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N, D.; Panda, B.; S, C.; V, P.M.; Singh, D.K.; L, R.A.; Sahoo, S.K. |
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Title |
Spatio-temporal variations of Uranium in groundwater: Implication to the environment and human health |
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Journal Article |
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Year |
2021 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
775 |
Issue |
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Pages  |
145787 |
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Keywords |
Groundwater, Health risk, Speciation, Stable isotopes, Statistics, Uranium |
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Abstract |
Groundwater overexploitation has resulted in huge scarcity and increase in the demand for water and food security in India. Groundwater in India has been observed to have experienced various water quality issues like arsenic, fluoride, and Uranium (U) contamination, leading to risk in human health. Markedly, the health risk of higher U in drinking water, as well as its chemical toxicity in groundwater have adverse effects on human. This study has reported occurrence of U as an emerging and widespread phenomenon in South Indian groundwater. Data on U in groundwater were generated from 284 samples along the Cretaceous Tertiary boundary within 4 seasons viz. pre-monsoon (PRM), southwest monsoon (SWM), northeast monsoon (NEM), and post-monsoon (POM). High U concentrations (74 μgL−1) showed to be above the World Health Organization’s provisional guideline value of 30 μgL−1. The geochemical, stable isotope and geophysical studies suggested that U in groundwater could vary with respect to season and was noted to be highest during NEM. The bicarbonate (HCO3) released by weathering process during monsoon could affect the saturation index (SI)Calcite and carbonate species of U. However, the primary source of U was found to be due to geogenic factors, like weathering, dissolution, and groundwater level fluctuation, and that, U mobilization could be enhanced due to anthropogenic activities. The findings further indicated that groundwater in the study area has reached the alarming stage of chemical toxicity. Hence, it is urgent and imperative that workable management strategies for sustainable drinking water source be developed and preventive measures be undertaken, relative to these water quality concerns to mitigate their disconcerting effect on human health. |
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0048-9697 |
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THL @ christoph.kuells @ n_spatio-temporal_2021 |
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146 |
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Emparanza, A.R.; Kampmann, R.; Caso, F.D.; Morales, C.; Nanni, A. |
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Title |
Durability assessment of GFRP rebars in marine environments |
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Journal Article |
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Year |
2022 |
Publication |
Construction and Building Materials |
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329 |
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Pages |
127028 |
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Keywords |
Composite FRP rebar, Durability, Service life, Marine structures, Reinforced concrete |
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Abstract |
Technologies developed over the last two decades have facilitated the use of glass fiber reinforced polymer (GFRP) bars as internal reinforcement for concrete structures, specially in coastal environments, mainly due to their corrosion resistance. To-date, most durability studies have focused on a single mechanical parameter (tensile strength) and a single aging environment (exposure to high alkalinity). However, knowledge gaps exists in understanding how other mechanical parameters and relevant conditioning environments may affect the durability of GFRP bars. To this end, this study assesses the durability for different physio-mechanical properties of GFRP rebars, post exposure to accelerated conditioning in seawater. Six different GFRP rebar types were submerged in seawater tanks, at various temperatures (23°C, 40°C and 60°C) for different time periods (60, 120, 210 and 365 days). In total six different physio-mechanical properties were assessed, including: tensile strength, E-modulus, transverse and horizontal shear strength, micro-structural composition and lastly, bond strength. It was inferred that rebars with high moisture absorption resulted in poor durability, in that it affected mainly the tensile strength. Based on the Arrhenius model, at 23°C all the rebars that met the acceptance criteria by ASTM D7957 are expected to retain 85% of the tensile strength capacity. |
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0950-0618 |
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THL @ christoph.kuells @ Ruizemparanza2022127028 |
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83 |
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Author |
Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. |
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Title |
Isotope hydrology and hydrogeochemical modeling of Troodos Fractured Aquifer, Cyprus: The development of hydrogeological descriptions of observed water types |
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Journal Article |
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Year |
2020 |
Publication |
Applied Geochemistry |
Abbreviated Journal |
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123 |
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104780 |
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Keywords |
Isotope hydrology, Hydrogeochemical modelling, Hydrochemistry, Kargiotis, Troodos |
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Abstract |
The origin of groundwater recharge and subsequent flow paths are often difficult to establish in fractured, multi-lithological, and highly compartmentalized aquifers such as the Troodos Fractured Aquifer (TFA). As the conjunctive use of stable isotopes and hydrogeochemical data provides additional information, we established a monitoring network for stable isotopes in precipitation in Cyprus. The local meteoric water line, altitude effect and seasonal variation of stable isotopes in precipitation are derived from monitoring data. Stable isotopes and hydrogeochemical data are combined to model water-rock interactions and groundwater evolution along a complete ophiolite sequence. As a result a generic hydrogeologic description for the observed water types is developed. Isotope hydrology was applied in conjunction with hydrogeochemical modelling in Kargiotis Watershed, a major north-south transect of the TFA. PHREEQC was used for hydrogeochemical modelling to establish generic descriptions for observed water types. Mean precipitation-weighted values from 16 monitoring stations were used to calculate the Local Meteoric Water Line (LMWL), which was found to be equal to δ2H = (6.58 ± 0.13)*δ18O + (12.64 ± 0.91). A general decrease of 1.22‰ for δ2H and 0.20‰ for δ18O in precipitation was calculated per 100 m altitude. A generic groundwater evolution path was established: 1. Na/MgClHCO3, 2. MgHCO3, 3. Ca/MgHCO3, 4. Ca/MgNaHCO3, 4a. MgNa/CaHCO3/Cl, 5. NaMg/CaHCO3/Cl, 6. NaHCO3, 7. Na/MgHCO3SO4, 8. NaSO4Cl/HCO3. Hydrogeologic descriptions, consisting of groundwater origin, flow path and possible active water-rock processes, have been realised for the observed water types. The first two water types occur in serpentine and ultramafic-gabbro springs. Type 3 waters represent early stages of recharge and/or short flow paths, in gabbro whereas types 4 and 5 are typical for further percolating waters in gabbro and diabase. Water types 6 and 7 occur both in diabase and in the basal group and represent the regional flow. Water type 8 is the end member of regional, upwelling groundwater in the basal group. The presented descriptions and methods have practical applications in groundwater exploration, characterization, and protection. The methodology can be applied in other complex aquifer systems. |
