Records |
Author |
Külls, C. |
Title |
Demonstration des Potentials der Nitrat-Isotopenanalytik für die Strategieentwicklung der Sanierung Nitrat-belasteter Brunnen |
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Report |
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2004 |
Publication |
Umweltbundesamt |
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Abstract |
Demonstration des Potentials der Nitrat-Isotopenanalytik für die Strategieentwicklung der Sanierung Nitrat-belasteter Brunnen |
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THL @ christoph.kuells @ |
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75 |
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Kharazi, P.; khazaeli, E.A.; Heshmatpour, A. |
Title |
Delineation of suitable sites for groundwater dams in the semi-arid environment in the northeast of Iran using GIS-based decision-making method |
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Journal Article |
Year |
2021 |
Publication |
Groundwater for Sustainable Development |
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15 |
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Pages |
100657 |
Keywords |
Subsurface dam, Hybrid decision-making method, Geographic information system, Analytical hierarchy process, EDAS, TOPSIS1 |
Abstract |
Competing commercial demands on water resources need to be balanced as the world’s population rises. Generally, groundwater is raised by subsurface dams. In this paper, the geographic information system (GIS) software and a decision-making method were applied. As the first step, the limitations that affect the establishment of the subsurface dam were identified using eliminating criteria by the Boolean logic. Regarding the second step, the most appropriate axis was determined for subsurface dam construction in each of the limits. The analytical hierarchy process (AHP) was applied according to the evaluation criteria in this study. The aim of using AHP was to weigh and prioritize the criteria of the groundwater dam for recognizing appropriate sites. Among various places and regarding the subsurface dam construction, AHP was conducted using a hierarchy process for finding the most suitable sites in the third stage of the decision-making method. Finally, among the ten appropriate sites, cross comparison was drawn by using Decision Expert (DEX), Evaluation based on Distance from Average Solution (EDAS), and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). Compared together (as a process of decision-making), DEX, TOPSIS, and EDAS methods assisted in ranking the most appropriate sites in the final step of subsurface dam pre-selection. A and C axes obtained scores between 1 and 2, among 10 axes according to the numerically ranked locations. Regarding the water shortage issue and better management of the underground water at certain levels, the findings of this study could be useful for the residents of Kajbid-Balaqly Watershed in the dry season. Further, water managers can use the above-mentioned methods for their decisions regarding the proper subsurface dam establishment. |
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2352-801x |
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THL @ christoph.kuells @ Kharazi2021100657 |
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250 |
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Moreau, M.; Daughney, C. |
Title |
Defining natural baselines for rates of change in New Zealand’s groundwater quality: Dealing with incomplete or disparate datasets, accounting for impacted sites, and merging into state of the-environment reporting |
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Journal Article |
Year |
2021 |
Publication |
Science of The Total Environment |
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755 |
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Pages |
143292 |
Keywords |
Baseline, Groundwater quality, Machine-learning, Monitoring, New Zealand, Trends |
Abstract |
To effectively manage sustainably groundwater bodies, it is essential to establish what the naturally occurring ranges of chemical concentrations in groundwaters are and how they change over time. We defined baseline trends for New Zealand groundwaters using: 1) pattern recognition techniques to deal with inconsistent monitoring suites between the national (110 sites) and the denser regional network (\textgreater1000 sites), and 2) multivariate statistics to identify and remove impacted sites from the enhanced dataset. Rates of changes were calculated for 13 parameters between January 2005 and December 2014 at more than 1000 groundwater quality monitoring sites. The resulting dataset included 262 complete cases (CC), which was enhanced using Machine-Learning (ML) techniques to a total of 607 sites. Hierarchical cluster analysis was used to identify trend clusters that were consistent between the CC, ML-enhanced datasets and a 2006 study based on solely on the national network. The largest cluster (WR) consisted of low magnitude changes across all parameters and was attributed to water-rock interaction processes. The second largest cluster (I) exhibited fast changes particularly for parameters linked to human-induced impact. The third largest cluster (D) comprised decreases of all parameters and was associated with dilution processes. Trend clusters were further refined using groundwater quality state information, enabling the identification of impacted sites outside of Cluster I in the ML-enhanced and CC datasets. Corresponding trend baselines were subsequently derived at unimpacted sites using univariate quantile distribution (5th and 95th percentile thresholds). Finally, we developed classifications combining baselines (state and trend) and natural variability to enhance state of the environment reporting. This allowed the new identification of deteriorating trends at sites where groundwater quality state is not yet affected in addition to trend reversals. These classifications can be adapted to incorporate new knowledge or align with surface water quality reporting. |
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0048-9697 |
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THL @ christoph.kuells @ moreau_defining_2021 |
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164 |
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Author |
Frumkin, A.; Gvirtzman, H. |
Title |
Cross-formational rising groundwater at an artesian karstic basin: the Ayalon Saline Anomaly, Israel |
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Journal Article |
Year |
2006 |
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Journal of Hydrology |
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318 |
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1 |
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316-333 |
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Confined karst, Groundwater, HS, Maze caves, Rising water, Yarkon–Taninim aquifer |
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It is proposed that a geothermal artesian karstic system at the central part of the Yarkon–Taninim aquifer creates the ‘Ayalon Saline Anomaly’ (ASA), whose mechanism has been under debate for several decades. A 4-year-long detailed groundwater monitoring was carried out at 68 new shallow boreholes in the Ayalon region, accompanied by a comprehensive survey of karstic voids. Results indicate the rising of warm-brackish groundwater through highly permeable swarms of karstic shafts, serving as an outflow of the artesian geothermal system. The ASA area contains ‘hot spots’, where groundwater contrasts with ‘normal’ water hundreds of meters away. The ASA temperature reaches 30°C (∼5°C warmer than its surroundings), chloride concentration reaches 528mg/l (50–100mg/l in the surrounding), H2S concentration reaches 5.6mg/l (zero all around) and pH value is 7.0 (compared with 7.8 around). Subsequently, the hydrothermal water flows laterally of at the watertable horizon through horizontal conduits, mixing with ‘normal’ fresh water which had circulated at shallow depth. Following rainy seasons, maximal watertable rise is observed in the ASA compared to its surroundings. Regional hydrogeology considerations suggest that the replenishment area for the ASA water is at the Samaria Mountains, east of the ASA. The water circulates to a great depth while flowing westward, and a cross-formational upward flow is then favored close the upper sub-aquifer’s confinement border. |
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0022-1694 |
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THL @ christoph.kuells @ frumkin_cross-formational_2006 |
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117 |
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Author |
Rallakis, D.; Michels, R.; Cathelineau, M.; Parize, O.; Brouand, M. |
Title |
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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