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Botha, R.; Lindsay, R.; Newman, R.T.; Maleka, P.P.; Chimba, G. |
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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 |
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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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Boumaiza, L.; Ammar, S.B.; Chesnaux, R.; Stotler, R.L.; Mayer, B.; Huneau, F.; Johannesson, K.H.; Levison, J.; Knöller, K.; Stumpp, C. |
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Title |
Nitrate sources and transformation processes in groundwater of a coastal area experiencing various environmental stressors |
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Journal Article |
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Year |
2023 |
Publication |
Journal of Environmental Management |
Abbreviated Journal |
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Volume |
345 |
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118803 |
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Aquifer, Denitrification, MixSIAR, Nitrate, Nitrification, Stable isotopes |
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In coastal salinized groundwater systems, contamination from various nitrate (NO3) inputs combined with complex hydrogeochemical processes make it difficult to distinguish NO3 sources and identify potential NO3 transformtation processes. Effective field-based NO3 studies in coastal areas are needed to improve the understanding of NO3 contamination dynamics in groundwater of such complex coastal systems. This study focuses on a typical Mediterranean coastal agricultural area, located in Tunisia, experiencing substantial NO3 contamination from multiple anthropogenic sources. Here, multiple isotopic tracers (δ18OH2O, δ2HH2O, δ15NNO3, δ18ONO3, and δ11B) combined with a Bayesian isotope MixSIAR model are used (i) to identify the major NO3 sources and their contributions, and (ii) to describe the potential NO3 transformation processes. The measured NO3 concentrations in groundwater are above the natural baseline threshold, suggesting anthropogenic influence. The measured isotopic composition of NO3 indicates that manure, soil organic matter, and sewage are the potential sources of NO3, while δ11B values constrain the NO3 contamination to manure; a finding that is supported by the results of MixSIAR model revealing that manure-derived NO3 dominates over other likely sources. Nitrate derived from manure in the study area is attributed to organic fertilizers used to promote crop growth, and livestock that deposit manure directly on the ground surface. Evidence for ongoing denitrification in groundwaters of the study area is supported by an enrichment in both 15N and 18O in the remaining NO3, although isotopic mass balances between the measured and the theoretical δ18ONO3 values also suggest the occurrence of nitrification. The simultaneous occurrence of these biogeochemical processes with heterogeneous distribution across the study area reflect the complexity of interactions within the investigated coastal aquifer. The multiple isotopic tracer approach used here can identify the effect of multiple NO3 anthropogenic activities in coastal environments, which is fundamental for sustainable groundwater resources management. |
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0301-4797 |
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THL @ christoph.kuells @ boumaiza_nitrate_2023 |
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170 |
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Gardiner, J.; Thomas, R.B.; Phan, T.T.; Stuckman, M.; Wang, J.; Small, M.; Lopano, C.; Hakala, J.A. |
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Title |
Utilization of produced water baseline as a groundwater monitoring tool at a CO2-EOR site in the Permian Basin, Texas, USA |
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Journal Article |
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Year |
2020 |
Publication |
Applied Geochemistry |
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121 |
Issue |
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104688 |
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Keywords |
CO storage, Enhanced oil recovery, Geochemical baseline, Groundwater monitoring, Produced water, Solubility trapping |
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Abstract |
Carbon dioxide (CO2) enhanced oil recovery (EOR) provides a pathway for economic reuse and storage of CO2, a greenhouse gas. One challenge with this practice is ensuring CO2 injection does not result in target reservoir fluids migrating into overlying shallow (\textless1000 m) groundwater formations. Effective monitoring for leakage from storage formations could involve measuring sensitive chemical indicators in overlying groundwater units and within the producing formation itself for evidence of deviation from an initial state. In this study, produced waters and overlying groundwaters were monitored over a five-year period to evaluate which geochemical signals may be useful to ensure that oilfield produced waters did not impact overlying groundwaters. During this five-year period, a mature carbonate oil reservoir in the Permian Basin transitioned from a waterflooding operation to a water-alternating-gas injection (WAG), in which the formation was flooded with CO2 and various mixtures of produced water. Significant increases in dissolved inorganic constituents [alkalinity, TDS, Na+, Cl−, SO42−] were observed in produced waters following CO2 injection; however, carbonate reservoir dissolution-precipitation reactions appear to be minimal and injected CO2 appears to be stored via solubility trapping. Although there are statistically significant geochemical variations following CO2 injection, applying isometric log-ratios to certain parameters establishes a narrow range for post-CO2 injection produced waters. This narrow range can be considered a baseline for post-CO2 injection produced waters; this baseline can be utilized to monitor overlying local groundwaters for produced water intrusion. Additionally, certain parameters [Na+, Ca2+, K+, Cl−, alkalinity, and TDS] display large concentration disparities between produced water and overlying groundwaters; these parameters would be sensitive indicators of produced water intrusion into overlying groundwaters. |
