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Author Krüger, N.; Külls, C.; Bruggeman, A.; Eliades, M.; Christophi, C.; Rigas, M.; Eracleous, T. openurl 
  Title Groundwater recharge estimates with soil isotope profiles-is there a bias on coarse-grained hillslopes? Type Conference Article
  Year 2020 Publication EGU General Assembly Conference Abstracts Abbreviated Journal  
  Volume Issue Pages 9840  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Krueger2020groundwater Serial 42  
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Author Tziritis, E.; Aschonitis, V.; Balacco, G.; Daras, P.; Doulgeris, C.; Fidelibus, M.D.; Gaubi, E.; Gueddari, M.; Güler, C.; Hamzaoui, F.; others openurl 
  Title MEDSAL Project-Salinization of critical groundwater reserves in coastal Mediterranean areas: Identification, risk assessment and sustainable management with the use of integrated modelling and smart ICT tools Type Conference Article
  Year 2020 Publication EGU General Assembly Conference Abstracts Abbreviated Journal  
  Volume Issue Pages 2326  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Tziritis2020medsal Serial 43  
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Author Uugulu, S.; Wanke, H. url  openurl
  Title Estimation of groundwater recharge in savannah aquifers along a precipitation gradient using chloride mass balance method and environmental isotopes, Namibia Type Journal Article
  Year 2020 Publication Physics and Chemistry of the Earth, Parts A/B/C Abbreviated Journal  
  Volume 116 Issue Pages 102844  
  Keywords Chloride mass balance, Groundwater recharge, Isotopic values, Precipitation gradient  
  Abstract The quantification of groundwater resources is essential especially in water scarce countries like Namibia. The chloride mass balance (CMB) method and isotopic composition were used in determining groundwater recharge along a precipitation gradient at three sites, namely: Tsumeb (600 mm/a precipitation); Waterberg (450 mm/a precipitation) and Kuzikus/Ebenhaezer (240 mm/a precipitation). Groundwater and rainwater were collected from year 2016–2017. Rainwater was collected monthly while groundwater was collected before, during and after rainy seasons. Rainwater isotopic values for δ18O and δ2H range from −10.70 to 6.10‰ and from −72.7 to 42.1‰ respectively. Groundwater isotopic values for δ18O range from −9.84 to −5.35‰ for Tsumeb; from −10.85 to −8.60‰ for Waterberg and from −8.24 to −1.56‰ for Kuzikus/Ebenhaezer, while that for δ2H range from −65.6 to −46.7‰ for Tsumeb; −69.4 to −61.2‰ for Waterberg and −54.2 to −22.7‰ for Kuzikus/Ebenhaezer. Rainwater scatters along the GMWL. Rainwater collected in January, February and March are more depleted in heavy isotopes than those in November, December, April and May. Waterberg groundwater plots on the GMWL which indicates absence of evaporation. Tsumeb groundwater plots on/close to the GMWL with an exception of groundwater from the karst Lake Otjikoto which is showing evaporation. Groundwater from Kuzikus/Ebenhaezer shows an evaporation effect, probably evaporation occurs during infiltration since it is observed in all sampling seasons. All groundwater from three sites plot in the same area with rainwater depleted in stable isotopic values, which could indicates that recharge only take place during January, February and March. CMB method revealed that Waterberg has the highest recharge rate ranging between 39.1 mm/a and 51.1 mm/a (8.7% – 11.4% of annual precipitation), Tsumeb with rates ranging from 21.1 mm/a to 48.5 mm/a (3.5% – 8.1% of annual precipitation), and lastly Kuzikus/Ebenhaezer from 3.2 mm/a to 17.5 mm/a (1.4% – 7.3% of annual precipitation). High recharge rates in Waterberg could be related to fast infiltration and absence of evaporation as indicated by the isotopic ratios. Differences in recharge rates cannot only be attributed to the precipitation gradient but also to the evaporation rates and the presence of preferential flow paths. Recharge rates estimated for these three sites can be used in managing the savannah aquifers especially at Kuzikus/Ebenhaezer where evaporation effect is observed that one can consider rain harvesting.  
