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Blanc T, Peel M, Brennwald MS, Kipfer R, Brunner P. Efficient injection of gas tracers into rivers: A tool to study Surface water-Groundwater interactions. WATER RESEARCH 2024; 254:121375. [PMID: 38442605 DOI: 10.1016/j.watres.2024.121375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/14/2024] [Accepted: 02/23/2024] [Indexed: 03/07/2024]
Abstract
Surface water (SW) - groundwater (GW) interactions exhibit complex spatial and temporal patterns often studied using tracers. However, most natural and artificial tracers have limitations in studying SW-GW interactions, particularly if no significant contrasts in concentrations between SW and GW exist or can be maintained for long durations. In such context, (noble) gases have emerged as promising alternatives to add to the available tracer methods, especially with the recent development of portable mass spectrometers, which enable continuous monitoring of dissolved gas concentrations directly in the field. However, long-duration gas injection into river water presents logistical challenges. To overcome this limitation, we present an efficient and robust diffusion-injection apparatus for labeling large amounts of river water. Our setup allows fine, real-time control of the gas injection rate, and is suitable for extended injection durations and different gas species. To illustrate the effectiveness of our approach, we present a case study where helium (He) is used as an artificial tracer to study river water infiltration into an alluvial aquifer. Our injection of He as a tracer increased the dissolved He concentration of the river water by one order of magnitude compared to air-saturated water concentration for 35 days. This experiment yields valuable information on travel times from the river to a pumping well and on the mixing ratios between freshly infiltrated river water and regional groundwater.
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Affiliation(s)
- Théo Blanc
- Centre for Hydrogeology and Geothermics of University of Neuchâtel (CHYN), Hydrochemistry and Contaminants and Hydrogeological processes, Rue Emile-Argand 11, Neuchâtel, 2000, Neuchâtel, Switzerland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Water Resources and Drinking Water, Ueberlandstrasse 133, Dübendorf, 8600, Zürich, Switzerland.
| | - Morgan Peel
- Centre for Hydrogeology and Geothermics of University of Neuchâtel (CHYN), Hydrochemistry and Contaminants and Hydrogeological processes, Rue Emile-Argand 11, Neuchâtel, 2000, Neuchâtel, Switzerland
| | - Matthias S Brennwald
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Water Resources and Drinking Water, Ueberlandstrasse 133, Dübendorf, 8600, Zürich, Switzerland
| | - Rolf Kipfer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Water Resources and Drinking Water, Ueberlandstrasse 133, Dübendorf, 8600, Zürich, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics and Institute of Geochemistry and Petrology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 16, Zürich, 8092, Zürich, Switzerland
| | - Philip Brunner
- Centre for Hydrogeology and Geothermics of University of Neuchâtel (CHYN), Hydrochemistry and Contaminants and Hydrogeological processes, Rue Emile-Argand 11, Neuchâtel, 2000, Neuchâtel, Switzerland
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2
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Wei R, Escher BI, Glaser C, König M, Schlichting R, Schmitt M, Störiko A, Viswanathan M, Zarfl C. Modeling the Dynamics of Mixture Toxicity and Effects of Organic Micropollutants in a Small River under Unsteady Flow Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14397-14408. [PMID: 36170232 DOI: 10.1021/acs.est.2c02824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The presence of anthropogenic organic micropollutants in rivers poses a long-term threat to surface water quality. To describe and quantify the in-stream fate of single micropollutants, the advection-dispersion-reaction (ADR) equation has been used previously. Understanding the dynamics of the mixture effects and cytotoxicity that are cumulatively caused by micropollutant mixtures along their flow path in rivers requires a new concept. Thus, we extended the ADR equation from single micropollutants to defined mixtures and then to the measured mixture effects of micropollutants extracted from the same river water samples. Effects (single and mixture) are expressed as effect units and toxic units, the inverse of effect concentrations and inhibitory concentrations, respectively, quantified using a panel of in vitro bioassays. We performed a Lagrangian sampling campaign under unsteady flow, collecting river water that was impacted by a wastewater treatment plant (WWTP) effluent. To reduce the computational time, the solution of the ADR equation was expressed by a convolution-based reactive transport approach, which was used to simulate the dynamics of the effects. The dissipation dynamics of the individual micropollutants were reproduced by the deterministic model following first-order kinetics. The dynamics of experimental mixture effects without known compositions were captured by the model ensemble obtained through Bayesian calibration. The highly fluctuating WWTP effluent discharge dominated the temporal patterns of the effect fluxes in the river. Minor inputs likely from surface runoff and pesticide diffusion might contribute to the general effect and cytotoxicity pattern but could not be confirmed by the model-based analysis of the available effect and chemical data.
