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Author (down) Liesch, T.; Hinrichsen, S.; Goldscheider, N.
Title Uranium in groundwater — Fertilizers versus geogenic sources Type Journal Article
Year 2015 Publication Science of The Total Environment Abbreviated Journal
Volume 536 Issue Pages 981-995
Keywords Drinking water, Fertilizer, Geogenic background, Groundwater, Uranium
Abstract Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N=1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater.
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ISSN 0048-9697 ISBN Medium
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Notes Approved no
Call Number THL @ christoph.kuells @ liesch_uranium_2015 Serial 145
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Author (down) Li, X.; Shen, K.; Li, Q.; Deng, Y.; Zhu, P.; Wang, D.
Title Roll-over behavior in current-voltage curve introduced by an energy barrier at the front contact in thin film CdTe solar cell Type Journal Article
Year 2018 Publication Solar Energy Abbreviated Journal
Volume 165 Issue Pages 27-34
Keywords AlO HRT layer, Band alignment, CdTe solar cell, Roll-over behavior
Abstract Roll-over phenomenon in the current–voltage (J–V) curve is often observed in a CdTe thin film solar cell. The roll-over phenomenon, which is occurred near the open-circuit voltage in a light J–V curve, is due to Schottky energy barrier formed at the CdTe/metal interface in a CdTe solar cell back contact. In this study we report a J–V roll-over phenomenon which is induced by an energy barrier at the front contact of a CdTe solar cell. Two kinds of oxides, namely, Al2O3 and SnO2, were deposited as high-resistance transparent (HRT) layer between the window layer CdS and the fluorine doped tin oxide (FTO) front electrode in CdTe solar cells. These two oxides present much different electronic band alignment with FTO and CdS. SnO2 formed almost no energy barrier with CdS, this allowed smooth transport for photo-generated electrons from CdTe to CdS and FTO. However, Al2O3 formed a high energy barrier with CdS. The rather high energy barrier with a value of 3.43 eV at the CdS/Al2O3 interface induced a J–V roll-over phenomenon in a CdTe thin film solar cell, which dramatically led to a quick decrease for the cell device efficiency. The electron transport at the FTO/Al2O3/CdS interface is governed by tunneling effect. The results presented in this study demonstrate that the band structure at the front electrode plays an important role for the performance of a CdTe thin film solar cell.
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ISSN 0038-092x ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ li_roll-over_2018 Serial 187
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Author (down) Li, J.; Pang, Z.; Liu, Y.; Hu, S.; Jiang, W.; Tian, L.; Yang, G.; Jiang, Y.; Jiao, X.; Tian, J.
Title 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 Type Journal Article
Year 2023 Publication Earth and Planetary Science Letters Abbreviated Journal
Volume 623 Issue Pages 118425
Keywords Kr dating, Cl dating, Geothermal water, Groundwater dynamics, Weihe basin
Abstract 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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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0012-821x ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ Li2023118425 Serial 212
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Author (down) Leibundgut, C.; Maloszewski, P.; Külls, C.
Title Tracers in Hydrology Type Book Whole
Year 2009 Publication Abbreviated Journal
Volume Issue 1. Ed. Pages
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Publisher John Wiley & Sons, Ltd Place of Publication Editor
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Notes Approved no
Call Number THL @ christoph.kuells @ Leibundgut2009tracers Serial 37
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Author (down) Leeuwen, Z.R. van; Klaar, M.J.; Smith, M.W.; Brown, L.E.
Title Quantifying the natural flood management potential of leaky dams in upland catchments, Part II: Leaky dam impacts on flood peak magnitude Type Journal Article
Year 2024 Publication Journal of Hydrology Abbreviated Journal
Volume 628 Issue Pages 130449
Keywords Nature based solutions, Large wood, Empirical, Hydrograph analysis, Ecosystem services, Transfer function noise model
Abstract Leaky dams are an increasingly popular natural flood management measure, yet their impacts on flood peak magnitude have not yet been empirically quantified for a range of event types and magnitudes, even at the stream scale. In this study, the novel application of a transfer function noise modelling approach to empirical Before-After-Control-Impact stage data from an upland catchment allowed leaky dam effectiveness in reducing flood peak magnitude to be quantified. Flood peak stage and discharge magnitude changes were assessed from empirical data for 50 single and multi-peaked high flow events with return periods ranging from less than one year to six years. Overall, event peak magnitude was significantly reduced following the installation of eight leaky dams on the impact stream. Effectiveness was highly variable, but on average, flood peak magnitude was reduced by 10% for events with a return period up to one year. Some of the variability was explained by the size of the event and whether it was a single or multi-peaked event. This finding emphasises the need to manage expectations by considering both a range of event magnitudes and types when designing or assessing leaky dam natural flood management schemes.
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ISSN 0022-1694 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number THL @ christoph.kuells @ Vanleeuwen2024130449 Serial 228
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