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Author Love, A.J.; Shand, P.; Karlstrom, K.; Crossey, L.; Rousseau-Gueutin, P.; Priestley, S.; Wholing, D.; Fulton, S.; Keppel, M. url  openurl
  Title Geochemistry and Travertine Dating Provide New Insights into the Hydrogeology of the Great Artesian Basin, South Australia Type Journal Article
  Year 2013 Publication (down) Procedia Earth and Planetary Science Abbreviated Journal  
  Volume 7 Issue Pages 521-524  
  Keywords GAB springs, Great Artesian Basin, Helium isotope data, Uranium series dating  
  Abstract While of great national and societal significance, and importance in its own right, the Great Artesian Basin of Australia is an iconic example of a continental scale artesian groundwater system. New geochemical, hydrological, and neo-tectonic data suggests that existing models that involve recharge in eastern Australia, relatively simple flowpaths and discharge in springs in the western margin require modification. New geochemical data indicate a small volume flux of deeply derived (endogenic) fluids mixing into the aquifer system at a continental scale. Neo- tectonic data indicates active tectonism today that provides a fluid pathway through faults for the deeply sourced endogenic fluids to discharge in GAB travertine depositing springs.  
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  Series Volume Series Issue Edition  
  ISSN 1878-5220 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ love_geochemistry_2013 Serial 122  
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Author Lach, P.; Cathelineau, M.; Brouand, M.; Fiet, N. url  openurl
  Title In-situ Isotopic and Chemical Study of Pyrite from Chu-Sarysu (Kazakhstan) Roll-front Uranium Deposit Type Journal Article
  Year 2015 Publication (down) Procedia Earth and Planetary Science Abbreviated Journal  
  Volume 13 Issue Pages 207-210  
  Keywords LA-ICP-MS, pyrite, roll-front, SIMS, sulfur isotopy, traces elements, uranium  
  Abstract Pyrite is common in roll-front type uranium deposit in Chu-sarysu basin, Kazakhstan. Combined in-situ microstructural, isotopic and chemical analysis of pyrite indicates variation in precipitation conditions and in fluid composition. Broad-scale δ34S heterogeneity indicates a complex multi-facet evolution. First generation authigenic framboïdal aggregates are biogenic as demonstrated by the lowest δ34S values of -48‰ to -28‰. The latest generation pyrites are probably hydrothermal with greater δ34S variation (-30‰ to +12‰). This hydrothermal pyrite commonly displays variable enrichment of several trace elements especially As, Co and Ni. Strong variation in δ34S values and variable trace element enrichment is interpreted in terms of continuous variations in fluid composition.  
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  Series Volume Series Issue Edition  
  ISSN 1878-5220 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ lach_-situ_2015 Serial 182  
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Author Hu, K.; Wang, Q.; Tao, G.; Wang, A.; Ding, D. url  openurl
  Title Experimental Study on Restoration of Polluted Groundwater from in Situ Leaching Uranium Mining with Sulfate Reducing Bacteria and ZVI-SRB Type Journal Article
  Year 2011 Publication (down) Procedia Earth and Planetary Science Abbreviated Journal  
  Volume 2 Issue Pages 150-155  
  Keywords In situ leaching of uranium, nitrate radical, sulfate radical, Sulfate-Reducing Bacteria (SRB), Zero Valent Iron (ZVI)  
  Abstract In the case of in situ leaching of uranium, the primitive geochemical environment for groundwater is changed since leachant is injected into the water beaving uranium deposit. This increases the concentration of uranium and results in the groundwater contamination.Microbial reduction technology by Sulfate reducing bacteria and Zero Valent Iron were employed to treat uranium wastewater. The experiments were conducted to evaluate the influence of anion (sulfate and nitrate) on dealing with uranium wastewater. Experimental results show that the utilization of both SRB system and ZVI – SRB system to process uranium wastewater is affected by sulfate ion and nitrate ion. As the concentration of sulfate radical is lower than 4000mg/L, sulfate-reducing bacteria has no influence on precipitated uranium. However, as the concentration of sulfate is more than 6,000mg/L, uranium removal rate decreases significantly, from 80% to 14.1%. When adding sulfate radical on ZVI – SRB system to process uranium wastewater, its uranium removal rate is higher than SRB system. Low concentration of nitrate contributes to reduction metabolism of SRB. High concentration of nitrate inhibits the growth and metabolism of SRB and affects the treatment efficiency of uranium wastewater. When the concentration of nitrate reaches 1500mg/L, uranium removal rate is less than 0.1%. Nevertheless, as the concentration of nitrate is lower than 1000mg/L, uranium removal rate could reach more than 75%. As existence of nitrate radical, uranium removal rate of SRB by adding ZVI is higher than that without adding.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1878-5220 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ hu_experimental_2011 Serial 202  
