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Author Lawrinenko, M.; Kurwadkar, S.; Wilkin, R.T. url  openurl
  Title Long-term performance evaluation of zero-valent iron amended permeable reactive barriers for groundwater remediation – A mechanistic approach Type Journal Article
  Year 2023 Publication Geoscience Frontiers Abbreviated Journal  
  Volume 14 Issue 2 Pages 101494  
  Keywords (down) Geochemistry, Iron, Permeable reactive barrier, Plating reactions, Reduction potential, Surface passivation  
  Abstract Permeable reactive barriers (PRBs) are used for groundwater remediation at contaminated sites worldwide. This technology has been efficient at appropriate sites for treating organic and inorganic contaminants using zero-valent iron (ZVI) as a reductant and as a reactive material. Continued development of the technology over the years suggests that a robust understanding of PRB performance and the mechanisms involved is still lacking. Conflicting information in the scientific literature downplays the critical role of ZVI corrosion in the remediation of various organic and inorganic pollutants. Additionally, there is a lack of information on how different mechanisms act in tandem to affect ZVI-groundwater systems through time. In this review paper, we describe the underlying mechanisms of PRB performance and remove isolated misconceptions. We discuss the primary mechanisms of ZVI transformation and aging in PRBs and the role of iron corrosion products. We review numerous sites to reinforce our understanding of the interactions between groundwater contaminants and ZVI and the authigenic minerals that form within PRBs. Our findings show that ZVI corrosion products and mineral precipitates play critical roles in the long-term performance of PRBs by influencing the reactivity of ZVI. Pore occlusion by mineral precipitates occurs at the influent side of PRBs and is enhanced by dissolved oxygen and groundwater rich in dissolved solids and high alkalinity, which negatively impacts hydraulic conductivity, allowing contaminants to potentially bypass the treatment zone. Further development of site characterization tools and models is needed to support effective PRB designs for groundwater remediation.  
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  Series Volume Series Issue Edition  
  ISSN 1674-9871 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ lawrinenko_long-term_2023 Serial 143  
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Author Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. url  doi
openurl 
  Title Hydrochemical evolution of groundwater in gabbro of the Troodos Fractured Aquifer. A comprehensive approach Type Journal Article
  Year 2020 Publication Applied Geochemistry Abbreviated Journal  
  Volume 114 Issue Pages 104524  
  Keywords (down) geochemistry  
  Abstract  
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  Corporate Author Thesis  
  Publisher Pergamon Place of Publication Editor  
  Language English Summary Language Original Title  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Christofi2020hydrochemical Serial 13  
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Author Post, V.E.A.; Vassolo, S.I.; Tiberghien, C.; Baranyikwa, D.; Miburo, D. url  openurl
  Title Weathering and evaporation controls on dissolved uranium concentrations in groundwater – A case study from northern Burundi Type Journal Article
  Year 2017 Publication Science of The Total Environment Abbreviated Journal  
  Volume 607-608 Issue Pages 281-293  
  Keywords (down) Geochemical modelling, Hydrochemistry, Lake Tshohoha South, Public health, Radionuclides, Water supply  
  Abstract The potential use of groundwater for potable water supply can be severely compromised by natural contaminants such as uranium. The environmental mobility of uranium depends on a suite of factors including aquifer lithology, redox conditions, complexing agents, and hydrological processes. Uranium concentrations of up to 734μg/L are found in groundwater in northern Burundi, and the objective of the present study was to identify the causes for these elevated concentrations. Based on a comprehensive data set of groundwater chemistry, geology, and hydrological measurements, it was found that the highest dissolved uranium concentrations in groundwater occur near the shores of Lake Tshohoha South and other smaller lakes nearby. A model is proposed in which weathering and evapotranspiration during groundwater recharge, flow and discharge exert the dominant controls on the groundwater chemical composition. Results of PHREEQC simulations quantitatively confirm this conceptual model and show that uranium mobilization followed by evapo-concentration is the most likely explanation for the high dissolved uranium concentrations observed. The uranium source is the granitic sand, which was found to have a mean elemental uranium content of 14ppm, but the exact mobilization process could not be established. Uranium concentrations may further be controlled by adsorption, especially where calcium-uranyl‑carbonate complexes are present. Water and uranium mass balance calculations for Lake Tshohoha South are consistent with the inferred fluxes and show that high‑uranium groundwater represents only a minor fraction of the overall water input to the lake. These findings highlight that the evaporation effects that cause radionuclide concentrations to rise to harmful levels in groundwater discharge areas are not only confined to arid regions, and that this should be considered when selecting suitable locations for water supply wells.  
