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Author Priestley, S.C.; Payne, T.E.; Harrison, J.J.; Post, V.E.A.; Shand, P.; Love, A.J.; Wohling, D.L. url  openurl
  Title Use of U-isotopes in exploring groundwater flow and inter-aquifer leakage in the south-western margin of the Great Artesian Basin and Arckaringa Basin, central Australia Type Journal Article
  Year 2018 Publication Applied Geochemistry Abbreviated Journal  
  Volume 98 Issue Pages 331-344  
  Keywords Activity ratios, Central Australia, Great Artesian Basin, Hydrogeology, Sequential extraction, Uranium isotopes  
  Abstract The distribution of uranium isotopes (238U and 234U) in groundwaters of the south-western margin of the Great Artesian Basin (GAB), Australia, and underlying Arckaringa Basin were examined using groundwater samples and a sequential extraction of aquifer sediments. Rock weathering, the geochemical environment and α-recoil of daughter products control the 238U and 234U isotope distributions giving rise to large spatial variations. Generally, the shallowest aquifer (J aquifer) contains groundwater with higher 238U activity concentrations and 234U/238U activity ratios close to secular equilibrium. However, the source input of uranium is spatially variable as intermittent recharge from ephemeral rivers passes through rocks that have already undergone extensive weathering and contain low 238U activity concentrations. Other locations in the J aquifer that receive little or no recharge contain higher 238U activity concentrations because uranium from localised uranium-rich rocks have been leached into solution and the geochemical environment allows the uranium to be kept in solution. The geochemical conditions of the deeper aquifers generally result in lower 238U activity concentrations in the groundwater accompanied by higher 234U/238U activity ratios. The sequential extraction of aquifer sediments showed that α-recoil of 234U from the solid mineral phases into the groundwater, rather than dissolution of, or exchange with the groundwater accessible minerals in the aquifer, caused enrichment of groundwater 234U/238U activity ratios in the Boorthanna Formation. Decay of 238U in uranium-rich coatings on J aquifer sediments caused resistant phase 234U/238U activity ratio enrichment. The groundwater 234U/238U activity ratio is dependent on groundwater residence time or flow rate, depending on the flow path trajectory. Thus, uranium isotope variations confirmed earlier groundwater flow interpretations based on other tracers; however, spatial heterogeneity, and the lack of clear regional correlations, made it difficult to identify recharge and inter-aquifer leakage.  
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  ISSN 0883-2927 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ priestley_use_2018 Serial 115  
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Author Kharaka, Y.; Harmon, R.; Darling, G. url  openurl
  Title W. Mike Edmunds (1941–2015) Type Journal Article
  Year 2015 Publication Applied Geochemistry Abbreviated Journal  
  Volume 59 Issue Pages 225-226  
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  ISSN 0883-2927 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ kharaka_w_2015 Serial 103  
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Author Khoury, H.N.; salameh, E.M.; Clark, I.D. url  openurl
  Title Mineralogy and origin of surficial uranium deposits hosted in travertine and calcrete from central Jordan Type Journal Article
  Year 2014 Publication Applied Geochemistry Abbreviated Journal  
  Volume 43 Issue Pages 49-65  
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  Abstract Secondary uranium encrustations are hosted in thick travertine and calcrete deposits of Pleistocene–Recent age in central Jordan. The central Jordan varicolored marble and travertine are equivalent to the active metamorphic area in Maqarin, north Jordan. More than 100 samples were collected from the outcrops of the varicolored marble, travertine, calcrete, and the yellow uranium encrustations. The secondary yellow encrustations are mainly composed of uranyl vanadate complexes. Tyuyamunite Ca(UO2)2V25+O8·3(H2O)–strelkinite Na2(UO2)2V2O8·6(H2O) solid solution series are the major components and their composition reflects changes in the Ca/Na ratio in solution. Potentially, new vanadium free calcium uranate phases (restricted to the varicolored marble) were identified with CaO:UO3 ratios different from the known mineral vorlanite (CaU6+)O4. Carbon and oxygen isotope data from calcite in the varicolored marble are characterized by Rayleigh-type enrichment in light isotopes associated with release of 13C and 18O enriched CO2 by high