| Records |
| Author |
Holmes, M.; Campbell, E.E.; Wit, M. de; Taylor, J.C. |
Title  |
Can diatoms be used as a biomonitoring tool for surface and groundwater?: Towards a baseline for Karoo water |
Type |
Journal Article |
| Year |
2023 |
Publication |
South African Journal of Botany |
Abbreviated Journal |
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| Volume |
161 |
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Pages |
211-221 |
| Keywords |
Bioindicator, Diatom, Hydraulic fracturing, Karoo, Water quality |
| Abstract |
The environmental risks from shale gas extraction through the unconventional method of ‘fracking’ are considerable and impact on water supplies below and above ground. Since 2010 the recovery of natural shale gas through fracking has been proposed in parts of the fragile semi-arid ecosystems that make up the Karoo biome in South Africa. These unique ecosystems are heavily reliant on underground water, intermittent and ephemeral springs, which are at great risk of contamination by fracking processes. Diatoms are present in all water bodies and reflect aspects of the environment in which they are located. As the possibility of fracking has not been removed, the aim of the project was to determine if diatoms could be used for rapid biomonitoring of underground and surface waters in the Karoo. Over a period of 24 months, water samples and diatom species were collected simultaneously from 65 sites. A total of 388 diatom taxa were identified from 290 samples with seasonal and substrate variation affecting species composition but not the environmental information. Species diversity information, on the other hand, often varied significantly between substrates within a single sample. Analysis using CCA established that the diatom composition was affected by lithium, oxidized nitrogen, electrical conductivity, and sulphate levels in the sampled water. We conclude that changes in diatom community composition in the Karoo do reflect the water chemistry and could be useful as bioindicators. |
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0254-6299 |
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THL @ christoph.kuells @ holmes_can_2023 |
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163 |
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Zhang, H.; Gao, J.; Xu, L.; Zhang, X. |
| Title |
Case studies of radioactivity of drilling mud for in situ leaching uranium mining in China |
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Journal Article |
| Year |
2022 |
Publication |
Journal of Environmental Radioactivity |
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| Volume |
251-252 |
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Pages |
106982 |
| Keywords |
Drilling mud, Exemption management, In situ leaching, Radioactivity |
| Abstract |
The drilling mud from in situ leaching uranium mining is a type of low-radioactivity waste that contains natural nuclides and other harmful substances. In order to determine whether the drilling mud can meet the requirements of radioactive exemption management standards, field investigations and data simulations were conducted in this study. Two typical uranium mines were selected for onsite investigations. Drilling mud from different layers (i.e., the upper covering layer and ore-bearing layer) and from different stages (e.g., logging stage mud, drilling expansion stage mud, and mixed mud) was sampled. For each sample, the 238U and 226Ra concentrations of the solid components and the U and 226Ra concentrations of the supernatant were analyzed. The results revealed that the highest 238U and 226Ra concentrations of the solid components were 4122 Bq/kg and 4077 Bq/kg, while the 238U and 226Ra concentrations of the mixed drilling mud were all less than 300 Bq/kg. A radioactivity estimation model was established for scenario analysis. Exemption management screening lines of waste drilling mud, which can be used to classify and treat the drilling project according to the deposit’s grade and conditions, were proposed for in situ leaching drilling projects. |
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0265-931x |
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THL @ christoph.kuells @ zhang_case_2022 |
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191 |
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Stone, A.E.C.; Thomas, D.S.G. |
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Casting new light on late Quaternary environmental and palaeohydrological change in the Namib Desert: A review of the application of optically stimulated luminescence in the region |
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Journal Article |
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2013 |
Publication |
Journal of Arid Environments |
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93 |
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40-58 |
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Namib Desert, Optically stimulated luminescence dating, Palaeoenvironment, Palaeohydrology, Quaternary, Southern Africa |
| Abstract |