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english |
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english |
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0883-2927 |
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Cyprus |
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Call Number |
THL @ christoph.kuells @ Christofi2020104780 |
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76 |
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Author |
Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. |
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Title |
Hydrochemical evolution of groundwater in gabbro of the Troodos Fractured Aquifer. A comprehensive approach |
Type |
Journal Article |
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Year |
2020 |
Publication |
Applied Geochemistry |
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Volume |
114 |
Issue |
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Pages |
104524 |
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Keywords |
geochemistry |
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Pergamon |
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English |
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THL @ christoph.kuells @ Christofi2020hydrochemical |
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13 |
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Paradis, C.J.; Hoss, K.N.; Meurer, C.E.; Hatami, J.L.; Dangelmayr, M.A.; Tigar, A.D.; Johnson, R.H. |
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Title |
Elucidating mobilization mechanisms of uranium during recharge of river water to contaminated groundwater |
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Journal Article |
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Year |
2022 |
Publication |
Journal of Contaminant Hydrology |
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251 |
Issue |
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104076 |
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Keywords |
Desorption, Dissolution, Groundwater, Surface water, Tracer, Uranium |
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Abstract |
The recharge of stream water below the baseflow water table can mobilize groundwater contaminants, particularly redox-sensitive and sorptive metals such as uranium. However, in-situ tracer experiments that simulate the recharge of stream water to uranium-contaminated groundwater are lacking, thus limiting the understanding of the potential mechanisms that control the mobility of uranium at the field scale. In this study, a field tracer test was conducted by injecting 100 gal (379 l) of oxic river water into a nearby suboxic and uranium-contaminated aquifer. The traced river water was monitored for 18 days in the single injection well and in the twelve surrounding observation wells. Mobilization of uranium from the solid to the aqueous phase was not observed during the tracer test despite its pre-test presence being confirmed on the aquifer sediments from lab-based acid leaching. However, strong evidence of oxidative immobilization of iron and manganese was observed during the tracer test and suggested that immobile uranium was likely in its oxidized state as U(VI) on the aquifer sediments; these observations ruled out oxidation of U(IV) to U(VI) as a potential mobilization mechanism. Therefore, desorption of U(VI) appeared to be the predominant potential mobilization mechanism, yet it was clearly not solely dependent on concentration as evident when considering that uranium-poor river water (\textless0.015 mg/L) was recharged to uranium-rich groundwater (≈1 mg/L). It was possible that uranium desorption was limited by the relatively higher pH and lower alkalinity of the river water as compared to the groundwater; both factors favor immobilization. However, it was likely that the immobile uranium was associated with a mineral phase, as opposed to a sorbed phase, thus desorption may not have been possible. The results of this field tracer study successfully ruled out two common mobilization mechanisms of uranium: (1) oxidative dissolution and (2) concentration-dependent desorption and ruled in the importance of advection, dispersion, and the mineral phase of uranium. |
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0169-7722 |
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THL @ christoph.kuells @ paradis_elucidating_2022 |
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135 |
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Author |
Jin, Z.; Külls, C. |
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Title |
FDM based OA-ICOS for high accuracy 13C quantification in gaseous CO2 |
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Journal Article |
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2020 |
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Earth and Environmental Science |
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EES |
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446 |
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3 |
Pages |
032061 |
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IOP Conference Series |
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THL @ christoph.kuells @ Jin2020fdm |
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16 |
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Author |
Külls, C.; Nunes, A.; Köbel-Batista, M.; Branquinho, C.; Bianconi, N.; Costantini, E. |
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Title |
Integrated use of soil physical and water isotope methods for ecohydrological characterization of desertified areas |
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Conference Article |
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2014 |
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EGU Geophysical Abstracts |
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15430 |
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THL @ christoph.kuells @ Kuells2014integrated |
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46 |
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Klaus, J.; Külls, C. |
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Integrating residence time data in mixing cell modeling-Application to the Lower Kuiseb Dune area |
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Conference Article |
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2009 |
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EGU Geophysical Abstracts |
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11026 |
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THL @ christoph.kuells @ Klaus2009integrating |
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54 |
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Krüger, N.; Külls, C.; Bruggeman, A.; Eliades, M.; Christophi, C.; Rigas, M.; Eracleous, T. |
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Title |
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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Gaj, M.; Beyer, M.; Hamutoko, J.; Uugulu, S.; Wanke, H.; Koeniger, P.; Külls, C.; Lohe, C.; Himmelsbach, T. |
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Title |
How do soil types affect stable isotope ratios of 2H and 18O under evaporation: A Fingerprint of the Niipele subbasin of the Cuvelai-Etosha basin, Namibia |
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Conference Article |
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2014 |
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EGU Geophysical Abstracts |
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5890 |
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THL @ christoph.kuells @ Gaj2014soil |
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44 |
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