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Affiliation(s)
- Ran Wei
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Beate I Escher
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Clarissa Glaser
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Maria König
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Markus Schmitt
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Anna Störiko
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Michelle Viswanathan
- Institute of Soil Science and Land Evaluation, University of Hohenheim, 70599 Stuttgart, Germany
| | - Christiane Zarfl
- Department of Geosciences, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
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3
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Höhne A, Müller BM, Schulz H, Dara R, Posselt M, Lewandowski J, McCallum JL. Fate of trace organic compounds in the hyporheic zone: Influence of microbial metabolism. WATER RESEARCH 2022; 224:119056. [PMID: 36126632 DOI: 10.1016/j.watres.2022.119056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
The hyporheic zone (HZ) is considered a hydrodynamically-driven bioreactor with significant pollutant removal capacities and can therefore not only improve wholestream water quality but also preserve human and ecosystem health. Microbial metabolism is hypothesized to play a key role in pollutant transformation in hyporheic sediments of natural streams. However, previous work investigating the influence of microbial metabolism on pollutant transformation has been predominantly laboratory studies. The key challenge for field studies is the appropriate determination of net microbial metabolism, i.e. information on the actual exposure times to specific microbial processes in the investigated system. The present study uses reactive fluorescent tracers to determine microbial metabolism and ultimately its influence on pollutant transformation, e.g. for trace organic compounds, in hyporheic sediments under natural conditions. In particular, the reactive fluorescent tracers resazurin and its main transformation product resorufin were used to determine the microbial metabolism of facultative or obligate aerobes. The influence of the derived microbial metabolism on the transformation of 20 trace organic compounds, such as pharmaceuticals, including 3 parent-daughter pairs, was examined. The present findings validate laboratory results on the microbially-mediated transformation of the anticonvulsant gabapentin to its main transformation product gabapentin lactam under natural conditions. All other TrOCs investigated did not show a clear link between TrOC reactivity to the microbial metabolism informed by the resazurin-resorufin-system. Overall, the present study not only demonstrates the use of the fluorescent tracer-system resazurin and resorufin for determining microbial metabolism of facultative or obligate aerobes but also generally highlights the potential of reactive fluorescent tracers to disentangle specific reactive properties and ultimately their influence on the fate of pollutants in natural HZs.
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Affiliation(s)
- Anja Höhne
- School of Earth Sciences, University of Western Australia, Perth, Western Australia, Australia; Department Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany.
| | - Birgit M Müller
- Department Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; Chair of Water Quality Engineering, Technical University Berlin, Strasse des 17. Juni, 10623 Berlin, Germany
| | - Hanna Schulz
- Department Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; Department Geography, Humboldt University Berlin, Rudower Chaussee 16, 12489 Berlin, Germany
| | - Rebwar Dara
- Department Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; Department of Earth Sciences and Petroleum, College of Science, Salahaddin University-Erbil, Erbil, Iraq
| | - Malte Posselt
- Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
| | - Jörg Lewandowski
- Department Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; Department Geography, Humboldt University Berlin, Rudower Chaussee 16, 12489 Berlin, Germany
| | - James L McCallum
- School of Earth Sciences, University of Western Australia, Perth, Western Australia, Australia
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Höhne A, Lewandowski J, Schaper JL, McCallum JL. Determining hyporheic removal rates of trace organic compounds using non-parametric conservative transport with multiple sorption models. WATER RESEARCH 2021; 206:117750. [PMID: 34678696 DOI: 10.1016/j.watres.2021.117750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
Assessing the transport and reactive processes of contaminants in freshwater streams is crucial in managing water resources sustainably. Particularly the hyporheic zone, the sediment-water interface where surface water and groundwater mix, may possess significant contaminant removal capacities due to its myriad physical, chemical, and microbiological processes. However, modelling approaches aiming at assessing the hyporheic zone's reactivity are either based on simple assumptions, such as, predefining the shape of the residence times distribution (RTD) function, or are computationally not feasible due to a too detailed system characterisation. In addition, parent-daughter reactions of contaminants are barely investigated. The present study introduces a numerical modelling framework for assessing hyporheic reactions of contaminant transformation reactions based on a non-parametric residence time approach combined with multiple sorption models and first-order removal reactions. The proposed framework uses natural electrical conductivity fluctuations to determine conservative transport properties and is demonstrated by interpreting time series of hyporheic point measurements of trace organic compounds, such as pharmaceuticals, and their transformation products using two commonly-used sorption models, namely the simple retardation and the first-order kinetic sorption model. The developed approach gives similar reaction rate coefficient estimates for all contaminants considered for both sorption models tested. The findings highlight that (i) the accurate shape of the RTD is most certainly important for reactive parameter determination and (ii) the daughter reaction rate coefficient may be underestimated if its parent transformation is ignored. The model provides reactive parameter estimates of contaminant transformation reactions with high parameter identifiability and informs which specific parent-daughter-pathway has occurred.
