| Records |
| Author |
Lim, S.; Chase, B.M.; Chevalier, M.; Reimer, P.J. |
| Title |
50,000years of vegetation and climate change in the southern Namib Desert, Pella, South Africa |
Type |
Journal Article |
| Year |
2016 |
Publication |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Abbreviated Journal |
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| Volume |
451 |
Issue |
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Pages  |
197-209 |
| Keywords |
Climate reconstruction, Late Quaternary, Namib Desert, Pollen, Rock hyrax middens, South Africa |
| Abstract |
This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability at the site relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, during which time high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome. During this latter period, increases in upwelling intensity created drier conditions at the site. Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000years. These findings pose interesting questions regarding the nature of environmental change in southwestern Africa, and the significance of the diverse records that have been obtained from the region. |
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0031-0182 |
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no |
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THL @ christoph.kuells @ lim_50000years_2016 |
Serial |
107 |
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| Author |
Min, M.; Xu, H.; Chen, J.; Fayek, M. |
| Title |
Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China |
Type |
Journal Article |
| Year |
2005 |
Publication |
Ore Geology Reviews |
Abbreviated Journal |
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| Volume |
26 |
Issue |
3 |
Pages |
198-206 |
| Keywords |
Biomineralization, China, Roll-front uranium deposit, Sandstone |
| Abstract |
We show evidence that the primary uranium minerals, uraninite and coffinite, from high-grade ore samples (U3O8\textgreater0.3%) in the Wuyiyi, Wuyier, and Wuyisan sandstone-hosted roll-front uranium deposits, Xinjiang, northwestern China were biogenically precipitated and psuedomorphically replace fungi and bacteria. Uranium (VI), which was the sole electron acceptor, was likely to have been enzymically reduced. Post-mortem accumulation of uranium may have also occurred through physio-chemical interaction between uranium and negatively-charged cellular sites, and inorganic adsorption or precipitation reactions. These results suggest that microorganisms may have played a key role in formation of the sandstone- or roll-type uranium deposits, which are among the most economically significant uranium deposits in the world. |
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0169-1368 |
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no |
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THL @ christoph.kuells @ min_evidence_2005 |
Serial |
186 |
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| Author |
Lach, P.; Cathelineau, M.; Brouand, M.; Fiet, N. |
| Title |
In-situ Isotopic and Chemical Study of Pyrite from Chu-Sarysu (Kazakhstan) Roll-front Uranium Deposit |
Type |
Journal Article |
| Year |
2015 |
Publication |
Procedia Earth and Planetary Science |
Abbreviated Journal |
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| Volume |
13 |
Issue |
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Pages |
207-210 |
| Keywords |
LA-ICP-MS, pyrite, roll-front, SIMS, sulfur isotopy, traces elements, uranium |
| Abstract |
Pyrite is common in roll-front type uranium deposit in Chu-sarysu basin, Kazakhstan. Combined in-situ microstructural, isotopic and chemical analysis of pyrite indicates variation in precipitation conditions and in fluid composition. Broad-scale δ34S heterogeneity indicates a complex multi-facet evolution. First generation authigenic framboïdal aggregates are biogenic as demonstrated by the lowest δ34S values of -48‰ to -28‰. The latest generation pyrites are probably hydrothermal with greater δ34S variation (-30‰ to +12‰). This hydrothermal pyrite commonly displays variable enrichment of several trace elements especially As, Co and Ni. Strong variation in δ34S values and variable trace element enrichment is interpreted in terms of continuous variations in fluid composition. |
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1878-5220 |
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no |
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THL @ christoph.kuells @ lach_-situ_2015 |
Serial |
182 |
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Rossetto, R.; Filippis, G.D.; Borsi, I.; Foglia, L.; Cannata, M.; Criollo, R.; Vázquez-Suñé, E. |
| Title |
Integrating free and open source tools and distributed modelling codes in GIS environment for data-based groundwater management |
Type |
Journal Article |
| Year |
2018 |
Publication |
Environmental Modelling & Software |
Abbreviated Journal |
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| Volume |
107 |
Issue |
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Pages |
210-230 |
| Keywords |
Free and Open Source Software, FREEWAT, Groundwater management, ICT, MODFLOW, QGIS |
| Abstract |
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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no |
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THL @ christoph.kuells @ rossetto_integrating_2018 |
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92 |
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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 |
