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  • Stable Isotopes
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  • 1
    Language: English
    In: Applied Geochemistry, 2008, Vol.23(10), pp.2945-2954
    Description: Naturally occurring stable and radioactive isotopes were used as environmental tracers to investigate contaminant metal mobilization processes in a metal smelter dump mainly consisting of slag. Water emerging from the dump at a spring is heavily contaminated by metals. The smelter dump contains minor amounts of flue dust, a material which shows a high potential for metal mobilization. Nearby dumps mainly consist of low-grade ore. Concentration patterns of U, Ra and Pb determined in sediment deposited close to the contaminated spring reveal the flue dust to be the major local metal source rather than the slag or the low-grade ore. Contamination pathways inside the dump were investigated using hydrological, chemical and isotopic data. Strong negative correlation between water discharge and metal concentration in the spring water suggests, besides short-term dilution of the metal concentration by direct rainwater runoff, distinct long-term dilution of the spring water by groundwater being discharged at a significantly increased rate as a result of heavy rains. δ O and δD signatures of rain, local groundwater and spring water confirm the importance of groundwater derived from the local aquifer. Another hydrological component with importance for metal mobilization was found to be water that is recharged in the dump itself. Tritium analysis allowed an assessment of the probable residence time of that water component in the smelter dump. Since that water component seems to represent a major local contamination pathway the findings of the study are of substantial importance for site remediation planning. As a primary result it could be stated that covering the dump would not result in any noteworthy short-term improvement of the spring water quality. First significant effects would only be visible after 2–3 decades at the earliest.
    Keywords: Geology
    ISSN: 0883-2927
    E-ISSN: 1872-9134
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  • 2
    Language: English
    In: Journal of Hydrology, 2011, Vol.402(3), pp.274-289
    Description: ► Using multiple isotopes to study groundwater flow in active rifts. ► Hydrochemical and isotopic evolution from escarpments to Rift floor. ► Mantle CO influences groundwater hydrochemistry. ► Apparent C ages are similar in Rift floor groundwater. ► Groundwater flow paths occur both longitudinal and transversal to rift axis. This study aims to investigate groundwater recharge and flow patterns in tectonically active rift systems, exemplified by a case study in the Main Ethiopian Rift. The chosen approach includes the investigation of hydrochemical parameters and environmental isotopes ( H, δ H, δ O, δ C-DIC, C-DIC, Sr/ Sr). Apparent groundwater ages were determined by radiocarbon dating after correction of C-DIC using a modified δ C-mixing model and further validation using geochemical modelling with NETPATH. Hydrochemical and isotopic data indicate an evolutionary trend existing from the escarpments towards the Rift floor. Groundwater evolves from tritium-containing and hence recently recharged Ca–HCO -type water on the escarpments to tritium-free Na–HCO groundwater dominating deep Rift floor aquifers. Correspondingly, rising pH and values coupled with increasingly enriched δ C signatures point to hydrochemical evolution of DIC and beginning dilution of the carbon isotope signature by other carbon sources, related to a diffuse influx of mantle CO into the groundwater system. Especially thermal groundwater sampled near the most recent fault zones in the Fantale/Beseka region displays clear influence of mantle CO and increased water–rock interaction, indicated by a shift in δ C and Sr/ Sr signatures. The calculation of apparent groundwater ages revealed an age increase of deep groundwater from the escarpments to the Rift floor, complying with hydrochemical evolution. Within the Rift, samples show a relatively uniform distribution of apparent C ages of ∼1800 to ∼2800 years, with the expected down-gradient aging trend lacking, contradicting the predominant intra-rift groundwater flow described in existing transect-based models of groundwater flow. By combining hydrochemical and new isotopic data with knowledge of the structural geology of the Rift, we improve the existing groundwater flow model and propose a new conceptual model by identifying flow paths both transversal and longitudinal to the main Rift axis, the latter being strongly controlled by faulted and tilted blocks on the escarpment steps. The connection between groundwater flow and fault direction make this model applicable to other active rift systems with similar structural settings.