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Affiliation(s)
- Anja Höhne
- School of Earth Sciences, University of Western Australia, Crawley, WA, Australia; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Ecohydrology and Biogeochemistry, Müggelseedamm 310, Berlin 12587, Germany.
| | - Jörg Lewandowski
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Ecohydrology and Biogeochemistry, Müggelseedamm 310, Berlin 12587, Germany; Humboldt University Berlin, Geography Department, Rudower Chaussee 16, Berlin 12489, Germany
| | - Jonas L Schaper
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - James L McCallum
- School of Earth Sciences, University of Western Australia, Crawley, WA, Australia
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Multi Frequency Isotopes Survey to Improve Transit Time Estimation in a Situation of River-Aquifer Interaction. WATER 2021. [DOI: 10.3390/w13192695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Barthelasse alluvial aquifer is used to supply water to 180,000 inhabitants. The pumping field is located less than 200 m from the Rhône and is 100% fed by water from the Rhône, which makes it particularly vulnerable to any pollution from the Rhône. Between the Rhône and the pumping field is a Girardon unit, an arrangement that can be found regularly along the banks of the lower and middle reaches of the Rhône, and whose role is to stabilise the banks (alluvial deposits) and to facilitate river navigation. In order to know the transfer times between the Rhône and the pumping field, fortnightly monitoring was carried out over a hydrological year, as well as hourly monitoring during a flood in the winter of 2019. The Rhône shows a cyclicality in its isotopic signature with enrichment in heavy isotopes during the winter period, particularly during floods, and a depletion during the summer period. This variation is found well within the associated alluvial aquifer. The application of LPMs models showed that the average transfer time between the Rhône and the Girardon unit was 20 days and 50 days between the Rhône and the Barthelasse pumping. This study highlighted the importance of using several sampling frequencies to consider the diversity of hydrological situations. For the Rhône, event-based monitoring (flooding) proved to be relevant to account for isotopic variability throughout the year. This work also highlighted the impact of the disruption of hydraulic exchanges between the river and the water table caused by the presence of the Girardon unit in terms of the propagation of contaminants.
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Huang H, Chen Z, Wang T, Zhang L, Liu T, Zhou G. Pattern and degree of groundwater recharge from river leakage in a karst canyon area under intensive mine dewatering. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 774:144921. [PMID: 33607431 DOI: 10.1016/j.scitotenv.2020.144921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/26/2020] [Accepted: 12/26/2020] [Indexed: 06/12/2023]
Abstract
Most lead-zinc (Pb-Zn) deposits in southwestern China located in karst canyon areas are faced with difficulties to identify the connection between surface water and groundwater. Hydrological dynamics monitoring, tracer injection test, and riverbed dredging test were applied to discuss the contribution of river leakage to the mining area under intensive mine dewatering. The water level of surface water (~887 m asl), pore groundwater (~886 m asl), and karst groundwater (882-886 m asl) decreased in turn in the Maoping Pb-Zn deposit, which suggested the Luoze River as a losing stream. The groundwater temperature dynamics did not respond to rainfall events. Karst groundwater presented a peak delay and amplitude decay when compared with the overlying pore groundwater. Lower electrical conductivity (40-70 μS/cm) was generated due to cation exchange process during vertical infiltration. It could be concluded firstly that pore groundwater ran horizontally and rapidly according to the synchronous response within an hour of groundwater level in the upstream and downstream boreholes to riverbed dredging test. Secondly, pore groundwater could supply the underlying karst groundwater vertically and slowly, which caused an increase of groundwater level lasting for one week during the dredging test until the recovery of decreasing trend in the dry season. Finally, the injected tracer cost more than seven months to eliminate, indicating a slow velocity around 0.01 m/d in the karst aquifer. Overall, it could be proved that surface water could be an indirect and limited water-filling source for the karst groundwater in the mining area under the control of the riverbed sediment structure. Despite the significant groundwater level drawdown caused by intensive mine dewatering, the mining area would not be threatened by the possible river leakage, and the river ecological system would not be reshaped greatly due to the weak interaction process between surface water and groundwater.
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Affiliation(s)
- He Huang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Zhihua Chen
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
| | - Tao Wang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Liang Zhang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Tianwen Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Gaoming Zhou
- Yiliang Chihong Mining Co., Ltd., Zhaotong 657600, China
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7
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Smoothing of Slug Tests for Laboratory Scale Aquifer Assessment—A Comparison Among Different Porous Media. WATER 2019. [DOI: 10.3390/w11081569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A filtering analysis of hydraulic head data deduced from slug tests injected in a confined aquifer with different porous media is proposed. Experimental laboratory tests were conducted in a large-scale physical model developed at the University of Calabria. The hydraulic head data were deduced from the records of a pressure sensor arranged in the injection well and subjected to a processing operation to filter the high-frequency noise. The involved smoothing techniques are the Fourier transform and two types of wavelet transform. The performances of the filtered hydraulic heads were examined for different slug volumes and four model layouts in terms of optimal fitting of the Cooper’s analytical solution. The hydraulic head variations in the confined aquifer were analyzed using wavelet transform in order to discover their energy contributions and frequency oscillations. Finally, the raw and smoothed hydraulic heads were adopted to calculate the hydraulic conductivity of the aquifer.