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0883-2927 |
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THL @ christoph.kuells @ gardiner_utilization_2020 |
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171 |
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Smedley, P.L.; Bearcock, J.M.; Ward, R.S.; Crewdson, E.; Bowes, M.J.; Darling, W.G.; Smith, A.C. |
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Title |
Monitoring of methane in groundwater from the Vale of Pickering, UK: Temporal variability and source discrimination |
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Journal Article |
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Year |
2023 |
Publication |
Chemical Geology |
Abbreviated Journal |
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636 |
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Pages |
121640 |
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Keywords |
Aquifer, Biogenic, Ethane, Hydrocarbons, Methane, Shale gas |
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Groundwater abstracted from aquifers in the Vale of Pickering, North Yorkshire, UK and monitored over the period 2015–2022, shows evidence of variable but commonly high concentrations of dissolved CH4. Sampled groundwater from the Jurassic organic-rich Kimmeridge Clay Formation (boreholes up to 180 m depth) has concentrations up to 57 mg/L, and concentrations up to 59 mg/L are found in groundwater from underlying confined Corallian Group limestone (borehole depths 50–227 m). The high concentrations are mainly from boreholes in the central parts of the vale. Small concentrations of ethane (C2H6, up to 800 μg/L) have been found in the Kimmeridge Clay and confined Corallian groundwaters, and of propane (C3H8, up to 160 μg/L) in deeper boreholes (110–180 m) from these formations. The concentrations are typically higher in groundwater from the deeper boreholes and vary with hydrostatic pressure, reflecting the pressure control on CH4 solubility. The occurrences contrast with groundwater from shallow Quaternary superficial deposits which have low CH4 concentrations (up to 0.39 mg/L), and with the unconfined and semi-confined sections of the Corallian aquifer (up to 0.7 mg/L) around the margins of the vale. Groundwater from the Quaternary, Kimmeridge Clay formations and to a small extent the confined Corallian aquifer, supports local private-water supplies, that from the peripheral unconfined sections of Corallian also supports public supply for towns and villages across the region. Dissolved methane/ethane (C1/C2) ratios and stable-isotopic compositions (δ13C-CH4, δ2H-CH4 and δ13C-CO2) suggest that the high-CH4 groundwater from both the Kimmeridge Clay and confined Corallian formations derives overwhelmingly from biogenic reactions, the methanogenesis pathway by CO2 reduction. A small minority of groundwater samples shows a more enriched δ13C-CH4 composition (−50 to −44 ‰) which has been interpreted as due to anaerobic or aerobic methylotrophic oxidation in situ or post-sampling oxidation, rather than derivation by a thermogenic route. Few of the existing groundwater sites are proximal to abandoned or disused conventional hydrocarbon wells that exist in the region, and little evidence has been found for an influence on groundwater dissolved gases from these sites. The Vale of Pickering has also been under recent consideration for development of an unconventional hydrocarbon (shale-gas) resource. In this context, the monitoring of dissolved gases has been an important step in establishing the high-CH4 baseline of groundwaters from Jurassic deposits in the region and in apportioning their sources and mechanisms of genesis. |
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0009-2541 |
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THL @ christoph.kuells @ smedley_monitoring_2023 |
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172 |
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Lima, G.F.C.; Filho, C.A. de C.; Ferreira, V.G.; Lima, J. da S.D.; Marques, E.D.; Minardi, P.S.P.; Dalmázio, I.; Moreira, R.M. |
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Establishing a water baseline for the unconventional gas industry: A multiple environmental isotopes assessment (18O, 2H, 3H, 13C, and 14C) of surface and groundwater in the São Francisco Basin, Brazil |
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Journal Article |
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Year |
2023 |
Publication |
Applied Geochemistry |
Abbreviated Journal |
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159 |
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Pages |
105818 |
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Fracking, Groundwater dating, Indaiá river, Isotopes assessment, Shale gas, Unconventional hydrocarbons |