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Author Merembayev, T.; Yunussov, R.; Yedilkhan, A. url  openurl
  Title Machine Learning Algorithms for Stratigraphy Classification on Uranium Deposits Type Journal Article
  Year 2019 Publication (down) Procedia Computer Science Abbreviated Journal  
  Volume 150 Issue Pages 46-52  
  Keywords classification, geophysics logging data, machine learning, stratigraphy, uranium deposit  
  Abstract Machine learning today becomes more and more effective instrument to solve many particular problems, where there are difficulties to apply well known and described math model. In other words – it is a great tool to describe non-linear phenomena. We tried to use this technique to improve existing process of stratigraphy, and reduce costs on site by applying computer leaded predictions on the basis of existing on-field collected data. Article describes usage of machine learning algorithms for stratigraphy boundaries classification based on geophysics logging data for uranium deposit in Kazakhstan. Correct marking of stratigraphy from geophysics logging data is complex non-linear task. To solve this task we applied several algorithms of machine learning: random forest, logistic regression, gradient boosting, k nearest neighbour and XGBoost.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1877-0509 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ merembayev_machine_2019 Serial 113  
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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 (down) 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 Alexander, A.C.; Ndambuki, J.M. url  openurl
  Title Impact of mine closure on groundwater resource: Experience from Westrand Basin-South Africa Type Journal Article
  Year 2023 Publication (down) Physics and Chemistry of the Earth, Parts A/B/C Abbreviated Journal  
  Volume 131 Issue Pages 103432  
  Keywords Acid mine drainage, Groundwater quality, Mine closure, Spatio-temporal variation, Westrand Basin  
  Abstract The mining sector is at the edge of expanding to cater for natural resources that are much needed for technological development and manufacturing. Mushrooming of mines will consequently increase the number of mines closure. Moreover, mines closure have adverse impact on the environment at large and specifically on water resources. This study analyses historical groundwater quality parameters in mine intensive basin of Westrand Basin (WRB) to understand the status of groundwater quality in relation to mining activities and mine closure. Geographic information system (GIS) was used to map the spatio-temporal variation of groundwater quality in the basin and groundwater quality index (GQI) to evaluate its status. The coefficient of variation (CV) was applied to understand the stability of groundwater quality after the mine closure. Results indicated unstable and altered trend with increasing levels of acidity and salts concentration around the mines vicinity following the mine closure. The resultant maps indicated a significant deterioration of groundwater quality around the WRB with concentrations decreasing downstream. Obtained average GQI for the study period of 1996–2015 suggested a moderate groundwater quality at a range of GQI = 64–73. The CV indicated varying water quality at CV \textgreater 30% suggesting presence of source of contamination. Observed groundwater quality trends in Westrand basin suggested that mines closure present potential threat on groundwater quality and thus, a need for a robust mine closure plan and implementation.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ alexander_impact_2023 Serial 134  
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Author Mathuthu, M.; Uushona, V.; Indongo, V. url  openurl
  Title Radiological safety of groundwater around a uranium mine in Namibia Type Journal Article
  Year 2021 Publication (down) Physics and Chemistry of the Earth, Parts A/B/C Abbreviated Journal  
  Volume 122 Issue Pages 102915  
  Keywords Groundwater, ICP-MS, Radiological hazard, Uranium mining  