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8
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Li C, Li B, Bi E. Characteristics of hydrochemistry and nitrogen behavior under long-term managed aquifer recharge with reclaimed water: A case study in north China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:1030-1037. [PMID: 31018445 DOI: 10.1016/j.scitotenv.2019.02.375] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/04/2019] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
Due to the quality difference between reclaimed water and natural groundwater, managed aquifer recharge (MAR) with reclaimed water may pose environmental risks. A river infiltration of reclaimed water for groundwater recharge in north China has been in operation for over 10 years. To investigate the actual impact on native groundwater under long-term MAR, 10-year monitoring data of recharge water and groundwater were analyzed. Due to the effect of recharge, the hydrochemical type of groundwater rapidly changed from Ca-Mg-HCO3 into Na-HCO3 which was the type of recharge water. Cl- was used as a conservative tracer in a physical mixing model, and the mixing was concluded to be dominant in the groundwater hydrochemical change under long-term MAR. The hydraulic travel time to the 30 m depth was determined to be about 6.5 months by obtaining the best-fit linear cross correlation between the concentrations of Cl- in recharge water and those in groundwater. In application of this method, the monitoring wells should be located downstream and as close as possible to the recharge site (e.g., <50 m). Based on the travel time, behaviors of total nitrogen (TN), NO3-N, NO2-N, and NH4-N were determined by attenuation factor (Af). As the main nitrogen compound, NO3-N was well attenuated under high hydraulic load, resulting in the Af > 1, with an attenuation rate of 99.6%. The Af < 1 of NH4-N indicated the additional input of NH4-N in groundwater. Fluctuations of NH4-N in recharge water exceeded 4 mg/L changes sorption equilibrium, resulting in the sorption/desorption of NH4-N in soil-groundwater system. The concentration of NH4-N in groundwater increased in the later period of monitoring. The overall attenuation rate of NH4-N was 26.3%. These findings contributed to improving the environmental benefits of this MAR site and provided guidance for other similar projects.
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Affiliation(s)
- Congzhou Li
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, Beijing Key Laboratory of Water Resources and Environmental Engineering, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Binghua Li
- Department of Water Resources, Beijing Water Science and Technology Institute, Beijing 100048, PR China
| | - Erping Bi
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, Beijing Key Laboratory of Water Resources and Environmental Engineering, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
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Guillet G, Knapp JLA, Merel S, Cirpka OA, Grathwohl P, Zwiener C, Schwientek M. Fate of wastewater contaminants in rivers: Using conservative-tracer based transfer functions to assess reactive transport. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 656:1250-1260. [PMID: 30625655 DOI: 10.1016/j.scitotenv.2018.11.379] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/24/2018] [Accepted: 11/25/2018] [Indexed: 06/09/2023]
Abstract
Interpreting the fate of wastewater contaminants in streams is difficult because their inputs vary in time and several processes synchronously affect reactive transport. We present a method to disentangle the various influences by performing a conservative-tracer test while sampling a stream section at various locations for chemical analysis of micropollutants. By comparing the outflow concentrations of contaminants with the tracer signal convoluted by the inflow time series, we estimated reaction rate coefficients and calculated the contaminant removal along a river section. The method was tested at River Steinlach, Germany, where 38 contaminants were monitored. Comparing day-time and night-time experiments allowed distinguishing photo-dependent degradation from other elimination processes. While photo-dependent degradation showed to be highly efficient for the removal of metroprolol, bisoprolol, and venlafaxine, its impact on contaminant removal was on a similar scale to the photo-independent processes when averaged over 24 h. For a selection of compounds analyzed in the present study, bio- and photodegradation were higher than in previous field studies. In the Steinlach study, we observed extraordinarily effective removal processes that may be due to the higher proportion of treated wastewater, temperature, DOC and nitrate concentrations, but also a higher surface to volume ratio from low flow conditions that favorizes photodegradation through the shallow water column and a larger transient storage than observed in comparable studies.
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Affiliation(s)
- Gaëlle Guillet
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Julia L A Knapp
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Sylvain Merel
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Olaf A Cirpka
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Peter Grathwohl
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Christian Zwiener
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Marc Schwientek
- Center for Applied Geoscience, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany.
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10
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Knapp JLA, Osenbrück K, Brennwald MS, Cirpka OA. In-situ mass spectrometry improves the estimation of stream reaeration from gas-tracer tests. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 655:1062-1070. [PMID: 30577100 DOI: 10.1016/j.scitotenv.2018.11.300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
The estimation of gas-exchange rates between streams and the atmosphere is of great importance for the fate of volatile compounds in rivers. For dissolved oxygen, this exchange process is called reaeration, and its accurate and precise estimation is essential for the quantification of metabolic rates. A common method for the determination of gas-exchange rates is through artificial gas-tracer tests with a proxy gas. We present the implementation of a portable gas-equilibrium membrane inlet mass spectrometer (GE-MIMS) to record concentrations of krypton and propane injected as tracer compound in the context of a gas-tracer test. The field-compatible GE-MIMS uses signals of atmospheric measurements for concentration standardization, and allows recording the dissolved-gas concentrations at a high temporal resolution, leading to overall low measurement uncertainty. Furthermore, the in-situ approach avoids loss of gas during the steps of sampling, transport, storage, and analysis required for ex-situ gas measurements. We compare obtained gas-exchange rate coefficients, reaeration and derived metabolic rates from the in-situ measurements to results obtained from head-space sampling of propane followed by laboratory analysis, and find much lower uncertainties with the in-situ method.