The application of optically stimulated luminescence (OSL) dating in the Namib Desert is casting new light on late Quaternary environments. OSL has been applied to: (i) complex linear dunes, alongside ground penetrating radar stratigraphy in order to establish dune migration rates, (ii) fluvial lithofacies associations that distinguish between flood deposits and river end points, in order to constrain the timing of periods of higher discharge and conditions relatively drier than present and (iii) aeolian sand interbedded with carbonate deposits in order to provide chronologies for water-lain interdune sediments. We present and review the contribution of these data to enhancing reconstructions of the palaeoenvironments and palaeohydrology of the west coast of Namibia, particularly the increased confidence in interpretations provided by lithofacies analysis of the river deposits. This includes major silt deposits, which have had a contested palaeohydrological interpretation, such as the Kuiseb River Homeb Silts. We conclude that OSL should remain a key chronological technique to further elucidate the palaeoenvironmental history of southern Africa. |
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0140-1963 |
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THL @ christoph.kuells @ stone_casting_2013 |
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98 |
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Li, J.; Pang, Z.; Liu, Y.; Hu, S.; Jiang, W.; Tian, L.; Yang, G.; Jiang, Y.; Jiao, X.; Tian, J. |
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Changes in groundwater dynamics and geochemical evolution induced by drainage reorganization: Evidence from 81Kr and 36Cl dating of geothermal water in the Weihe Basin of China |
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Journal Article |
| Year |
2023 |
Publication |
Earth and Planetary Science Letters |
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623 |
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Pages |
118425 |
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Kr dating, Cl dating, Geothermal water, Groundwater dynamics, Weihe basin |
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81Kr and 36Cl can both be used to date groundwater beyond the dating range of 14C. 81Kr usually provides reliable groundwater ages because it has uniform initial distribution and negligible subsurface generation, while 36Cl is commonly influenced by subsurface sources or “dead” chloride dissolution. Therefore, the combined use of 81Kr and 36Cl could provide clues on the evolution history of groundwater. In the present study, we performed 36Cl and 81Kr dating of geothermal water in Weihe Basin of China and interpreted the possible cause of disagreement. Two distinct water masses were identified with distinctive isotopic signals: groundwater with significant δ18O shifts (up to −2.0‰), dissolved dead Cl and ages < 1.0 Ma (Cluster A), and older water with little δ18O shifts, negligible dissolved Cl and ages >1.0 Ma (Cluster B). The results confirm the eastward flow path of Cluster B to the Ancient Sanmen Lake with an increasing trend of Cl concentration and age. Modern recharge from the mountains flows to the basin center with intense interaction between water and carbonate under respective reservoir temperatures (100 ∼ 130 °C). These waters flow through the saline stratum emerging from the spillover of the Ancient Sanmen Lake, resulting in higher dead Cl dissolution. A significant linear relationship is observed with the older end-member of ∼1.3Ma under the topographically-driven faster circulation effect. 81Kr ages seem to support the hypothesis that the birth of the modern Yellow River was at about 1.0–1.3 Ma. We inferred the drainage reorganization from the Ancient Sanmen Lake to the modern Yellow River since the Mid-Pleistocene Transition induced the change in groundwater dynamics as well as its chemical evolution. The excavation of the Ancient Sanmen Lake and the accentuated incision of the Weihe River induced groundwater gradient, and therefore the recharge from precipitation from both slopes of the Qinling Mountains in the south and the Beishan Mountains in the north. Our results highlight the effects of dead Cl on 36Cl dating and demonstrate the significant impact of catchment reorganization on groundwater dynamics and its chemistry. |
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0012-821x |
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THL @ christoph.kuells @ Li2023118425 |
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212 |
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Külls, C.; Leibundgut, C.; Schwarz, U.; Schick, A.P. |
| Title |
Channel infiltration study using dye tracers |
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Journal Article |
| Year |
1995 |
Publication |
IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences |
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232 |
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429-436 |
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Wallingford [Oxfordshire]: IAHS, 1981- |
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THL @ christoph.kuells @ Kuells1995channel |
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36 |
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