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Unconventional hydrocarbon production has become the target of an intensive environmental debate due to the risks it poses to water resources. Fracking, while enabling the extraction of oil and gas from ultra-low permeability reservoirs, also possesses the risk of polluting water systems through failures from hydraulic fracturing and its associated procedures. The need to foster national industrial development with a transitional energy matrix has led Brazil to discuss the environmental suitability before producing its large unconventional reserves. Many studies have highlighted the need for a robust environmental characterization before the development of the unconventional industry. In this sense, multiple environmental isotopes may work as a proxy for identifying water contamination right from the early stages. Environmental isotopes may also be applied to enhance the understanding of the natural geochemical processes intrinsic to a given area. This study presents an environmental isotopes baseline for the groundwater and riverine water systems within the São Francisco Basin, a proven tight gas reservoir in Brazil, in a pre-operational context. δ18O, δ2H, 3H, δ13C, and Δ14C were evaluated in three different seasons in groundwater and surface water samples, along with other auxiliary parameters such as physical-chemical parameters (in situ), major ions, and d-excess. The δ2H and δ18O in surface water shows an upstream → downstream enrichment trend, with some variations suggesting baseflow interactions in the surface water systems. An evaporation line for the study area was defined as δ2H = 4.6903 δ18O + 10.362. δ13C indicates a mutual dissolution of silicates and carbonates in the groundwater system and suggests a group of samples highly related to the recharge areas. Groundwater dating denotes the Serra da Saudade Formation as a modern fractured aquifer with a strong recharge capacity. These findings support stakeholders in environmental monitoring and management of the unconventional gas industry. |
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0883-2927 |
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THL @ christoph.kuells @ lima_establishing_2023 |
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173 |
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Pham, Q.-N.; Nguyen, T.-C.; Ta, T.-T.; Tran, T.-L. |
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Comprehensive approach to sustainable groundwater management in semi-arid Ninh Thuan plain, Vietnam |
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Journal Article |
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2023 |
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Groundwater for Sustainable Development |
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23 |
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101031 |
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Climate change, Groundwater, Managed aquifer recharge (MAR), Modeling, Sea level rise, Seawater intrusion, Sustainable groundwater management |
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Vietnam is a country with a long coastline and a high population density residing in the coastal plains. The largest dry area in Vietnam, the coastal plain of Ninh Thuan province, always lacks water in the first dry months of the year (Jan., Feb., Mar., and Apr.). Groundwater is an extremely valuable resource for supplies at this time. Therefore, the objective of this study is to establish a comprehensive approach to sustainable groundwater management in this semi-arid region. This approach is not only mitigating the negative impacts of factors such as climate change, sea level rise, and socio-economic development but also suggesting measures for management of aquifer recharge. A groundwater model for a 3-layer system with variable density flow SEAWAT is built to predict the impacts of climate change and sea level rise without a change in groundwater abstraction. This model helps to understand the trend of salt intrusion and lowering groundwater level in the study area. Afterwards, scenarios with different ground water abstraction and groundwater development such as ground dam, infiltration basin have been set up to meet the demands of socio-economic development in the future. Predicted results will show the impacts of the groundwater systems in the area such as groundwater level change, and saltwater intrusion. Controlled groundwater abstraction and some measures of groundwater development such as infiltration basin, underground dam would allow for an increase of up to 50000m3/day in the year 2050 without negative impacts on the aquifer system. |
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2352-801x |
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THL @ christoph.kuells @ pham_comprehensive_2023 |
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174 |
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Min, M.; Chen, J.; Wang, J.; Wei, G.; Fayek, M. |
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Mineral paragenesis and textures associated with sandstone-hosted roll-front uranium deposits, NW China |
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Journal Article |
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2005 |
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Ore Geology Reviews |
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26 |
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1 |
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51-69 |
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China, Mineralogy, Paragenesis, Sandstone-hosted roll-type uranium deposit |
