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Liu, Z.; Li, C.; Tan, K.; Li, Y.; Tan, W.; Li, X.; Zhang, C.; Meng, S.; Liu, L. |
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Title |
Study of natural attenuation after acid in situ leaching of uranium mines using isotope fractionation and geochemical data |
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Journal Article |
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Year |
2023 |
Publication  |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
865 |
Issue |
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Pages |
161033 |
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Keywords |
Acid in situ leaching, Geochemical and isotopic tracing, Groundwater contamination, Natural attenuation, Uranium post-mining |
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Abstract |
Acid in situ leaching (AISL) is a subsurface mining approach suitable for low-grade ores which does not generate tailings, and has been adopted widely in uranium mining. However, this technique causes an extremely high concentration of contaminants at post-mining sites and in the surroundings soon after the mining ceases. As a potential AISL remediation strategy, natural attenuation has not been studied in detail. To address this problem, groundwater collected from 26 wells located within, adjacent, upgradient, and downgradient of a post-mining site were chosen to analyze the fate of U(VI), SO42−, δ34S, and δ238U, to reveal the main mechanisms governing the migration and attenuation of the dominant contaminants and the spatio-temporal evolutions of contaminants in the confined aquifer of the post-mining site. The δ238U values vary from −0.07 ‰ to 0.09 ‰ in the post-mining site and from −1.43 ‰ to 0.03 ‰ around the post-mining site. The δ34S values were found to vary from 3.3 ‰ to 6.2 ‰ in the post-mining site and from 6.0 ‰ to 11.0 ‰ around the post-mining site. Detailed analysis suggests that there are large differences between the range of isotopic composition variation and the range of pollutants concentration distribution, and the estimated Rayleigh isotope fractionation factor is 0.9994–0.9997 for uranium and 1.0032–1.0061 for sulfur. The isotope ratio of uranium and sulfur can be used to deduce the migration history of the contaminants and the irreversibility of the natural attenuation process in the anoxic confined aquifer. Combining the isotopic fractionation data for U and S with the concentrations of uranium and sulfate improved the accuracy of understanding of reducing conditions along the flow path. The study also indicated that as long as the geological conditions are favorable for redox reactions, natural attenuation could be used as a cost-effective remediation scheme. |
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0048-9697 |
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THL @ christoph.kuells @ liu_study_2023 |
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155 |
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Author |
Tisherman, R.A.; Rossi, R.J.; Shonkoff, S.B.C.; DiGiulio, D.C. |
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Title |
Groundwater uranium contamination from produced water disposal to unlined ponds in the San Joaquin Valley |
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Journal Article |
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Year |
2023 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
904 |
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Pages |
166937 |
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Keywords |
Groundwater, Oil & gas, Produced water, San Joaquin Valley, Uranium |
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Abstract |
In the southern San Joaquin Valley (SJV) of California, an agriculturally productive region that relies on groundwater for irrigation and domestic water supply, the infiltration of produced water from oil reservoirs is known to impact groundwater due to percolation from unlined disposal ponds. However, previously documented impacts almost exclusively focus on salinity, while contaminant loadings commonly associated with produced water (e.g., radionuclides) are poorly constrained. For example, the infiltration of bicarbonate-rich produced waters can react with sediment-bound uranium (U), leading to U mobilization and subsequent transport to nearby groundwater. Specifically, produced water infiltration poses a particular concern for SJV groundwater, as valley-fill sediments are well documented to be enriched in geogenic, reduced U. Here, we analyzed monitoring well data from two SJV produced water pond facilities to characterize U mobilization and subsequent groundwater contamination. Groundwater wells installed within 2 km of the facilities contained produced water and elevated levels of uranium. There are \textgreater400 produced water disposal pond facilities in the southern SJV. If our observations occur at even a fraction of these facilities, there is the potential for widespread U contamination in the groundwaters of one of the most productive agricultural regions in the world. |
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0048-9697 |
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THL @ christoph.kuells @ tisherman_groundwater_2023 |
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159 |
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Musy, S.; Purtschert, R. |
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Title |
Reviewing 39Ar and 37Ar underground production in shallow depths with implications for groundwater dating |
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Journal Article |
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Year |
2023 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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884 |
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163868 |
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Keywords |
Subsurface production, Argon-39, Argon-37, Muons, Isotope hydrology, Tracers |