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  ISSN 1474-7065 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ uugulu_estimation_2020 Serial 99  
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Author Belz, L.; Schüller, I.; Wehrmann, A.; Köster, J.; Wilkes, H. url  openurl
  Title The leaf wax biomarker record of a Namibian salt pan reveals enhanced summer rainfall during the Last Glacial-Interglacial Transition Type Journal Article
  Year 2020 Publication Palaeogeography, Palaeoclimatology, Palaeoecology Abbreviated Journal  
  Volume 543 Issue Pages 109561  
  Keywords -Alkanes, -Alkanols, Late Quaternary, Organic geochemistry, Palaeohydrology, Southern Africa  
  Abstract Conventional continental geoarchives are rarely available in arid southern Africa. Therefore, palaeoclimate data in this area are still patchy and late Quaternary climate development is only poorly understood. In the western Kalahari, salt pans (playas, ephemeral lakes) are common and can feature quasi-continuous sedimentation. This study presents the first climate-related biomarker record using sediments from the Omongwa Pan, a Kalahari salt pan located in eastern Namibia. Our approach to reconstruct vegetation and hydrology focuses on biogeochemical bulk parameters and plant wax-derived lipid biomarkers (n-alkanes, n-alkanols, and fatty acids) and their compound-specific carbon and hydrogen isotopic compositions. The presented record reaches back to 27 ka. During the glacial, rather low δ2H values of n-alkanes and low sediment input exclude a strong influence of winter rainfall. n-Alkane and n-alkanol distributions and δ13C values of n-hentriacontane (n-C31) indicate a shift to a vegetation with a higher proportion of C4 plants at the end of the Last Glacial Maximum until the end of Heinrich Stadial I (ca. 18–14.8 ka), which we interpret to indicate an abrupt excursion to a short wetter period likely to be caused by a temporary southward shift of the Intertropical Convergence Zone. Shifts in δ2H values of n-C31 and plant wax parameters give evidence for changes to drier conditions during early Holocene. Comparison of this dataset with representative continental records from the region points to a major influence of summer rainfall at Omongwa Pan during the regarded time span and demonstrates the potential of southern African salt pans as archives for biomarker-based climate proxies.  
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  ISSN 0031-0182 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ belz_leaf_2020 Serial 104  
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Author Ammar, F.H.; Deschamps, P.; Chkir, N.; Zouari, K.; Agoune, A.; Hamelin, B. url  openurl
  Title Uranium isotopes as tracers of groundwater evolution in the Complexe Terminal aquifer of southern Tunisia Type Journal Article
  Year 2020 Publication Quaternary International Abbreviated Journal  
  Volume 547 Issue Pages 33-49  
  Keywords CT southern Tunisia, Holocene, Mixing, Radicarbon, Uranium isotopes, Water-rock interaction  
  Abstract The Complexe Terminal (CT) multi-layer aquifer is formed by Neogene/Paleogene sand deposits, Upper Senonian (Campanian-Maastrichtian limestones) and Turonian carbonates. The chemical composition and isotopes of carbon and uranium were investigated in groundwater sampled from the main hydrogeological units of the (CT) aquifer in southern Tunisia. We paid special attention to the variability of uranium contents and isotopes ratio (234U/238U) to provide a better understanding of the evolution of the groundwater system. Uranium concentrations range from 1.5 to 19.5 ppb, typical of oxic or mildly reducing conditions in groundwaters. The lowest concentrations are found southeast of the study area, where active recharge is supposed to take place. When looking at the isotope composition, it appears that all the samples, including those from carbonate levels, are in radioactive disequilibrium with significant 234U excess. A clear-cut distinction is observed between Turonian and Senonian carbonate aquifers on the one hand, with 234U/238U activity ratios between 1.1 and 1.8, and the sandy aquifer on the other hand, showing higher ratios from 1.8 to 3.2. The distribution of uranium in this complex aquifer system seems to be in agreement with the lithological variability and are ultimately a function of a number of physical and chemical factors including the uranium content of the hosting geological formation, water-rock interaction and mixing between waters having different isotopic signatures. Significant relationships also appear when comparing the uranium distribution with the major ions composition. It is noticeable that uranium is better correlated with sulfate, calcium and magnesium than with other major ions as chloride or bicarbonate. The 14C activities and δ13C values of DIC cover a wide range of values, from 1.1 pmc to 30.2 pmc and from −3.6‰ to −10.7‰, respectively. 14C model ages estimated by the Fontes and Garnier model are all younger than 22 Ka and indicate that the recharge of CT groundwater occurred mainly during the end of the last Glacial and throughout the Holocene.  
