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Botha, R.; Lindsay, R.; Newman, R.T.; Maleka, P.P.; Chimba, G. |
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Title |
Radon in groundwater baseline study prior to unconventional shale gas development and hydraulic fracturing in the Karoo Basin (South Africa) |
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Journal Article |
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Year  |
2019 |
Publication |
Applied Radiation and Isotopes |
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147 |
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7-13 |
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The prospect of unconventional shale gas development in the semi-arid Karoo Basin (South Africa) has created the prerequisite to temporally characterise the natural radioactivity in associated groundwater which is solely depended on for drinking and agriculture purposes. Radon (222Rn) was the primary natural radionuclide of interest in this study; however, supplementary radium (226Ra and 228Ra) in-water measurements were also conducted. A total of 53 aquifers spanning three provinces were studied during three separate measurement campaigns from 2014 to 2016. The Karoo Basin’s natural radon-in-water levels can be characterised by a minimum of 1 ± 1 Bq/L (consistent with zero or below LLD), a maximum of 183 ± 18 Bq/L and mean of 41 ± 5 Bq/L. The mean radon-in-water levels for shallow aquifers were systematically higher (55 ± 10 Bq/L) compared to deep (14 ± 3 Bq/L) or mixed aquifers (20 ± 6 Bq/L). Radon-in-water activity concentration fluctuations were predominantly observed from shallow aquifers compared to the generally steady levels of deep aquifers. A collective seasonal mean radon-in-water levels increase from the winter of 2014 (44 ± 8 Bq/L) to winter of 2016 (61 ± 16 Bq/L) was noticed which could be related to the extreme national drought experienced in 2015. Radium-in-water (228Ra and 226Ra) levels ranged from below detection level to a maximum of 0.008 Bq/L (226Ra) and 0.015 Bq/L (228Ra). The 228Ra/226Ra ratio was characterised by a minimum of 0.93, a maximum of 6.5 and a mean value of 3.3 ± 1.3. Developing and improving baseline naturally occurring radionuclide groundwater databases is vital to study potential radiological environmental impacts attributed to industrial processes such as hydraulic fracturing or mining. |
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0969-8043 |
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THL @ christoph.kuells @ botha_radon_2019 |
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169 |
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Boulesteix, T.; Cathelineau, M.; Deloule, E.; Brouand, M.; Toubon, H.; Lach, P.; Fiet, N. |
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Title |
Ilmenites and their alteration products, sinkholes for uranium and radium in roll-front deposits after the example of South Tortkuduk (Kazakhstan) |
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Journal Article |
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Year |
2019 |
Publication |
Journal of Geochemical Exploration |
Abbreviated Journal |
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Volume |
206 |
Issue |
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Pages |
106343 |
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The approximate determination of average Ra/U disequilibria in orebodies is one of the most common causes of errors in U reserve estimations. In roll-front deposits, the disequilibria are however frequently distributed following complex geometries, which must be fully understood to prevent major U reserve overestimates and costly unproductive extractive operations. The processes responsible for disruption of the radioactive equilibria and the U and Ra carriers in such complex natural systems remain poorly constrained. In this contribution, we propose an innovative approach, mixing orebody to sub-grain scale studies to unravel the distribution of U and Ra and the processes responsible for their concentration and uncoupling. Using mineral separations, gamma spectrometry and mineral-chemical analyses, we identified the Fe-Ti clusters (altered ilmenite + pyrite/marcasite) as the microsites for coffinite precipitation and Ra concentration. To understand the influence of such clusters on the distribution of U and Ra at the deposit scale, whole-rock Ra/U disequilibria were measured and mapped at a series of ten drill holes along a profile crosscutting the studied roll-front. The main Ra/U disequilibria are encountered around the mineralization in low U content zones. They are controlled by two main processes. (1) In the oxidized zones, the immobility of 230Th with respect to the U produces patches of Ra disequilibria (carried by the altered U minerals). (2) In the immediate vicinity of the roll-front, the dissolution of the mineralization produces an Ra flux trapped by the alteration products of ilmenites, as definitely confirmed by direct SIMS measurements. Such a process is responsible for the Ra disequilibria envelope located downstream of the richest ores, also known as Ra halo. The highest Ra/U ratios correspond to oxidized upstream samples, but most other high Ra/U ratios are from reduced downstream samples close to the mineralization. Such a low to medium U content envelope with high Ra/U ratios constitutes the main cause of U reserve overestimations. |
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0375-6742 |
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THL @ christoph.kuells @ boulesteix_ilmenites_2019 |
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181 |
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Author |
Hebert, B.; Baron, F.; Robin, V.; Lelievre, K.; Dacheux, N.; Szenknect, S.; Mesbah, A.; Pouradier, A.; Jikibayev, R.; Roy, R.; Beaufort, D. |
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Title |
