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Brook, G.A.; Marais, E.; Srivastava, P.; Jordan, T. |
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Title  |
Timing of lake-level changes in Etosha Pan, Namibia, since the middle Holocene from OSL ages of relict shorelines in the Okondeka region |
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Journal Article |
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2007 |
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Quaternary International |
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175 |
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1 |
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29-40 |
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In 2003 examination of aerial photographs revealed a series of previously unknown relict shorelines on the arcuate ridge, possibly a clay lunette dune, that marks the western boundary of Etosha Pan in Namibia. The shorelines are 120–600m wide and the most prominent extend for tens of km around the lunette dune. The shorelines were examined on the ground in 2004 and an attempt was made to date the three lowest levels at ca. 5, 2.5 and 1m above the present pan surface. The OSL ages obtained indicate higher and more prolonged lake conditions than today at ca. 6.4, 4.0 and 2.1ka with the youngest shoreline sediments resting on an ancient pan surface dating to ca. 13ka. The evidence indicates dry conditions in the pan at ca. 13ka, wetter conditions and higher lake levels in the middle Holocene followed by a decline in lake levels to the present. Periods of inundation were of sufficient duration to produce shorelines at the southwestern end of the pan due to the prevailing northeasterly winds that would have maximized wave action along this section of the pan margin. The Etosha findings, together with other regional paleoclimate data, suggest four periods of increased wetness in SW Africa during the Holocene at 7–5, 4.5–3.5, 2.5–1.7 and ca. 1.0ka. There is widespread evidence for the oldest of these periods suggesting that it was a prominent and widespread interval of wetness. Prior to ca. 8.0ka the climate may have been drier than today. |
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THL @ christoph.kuells @ brook_timing_2007 |
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97 |
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Pree, T.A.D. |
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Title |
The politics of baselining in the Grants uranium mining district of northwestern New Mexico |
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Journal Article |
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2020 |
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Journal of Environmental Management |
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268 |
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110601 |
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Critical stakeholder analysis, Environmental cleanup, Environmental monitoring, Mining reclamation/remediation/restoration, Politics of baselining |
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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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0301-4797 |
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THL @ christoph.kuells @ pree_politics_2020 |
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151 |
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Edmunds, W.M.; Shand, P.; Hart, P.; Ward, R.S. |
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Title |
The natural (baseline) quality of groundwater: a UK pilot study |
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Journal Article |
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2003 |
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Science of The Total Environment |
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310 |
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1 |
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25-35 |
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Baseline quality, Groundwater, Hydrogeochemistry, Monitoring, Water Policy |
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Knowledge of the natural baseline quality of groundwaters is an essential prerequisite for understanding pollution and for imposing regulatory limits. The natural baseline of groundwaters may show a range of concentrations depending on aquifer mineralogy, facies changes, flow paths and residence time. The geochemical controls on natural concentrations are discussed and an approach to defining baseline concentrations using geochemical and statistical tools is proposed. The approach is illustrated using a flowline from the Chalk aquifer in Berkshire, UK where aerobic and anaerobic sections of the aquifer are separately considered. The baseline concentrations for some elements are close to atmospheric values whereas others evolve through time-dependent water–rock interaction. Certain solutes (K, NH4+), often considered contaminants, reach naturally high concentrations due to geochemical controls; transition metal concentrations are generally low, although their concentrations may be modified by redox controls. It is recommended that the baseline approach be incorporated into future management strategies, notably monitoring. |
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0048-9697 |
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THL @ christoph.kuells @ edmunds_natural_2003 |
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166 |
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Belz, L.; Schüller, I.; Wehrmann, A.; Köster, J.; Wilkes, H. |
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Title |
The leaf wax biomarker record of a Namibian salt pan reveals enhanced summer rainfall during the Last Glacial-Interglacial Transition |
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Journal Article |
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2020 |
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Palaeogeography, Palaeoclimatology, Palaeoecology |
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543 |
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109561 |
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-Alkanes, -Alkanols, Late Quaternary, Organic geochemistry, Palaeohydrology, Southern Africa |
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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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0031-0182 |
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THL @ christoph.kuells @ belz_leaf_2020 |
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104 |
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Haque, N.; Norgate, T. |
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Title |
The greenhouse gas footprint of in-situ leaching of uranium, gold and copper in Australia |