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  ISSN 1040-6182 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ ammar_uranium_2020 Serial 119  
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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 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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Author Sahoo, S.K.; Jha, V.N.; Patra, A.C.; Jha, S.K.; Kulkarni, M.S. url  openurl
  Title Scientific background and methodology adopted on derivation of regulatory limit for uranium in drinking water – A global perspective Type Journal Article
  Year 2020 Publication Environmental Advances Abbreviated Journal  
  Volume 2 Issue Pages 100020  
  Keywords Drinking water, Global policy, Regulatory limits, Toxicity, Uranium  
  Abstract Guideline values are prescribed for drinking water to ensure long term protection of the public against anticipated potential adverse effects. There is a great public and regulatory agencies interest in the guideline values of uranium due to its complex behavior in natural aquatic system and divergent guideline values across the countries. Wide variability in guideline values of uranium in drinking water may be attributed to toxicity reference point, variation in threshold values, uncertainty within intraspecies and interspecies, resource availability, socio-economic condition, variation in ingestion rate, etc. Although guideline values vary to a great extent, reasonable scientific basis and technical judgments are essential before it could be implemented. Globally guideline values are derived considering its radiological or chemical toxicity. Minimal or no adverse effect criterions are normally chosen as the basis for deriving the guideline values of uranium. In India, the drinking water limit of 60 µg/L has been estimated on the premise of its radiological concern. A guideline concentration of 2 µg/L is recommended in Japan while 1700 µg/L in Russia. The relative merit of different experimental assumption, scientific approach and its methodology adopted for derivation of guideline value of uranium in drinking water in India and other countries is discussed in the paper.  
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  ISSN 2666-7657 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ sahoo_scientific_2020 Serial 127  
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Author Lartigue, J.E.; Charrasse, B.; Reile, B.; Descostes, M. url  openurl
  Title Aqueous inorganic uranium speciation in European stream waters from the FOREGS dataset using geochemical modelling and determination of a U bioavailability baseline Type Journal Article
  Year 2020 Publication Chemosphere Abbreviated Journal  
  Volume 251 Issue Pages 126302  
  Keywords Bioavailable fraction, Geochemical mapping / baseline, Modelling, Speciation, Stream water, Uranium  
  Abstract The concentration of the bioavailable uranium fraction (Ubio) at the European scale was deduced by geochemical modelling considering several definitions found in the literature and the FOREGS European stream waters geochemical atlas dataset to produce a Ubio baseline. A sensitivity analysis was performed using three thermodynamic databases. We also investigated the link between total dissolved uranium (Uaq) concentrations, speciation and global stream water chemistry on the one hand, and the lithology and ages of the surrounding rocks on the other. The more U-enriched the stream sediments or rock type contexts are, which tends to be the case with rocks containing silicates (4.1 mg/kg), the less U-concentrated the stream waters are (0.15 μg/L). Sedimentary rocks lead to slightly higher Uaq concentrations (0.34 μg/L) even if the concentration in sediment (Used) is relatively low (1.6 mg/kg). This trend is reversed for Ubio, with higher concentrations in a crystalline context. The mean estimated Ubio value ranges from 1.5.10−3 to 65.3 ng/L and can fluctuate by 3 orders of magnitude depending on the considered definition as opposed to by 2 orders of magnitude accountable to differences between thermodynamic databases. The classification of the water in relation to the two surrounding rock lithologies makes it possible to reduce the mean variability for the Ubio concentrations. Irrespective of the definition of Ubio considered, in 59% of cases the Ubio fraction represents less than 1% of Uaq. Several threshold values relating to Ubio were proposed, assuming knowledge only of the aqueous concentrations of the major elements and Uaq.  