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Affiliation(s)
- Julia L A Knapp
- Center for Applied Geoscience, University of Tübingen, Germany; Department of Environmental Systems Science, ETH, Zürich, Switzerland.
| | | | - Matthias S Brennwald
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Olaf A Cirpka
- Center for Applied Geoscience, University of Tübingen, Germany
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11
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Jaeger A, Posselt M, Betterle A, Schaper J, Mechelke J, Coll C, Lewandowski J. Spatial and Temporal Variability in Attenuation of Polar Organic Micropollutants in an Urban Lowland Stream. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2383-2395. [PMID: 30754970 DOI: 10.1021/acs.est.8b05488] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Contamination of rivers by trace organic compounds (TrOCs) poses a risk for aquatic ecosystems and drinking water quality. Spatially- and temporally varying environmental conditions are expected to play a major role in controlling in-stream attenuation of TrOCs. This variability is rarely captured by in situ studies of TrOC attenuation. Instead, snap-shots or time-weighted average conditions and corresponding attenuation rates are reported. The present work sought to investigate this variability and factors controlling it by analysis of 24 TrOCs over a 4.7 km reach of the River Erpe (Berlin, Germany). The factors investigated included sunlight and water temperature as well as the presence of macrophytes. Attenuation rate constants in 48 consecutive hourly water parcels were tracked along two contiguous river sections of different characteristics. Section 1 was less shaded and more densely covered with submerged macrophytes compared to section 2. The sampling campaign was repeated after macrophyte removal from section 1. The findings show, that section 1 generally provided more favorable conditions for both photo- and biodegradation. Macrophyte removal enhanced photolysis of some compounds (e.g., hydrochlorothiazide and diclofenac) while reducing the biodegradation of metoprolol. The transformation products metoprolol acid and valsartan acid were formed along the reach under all conditions.
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Affiliation(s)
- Anna Jaeger
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , Department Ecohydrology , Berlin , Germany
- Humboldt University Berlin , Geography Department , Berlin , Germany
| | - Malte Posselt
- Stockholm University , Department of Environmental Science and Analytical Chemistry , Stockholm , Sweden
| | - Andrea Betterle
- Eawag , Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water , Dübendorf , Switzerland
- University of Neuchâtel , Centre of Hydrogeology and Geothermics , Neuchâtel , Switzerland
- University of Padova , Department of ICEA and International Center for Hydrology , Padua , Italy
| | - Jonas Schaper
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , Department Ecohydrology , Berlin , Germany
- Technical University of Berlin , Chair of Water Quality Engineering , Berlin , Germany
| | - Jonas Mechelke
- Eawag , Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water , Dübendorf , Switzerland
- ETH Zürich , Institute of Biogeochemistry and Pollutant Dynamics , Zürich , Switzerland
| | - Claudia Coll
- Stockholm University , Department of Environmental Science and Analytical Chemistry , Stockholm , Sweden
| | - Joerg Lewandowski
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , Department Ecohydrology , Berlin , Germany
- Humboldt University Berlin , Geography Department , Berlin , Germany
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Variations of Groundwater Quality in the Multi-Layered Aquifer System near the Luanhe River, China. SUSTAINABILITY 2019. [DOI: 10.3390/su11040994] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitrate pollution is an environmental problem in the North China Plain. This paper investigates the variation of groundwater levels and nitrate concentrations in an alluvial fan of the Luanhe river, northeast of the North China Plain. Three transects perpendicular to the riverbank were selected to investigate the exchange between river water and groundwater, and nitrate concentration with its isotopic composition (δ15N-NO3 and δ18O-NO3). The results showed that the groundwater level decreased slightly during the dry season, and increased regularly during the period of river stage rise. The groundwater is recharged by the river over 10 months each year. The nitrate concentration in the groundwater and river water varied with seasons. The nitrate concentration of groundwater in wells near the river is affected by the river water, which varied in basically the same way as the river. The nitrate concentrations in the zone of groundwater level depression cone were lower than those in the wells near the river, due to the long-term pumping of groundwater. However, the nitrate concentrations of river water have little influence on those of groundwater in wells far from the river. The values of δ15N-NO3 and the relationship between the two isotopes (δ15N-NO3 and δ18O-NO3) suggested that NO3-N was mainly attributable to sewage, livestock manure and natural soil organic matter. Due to the existence of a groundwater depression cone near the river, nitrate contamination can be transported into the aquifer with the flow. The average time lag of nitrate migration from the river to the zone of groundwater level depression cone is different in different sections, which shows an increasing trend from the upstream to downstream along the river, with an average of two to six months. It is mainly related to the stratigraphic structure, the migration distance, the hydraulic conductivities of the aquifer and the riverbed sediment. Compared with the case of considering the silt layer, the time lag of nitrate migration is greater than that of the case of ignoring the silt layer. The results will provide useful information for detecting nitrate concentrations in the alluvial fan area of the Luanhe river, northeast of the NCP (North China Plain).
