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Author Strandmann, P.A.E.P. von; Reynolds, B.C.; Porcelli, D.; James, R.H.; Calsteren, P. van; Baskaran, M.; Burton, K.W.
Title Assessing continental weathering rates and actinide transport in the Great Artesian Basin Type Journal Article
Year 2006 Publication Geochimica et Cosmochimica Acta Abbreviated Journal
Volume (down) 70 Issue 18, Supplement Pages 497
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ISSN 0016-7037 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ strandmann_assessing_2006 Serial 116
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Author French, K.
Title Indigenous knowledge, water management, and learning from our collective past Type Journal Article
Year 2022 Publication Journal of Anthropological Archaeology Abbreviated Journal
Volume (down) 68 Issue Pages 101466
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ISSN 0278-4165 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ French2022101466 Serial 253
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Author Heaton, T.H.E.
Title Sources of the nitrate in phreatic groundwater in the western Kalahari Type Journal Article
Year 1984 Publication Journal of Hydrology Abbreviated Journal
Volume (down) 67 Issue 1 Pages 249-259
Keywords
Abstract Elevated levels of nitrate occur in phreatic groundwater in the western Kalahari, Namibia. Nitrate in water containing 0.4–3.1 meq NO−3l−1, of widespread occurrence, has δ15N values in the range +4.9 to +8.0‰, suggesting natural derivation from the soil. The sporadic occurrence of very high levels of nitrate (> 4 meq NO−3l−1), which has δ15N between +9.3 to +18.7‰, reflects pollution derived from animal waste. The importance of considering the possible isotopic effects of denitrification, and the significance of leaching in the nitrogen budget of the Kalahari soil, are also discussed.
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Series Editor Series Title Abbreviated Series Title
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ISSN 0022-1694 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ Heaton1984249 Serial 278
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Author Vogel, J.C.; Talma, A.S.; Heaton, T.H.E.; Kronfeld, J.
Title Evaluating the rate of migration of an uranium deposition front within the Uitenhage Aquifer Type Journal Article
Year 1999 Publication Journal of Geochemical Exploration Abbreviated Journal
Volume (down) 66 Issue 1 Pages 269-276
Keywords redox changes in aquifer, sandstone-type uranium deposit, South Africa, uranium series
Abstract The solubility of uranium in groundwater is very sensitive to changes in redox conditions. Many secondary (sandstone-type) uranium deposits have been formed when soluble U has precipitated after encountering reducing conditions in the subsurface. In the groundwater of the Uitenhage Aquifer (Cape Province, South Africa), 238U-series isotopes were used to assist in studying the history of the reducing barrier. Uranium isotopes were used to determine the present position of the barrier. Radium and radon were used to evaluate the path of migration that the front of the oxygen depletion zone has taken over the past 105 years. During this time the reducing barrier has moved, leaving in its wake a trail of U in various stages of secular equilibrium with its daughter 230Th. The 226Ra daughter of 230Th is not very mobile. Its growth upon the aquifer wall is reflected in the Rn content of the water. This in turn, due to the relatively great age of the water, indicates the extent of the 230Th ingrowth (from precipitated U) that took place before the barrier migrated.
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ISSN 0375-6742 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ vogel_evaluating_1999 Serial 126
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Author Zhang, Y.; Liu, X.; Yuan, S.; Song, J.; Chen, W.; Dias, D.
Title A two-dimensional experimental study of active progressive failure of deeply buried Qanat tunnels in sandy ground Type Journal Article
Year 2023 Publication Soils and Foundations Abbreviated Journal
Volume (down) 63 Issue 3 Pages 101323
Keywords Qanat tunnel, Sand, Failure effect, Soil arching, Model test
Abstract 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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ISSN 0038-0806 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ Zhang2023101323 Serial 274
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Author Heaton, T.H.E.; Talma, A.S.; Vogel, J.C.
Title Origin and history of nitrate in confined groundwater in the western Kalahari Type Journal Article
Year 1983 Publication Journal of Hydrology Abbreviated Journal
Volume (down) 62 Issue 1 Pages 243-262
Keywords
Abstract Data are presented for nitrate, dinitrogen and argon concentrations and 15N14N ratios in groundwater, with radiocarbon ages up to 40,000 yr. for three confined sandstone aquifers in the western Kalahari of South West Africa/Namibia. The nitrate is probably generated within the soil of the recharge areas, and its production rate during the period 3000-40,000 B.P. has remained between 0.5 and 1.6 meq NO−3l−1 of recharge water, with ° 15N between + 4 and + 8‰. Variations in the amount of nitrate and of “excess air” in groundwater recharge are found, and can only reflect changes in the environmental conditions during recharge. They must therefore be caused by the climatic changes that have taken place during the past 25,000 yr.
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Series Editor Series Title Abbreviated Series Title
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ISSN 0022-1694 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ heaton_origin_1983 Serial 95
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Author Heaton, T.H.E.; Talma, A.S.; Vogel, J.C.
Title Origin and history of nitrate in confined groundwater in the western Kalahari Type Journal Article
Year 1983 Publication Journal of Hydrology Abbreviated Journal
Volume (down) 62 Issue 1 Pages 243-262
Keywords
Abstract Data are presented for nitrate, dinitrogen and argon concentrations and 15N14N ratios in groundwater, with radiocarbon ages up to 40,000 yr. for three confined sandstone aquifers in the western Kalahari of South West Africa/Namibia. The nitrate is probably generated within the soil of the recharge areas, and its production rate during the period 3000-40,000 B.P. has remained between 0.5 and 1.6 meq NO−3l−1 of recharge water, with ° 15N between + 4 and + 8‰. Variations in the amount of nitrate and of “excess air” in groundwater recharge are found, and can only reflect changes in the environmental conditions during recharge. They must therefore be caused by the climatic changes that have taken place during the past 25,000 yr.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-1694 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ Heaton1983243 Serial 282
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Author Dávila, P.; Külls, C.; Weiler, M.
Title A toolkit for groundwater mean residence time interpretation with gaseous tracers Type Journal Article
Year 2013 Publication Computers & Geosciences Abbreviated Journal
Volume (down) 61 Issue Pages 116-125
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Corporate Author Thesis
Publisher Pergamon Place of Publication Editor
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Notes Approved no
Call Number THL @ christoph.kuells @ Davila2013toolkit Serial 22
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Author Kharaka, Y.; Harmon, R.; Darling, G.
Title W. Mike Edmunds (1941–2015) Type Journal Article
Year 2015 Publication Applied Geochemistry Abbreviated Journal
Volume (down) 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 Liu, Z.; Tan, K.; Li, C.; Li, Y.; Zhang, C.; Song, J.; Liu, L.
Title Geochemical and S isotopic studies of pollutant evolution in groundwater after acid in situ leaching in a uranium mine area in Xinjiang Type Journal Article
Year 2023 Publication Nuclear Engineering and Technology Abbreviated Journal
Volume (down) 55 Issue 4 Pages 1476-1484
Keywords Acid in situ leaching of uranium, Pollution evolution, Sulfate elimination, Sulfur isotopes analysis
Abstract Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ34S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%–48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.
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ISSN 1738-5733 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ liu_geochemical_2023 Serial 192
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