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  ISSN 0045-6535 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ lartigue_aqueous_2020 Serial 141  
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Author Pree, T.A.D. url  openurl
  Title The politics of baselining in the Grants uranium mining district of northwestern New Mexico Type Journal Article
  Year 2020 Publication Journal of Environmental Management Abbreviated Journal  
  Volume 268 Issue Pages 110601  
  Keywords Critical stakeholder analysis, Environmental cleanup, Environmental monitoring, Mining reclamation/remediation/restoration, Politics of baselining  
  Abstract During the second half of the twentieth century, northwestern New Mexico served as the primary production site for one of the world’s largest nuclear arsenals. From 1948 to 1970 the “Grants uranium district” provided almost half of the total uranium ore accumulated by the United States federal government for the production of nuclear weapons, in addition to becoming a national source for commercial nuclear energy from the late 1960s to the early 1990s. By the twenty-first century, after a prolonged period of economic decline that began in the late 1970s, all uranium mining and milling in New Mexico had ceased, leaving a legacy of environmental health impacts. What was once referred to as “The Uranium Capital of the World” now encompasses over a thousand abandoned uranium mines and seven massive uranium mill tailings piles, which are associated with airborne and soil contamination as well as groundwater plumes of uranium and other contaminants of concern, in a landscape that has been fractured by underground mine workings and punctured by thousands of exploratory boreholes. This article presents an ethnographic study of the diverse forms of expertise involved in monitoring and managing the mine waste and mill tailings. Drawing from over two years of ethnographic research, I describe the relationship between different stakeholders from local communities, government agencies, and transnational mining corporations as they deliberate about the possibility of cleaning up the former mining district. My thesis is that the possibility of cleaning up the Grants district hinges on the “politics of baselining”—a term I introduce to describe the relationship between stakeholders and their competing environmental models and hydrogeological theories; each accounts for a different geological past prior to mining that can be deemed “natural,” as the background against which to measure the anthropogenic impacts from mining.  
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  ISSN 0301-4797 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ pree_politics_2020 Serial 151  
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Author Gardiner, J.; Thomas, R.B.; Phan, T.T.; Stuckman, M.; Wang, J.; Small, M.; Lopano, C.; Hakala, J.A. url  openurl
  Title Utilization of produced water baseline as a groundwater monitoring tool at a CO2-EOR site in the Permian Basin, Texas, USA Type Journal Article
  Year 2020 Publication Applied Geochemistry Abbreviated Journal  
  Volume 121 Issue Pages 104688  
  Keywords CO storage, Enhanced oil recovery, Geochemical baseline, Groundwater monitoring, Produced water, Solubility trapping  
  Abstract Carbon dioxide (CO2) enhanced oil recovery (EOR) provides a pathway for economic reuse and storage of CO2, a greenhouse gas. One challenge with this practice is ensuring CO2 injection does not result in target reservoir fluids migrating into overlying shallow (\textless1000 m) groundwater formations. Effective monitoring for leakage from storage formations could involve measuring sensitive chemical indicators in overlying groundwater units and within the producing formation itself for evidence of deviation from an initial state. In this study, produced waters and overlying groundwaters were monitored over a five-year period to evaluate which geochemical signals may be useful to ensure that oilfield produced waters did not impact overlying groundwaters. During this five-year period, a mature carbonate oil reservoir in the Permian Basin transitioned from a waterflooding operation to a water-alternating-gas injection (WAG), in which the formation was flooded with CO2 and various mixtures of produced water. Significant increases in dissolved inorganic constituents [alkalinity, TDS, Na+, Cl−, SO42−] were observed in produced waters following CO2 injection; however, carbonate reservoir dissolution-precipitation reactions appear to be minimal and injected CO2 appears to be stored via solubility trapping. Although there are statistically significant geochemical variations following CO2 injection, applying isometric log-ratios to certain parameters establishes a narrow range for post-CO2 injection produced waters. This narrow range can be considered a baseline for post-CO2 injection produced waters; this baseline can be utilized to monitor overlying local groundwaters for produced water intrusion. Additionally, certain parameters [Na+, Ca2+, K+, Cl−, alkalinity, and TDS] display large concentration disparities between produced water and overlying groundwaters; these parameters would be sensitive indicators of produced water intrusion into overlying groundwaters.  
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  ISSN 0883-2927 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ gardiner_utilization_2020 Serial 171  
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