Quantification of coffinite (USiO4) in roll-front uranium deposits using visible to near infrared (Vis-NIR) portable field spectroscopy |
Type |
Journal Article |
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Year |
2019 |
Publication |
Journal of Geochemical Exploration |
Abbreviated Journal |
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Volume |
199 |
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53-59 |
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Keywords |
Coffinite, Mineral quantification, Near infrared, Ore exploration, Portable field spectroscopy, Roll-front deposits |
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Abstract |
Coffinite (USiO4) is a common uranium-bearing mineral of roll-front uranium deposits. This mineral can be identified by the visible near infrared (Vis-NIR) portable field spectrometers used in mining exploration. However, due to the low detection limits and associated errors, the quantification of coffinite abundance in the mineralized sandstones or sandy sediments of roll-front uranium deposits using Vis-NIR spectrometry requires a specific methodological development. In this study, the 1135 nm absorption band area is used to quantify the abundance of coffinite. This absorption feature does not interfere with NIR absorption bands of any other minerals present in natural sands or sandstones of uranium roll-front deposits. The correlation between the 1135 nm band area and coffinite content was determined from a series of spectra measured from prepared mineral mixtures. The samples were prepared with a range of weighted amounts of arenitic sands and synthetic coffinite simulating the range of uranium concentration encountered in roll-front uranium deposits. The methodology presented in this study provides the quantification of the coffinite content present in sands between 0.03 wt% to 1 wt% coffinite with a detection limit as low as 0.005 wt%. The integrated area of the 1135 nm band is positively correlated with the coffinite content of the sand in this range, showing that the method is efficient to quantify coffinite concentrations typical of roll-front uranium deposits. The regression equation defined in this study was then used as a reference to predict the amount of natural coffinite in a set of mineralized samples from the Tortkuduk uranium roll-front deposit (South Kazakhstan). |
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0375-6742 |
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THL @ christoph.kuells @ hebert_quantification_2019 |
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184 |
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Author |
Karaimeh, S.A. |
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Title |
Maintaining desert cultivation: Roman, Byzantine, and Early Islamic water-strategies at Udhruh region, Jordan |
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Journal Article |
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Year |
2019 |
Publication |
Journal of Arid Environments |
Abbreviated Journal |
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Volume |
166 |
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Pages |
108-115 |
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Keywords |
Irrigation, Qanat, Cultivation, Arid environment, Nabataean, Jordan |
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Abstract |
The site of Udhruh is located in the arid desert of southern Jordan, about 15 km to the east of Petra. The site was built by the Nabataeans but expanded by the Romans (as a defensive site) and was continuously occupied until the Early Islamic period. It receives less than the 200 mm of annual precipitation, which is crucial for agricultural cultivation. Archaeological evidence from earlier excavations together with new data from several survey projects indicate that areas around Udhruh were cultivated throughout the Roman, Byzantine, and Early Islamic periods (300 BCE–800 CE). The fundamental question is: how did the people of Udhruh sustain their community in the desert, and how did they transform the desert into arable land? The landscape could be utilised thanks to sophisticated water management and irrigation techniques. At least four underground qanat systems were identified providing Udhruh with access to groundwater. At the terminal end of the qanat systems, several types of closed surface channels conveyed the water to reservoirs, which subsequently distributed the water to the field systems. The water systems of Udhruh differ from the well-known Nabataean systems in the surrounding area. As Udhruh was taken over by the Roman army in 106 CE, this study analyses how the Nabataean water systems continued to function and adapt through the Roman and Byzantine periods. A complete understanding of Udhruh’s water systems helps to reconstruct past land use, agricultural activity, and irrigation practices in a currently arid region. |
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0140-1963 |
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THL @ christoph.kuells @ Alkaraimeh2019108 |
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271 |
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Author |
Vushe, A.; Amutenya, M. |
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Investigating nitrate retention capacity, elementary and mineral composition of Kalahari sandy soils at Mashare farm in Namibia, Okavango river basin |
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Journal Article |
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Year |
2019 |
Publication |
Scientific African |
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6 |
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00193 |
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Irrigated field, Cultivated Kalahari sandy soil, Leaching, Nitrate retention capacity, Quartz mineral, Water saturated |