Issue |
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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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no |
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THL @ christoph.kuells @ holmes_can_2023 |
Serial |
163 |
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| Author |
Mühr-Ebert, E.L.; Wagner, F.; Walther, C. |
| Title |
Speciation of uranium: Compilation of a thermodynamic database and its experimental evaluation using different analytical techniques |
Type |
Journal Article |
| Year |
2019 |
Publication |
Applied Geochemistry |
Abbreviated Journal |
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100 |
Issue |
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Pages |
213-222 |
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| Abstract |
Environmental hazards are caused by uranium mining legacies and enhanced radioactivity in utilized groundwater and surface water resources. Knowledge of uranium speciation in these waters is essential for predicting radionuclide migration and for installing effective water purification technology. The validity of the thermodynamic data for the environmental media affected by uranium mining legacies is of utmost importance. Therefore, a comprehensive and consistent database was established according to current knowledge. The uranium data included in the database is based on the NEA TDB (Guillaumont et al., 2003) and is modified or supplemented as necessary e.g. for calcium and magnesium uranyl carbonates. The specific ion interaction theory (Brönsted, 1922) is used to estimate activity constants, which is sufficient for the considered low ionic strengths. The success of this approach was evaluated by comparative experimental investigations and model calculations (PHREEQC (Parkhurst and Appelo, 1999)) for several model systems. The waters differ in pH (2.7–9.8), uranium concentration (10−9-10−4 mol/L) and ionic strength (0.002–0.2 mol/L). We used chemical extraction experiments, ESI-Orbitrap-MS and time-resolved laser-induced fluorescence spectroscopy (TRLFS) to measure the uranium speciation. The latter method is nonintrusive and therefore does not change the chemical composition of the investigated waters. This is very important, because any change of the system under study may also change the speciation. |
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0883-2927 |
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no |
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THL @ christoph.kuells @ muhr-ebert_speciation_2019 |
Serial |
142 |
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Tanwer, N.; Arora, V.; Kant, K.; Singh, B.; Laura, J.S.; Khosla, B. |
| Title |
Chapter 17 – Prevalence of Uranium in groundwater of rural and urban regions of India |
Type |
Book Chapter |
| Year |
2024 |
Publication |
Water Resources Management for Rural Development |
Abbreviated Journal |
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Issue |
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Pages |
213-234 |
| Keywords |
Distribution, Heath impacts, Remediation techniques, Sources, Uranium |
| Abstract |
Abnormally high uranium (U) prevalence in groundwater is a neoteric subject of concern throughout the world because of its direct impact on human health and well-being. Groundwater is used as the most preferred choice for drinking because of its good quality and ease of availability in rural and urban parts of India, and also in different parts of the world. India is an agriculture-dominant country and its 50–80% irrigational requirement is met by groundwater, besides this nearly 90% of rural and 50% of urban water needs are fulfilled by groundwater. The uranium concentration in groundwater in different parts of India namely Punjab, Haryana, Rajasthan, Madhya Pradesh, Karnataka, etc. found to be varying from 0 mg/L to 1443 mg/L, and in different parts of the world, it is found up to 1400 mg/L in the countries like United States, Canada, Finland, Mongolia, Nigeria, South Korea, Pakistan, Burundi, China, Afghanistan, etc. Various natural factors such as geology, hydro-geochemistry, and prevailing conditions as well as anthropogenic factors including mining, nuclear activities, erratic use of fertilizers, and overexploitation of groundwater resources are responsible for adding uranium in groundwater. Groundwater is considered a primary source of uranium ingestion in human beings as it contributes 85% while food contributes 15%. Uranium affects living beings as a two-way sword, being a radioactive element, causing radiotoxicity, and on the other hand as a heavy metal, it causes chemotoxicity. The main target organs affected by the consumption of uranium-contaminated water are kidneys, bones, lungs, etc. It can cause renal failure, impair cell functioning and bone growth, and mutation in DNA. Although, its toxic effects, being a heavy metal, are more severe than its radiotoxicity. Various techniques are available for the efficient removal of uranium from the groundwater such as bioremediation, nanotechnology-enhanced remediation, adsorption, filtration, etc. This chapter entails a comprehensive investigation of uranium contamination in groundwater of rural and urban parts of India their probable sources, health impacts, treatment, and mitigation techniques available to manage groundwater resources. |
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Elsevier |