    Keywords: Rift Tectonics ; Hydrochemistry ; Isotope Hydrology ; Groundwater Cycle and Dating ; 87sr/ 86sr ; 14c ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 3
    Language: English
    In: Hydrology Research, 11/2013, Vol.44(6), p.995
    Description: This study uses a high-frequency discharge and nitrate concentration dataset from the Weida catchment in Germany for the catchment scale hydrologic response analysis. Nitrate transport in the catchment is mostly conservative as indicated by the nitrate stable isotope ( delta 15N and delta 18O) analysis. Discharge-nitrate concentration data from the catchment show distinctive patterns, suggesting flushing and dilution response. A self-organizing feature map-based methodology was employed to identify such patterns or cluster in the datasets. Based on knowledge of the catchment conditions and prevailing understanding of discharge-nitrate concentration relationship, the clusters were characterized into five qualitative flow responses: (1) baseflow; (2) subsurface flow increase; (3) surface runoff increase; (4) surface runoff recession; and (5) subsurface flow decrease. Such qualitative flowpaths were used as soft data for a multi-objective calibration of a hydrological model (WaSiM-ETH). The calibration led to a reasonable simulation of overall discharge (Nash-Sutcliffe coefficient: 0.84) and qualitative flowpaths (76% agreement). A prerequisite for using such methodology is limited biogeochemical transformation of nitrate (such as denitrification).
    Keywords: Catchment Area ; Biogeochemistry ; Denitrification ; River Discharge ; Hydrology ; Nitrogen Isotopes ; Oxygen Isotope Ratio ; Runoff ; Response Analysis ; Oxygen Isotopes ; Hydrologic Analysis ; Nitrate Transport ; Numerical Simulations ; Catchment Basins ; Base Flow ; Surface Runoff ; Nitrogen Isotopes ; Subsurface Flow ; Isotopes ; Nitrates ; Biogeochemistry ; Denitrification ; Catchments ; Simulation ; Hydrology ; Hydrologic Models ; Assessments ; Surface Runoff ; Calibrations ; Nitrates ; Denitrification ; Catchment Areas ; Storm Seepage ; Hydrologic Data ; Hydrologic Models ; Assessments ; Surface Runoff ; Calibrations ; Nitrates ; Denitrification ; Catchment Areas ; Storm Seepage ; Hydrologic Data ; Germany ; Freshwater ; Identification of Pollutants ; Sewage ; General (556) ; General ; General ; Cluster Analysis ; Discharge-Nitrate Concentration Relationship ; Hydrological Flowpaths ; Model Calibration ; Nitrate Stable Isotopes ; Self-Organizing Feature Maps;
    ISSN: 0029-1277
    ISSN: 19989563
    E-ISSN: 22247955
    Source: CrossRef
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  • 4
    Language: English
    In: Geochimica et Cosmochimica Acta, 1998, Vol.62(18), pp.3041-3045
    Description: The {sup 4}He, {sup 40}Ar, and {sup 136}Xe content dissolved in the pore water of sedimentary rock samples was measured on samples from borehole cores near the repository for nuclear waste in Morsleben, Germany. Due to the very low permeabilities of the rock formations, conventional groundwater sampling was almost impossible. Hence, the authors developed a new sampling method for noble gases in the pore water of freshly drilled rock cores. This method provides vertical noble gas profiles in high depth resolution, even in impermeable rocks. By application of the new technique quantitative age information of groundwater and pore water have been derived. The authors find palaeowaters from the last glaciation depleted in {delta}D and {delta}{sup 18}O with a {sup 4}He age of about 55 kyr. The high saline pore solutions below are at least 6 Mio years old. This has been concluded from the profiles of radiogenic {sup 4}He and {sup 40}Ar close to diffusion in steady-state and from xenon isotopes produced by spontaneous fission of {sup 238}U in the rocks. A {sup 4}He flux of 2 {center_dot} 10{sup {minus}7} cc STP/cm{sup 2} yr is derived from the profile, which is due to local {sup 4}He production within the investigated sediments.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 5
    Language: English
    In: Environmental Earth Sciences, 2013, Vol.69(2), pp.359-372