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We present a first paragenetic study of the Wuyier, Wuyisan, Wuyiyi and Shihongtan sandstone-hosted roll-front uranium deposits, northwest China. The mineralization is hosted by Lower–Middle Jurassic coarse- to medium-grained sandstones, which are dark-gray to black due to a mixture of ore minerals and carbonaceous debris. The sandstone is alluvial fan-braided river facies. Minerals associated with these deposits can be broadly categorized as detrital, authigenic, and ore-stage mineralization. Ore minerals consist of uraninite and coffinite. This is the first noted occurrence of coffinite in this type of deposit in China. Sulfide minerals associated with the uranium minerals are pyrite, marcasite, and less commonly, sphalerite and galena. The sulfide minerals are largely in textural equilibrium with the uranium minerals. However, these sulfide minerals occasionally appear to predate, as well as postdate, the uranium minerals. This implies that there are multiple generations of sulfides associated with these deposits. The ore minerals occur interstitially between fossilized wood cells in the sandstones as well as replace fossilized wood and biotite. The deposits are generally low-grade. Primary uranium minerals associated with the low-grade deposits are generally too small, ranging from 0.2 to 0.3 μm in diameter, to be observed by optical microscopy and are only observed by electron microscopy. Mineral paragenesis and textures indicate that these deposits formed under low temperature (30–50 °C) conditions. |
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0169-1368 |
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THL @ christoph.kuells @ min_mineral_2005 |
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175 |
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Rallakis, D.; Michels, R.; Cathelineau, M.; Parize, O.; Brouand, M. |
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Conditions for uranium biomineralization during the formation of the Zoovch Ovoo roll-front-type uranium deposit in East Gobi Basin, Mongolia |
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Journal Article |
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2021 |
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Ore Geology Reviews |
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138 |
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104351 |
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Bioreduction, East Gobi Basin, Mongolia, Organic matter, Roll-front, Sulfur isotopes, Uranium |
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The Zoovch Ovoo uranium roll-front-type deposit is hosted in the Sainshand Formation, a Late Cretaceous siliciclastic reservoir, which constitutes the upper part of the post-rift infilling of the Mesozoic East Gobi Basin in SE Mongolia. The Sainshand Formation consists of unconsolidated medium-grained sand, silt and clay intervals deposited in fluvial-lacustrine settings. The uranium deposit is confined within a 60–80 m thick siliciclastic sequence inside aquifer-driven systems. The overall system experienced shallow burial and was never subjected to temperatures higher than 40 °C. This study proposes a comprehensive metallogenic model for this uranium deposit. Sedimentological and mineralogical observations from drill core samples to the microscopic scale (optical and Scanning Electron Microscopy) together with in situ geochemistry of late-formed phases (Laser Ablation–Inductively Coupled Plasma Mass Spectrometry, Electron Probe Microanalysis, Fourier Transform–Infrared Spectroscopy) were considered for the reconstruction of the main stages of U trapping. In the mineralized zone, the uranium ore is expressed as Ca–enriched uraninite (UO2) and less commonly as Ca–enriched phospho-coffinite (U, P)SiO4. Trapping mechanisms include i) complexation (i.e. uranyl-carboxyl complexes), ii) adsorption on organic or clay particles) and iii) reduction by pyrite and by bacterial activity to amorphous uraninite. In all cases, the organic matter plays either the role of trap for uranium or nutrient for bacteria that can trap uranium through their metabolism. The shallow burial diagenesis conditions do not allow direct reduction of U(VI) by organic carbon. The δ34S values of the iron disulfide are very diverse, fluctuating in extreme cases between −50 to + 50‰, with an average δ34S value for framboidal pyrite at 2‰, and −20‰ for euhedral pyrite. The positive and negative values reflect close versus open fractionation systems, while bacterial sulphate reduction (BSR) is active during the whole diagenetic history of the deposit as an essential source of reduced sulfur. Therefore, using detrital organic matter as a carbon source, microorganisms play a significant role in uranium trapping, either as a direct reducing agent for uranium or pyrite formation, which will trap uranium through redox driven epigenetic processes. |
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0169-1368 |
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THL @ christoph.kuells @ rallakis_conditions_2021 |
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176 |
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Jroundi, F.; Descostes, M.; Povedano-Priego, C.; Sánchez-Castro, I.; Suvannagan, V.; Grizard, P.; Merroun, M.L. |
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Profiling native aquifer bacteria in a uranium roll-front deposit and their role in biogeochemical cycle dynamics: Insights regarding in situ recovery mining |
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Journal Article |
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2020 |
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Science of The Total Environment |
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721 |
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137758 |
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Bacterial diversity, Bioremediation, In-situ recovery, Natural attenuation, Network analysis, Uranium |