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Madhav, S.; Srivastav, A.L.; Izah, S.C.; Hullebusch, E. van |
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978-0-443-18778-0 |
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no |
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THL @ christoph.kuells @ madhav_chapter_2024 |
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152 |
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Yabusaki, S.B.; Fang, Y.; Long, P.E.; Resch, C.T.; Peacock, A.D.; Komlos, J.; Jaffe, P.R.; Morrison, S.J.; Dayvault, R.D.; White, D.C.; Anderson, R.T. |
| Title |
Uranium removal from groundwater via in situ biostimulation: Field-scale modeling of transport and biological processes |
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Journal Article |
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2007 |
Publication |
Journal of Contaminant Hydrology |
Abbreviated Journal |
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93 |
Issue |
1 |
Pages |
216-235 |
| Keywords |
Bioremediation, Biostimulation, Field experiment, Iron, Reactive transport, Sulfate, Uranium |
| Abstract |
During 2002 and 2003, bioremediation experiments in the unconfined aquifer of the Old Rifle UMTRA field site in western Colorado provided evidence for the immobilization of hexavalent uranium in groundwater by iron-reducing Geobacter sp. stimulated by acetate amendment. As the bioavailable Fe(III) terminal electron acceptor was depleted in the zone just downgradient of the acetate injection gallery, sulfate-reducing organisms came to dominate the microbial community. In the present study, we use multicomponent reactive transport modeling to analyze data from the 2002 field experiment to identify the dominant transport and biological processes controlling uranium mobility during biostimulation, and determine field-scale parameters for these modeled processes. The coupled process simulation approach was able to establish a quantitative characterization of the principal flow, transport, and reaction processes based on the 2002 field experiment, that could be applied without modification to describe the 2003 field experiment. Insights gained from this analysis include field-scale estimates of the bioavailable Fe(III) mineral threshold for the onset of sulfate reduction, and rates for the Fe(III), U(VI), and sulfate terminal electron accepting processes. |
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0169-7722 |
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THL @ christoph.kuells @ yabusaki_uranium_2007 |
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156 |
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| Author |
Hdeib, R.; Aouad, M. |
| Title |
Rainwater harvesting systems: An urban flood risk mitigation measure in arid areas |
Type |
Journal Article |
| Year |
2023 |
Publication |
Water Science and Engineering |
Abbreviated Journal |
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16 |
Issue |
3 |
Pages |
219-225 |
| Keywords |
Rainwater harvesting, Urban floods, Flood map, Hydrodynamic model, Built environment, Arid areas |
| Abstract |
Rainwater harvesting (RWH) systems have been developed to compensate for shortage in the water supply worldwide. Such systems are not very common in arid areas, particularly in the Gulf Region, due to the scarcity of rainfall and their reduced efficiency in covering water demand and reducing water consumption rates. In spite of this, RWH systems have the potential to reduce urban flood risks, particularly in densely populated areas. This study aimed to assess the potential use of RWH systems as urban flood mitigation measures in arid areas. Their utility in the retention of stormwater runoff and the reduction of water depth and extent were evaluated. The study was conducted in a residential area in Bahrain that experienced waterlogging after heavy rainfall events. The water demand patterns of housing units were analyzed, and the daily water balance for RWH tanks was evaluated. The effect of the implementation of RWH systems on the flood volume was evaluated with a two-dimensional hydrodynamic model. Flood simulations were conducted in several rainfall scenarios with different probabilities of occurrence. The results showed significant reductions in the flood depth and flood extent, but these effects were highly dependent on the rainfall intensity of the event. RWH systems are effective flood mitigation measures, particularly in urban arid regions short of proper stormwater control infrastructure, and they enhance the resilience of the built environment to urban floods. |
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1674-2370 |
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no |
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THL @ christoph.kuells @ Hdeib2023219 |
Serial |
242 |
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| Author |
Kharaka, Y.; Harmon, R.; Darling, G. |
| Title |
W. Mike Edmunds (1941–2015) |
Type |
Journal Article |
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2015 |
Publication |
Applied Geochemistry |
Abbreviated Journal |
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59 |
Issue |
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Pages |
225-226 |
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0883-2927 |
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THL @ christoph.kuells @ kharaka_w_2015 |
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103 |
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