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Gilfedder BS, Cartwright I, Hofmann H, Frei S. Explicit Modeling of Radon-222 in HydroGeoSphere During Steady State and Dynamic Transient Storage. GROUND WATER 2019; 57:36-47. [PMID: 30450548 DOI: 10.1111/gwat.12847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 11/12/2018] [Accepted: 11/14/2018] [Indexed: 06/09/2023]
Abstract
Transient storage zones (TSZs) are located at the interface of rivers and their abutting aquifers and play an important role in hydrological and biogeochemical functioning of rivers. The natural radioactive tracer 222 Rn is a particularly well-suited tracer for studying TSZ water exchange and age. Although 222 Rn measurement techniques have developed rapidly, there has been less progress in modeling 222 Rn activities. Here, we combine field measurements with the numerical model HydroGeoSphere (HGS) to simulate 222 Rn emanation, decay and transport during steady state (riffle-pool sequence) and transient (bank storage) conditions. Comparing the HGS mean water ages with the conventional 222 Rn apparent ages during steady state showed a systemic underestimation of apparent age with increasing dispersion and especially where large concentration gradients exist within the subsurface. A large underestimation of apparent water age was also observed at the advective front during bank storage where regional high 222 Rn groundwater mixes with newly infiltrated surface water. The explicit modeling of radiogenic tracers such as 222 Rn offers a physical interpretation of this data as well as a useful way to test simplified apparent age models.
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Affiliation(s)
- B S Gilfedder
- Limnological Research Station University of Bayreuth, Department of Hydrology, Bayreuth Center of Ecology and Environmental Research (Bayceer) Universitätsstrasse 30, 95447, Bayreuth, Germany
| | - I Cartwright
- School of Geosciences Building 28, Monash University, Clayton, Victoria, Australia 3800
| | - H Hofmann
- School of Earth Sciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - S Frei
- Department of Hydrology, Bayreuth Center of Ecology and Environmental Research (Bayceer) University of Bayreuth, Universitätsstrasse 30, 95447, Bayreuth, Germany
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14
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Hollender J, Rothardt J, Radny D, Loos M, Epting J, Huggenberger P, Borer P, Singer H. Comprehensive micropollutant screening using LC-HRMS/MS at three riverbank filtration sites to assess natural attenuation and potential implications for human health. WATER RESEARCH X 2018; 1:100007. [PMID: 31194029 PMCID: PMC6549901 DOI: 10.1016/j.wroa.2018.100007] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/06/2018] [Accepted: 10/25/2018] [Indexed: 05/22/2023]
Abstract
Riverbank filtration (RBF) is used worldwide to produce high quality drinking water. With river water often contaminated by micropollutants (MPs) from various sources, this study addresses the occurrence and fate of such MPs at three different RBF sites with oxic alluvial sediments and short travel times to the drinking water well down to hours. A broad range of MPs with various physico-chemical properties were analysed with detection limits in the low ng L-1 range using solid phase extraction followed by liquid chromatography coupled to tandem high resolution mass spectrometry. Out of the 526 MPs targeted, a total of 123 different MPs were detected above the limit of quantification at the three different RBF sites. Of the 75-96 MPs detected in each river, 43-59% were attenuated during RBF. The remaining total concentrations of the MPs in the raw drinking water accounted to 0.6-1.6 μgL-1 with only a few compounds exceeding 0.1 μgL-1, an often used threshold value. The attenuation was most pronounced in the first meters of infiltration with a full elimination of 17 compounds at all three sites. However, a mixing with groundwater related to regional groundwater flow complicated the characterisation of natural attenuation potentials along the transects. Additional non-target screening at one site revealed similar trends for further non-target components. Overall, a risk assessment of the target and estimated non-target compound concentrations finally indicated during the sampling period no health risk of the drinking water according to current guidelines. Our results demonstrate that monitoring of contamination sources within a catchment and the affected water quality remains important in such vulnerable systems with partially short residence times.
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Affiliation(s)
- Juliane Hollender
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, Universitätstrasse 16, ETH Zürich, 8092 Zurich, Switzerland
- Corresponding author. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland.
| | - Judith Rothardt
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Dirk Radny
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Martin Loos
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Jannis Epting
- Applied and Environmental Geology, University of Basel, Bernoullistrasse 32, 4056 Basel, Switzerland
| | - Peter Huggenberger
- Applied and Environmental Geology, University of Basel, Bernoullistrasse 32, 4056 Basel, Switzerland
| | - Paul Borer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Heinz Singer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
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15
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Mikutis G, Deuber CA, Schmid L, Kittilä A, Lobsiger N, Puddu M, Asgeirsson DO, Grass RN, Saar MO, Stark WJ. Silica-Encapsulated DNA-Based Tracers for Aquifer Characterization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12142-12152. [PMID: 30277386 DOI: 10.1021/acs.est.8b03285] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Environmental tracing is a direct way to characterize aquifers, evaluate the solute transfer parameter in underground reservoirs, and track contamination. By performing multitracer tests, and translating the tracer breakthrough times into tomographic maps, key parameters such as a reservoir's effective porosity and permeability field may be obtained. DNA, with its modular design, allows the generation of a virtually unlimited number of distinguishable tracers. To overcome the insufficient DNA stability due to microbial activity, heat, and chemical stress, we present a method to encapsulated DNA into silica with control over the particle size. The reliability of DNA quantification is improved by the sample preservation with NaN3 and particle redispersion strategies. In both sand column and unconsolidated aquifer experiments, DNA-based particle tracers exhibited slightly earlier and sharper breakthrough than the traditional solute tracer uranine. The reason behind this observation is the size exclusion effect, whereby larger tracer particles are excluded from small pores, and are therefore transported with higher average velocity, which is pore size-dependent. Identical surface properties, and thus flow behavior, makes the new material an attractive tracer to characterize sandy groundwater reservoirs or to track multiple sources of contaminants with high spatial resolution.