  Abstract Uranium mining activities produce the main element used in nuclear energy production. However, it can also negatively affect the environment including groundwater by release of residues or effluent containing radioactive elements. The study investigated the concentration and radiological hazard of uranium in groundwater and seepage water from the tailings of a uranium mine in Namibia. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to assess the concentration of uranium in the groundwater and seepage water and the radiological hazards were determined. The radiological hazard indices Radium equivalent activity (Raeq), Absorbed dose (D), Annual Effective Dose equivalent (AEDE), External hazard index (Hex) and Internal hazard index (Hin) were determined and compared to limits recommended by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The calculated average value of D and Hin of groundwater is 108.11nGyh−1 and 1.26, respectively and are above the UNSCEAR values (55 nGyh−1 and 1). Further, the average values of Raeq, AEDE and Hex were below the recommended values. The isotopic ratio of uranium radionuclides in groundwater indicates that the uranium in the sampled groundwater is below 1 suggesting it is not natural uranium present but a possible contamination from the mine seepage. The radiological hazard parameters of the seepage water were above the recommended values and thus pose a radiation risk to human and environment.  
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  ISSN 1474-7065 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ mathuthu_radiological_2021 Serial 160  
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Author Schwiede, M.; Duijnisveld, W.H.M.; Böttcher, J. url  openurl
  Title Investigation of processes leading to nitrate enrichment in soils in the Kalahari Region, Botswana Type Journal Article
  Year 2005 Publication (down) Physics and Chemistry of the Earth, Parts A/B/C Abbreviated Journal  
  Volume 30 Issue 11 Pages 712-716  
  Keywords Nitrate, Arenosol soils, Semi-arid, Kalahari, Cattle, Chloride, Travel time  
  Abstract In Southern Africa elevated nitrate concentrations are observed in mostly uninhabited semi-arid areas. In the Kalahari of Botswana groundwater locally exhibits concentrations up to 600mg/l. It is assumed, that nitrate found in the groundwater originates mainly from nitrogen input and transformations in the soils. Our investigations in the Kalahari between Serowe and Orapa show that cattle raising is an important source for enhanced nitrate concentrations in the soils (Arenosols). But also in termite mounds very high nitrate stocks were found, and under natural vegetation (acacia trees and shrubs) nitrate concentrations were mostly unexpectedly high. This nitrate enrichment in the soils poses a serious threat to the groundwater quality. However, calculated soil water age distributions in the unsaturated zone clearly show that today’s nitrate pollution of the groundwater below the investigation area could originate from natural sources, but cannot be caused by the current land use for cattle raising.  
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  ISSN 1474-7065 ISBN Medium  
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  Notes Integrated Water Resources Management (IWRM) and the Millennium Development Goals: Managing Water for Peace and Prosperity Approved no  
  Call Number THL @ christoph.kuells @ Schwiede2005712 Serial 276  
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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 (down) 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 Lim, S.; Chase, B.M.; Chevalier, M.; Reimer, P.J. url  openurl
  Title 50,000years of vegetation and climate change in the southern Namib Desert, Pella, South Africa Type Journal Article
  Year 2016 Publication (down) Palaeogeography, Palaeoclimatology, Palaeoecology Abbreviated Journal  
  Volume 451 Issue Pages 197-209  
  Keywords Climate reconstruction, Late Quaternary, Namib Desert, Pollen, Rock hyrax middens, South Africa  
  Abstract This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability at the site relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, during which time high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome. During this latter period, increases in upwelling intensity created drier conditions at the site. Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000years. These findings pose interesting questions regarding the nature of environmental change in southwestern Africa, and the significance of the diverse records that have been obtained from the region.  
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  ISSN 0031-0182 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ lim_50000years_2016 Serial 107  
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