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Kalahari sands which cover a large part of Southern Africa and extend into Central Africa are infertile and marginal soils for intensive agriculture. Therefore, high nitrogen fertilisation rates may degrade ecosystems of rivers with catchments covered by the Kalahari sands. A study on Mashare Farm located in the Okavango River basin showed that irrigated Kalahari sandy soils had a nitrate retention capacity, which enabled the soil to resist nitrate leaching in water saturated conditions. The irrigated soils were modified by agricultural activities; hence this study investigated if uncultivated and cultivated Kalahari sand soils had similar nitrate retention properties. The elementary composition of the soils was investigated for obtaining an insight into chemical properties that may be causing the nitrate retention capacity. A permeameter was used to leach out nitrates from irrigated and uncultivated soil samples, and nitrate concentrations were measured on the leaching effluent from the permeameter. Elemental analysis was done on the cultivated and the uncultivated soil samples using a Scanning Electron Microscope, a portable X-Ray Fluorescence analyzer, and an X-Ray Diffraction machine, and the later was also used for crystalline structure analyses. Sieve analyses confirmed that the Mashare’s cultivated and uncultivated topsoils were similar, and both were similar to Botswana Kalahari topsoil. The irrigated and cultivated subsoil had a higher average nitrate retention capacity of 76% compared to 73% for the uncultivated subsoil. Both samples had the same elements, although the proportions were different. Both soil samples were dominated by a quartz mineral, but the field soil had traces of palygorskite. The presence of aluminum and transition metals outside the minerals structure, but as coatings on the quartz sand grains enhanced nitrate retention capacity properties of the Kalahari sand soils. |
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2468-2276 |
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THL @ christoph.kuells @ VUSHE2019e00193 |
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277 |
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Author |
Röttcher, K. |
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Book Chapter |
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2018 |
Publication |
Risikomanagement und Nachhaltigkeit in der Wasserwirtschaft: Erfolgreiche Navigation durch die Komplexität und Dynamik des Risikos |
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165-174 |
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Im vorliegenden Beitrag werden beispielhaft unterschiedliche Ansätze des Risikomanagements und das Verständnis von Nachhaltigkeit in der Wasserwirtschaft dargelegt. Die Darstellung richtet sich insbesondere an Leser aus anderen Fachdisziplinen, wie das Rechts- und Finanzwesen, den Fahrzeug- und Maschinenbau oder auch die sozialen Berufe. Die Zusammenhänge werden überblicksartig mit einzelnen konkreten Beispielen dargestellt mit dem Fokus auf die grundsätzlichen Denk- und Vorgehensweisen. |
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Springer Fachmedien Wiesbaden |
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Wiesbaden |
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Michalke, A.; Rambke, M.; Zeranski, S. |
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978-3-658-19684-4 |
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THL @ christoph.kuells @ Röttcher2018 |
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90 |
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Rossetto, R.; Filippis, G.D.; Borsi, I.; Foglia, L.; Cannata, M.; Criollo, R.; Vázquez-Suñé, E. |
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Integrating free and open source tools and distributed modelling codes in GIS environment for data-based groundwater management |
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Journal Article |
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2018 |
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Environmental Modelling & Software |
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107 |
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210-230 |
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Free and Open Source Software, FREEWAT, Groundwater management, ICT, MODFLOW, QGIS |
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Integrating advanced simulation techniques and data analysis tools in a freeware Geographic Information System (GIS) provides a valuable contribution to the management of conjunctive use of groundwater (the world’s largest freshwater resource) and surface-water. To this aim, we describe here the FREEWAT (FREE and open source software tools for WATer resource management) platform. FREEWAT is a free and open source, QGIS-integrated interface for planning and management of water resources, with specific attention to groundwater. The FREEWAT platform couples the power of GIS geo-processing and post-processing tools in spatial data analysis with that of process-based simulation models. The FREEWAT environment allows storage of large spatial datasets, data management and visualization, and running of several distributed modelling codes (mainly belonging to the MODFLOW family). It simulates hydrologic and transport processes, and provides a database framework and visualization capabilities for hydrochemical analysis. Examples of real case study applications are provided. |
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1364-8152 |
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THL @ christoph.kuells @ rossetto_integrating_2018 |
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92 |
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Nijsten, G.-J.; Christelis, G.; Villholth, K.G.; Braune, E.; Gaye, C.B. |