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Affiliation(s)
- Gediminas Mikutis
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
| | - Claudia A Deuber
- Geothermal Energy and Geofluids Group, Department of Earth Sciences , ETH Zurich , Sonneggstrasse 5 , 8092 Zurich , Switzerland
| | - Lucius Schmid
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
| | - Anniina Kittilä
- Geothermal Energy and Geofluids Group, Department of Earth Sciences , ETH Zurich , Sonneggstrasse 5 , 8092 Zurich , Switzerland
| | - Nadine Lobsiger
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
| | - Michela Puddu
- Haelixa AG, Otto-Stern-Weg 7 , 8093 Zurich , Switzerland
| | - Daphne O Asgeirsson
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
| | - Robert N Grass
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
| | - Martin O Saar
- Geothermal Energy and Geofluids Group, Department of Earth Sciences , ETH Zurich , Sonneggstrasse 5 , 8092 Zurich , Switzerland
| | - Wendelin J Stark
- Functional Materials Laboratory, Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 1 , 8093 Zurich , Switzerland
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16
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Bachand PAM, Bachand SM, Stern D, Deverel S, Horwath WR. Rice Drain Management to Reduce Seepage Exports in the Sacramento-San Joaquin Delta, California. JOURNAL OF ENVIRONMENTAL QUALITY 2018; 47:1186-1195. [PMID: 30272765 DOI: 10.2134/jeq2018.03.0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Many deltas worldwide face subsidence issues due to increased anthropogenic activity. The Sacramento-San Joaquin delta similarly faces ongoing subsidence, more than 8 m in some areas, that increases levee failure risks and threatens the security of this water source for 25 million California residents and 1.2 million ha of agriculture. Rice ( L.) fields are an integral part of a proposed new strategy for managing subsidence because they have been shown to stop subsidence and provide an alternative crop for growers. Two important considerations for implementing rice fields are additional water requirement and the effect on water quality from mobilized dissolved organic carbon (DOC) and disinfection byproduct precursors. To understand constituent transport and potential management opportunities for rice farming, a plug flow reactor mass balance model was used to quantify surface and subsurface hydrologic pathways. Management of adjacent drainage ditch water levels under low and high scenarios were tested as a strategy to reduce seepage and water quality loads. Under high drains, groundwater met 10% of evapotranspiration (ET). Low drains resulted in a 100% increase in ET demand, which was met by surface water applied for irrigation. High drains reduced subsurface seepage by 95%. Subsurface DOC, trihalomethane, and total dissolved nitrogen loads were reduced 10-fold in high drains compared with low drains. Flow rate accounted for 74 to 90% of load variance and was the primary determinant of constituent loads. Thoughtful implementation of rice cultivation, with high water levels in adjacent drains, can be leveraged to reduce irrigation water demand and constituent load outputs.
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17
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Knapp JLA, Osenbrück K, Cirpka OA. Impact of non-idealities in gas-tracer tests on the estimation of reaeration, respiration, and photosynthesis rates in streams. WATER RESEARCH 2015; 83:205-216. [PMID: 26150069 DOI: 10.1016/j.watres.2015.06.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/13/2015] [Accepted: 06/19/2015] [Indexed: 06/04/2023]
Abstract
Estimating respiration and photosynthesis rates in streams usually requires good knowledge of reaeration at the given locations. For this purpose, gas-tracer tests can be conducted, and reaeration rate coefficients are determined from the decrease in gas concentration along the river stretch. The typical procedure for analysis of such tests is based on simplifying assumptions, as it neglects dispersion altogether and does not consider possible fluctuations and trends in the input signal. We mathematically derive the influence of these non-idealities on estimated reaeration rates and how they are propagated onto the evaluation of aerobic respiration and photosynthesis rates from oxygen monitoring. We apply the approach to field data obtained from a gas-tracer test using propane in a second-order stream in Southwest Germany. We calculate the reaeration rate coefficients accounting for dispersion as well as trends and uncertainty in the input signals and compare them to the standard approach. We show that neglecting dispersion significantly underestimates reaeration, and results between sections cannot be compared if trends in the input signal of the gas tracer are disregarded. Using time series of dissolved oxygen and the various estimates of reaeration, we infer respiration and photosynthesis rates for the same stream section, demonstrating that the bias and uncertainty of reaeration using the different approaches significantly affects the calculation of metabolic rates.
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Affiliation(s)
- Julia L A Knapp
- University of Tübingen, Center for Applied Geoscience, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Karsten Osenbrück
- Water and Earth System Science (WESS) Competence Cluster, c/o University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
| | - Olaf A Cirpka
- University of Tübingen, Center for Applied Geoscience, Hölderlinstr. 12, 72074 Tübingen, Germany.
