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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 |
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Journal Article |
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2019 |
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Journal of Geochemical Exploration |
Abbreviated Journal |
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199 |
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53-59 |
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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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Karaimeh, S.A. |
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Maintaining desert cultivation: Roman, Byzantine, and Early Islamic water-strategies at Udhruh region, Jordan |
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Journal Article |
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2019 |
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Journal of Arid Environments |
Abbreviated Journal |
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166 |
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108-115 |
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Irrigation, Qanat, Cultivation, Arid environment, Nabataean, Jordan |
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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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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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2019 |
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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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Krüger, N.; Külls, C.; Bruggeman, A.; Eliades, M.; Christophi, C.; Rigas, M.; Eracleous, T. |
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Groundwater recharge estimates with soil isotope profiles-is there a bias on coarse-grained hillslopes? |
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2020 |
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EGU General Assembly Conference Abstracts |
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9840 |
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THL @ christoph.kuells @ Krueger2020groundwater |
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42 |
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Doulgeris, C.; Tziritis, E.; Pisinaras, V.; Panagopoulos, A.; Külls, C. |
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Prediction of seawater intrusion to coastal aquifers based on non-dimensional diagrams |
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Conference Article |
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2020 |
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EGU Geophysical Abstracts |
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4073 |
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THL @ christoph.kuells @ Doulgeris2020prediction |
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41 |
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