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  ISSN 0048-9697 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ post_weathering_2017 Serial 132  
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Author Gómez, P.; Garralón, A.; Buil, B.; Turrero, M.J.; Sánchez, L.; Cruz, B. de la url  openurl
  Title Modeling of geochemical processes related to uranium mobilization in the groundwater of a uranium mine Type Journal Article
  Year 2006 Publication Science of The Total Environment Abbreviated Journal  
  Volume 366 Issue 1 Pages 295-309  
  Keywords (down) Geochemical modeling, Granite, Groundwater, Uranium mine, Uranium retention  
  Abstract This paper describes the processes leading to uranium distribution in the groundwater of five boreholes near a restored uranium mine (dug in granite), and the environmental impact of restoration work in the discharge area. The groundwater uranium content varied from \textless1 μg/L in reduced water far from the area of influence of the uranium ore-containing dyke, to 104 μg/L in a borehole hydraulically connected to the mine. These values, however, fail to reflect a chemical equilibrium between the water and the pure mineral phases. A model for the mobilization of uranium in this groundwater is therefore proposed. This involves the percolation of oxidized waters through the fractured granite, leading to the oxidation of pyrite and arsenopyrite and the precipitation of iron oxyhydroxides. This in turn leads to the dissolution of the primary pitchblende and, subsequently, the release of U(VI) species to the groundwater. These U(VI) species are retained by iron hydroxides. Secondary uranium species are eventually formed as reducing conditions are re-established due to water–rock interactions.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ gomez_modeling_2006 Serial 162  
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Author Su, X.; Liu, Z.; Yao, Y.; Du, Z. url  openurl
  Title Petrology, mineralogy, and ore leaching of sandstone-hosted uranium deposits in the Ordos Basin, North China Type Journal Article
  Year 2020 Publication Ore Geology Reviews Abbreviated Journal  
  Volume 127 Issue Pages 103768  
  Keywords (down) Geochemical composition, leach mining, Mineralogy, Ordos Basin, Sandstone-hosted uranium deposit  
  Abstract The Nalinggou–Daying uranium metallogenic belt is situated at the northern Ordos Basin, China. Petrographical, mineralogical and geochemical techniques were used to study the ore-bearing sandstones and host rocks in the Nalinggou–Daying uranium metallogenic belt. The present study shows that uranium minerals, i.e., coffinite, pitchblende, and brannerite, are mostly disseminated around pyrite and detrital particles. The ore-bearing sandstones are enriched in organic matter, with which this reductive environment influenced uranium leaching. The carbonate concentration of the uranium ores is markedly higher than that of the host rocks, and intense carbonatization occurs in the ore-bearing sandstones. In this case, the usage of the classical in-situ leach uranium mining technique by injecting H2SO4 + H2O2 solution produces calcium sulfate precipitate, which can lead to blocking of the ore-bearing strata. For this reason, laboratory and field uranium mining tests were conducted using CO2 + O2 in-situ leaching technology and were demonstrated to be successful, illustrating that this approach is technically feasible. Inhibiting ore bed blockage and increasing the amount of injected O2 are important for uranium leaching in this setting.  
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  ISSN 0169-1368 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ su_petrology_2020 Serial 120  
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