    Description: First results of a multi-disciplinary hyporheic monitoring study are presented from the newly established Steinlach Test Site in Southern Germany. The site is located in a bend of the River Steinlach (mean discharge of 1.8 m³/s) underlain by an alluvial sandy gravel aquifer connected to the stream. The overall objective is a better understanding of hyporheic exchange processes at the site and their interrelations with microbial community dynamics and biochemical reactions at the stream–groundwater interface. The present paper focuses on the distribution of lateral hyporheic exchange fluxes and their associated travel times at the Steinlach Test Site. Water level dynamics in various piezometers correspond to the different domains of hydraulic conductivity in the shallow aquifer and confirms hyporheic exchange of infiltrated stream water across the test site. Hydrochemical compositions as well as increased damping of continuous time series of electrical conductivity (EC) and temperature at the respective piezometers confirmed the inferred distribution of hyporheic flowpaths. Mean travel times ranging from 0.5 days close to the stream to more than 8 days in the upstream part of the test site could be estimated from deconvolution of EC and δ 18 O–H 2 O data. The travel times agree well with the presumed flowpaths. Mg/Ca ratios as well as model fits to the EC and δ 18 O data indicate the presence of an additional water component in the western part of the test site which most likely consists of hillslope water or groundwater. Based on the mean travel times, the total lateral hyporheic exchange flux at the site was estimated to be of the order of 1–2 L/s.
    Keywords: Hyporheic zone ; Stream–groundwater interaction ; Travel time distribution ; Deconvolution ; Monitoring
    ISSN: 1866-6280
    E-ISSN: 1866-6299
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  • 6
    Language: English
    In: Water Research, 2007, Vol.41(15), pp.3259-3270
    Description: In this study, we used isotopic ( O, H, S-SO ) and chemical tracers (boron) to assess the sources and transport processes of the micropollutants carbamazepine, galaxolide, and bisphenol A in groundwater underlying the city of Halle (Saale), Germany. Their ubiquitous presence in urban groundwater results from a combination of local river water infiltration, sewer exfiltration, and urban stormwater recharge. Attenuation during transport with infiltrating river water increased from carbamazepine (0–60%) to galaxolide (60–80%) in accordance with their increasing sorption affinity and decreasing recalcitrance against biodegradation. Distinctly higher attenuation during transport was found for carbamazepine (85–100%) and galaxolide (95–100%) if micropollutants originated from sewer exfiltration. Most likely, this is related to higher contents of organic matter and higher transit times of the respective flow paths. Although attenuation undoubtedly also affects the transport of bisphenol A, quantification is limited due to additional contributions from the urban stormwater recharge. As a consequence, micropollutant loads in groundwater indicate that groundwater discharge may dominate the export of bisphenol A from urban areas.
    Keywords: Urban Groundwater ; Pharmaceuticals ; Personal Care Products ; Endocrine Disruptors ; Stable Isotopes ; Sewer Exfiltration ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 7
    In: Water Resources Research, December 2006, Vol.42(12), pp.n/a-n/a
    Description: Nitrate pollution from agricultural activities often persistently affects groundwater quality due to long residence times in the vadose and saturated zone. In this study we used a lumped parameter approach to estimate the residence time of groundwater and nitrate from the agriculturally used Jahna‐Aue drinking water catchment in Saxonia, Germany. Inverse modeling of measured concentrations of tritium and tritiogenic He revealed consistent mean residence times between 25 and 50 years for the young, nitrate‐rich groundwater component, and high contributions (〉75%) of an old, tracer‐free, and nitrate‐poor groundwater. The obtained age distributions are in accordance with the complex hydrogeological situation of the investigated catchment, suggesting that the shallow and therefore most vulnerable part of the aquifer is not connected to the production wells. High residence times are supported by low concentrations of CFCs and by radiogenic He as an independent age indicator. CFC concentrations only yield lower age limits due to identified problems with CFC contamination. Using the tracer‐calibrated age distributions, future nitrate concentrations in the production wells most probably will remain below the drinking water limit because of the high dilution with old, nitrate‐poor groundwater. Deterioration of the groundwater quality with respect to nitrate may occur if the groundwater pumping regime is changed so that the fraction of the younger, nitrate‐bearing water is increased.