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Journal Article |
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Year |
2014 |
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Journal of Cleaner Production |
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84 |
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382-390 |
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Copper, GHG emission, Gold, In-situ leaching, LCA, Uranium |
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In-situ leaching (ISL) is a chemical method for recovering useful minerals and metals directly from underground ore bodies which is also referred to as ‘solution mining’. ISL is commonly used for uranium mining, accounting for about 45% of global production. The main benefits are claimed to be a lower environmental impact in terms of visual disturbances, emissions, lower energy use, cost compared with conventional open-cut or underground mining methods, and potential utilisation of lower grade resources. However, there is a lack of reported studies on the assessment of the environmental impacts of ISL, particularly greenhouse gas (GHG) emissions using life cycle assessment (LCA) methodology. The SimaPro LCA software was used to estimate the GHG footprint of the ISL of uranium, gold and copper. The total GHG emissions were estimated to be 38.0 kg CO2-e/kg U3O8 concentrate (yellowcake), 29 t CO2-e/kg gold, and 4.78 kg CO2-e/kg Cu. The GHG footprint of ISL uranium was significantly lower than that of conventional mining, however, the footprints of copper and gold were not much less compared with conventional mining methods. This is due to the lower ore grade of ISL deposits and recovery compared with high ore grades and recovery of conventional technology. Additionally, the use of large amount of electricity for pumping in case of ISL contributes to this result. The electricity consumed in pumping leaching solutions was by far the greatest contributor to the well-field related activities associated with ISL of uranium, gold and copper. The main strategy to reduce the GHG footprint of ISL mining should be to use electricity derived from low emission sources. In particular, renewable sources such as solar would be suitable for ISL as these operations are typically in remote locations with smaller deposits compared with conventional mining sites. |
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0959-6526 |
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THL @ christoph.kuells @ haque_greenhouse_2014 |
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208 |
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Benites Lazaro, L.L.; Bellezoni, R.; Puppim de Oliveira, J.; Jacobi, P.R.; Giatti, L. |
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Title |
Ten Years of Research on the Water-Energy-Food Nexus: An Analysis of Topics Evolution |
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Journal Article |
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2022 |
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Frontiers in Water |
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4 |
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THL @ christoph.kuells @ article |
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86 |
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Author |
Abiye, T. |
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Title |
Synthesis on groundwater recharge in Southern Africa: A supporting tool for groundwater users |
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Journal Article |
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2016 |
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Groundwater for Sustainable Development |
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2-3 |
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182-189 |
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Arid and semi-arid areas, Groundwater recharge, Recharge estimation methods, Southern Africa |
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This synthesis on groundwater recharge targets the Southern African region as a result of the dependence of the community and economic sector on the groundwater resource. Several literature based recharge studies were collected and assessed in order to find out the main controls to the occurrence of recharge. The Water Table Fluctuation and Base flow separation methods have been tested in the catchment that drains crystalline basement rocks and dolostones close to the city of Johannesburg, South Africa. Based on the assessed data the Chloride Mass Balance method resulted in groundwater recharge of less than 4% of the rainfall, while it reaches 20%, when rainfall exceeds 600mm. For the classical water balance method, recharge proportion is less than 3% of rainfall as a result of very high ambient temperature in the region. Based on the Saturated Volume Fluctuation and Water Table Fluctuation methods, recharge could be less than 6% for annual rainfall of less than 600mm. Observational results further suggest that sporadic recharge from high intensity rainfall has important contribution to the groundwater recharge in the region, owing to the presence of permeable geological cover, which could not be fully captured by most of the recharge estimation methods. This study further documents an evaluation of the most reliable recharge estimation methods in the area such as the chloride mass balance, saturated volume fluctuation and water table fluctuation methods in order to successfully manage the groundwater resource. |
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2352-801x |
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THL @ christoph.kuells @ abiye_synthesis_2016 |
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101 |
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Khaneiki, M.L.; Al-Ghafri, A.S.; Klöve, B.; Haghighi, A.T. |
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Title |
Sustainability and virtual water: The lessons of history |
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Journal Article |
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2022 |
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Geography and Sustainability |
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3 |
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4 |
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358-365 |
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Proto-industrialization, Water scarcity, Non-hydraulic polity, Virtual water, Political economy |