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A uranium-mineralized sandy aquifer, planned for mining by means of uranium in situ recovery (U ISR), harbors a reservoir of bacterial life that may influence the biogeochemical cycles surrounding uranium roll-front deposits. Since microorganisms play an important role at all stages of U ISR, a better knowledge of the resident bacteria before any ISR actuations is essential to face environmental quality assessment. The focus here was on the characterization of bacteria residing in an aquifer surrounding a uranium roll-front deposit that forms part of an ISR facility project at Zoovch Ovoo (Mongolia). Water samples were collected following the natural redox zonation inherited in the native aquifer, including the mineralized orebody, as well as compartments located both upstream (oxidized waters) and downstream (reduced waters) of this area. An imposed chemical zonation for all sensitive redox elements through the roll-front system was observed. In addition, high-throughput sequencing data showed that the bacterial community structure was shaped by the redox gradient and oxygen availability. Several interesting bacteria were identified, including sulphate-reducing (e.g. Desulfovibrio, Nitrospira), iron-reducing (e.g. Gallionella, Sideroxydans), iron-oxidizing (e.g. Rhodobacter, Albidiferax, Ferribacterium), and nitrate-reducing bacteria (e.g. Pseudomonas, Aquabacterium), which may also be involved in metal reduction (e.g. Desulfovibrio, Ferribacterium, Pseudomonas, Albidiferax, Caulobacter, Zooglea). Canonical correspondence analysis (CCA) and co-occurrence patterns confirmed strong correlations among the bacterial genera, suggesting either shared/preferred environmental conditions or the performance of similar/complementary functions. As a whole, the bacterial community residing in each aquifer compartment would appear to define an ecologically functional ecosystem, containing suitable microorganisms (e.g. acidophilic bacteria) prone to promote the remediation of the acidified aquifer by natural attenuation. Assessing the composition and structure of the aquifer’s native bacteria is a prerequisite for understanding natural attenuation and predicting the role of bacterial input in improving ISR efficiency. |
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THL @ christoph.kuells @ jroundi_profiling_2020 |
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Hubbard, B.E.; Gallegos, T.J.; Stengel, V.; Hoefen, T.M.; Kokaly, R.F.; Elliott, B. |
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Hyperspectral (VNIR-SWIR) analysis of roll front uranium host rocks and industrial minerals from Karnes and Live Oak Counties, Texas Coastal Plain |
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2024 |
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Journal of Geochemical Exploration |
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257 |
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107370 |
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Critical minerals, Hyperspectral, Industrial minerals, Mine waste, Texas coastal plain, Uranium |
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VNIR-SWIR (400–2500 nm) reflectance measurements were made on the surfaces of various cores, cuttings and sample splits of sedimentary rocks from the Tertiary Jackson Group, and Catahoula, Oakville and Goliad Formations. These rocks vary in composition and texture from mudstone and claystone to sandstone and are known host rocks for roll front uranium occurrences in Karnes and Live Oak Counties, Texas. Spectral reflectance profiles, 569 in total, were reduced to 125 representative spectral signatures, which were analyzed using the U.S. Geological Survey’s (USGS) Material Identification and Characterization Algorithm (MICA). MICA uses an automated continuum-removal procedure together with a least-squares linear regression to determine the fit of observed sample spectral absorption features to those of reference mineral standards in a spectral library. The reference minerals include various clay, mica, carbonate, ferric and ferrous iron minerals and their mixtures. In addition, absorption feature band-depth analysis was done to identify rock surfaces exhibiting absorption features related to uranium and zeolite minerals, which were not included in the command files used to execute MICA. Rocks from each of the four geologic units produced broadly similar spectral signatures as a result of comparable mineral compositions, but there were some notable differences. For example, Ca- and Na-montmorillonite was matched most frequently to the spectral absorption features in 2-μm (∼2000–2500 nm) wavelengths, while goethite occurred often at 1-μm (∼400–1000 nm) wavelengths. The latter is related to limonitic iron-staining in and around oxidized zones of the uranium roll front as described in previous papers. Rocks of the Jackson Group differed from those of the Catahoula, Oakville and Goliad units in that the former exhibited spectral features we interpret as being due to the presence of lignite-bearing mudstone layers. Goliad rocks exhibit spectral features related to dolomite, gypsum, anhydrite, and an unidentified green clay mineral that is possibly glauconite. Jackson Group rocks also exhibit weak but well-resolved absorption features at 964 and 1157 nm related to either or both zeolite minerals clinoptilolite and heulandite. These zeolite minerals and a few spectra exhibiting hydrous silica absorption features are indicative of alteration of volcanic glass in tuffaceous mudstone and claystone layers. A few sample spectra exhibited strong absorption features at around 1135 nm related to the uranium mineral coffinite. Both the 1135 nm coffinite and 1157 nm zeolite absorption features overlap somewhat, potentially making them difficult to distinguish without additional hyperspectral field, laboratory or remote sensing data. The results of this study were compared to mixtures of minerals described for ore, gangue and alteration minerals in deposit models for sandstone-hosted uranium, sedimentary bentonite and sedimentary zeolite. Use of these spectra can help facilitate mapping of both waste materials from the legacy mining of the above commodities, as well as future exploration and resource assessment activities. |
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THL @ christoph.kuells @ hubbard_hyperspectral_2024 |
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178 |
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