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Argon-37 (37Ar) and Argon-39 (39Ar) are used for groundwater dating on timescales from weeks to centuries. For both isotopes, the quantification of underground sources is essential to accurately infer water residence times from sampled dissolved activities. Subsurface production resulting from interactions with neutrons from the natural radioactivity in rocks and with primary cosmogenic neutrons has been known for a long time. More recently, the capture of slow negative muons and reactions with muon-induced neutrons were documented for 39Ar subsurface production in the context of underground particle detectors (e.g. for Dark Matter research). However, the contribution from these particles was never considered for groundwater dating applications. Here, we reevaluate the importance of all potential depth-related production channels at depth ranges relevant for 39Ar groundwater dating [0 − 200 meters below the surface (m.b.s)]. The production of radioargon by muon-induced processes is considered in this depth range for the first time. The uncertainty on the total depth-dependent production rate is estimated with Monte Carlo simulations assuming a uniform distribution of the parameter uncertainties. This work aims to provide a comprehensive framework for interpreting 39Ar activities in terms of groundwater residence times and for exposure age dating of rocks. The production of 37Ar is also addressed since this isotope is relevant as a proxy for 39Ar production, for the timing of river-groundwater exchanges, and in the context of on-site inspections (OSI) within the verification framework of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). In this perspective, we provide an interactive web-based application for the calculation of 37Ar and 39Ar production rates in rocks. |
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0048-9697 |
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THL @ christoph.kuells @ Musy2023163868 |
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217 |
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Author |
Zhang, Y.; Liu, X.; Yuan, S.; Song, J.; Chen, W.; Dias, D. |
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Title |
A two-dimensional experimental study of active progressive failure of deeply buried Qanat tunnels in sandy ground |
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Journal Article |
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Year |
2023 |
Publication |
Soils and Foundations |
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63 |
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3 |
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101323 |
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Keywords |
Qanat tunnel, Sand, Failure effect, Soil arching, Model test |
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As an ancient underground hydraulic engineering facility, the Qanat system has been used to draw groundwater from arid regions. A qanat is a horizontal tunnel with a slight incline that draws groundwater from a higher location and delivers it to lower agricultural land. During long-term water delivery, the qanat tunnel has experienced different degrees of aging and collapse, which may result in the significant ground settlement and even disasters. This paper developed a two-dimensional laboratory system to investigate the influence of progressive failure on the stability of deeply buried qanat tunnels. The developed system is fully instrumented with a particle image velocimetry (PIV) system and earth pressure and displacement monitoring. A special cylindrical membrane tube is designed and connected to an advanced pressure–volume controller to simulate the step-wise failure process of the tunnel. Three model tests were conducted on a dry sand considering the buried qanat tunnels at three different depths. Experimental results clearly show the progressive evolution of soil arching effect in the dry sand associated with the progressive failure of the tunnels. The failure of the Qanat ground starts from the vault and develops upwards, which is closely related to the evolution of stress contour at three consecutive stages. Ground surface settlement and volume loss corresponding to three burial depths were compared. A deeply buried qanat tunnel has a small effect on surface settlement. Earth pressure evolution on the 2D plane shows the load redistribution when the qanat collapses. The maximum arch and the initial point of the limit state correspond to a volume loss of 12.5 % and 50 %, respectively. For the collapse of the deep buried qanat tunnel, ground earth pressure evolution can be divided into a stress-increasing region, stress-decreasing region, and no redistribution region. Furthermore, a multi trap-door model considering soil expansion is proposed to describe the progressive failure behavior and its effects. |
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0038-0806 |
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THL @ christoph.kuells @ Zhang2023101323 |
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274 |
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Author |
Holmes, M.; Campbell, E.E.; Wit, M. de; Taylor, J.C. |
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Can diatoms be used as a biomonitoring tool for surface and groundwater?: Towards a baseline for Karoo water |
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Journal Article |
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2023 |
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South African Journal of Botany |
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161 |
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211-221 |
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Bioindicator, Diatom, Hydraulic fracturing, Karoo, Water quality |
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Abstract |
The environmental risks from shale gas extraction through the unconventional method of ‘fracking’ are considerable and impact on water supplies below and above ground. Since 2010 the recovery of natural shale gas through fracking has been proposed in parts of the fragile semi-arid ecosystems that make up the Karoo biome in South Africa. These unique ecosystems are heavily reliant on underground water, intermittent and ephemeral springs, which are at great risk of contamination by fracking processes. Diatoms are present in all water bodies and reflect aspects of the environment in which they are located. As the possibility of fracking has not been removed, the aim of the project was to determine if diatoms could be used for rapid biomonitoring of underground and surface waters in the Karoo. Over a period of 24 months, water samples and diatom species were collected simultaneously from 65 sites. A total of 388 diatom taxa were identified from 290 samples with seasonal and substrate variation affecting species composition but not the environmental information. Species diversity information, on the other hand, often varied significantly between substrates within a single sample. Analysis using CCA established that the diatom composition was affected by lithium, oxidized nitrogen, electrical conductivity, and sulphate levels in the sampled water. We conclude that changes in diatom community composition in the Karoo do reflect the water chemistry and could be useful as bioindicators. |
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0254-6299 |
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THL @ christoph.kuells @ holmes_can_2023 |
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163 |
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