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Transboundary aquifers of Africa: Review of the current state of knowledge and progress towards sustainable development and management |
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Journal Article |
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2018 |
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Journal of Hydrology: Regional Studies |
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20 |
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21-34 |
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Africa, Assessment, Governance, Indicators, Transboundary aquifers |
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Study region Transboundary aquifers (TBAs) of Africa. Study focus Review of work on TBAs in Africa, including an overview of assessments and management efforts that have taken place over the last half century. New hydrological insights Seventy-two TBAs have been mapped in Africa. They underlie 40% of the continent, where 33% of the population lives, often in arid or semi-arid regions. TBA inventories have progressed since 2000 and remain work in progress. Despite their importance only eleven TBAs have been subjected to more detailed studies. Cooperation has been formalised for seven TBAs. Most of these TBAs are in North Africa and the Sahel. The recent global Transboundary Waters Assessment Programme compiled information at the national level to describe TBAs in terms of key indicators related to the water resource, socio-economic, and legal and institutional conditions. Availability of data at national level is low, hampering regional assessment. Comparing indicators, from questionnaire surveys, with those from a global water-use model showed variable levels of agreement, calling for further research. Reports on agreements scoping TBA management, indicate that this may be dealt with within international river/lake agreements, but reported inconsistencies between TBA sharing countries also indicate that implementation is limited. Increasing awareness and support to joint TBA management is noticeable amongst international organisations. However, such cooperation requires long-term commitment to produce impacts at the local level. |
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2214-5818 |
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THL @ christoph.kuells @ nijsten_transboundary_2018 |
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93 |
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Author |
Burchi, S. |
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Title |
Legal frameworks for the governance of international transboundary aquifers: Pre- and post-ISARM experience |
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Journal Article |
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2018 |
Publication |
Journal of Hydrology: Regional Studies |
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20 |
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15-20 |
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International aquifers, International aquifers agreements, International groundwater law, UN draft articles on the law of transboundary aquifers |
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Study region Africa, Latin America, Europe. Study focus Through the extensive study and mapping of the world’s aquifers that lie astride the international boundary lines of sovereign States, ISARM has awakened concerned States to the existence of aquifers stretching beyond their borders, and precipitated cooperation in generating a body of knowledge that facilitated cooperation in governance arrangements for such aquifers. In parallel, ISARM influenced the shape and direction of the United Nations “Draft articles on the law of transboundary aquifers” appended to UN Resolution 63/124 of 2008. Both stimulated cooperation among concerned States, and provided a frame of reference for the legal grounding of such cooperation in aquifer-specific agreements. New hydrological insights Through this synergistic paradigm, ISARM has made an impact on the shape and direction of cooperation in the Guaraní Aquifer in South America, and in the Iullemeden and Taoudeni/Tanezrouft Aquifer Systems (ITAS) in the Sahel region of Africa. It is having an influence on the shape and direction of cooperation being negotiated on the Stampriet Aquifer System in Southern Africa, and on the Ocotepeque-Citalá Aquifer in Central America. The link of ISARM to other international aquifer agreements on record is tenuous, and ISARM’s influence on their generation speculative. The visibility of ISARM has faded since 2012, however its legacy is lasting. |
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2214-5818 |
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THL @ christoph.kuells @ burchi_legal_2018 |
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100 |
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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. |
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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 |
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Journal Article |
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Year |
2018 |
Publication |
Applied Geochemistry |
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98 |
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331-344 |
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Activity ratios, Central Australia, Great Artesian Basin, Hydrogeology, Sequential extraction, Uranium isotopes |
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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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0883-2927 |
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THL @ christoph.kuells @ priestley_use_2018 |
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115 |
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