Records |
Author |
Hamutoko, J.; Mapani, B.; Ellmies, R.; Bittner, A.; Külls, C. |
Title |
A fingerprinting method for the identification of uranium sources in alluvial aquifers: An example from the Khan and Swakop Rivers, Namibia |
Type |
Journal Article |
Year |
2014 |
Publication |
Physics and Chemistry of the Earth, Parts A/B/C |
Abbreviated Journal |
|
Volume |
72 |
Issue |
|
Pages |
34-42 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Pergamon |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Hamutoko2014fingerprinting |
Serial |
19 |
Permanent link to this record |
|
|
|
Author |
Emparanza, A.R.; Kampmann, R.; Caso, F.D.; Morales, C.; Nanni, A. |
Title |
Durability assessment of GFRP rebars in marine environments |
Type |
Journal Article |
Year |
2022 |
Publication |
Construction and Building Materials |
Abbreviated Journal |
|
Volume |
329 |
Issue |
|
Pages |
127028 |
Keywords |
Composite FRP rebar, Durability, Service life, Marine structures, Reinforced concrete |
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. |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0950-0618 |
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Ruizemparanza2022127028 |
Serial |
83 |
Permanent link to this record |
|
|
|
Author |
Paradis, C.J.; Hoss, K.N.; Meurer, C.E.; Hatami, J.L.; Dangelmayr, M.A.; Tigar, A.D.; Johnson, R.H. |
Title |
Elucidating mobilization mechanisms of uranium during recharge of river water to contaminated groundwater |
Type |
Journal Article |
Year |
2022 |
Publication |
Journal of Contaminant Hydrology |
Abbreviated Journal |
|
Volume |
251 |
Issue |
|
Pages |
104076 |
Keywords |
Desorption, Dissolution, Groundwater, Surface water, Tracer, Uranium |
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. |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0169-7722 |
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ paradis_elucidating_2022 |
Serial |
135 |
Permanent link to this record |
|
|
|
Author |
Dávila, P.; Külls, C.; Weiler, M. |
Title |
A toolkit for groundwater mean residence time interpretation with gaseous tracers |
Type |
Journal Article |
Year |
2013 |
Publication |
Computers & Geosciences |
Abbreviated Journal |
|
Volume |
61 |
Issue |
|
Pages |
116-125 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Pergamon |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Davila2013toolkit |
Serial |
22 |
Permanent link to this record |
|
|
|
Author |
N, D.; Panda, B.; S, C.; V, P.M.; Singh, D.K.; L, R.A.; Sahoo, S.K. |
Title |
Spatio-temporal variations of Uranium in groundwater: Implication to the environment and human health |
Type |
Journal Article |
Year |
2021 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
|
Volume |
775 |
Issue |
|
Pages |
145787 |
Keywords |
Groundwater, Health risk, Speciation, Stable isotopes, Statistics, Uranium |
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. |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0048-9697 |
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ n_spatio-temporal_2021 |
Serial |
146 |
Permanent link to this record |
|
|
|
Author |
Müller, M.; Alaoui, A.; Külls, C.; Leistert, H.; Meusburger, K.; Stumpp, C.; Weiler, M.; Alewell, C. |
Title |
Tracking water pathways in steep hillslopes by δ18O depth profiles of soil water |
Type |
Journal Article |
Year |
2014 |
Publication |
Journal of hydrology |
Abbreviated Journal |
|
Volume |
519 |
Issue |
|
Pages |
340-352 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Elsevier |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Mueller2014tracking |
Serial |
20 |
Permanent link to this record |
|
|
|
Author |
Morin, E.; Grodek, T.; Dahan, O.; Benito, G.; Külls, C.; Jacoby, Y.; Van Langenhove, G.; Seely, M.; Enzel, Y. |
Title |
Flood routing and alluvial aquifer recharge along the ephemeral arid Kuiseb River, Namibia |
Type |
Journal Article |
Year |
2009 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
|
Volume |
368 |
Issue |
1-4 |
Pages |
262-275 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Elsevier |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Morin2009flood |
Serial |
26 |
Permanent link to this record |
|
|
|
Author |
Klaus, J.; Külls, C.; Dahan, O. |
Title |
Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data |
Type |
Journal Article |
Year |
2008 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
|
Volume |
358 |
Issue |
3-4 |
Pages |
304-316 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Elsevier |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Klaus2008evaluating |
Serial |
28 |
Permanent link to this record |
|
|
|
Author |
Christofi, C.; Bruggeman, A.; Külls, C.; Constantinou, C. |
Title |
Hydrochemical evolution of groundwater in gabbro of the Troodos Fractured Aquifer. A comprehensive approach |
Type |
Journal Article |
Year |
2020 |
Publication |
Applied Geochemistry |
Abbreviated Journal |
|
Volume |
114 |
Issue |
|
Pages |
104524 |
Keywords |
geochemistry |
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
Pergamon |
Place of Publication |
|
Editor |
|
Language |
English |
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Christofi2020hydrochemical |
Serial |
13 |
Permanent link to this record |
|
|
|
Author |
Ardelt, G.; Külls, C.; Hellbrück, H. |
Title |
Towards intrinsic molecular communication using isotopic isomerism |
Type |
Journal Article |
Year |
2018 |
Publication |
Open Journal of Internet Of Things (OJIOT) |
Abbreviated Journal |
|
Volume |
4 |
Issue |
1 |
Pages |
135-143 |
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
RonPub |
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
THL @ christoph.kuells @ Ardelt2018towards |
Serial |
18 |
Permanent link to this record |