temperature decarbonation during combustion of the bituminous marl. Stable isotope results from uranium hosted travertine and calcrete varieties exhibit a wide range in isotopic values, between decarbonated and normal sedimentary carbonate rocks. The depleted δ13C and δ18O values in the travertine are related to the kinetic reaction of atmospheric CO2 with hyperalkaline Ca(OH)2 water. The gradual enrichment of δ13C and δ18O values in the calcrete towards equilibrium with the surrounding environment is related to continuous evaporation during seasonal dry periods. Uranium mineralization in central Jordan resulted from the interplay of tectonic, climatic, hydrologic, and depositional events. The large distribution of surficial uranium occurrences hosted in travertine and calcrete deposits is related to the artesian ascending groundwater that formed extensive lakes along NNW–SSE trending depressions. Fresh groundwater moved upward through the highly fractured phosphate, bituminous marl and varicolored marble to form unusual highly alkaline water (hydroxide–sulfate type) enriched with sensitive redox elements among which were U and V.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ khoury_mineralogy_2014 Serial 121  
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Author Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. url  doi
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  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 geochemistry  
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  Address  
  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 Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. url  openurl
  Title Isotope hydrology and hydrogeochemical modeling of Troodos Fractured Aquifer, Cyprus: The development of hydrogeological descriptions of observed water types Type Journal Article
  Year 2020 Publication Applied Geochemistry Abbreviated Journal  
  Volume 123 Issue Pages 104780  
  Keywords Isotope hydrology, Hydrogeochemical modelling, Hydrochemistry, Kargiotis, Troodos  
  Abstract The origin of groundwater recharge and subsequent flow paths are often difficult to establish in fractured, multi-lithological, and highly compartmentalized aquifers such as the Troodos Fractured Aquifer (TFA). As the conjunctive use of stable isotopes and hydrogeochemical data provides additional information, we established a monitoring network for stable isotopes in precipitation in Cyprus. The local meteoric water line, altitude effect and seasonal variation of stable isotopes in precipitation are derived from monitoring data. Stable isotopes and hydrogeochemical data are combined to model water-rock interactions and groundwater evolution along a complete ophiolite sequence. As a result a generic hydrogeologic description for the observed water types is developed. Isotope hydrology was applied in conjunction with hydrogeochemical modelling in Kargiotis Watershed, a major north-south transect of the TFA. PHREEQC was used for hydrogeochemical modelling to establish generic descriptions for observed water types. Mean precipitation-weighted values from 16 monitoring stations were used to calculate the Local Meteoric Water Line (LMWL), which was found to be equal to δ2H = (6.58 ± 0.13)*δ18O + (12.64 ± 0.91). A general decrease of 1.22‰ for δ2H and 0.20‰ for δ18O in precipitation was calculated per 100 m altitude. A generic groundwater evolution path was established: 1. Na/MgClHCO3, 2. MgHCO3, 3. Ca/MgHCO3, 4. Ca/MgNaHCO3, 4a. MgNa/CaHCO3/Cl, 5. NaMg/CaHCO3/Cl, 6. NaHCO3, 7. Na/MgHCO3SO4, 8. NaSO4Cl/HCO3. Hydrogeologic descriptions, consisting of groundwater origin, flow path and possible active water-rock processes, have been realised for the observed water types. The first two water types occur in serpentine and ultramafic-gabbro springs. Type 3 waters represent early stages of recharge and/or short flow paths, in gabbro whereas types 4 and 5 are typical for further percolating waters in gabbro and diabase. Water types 6 and 7 occur both in diabase and in the basal group and represent the regional flow. Water type 8 is the end member of regional, upwelling groundwater in the basal group. The presented descriptions and methods have practical applications in groundwater exploration, characterization, and protection. The methodology can be applied in other complex aquifer systems.  
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  Language english Summary Language english Original Title  
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  ISSN 0883-2927 ISBN Medium  
  Area Cyprus Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ Christofi2020104780 Serial 76  
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