrations of Fe (up to 200 mg/L) and other metals (e.g. Zn, Cu). When relating the metal concentrations in sediments in pit lakes with the concentration found in natural lakes, some sites had relatively high levels of Cu, As, Cr and Pb. The activity concentration of 210Po, and U and Th isotopes in water and sediment samples were at environmental levels, as was the ambient dose equivalent rate at these sites (range 0.08–0.14 μSv/h).

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Section: Resultsmentioning

confidence: 99%

Natural radioactivity and element characterization in pit lakes in Northern Sweden

et al. 2022

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“…Uranium isotopes are a powerful tool for refining conceptual models of groundwater [1][2][3][4], groundwater dating [5][6][7], and descriptions of chemical weathering processes [8][9][10] for periods of up to hundreds of thousands of years [11]. The main initial parameters are (i) measured concentration of 238 U in the combined solution and solid phase, and (ii) measured 234 U: 238 U activity ratio in the combined pore fluid and solid phase and they can be obtained by direct measurements in water and rock samples collected in the field.…”

Section: Introductionmentioning

confidence: 99%

Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer in Combination with Groundwater Data

Малов

Zykov

2019

Water

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This work is part of a research project that aims to develop a method for combined radiocarbon and uranium-isotope dating of groundwater. The specific objective of this study was to investigate the mobility of uranium isotopes in the various mineral phases of rocks of an aquifer of sandy-clay deposits of the Vendian in the northwest of Russia, for which a partial extraction procedure was used. Representative aliquots of each core sample were treated with various reagents: distilled water, low mineralized fresh natural groundwater, minopolycarboxylic acid chelating agent (0.05 M EDTA), 0.5M HCl, 15 M HNO 3 , as well as total digestion, and the U isotope data for each procedure are reported in this study. The following mineral phases of core samples were characterized: sorbed material, carbonate minerals, amorphous iron oxides, partially soluble aluminosilicates and crystalline iron oxides, totally digestible aluminosilicates and a clay/quartz resistate. Red-colored siltstones and sandstones were depleted in uranium in relatively readily soluble mineral phases. The concentration of sorbed uranium was established in the range 15.8 ± 2.1-30.5 ± 3.9 µg/kg and carbonate minerals contained even less uranium. For iron hydroxides and the most readily soluble aluminosilicates, uranium concentrations were in the range 168 ± 24-212 ± 28 µg/kg. The most insoluble fraction contained uranium in the range 1.65 ± 0.21-4.32 ± 0.45 mg/kg. In green-colored siltstones, the concentration of sorbed uranium was much higher in the range 106 ± 14-364 ± 43 µg/kg. Carbonate minerals and amorphous iron oxides contained uranium in the range 1.91 ± 0.21-2.34 ± 0.26 mg/kg. In aluminosilicates and a clay/quartz resistate, uranium concentrations were in the range 5.6 ± 0.5-16.8 ± 1.4 mg/kg. Elevated values of 234 U: 238 U activity ratio prevailed in the sorbed material and iron hydroxides. In aluminosilicates and clay/quartz resistate, the values decreased. This indicates the replacement of primary sedimentogenic uranium by secondary hydrogenic uranium sorbed on the surface of minerals and coprecipitation with iron hydroxides. The results obtained made it possible to carry out preliminary quantitative estimates of the retardation factor and recoil loss factor of uranium in the groundwater of siltstones and sandstones of the studied Vendian aquifer.

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“…Uranium isotopes are a powerful tool for refining conceptual models of groundwater [1][2][3][4], groundwater dating [5][6][7] and descriptions of chemical weathering processes [8][9][10] for up to hundreds of thousands of years [11]. The main initial parameters are i) measured concentration of 238 U in the combined solution and solid phase, and ii) measured 234 U: 238 U activity ratio in the 2 of 15 combined pore fluid and solid phase.…”

Section: Introductionmentioning

confidence: 99%

<strong></strong>Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer Using Methods for the Extraction of Uranium with Different Strength Reagents in Combination with Groundwater Data

Ai¹,

Sb²

2019

Preprint

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A partial extraction procedure was used to study the distribution of uranium in the mineral phases of rocks of an aquifer of sandy-clay deposits of the Vendian in the northwest of Russia. This work is a part of a research project to develop a method for combined radiocarbon and uranium-isotope dating of groundwater. Representative aliquots of each core sample were subjected to five "partial" extractions by treatment with: distilled water, low mineralized fresh natural groundwater, minopolycarboxylic acid chelating agent (0.05M EDTA), 0.5M HCl, 15M HNO3, and a total digestion, with U isotopes reported in this study for each procedure. The following mineral phases of core samples: adsorbed material, carbonate minerals, amorphous iron oxides, aluminosilicates partial digestion and a crystalline iron oxides, aluminosilicates total digestion and a clay/quartz resistate were characterized. Red-colored siltstones depleted in uranium in relatively readily soluble mineral phases. The concentration of adsorbed uranium was established in the amount of 15.8±2.1 - 30.5±3.9 μg/kg. Carbonate minerals contain even less of this element. In iron hydroxides and the most readily soluble aluminosilicates, its concentrations are in the range 168±24 - 212±28 μg/kg. The most insoluble fraction contains 1.65±0.21 - 4.32±0.45 mg/kg of uranium. In green-colored siltstones, the concentration of adsorbed uranium is much higher: 106±14 - 364±43 μg/kg. Carbonate minerals and amorphous iron oxides contain 1.91±0.21 - 2.34±0.26 mg/kg of uranium. In aluminosilicates and a clay/quartz resistate, uranium concentrations are 5.6±0.5 - 16.8±1.4 mg/kg. Elevated values of 234U:238U activity ratio prevail in the adsorbed material and iron hydroxides. In aluminosilicates and clay/quartz resistate, the values decrease. This indicates the replacement of primary sedimentogenic uranium by secondary hydrogenic uranium adsorbed on the surface of minerals and coprecipitated with iron hydroxides. The results obtained made it possible to carry out preliminary quantitative estimates of the retardation factor and recoil loss factor of uranium in the groundwater of siltstones of the studied Vendian aquifer.

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U isotopic fractionation — a process characterising groundwater systems

Cited by 4 publications

References 4 publications

Natural radioactivity and element characterization in pit lakes in Northern Sweden

Natural radioactivity and element characterization in pit lakes in Northern Sweden

Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer in Combination with Groundwater Data

<strong></strong>Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer Using Methods for the Extraction of Uranium with Different Strength Reagents in Combination with Groundwater Data

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