    Keywords: Groundwater Age Distribution ; Lumped Parameter Model ; Nitrate Pollution ; Nitrate Stable Isotopes ; Tritium/He
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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  • 8
    Language: English
    In: Journal of Soils and Sediments, 2008, Vol.8(1), pp.23-33
    Description: Byline: Gerhard Strauch (1), Monika Moder (2), Rainer Wennrich (2), Karsten Osenbruck (3), Hans-Reinhard Glaser (1), Timo Schladitz (1), Claudia Muller (1), Kristin Schirmer (4), Frido Reinstorf (1), Mario Schirmer (1) Keywords: Carbamacepine; endocrine disrupters; gadolinium; indicators; stable isotopes; urban water; xenobiotics Abstract: Background, Aim and Scope Our study focuses on the indication of anthropogenic impacts on the urban surface and groundwater in large cities, demonstrated for the cities of Halle/Saale and Leipzig (Germany). For the study we selected indicator substances such as xenobiotics, trace elements, and stable isotopes which are connected to human activities in urban areas. The xenobiotics reported here are the pharmaceutical carbamacepine, the polycylic musk compounds galaxolide and tonalide, the life style product caffeine, and industrial chemicals such as bisphenol A and t-nonylphenol. The investigated xenobiotics pose largely unknown risks to human health and the aquatic ecosystem. Trace elements are represented by the rare earth element gadolinium (Gd), used as magnetic resonance imaging contrast substance. Nitrogen isotopes in dissolved nitrate characterize the origin of nitrogen compounds, mixing and reaction processes. Methodology River water was sampled along the flow path of the rivers Saale and Weisse Elster through the city of Halle/Saale, the rivers Luppe and Weisse Elster through the city of Leipzig. Separate samples were collected from the effluent of the local waste water treatment plants. Groundwater from Quaternary plain aquifers along the rivers and from different urban locations was collected at the same time. The indicators were analysed and assessed according to their sources, concentration and distribution patterns. Results and Discussion Based on the nitrogen isotopic signature, dissolved nitrate in river water of the Saale was referred mainly to two sources: the effluent of the water treatment plant and a mixture of diffusive inputs from rain water channels, sewage leakages and agriculture activities along the rivers. The Gd anomaly was recognized in surface water of both cities, particularly in the effluent of the water treatment plants, but clearly attenuated in groundwater. We measured concentrations of xenobiotics in river and sewer water between 10 and 60,000 ng L.sup.-1, and, in groundwater, one order of magnitude lower. Distinctions of xenobiotic patterns were found in river water before and after the effluent of treated waste water into the rivers. Degradation of endocrine disrupters and fragrances, but also persistence of carbamacepine were recognized as essential processes during waste water treatment. At the study site Halle/Saale, mass balances were set up for xenobiotics and water fluxes. Conclusions At both sites, we demonstrated that indicators such as xenobiotics, gadolinium, and nitrogen isotopes are suitable for assessing anthropogenic impacts on urban water. However, the behaviour of these indicators in surface and groundwater has to be considered according to the different geochemical environments. Author Affiliation: (1) Department of Hydrogeology, UFZ Helmholtz Centre for Environmental Research, Leipzig, Germany (2) Deptartment of Analytical Chemistry, UFZ Helmholtz Centre for Environmental Research, Leipzig, Germany (3) Department of Isotope Hydrology, UFZ Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, 06120, Halle, Germany (4) Department of Cell Toxicology, UFZ Helmholtz Centre for Environmental Research, Permoserstrasse 15, 04318, Leipzig, Germany Article History: Registration Date: 03/03/2007 Received Date: 06/11/2006 Accepted Date: 11/06/2007 Online Date: 12/06/2007
    Keywords: Carbamacepine ; endocrine disrupters ; gadolinium ; indicators ; stable isotopes ; urban water ; xenobiotics
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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