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This article aims to show that virtual water has historically been an adaptation strategy that enabled some arid regions to develop a prosperous economy without putting pressure on their scarce water resources. Virtual water is referred to as the total amount of water that is consumed to produce goods and services. As an example, in arid central Iran, the deficiency in agricultural revenues was offset by more investment in local industries that enjoyed a perennial capacity to employ more workers. The revenues of local industries weaned the population from irrigated agriculture, since most of their raw materials and also food stuff were imported from other regions, bringing a remarkable amount of virtual water. This virtual water not only sustained the region’s inhabitants, but also set the stage for a powerful polity in the face of a rapid population growth between the 13th and 15th centuries AD. The resultant surplus products entailed a vast and safe network of roads, provided by both entrepreneurs and government. Therefore, it became possible to import more feedstock such as cocoons from water-abundant regions and then export silk textiles with considerable value-added. This article concludes that a similar model of virtual water can remedy the ongoing water crisis in central Iran, where groundwater reserves are overexploited, and many rural and urban centers are teetering on the edge of socio-ecological collapse. History holds an urgent lesson on sustainability for our today’s policy that stubbornly peruses agriculture and other high-water-demand sectors in an arid region whose development has always been dependent on virtual water. |
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2666-6839 |
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THL @ christoph.kuells @ Khaneiki2022358 |
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272 |
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Liu, Z.; Li, C.; Tan, K.; Li, Y.; Tan, W.; Li, X.; Zhang, C.; Meng, S.; Liu, L. |
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Title |
Study of natural attenuation after acid in situ leaching of uranium mines using isotope fractionation and geochemical data |
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Journal Article |
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2023 |
Publication |
Science of The Total Environment |
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865 |
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161033 |
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Acid in situ leaching, Geochemical and isotopic tracing, Groundwater contamination, Natural attenuation, Uranium post-mining |
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Acid in situ leaching (AISL) is a subsurface mining approach suitable for low-grade ores which does not generate tailings, and has been adopted widely in uranium mining. However, this technique causes an extremely high concentration of contaminants at post-mining sites and in the surroundings soon after the mining ceases. As a potential AISL remediation strategy, natural attenuation has not been studied in detail. To address this problem, groundwater collected from 26 wells located within, adjacent, upgradient, and downgradient of a post-mining site were chosen to analyze the fate of U(VI), SO42−, δ34S, and δ238U, to reveal the main mechanisms governing the migration and attenuation of the dominant contaminants and the spatio-temporal evolutions of contaminants in the confined aquifer of the post-mining site. The δ238U values vary from −0.07 ‰ to 0.09 ‰ in the post-mining site and from −1.43 ‰ to 0.03 ‰ around the post-mining site. The δ34S values were found to vary from 3.3 ‰ to 6.2 ‰ in the post-mining site and from 6.0 ‰ to 11.0 ‰ around the post-mining site. Detailed analysis suggests that there are large differences between the range of isotopic composition variation and the range of pollutants concentration distribution, and the estimated Rayleigh isotope fractionation factor is 0.9994–0.9997 for uranium and 1.0032–1.0061 for sulfur. The isotope ratio of uranium and sulfur can be used to deduce the migration history of the contaminants and the irreversibility of the natural attenuation process in the anoxic confined aquifer. Combining the isotopic fractionation data for U and S with the concentrations of uranium and sulfate improved the accuracy of understanding of reducing conditions along the flow path. The study also indicated that as long as the geological conditions are favorable for redox reactions, natural attenuation could be used as a cost-effective remediation scheme. |
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0048-9697 |
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THL @ christoph.kuells @ liu_study_2023 |
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155 |
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Kurmanseiit, M.B.; Tungatarova, M.S.; Royer, J.-J.; Aizhulov, D.Y.; Shayakhmetov, N.M.; Kaltayev, A. |
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Streamline-based reactive transport modeling of uranium mining during in-situ leaching: Advantages and drawbacks |
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2023 |
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Hydrometallurgy |
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220 |
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106107 |
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3D modeling, In-situ leaching, Reactive transport model, Streamlines, Uranium recovery |
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Reactive transport modeling is known to be computationally intensive when applied to 3D problems. Transforming sequential computing on the computer processor units (CPU) into parallelized computation on the high-performance parallel graphic processor units (GPU) is a classical approach to increasing computational performance. Another complementary approach is to decompose a complex 3D modeling problem into a set of simpler 1D problems using streamline approaches which can be easily parallelized, therefore reducing computation time. This paper investigates solutions to the equations governing dissolution and transport using streamlines coupled with a parallelization approach. In addition, an analytical solution to the dissolution and transfer equations of uranium describing the In-Situ Leaching (ISL) mining recovery is found using an approximation series to the 2nd order. The analytical solution is compared to the 1D numerical resolution along the streamlines and to the 3D simulation results superimposed on the streamline. Both approaches give similar results with a relative error of \textless2 % (2%). The proposed methodology is then applied to a case study in which the classical 3D resolution is compared to the newly suggested streamline solution, demonstrating that the streamline approach increases computational performances by a factor ranging from hundred to thousand depending on the complexity of the grid-block model. |
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0304-386x |
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THL @ christoph.kuells @ kurmanseiit_streamline-based_2023 |
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190 |
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