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18
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Mächler L, Brennwald MS, Kipfer R. Argon concentration time-series as a tool to study gas dynamics in the hyporheic zone. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7060-7066. [PMID: 23611693 DOI: 10.1021/es305309b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The oxygen dynamics in the hyporheic zone of a peri-alpine river (Thur, Switzerland), were studied through recording and analyzing the concentration time-series of dissolved argon, oxygen, carbon dioxide, and temperature during low flow conditions, for a period of one week. The argon concentration time-series was used to investigate the physical gas dynamics in the hyporheic zone. Differences in the transport behavior of heat and gas were determined by comparing the diel temperature evolution of groundwater to the measured concentration of dissolved argon. These differences were most likely caused by vertical heat transport which influenced the local groundwater temperature. The argon concentration time-series were also used to estimate travel times by cross correlating argon concentrations in the groundwater with argon concentrations in the river. The information gained from quantifying the physical gas transport was used to estimate the oxygen turnover in groundwater after water recharge. The resulting oxygen turnover showed strong diel variations, which correlated with the water temperature during groundwater recharge. Hence, the variation in the consumption rate was most likely caused by the temperature dependence of microbial activity.
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Affiliation(s)
- Lars Mächler
- Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
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19
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Dürrenmatt DJ, Del Giudice D, Rieckermann J. Dynamic time warping improves sewer flow monitoring. WATER RESEARCH 2013; 47:3803-3816. [PMID: 23664432 DOI: 10.1016/j.watres.2013.03.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 03/18/2013] [Accepted: 03/21/2013] [Indexed: 06/02/2023]
Abstract
Successful management and control of wastewater and storm water systems requires accurate sewer flow measurements. Unfortunately, the harsh sewer environment and insufficient flow meter calibration often lead to inaccurate and biased data. In this paper, we improve sewer flow monitoring by creating redundant information on sewer velocity from natural wastewater tracers. Continuous water quality measurements upstream and downstream of a sewer section are used to estimate the travel time based on i) cross-correlation (XCORR) and ii) dynamic time warping (DTW). DTW is a modern data mining technique that warps two measured time series non-linearly in the time domain so that the dissimilarity between the two is minimized. It has not been applied in this context before. From numerical experiments we can show that DTW outperforms XCORR, because it provides more accurate velocity estimates, with an error of about 7% under typical conditions, at a higher temporal resolution. In addition, we can show that pre-processing of the data is important and that tracer reaction in the sewer reach is critical. As dispersion is generally small, the distance between the sensors is less influential if it is known precisely. Considering these findings, we tested the methods on a real-world sewer to check the performance of two different sewer flow meters based on temperature measurements. Here, we were able to detect that one of two flow meters was not performing satisfactorily under a variety of flow conditions. Although theoretical analyses show that XCORR and DTW velocity estimates contain systematic errors due to dispersion and reaction processes, these are usually small and do not limit the applicability of the approach.
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Affiliation(s)
- D J Dürrenmatt
- Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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20
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Mächler L, Brennwald MS, Kipfer R. Membrane inlet mass spectrometer for the quasi-continuous on-site analysis of dissolved gases in groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:8288-8296. [PMID: 22775356 DOI: 10.1021/es3004409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We developed a stand-alone system based on a membrane inlet mass spectrometer (MIMS) for measuring dissolved gas concentrations in groundwater under field conditions. The system permits the concentrations of dissolved gases (He, Ar, Kr, N(2), and O(2)) in groundwater to be determined quasi-continuously (every 12 min) with a precision of better than 4% for He and Kr, and with a precision of 1% for Ar, N(2), and O(2) in air-saturated water. The detection limits are below 3 × 10(-9) cm(3)(STP)(g) for the noble gases and below 400 × 10(-9)cm(3)(STP)(g) for N(2) and O(2). The results of a first deployment of the system in the field indicate that changes in the concentration of Ar that result from diel fluctuations of 3°C in the river water temperature were still able to be resolved in groundwater, although the corresponding temperature signal almost vanished.
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Affiliation(s)
- Lars Mächler
- Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
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Molina-Giraldo N, Bayer P, Blum P, Cirpka OA. Propagation of seasonal temperature signals into an aquifer upon bank infiltration. GROUND WATER 2011; 49:491-502. [PMID: 21039448 DOI: 10.1111/j.1745-6584.2010.00745.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Infiltrating river water carries the temperature signal of the river into the adjacent aquifer. While the diurnal temperature fluctuations are strongly dampened, the seasonal fluctuations are much less attenuated and can be followed into the aquifer over longer distances. In one-dimensional model with uniform properties, this signal is propagated with a retarded velocity, and its amplitude decreases exponentially with distance. Therefore, time shifts in seasonal temperature signals between rivers and groundwater observation points may be used to estimate infiltration rates and near-river groundwater velocities. As demonstrated in this study, however, the interpretation is nonunique under realistic conditions. We analyze a synthetic test case of a two-dimensional cross section perpendicular to a losing stream, accounting for multi-dimensional flow due to a partially penetrating channel, convective-conductive heat transport within the aquifer, and heat exchange with the underlying aquitard and the land surface. We compare different conceptual simplifications of the domain in order to elaborate on the importance of different system elements. We find that temperature propagation within the shallow aquifer can be highly influenced by conduction through the unsaturated zone and into the underlying aquitard. In contrast, regional groundwater recharge has no major effect on the simulated results. In our setup, multi-dimensionality of the flow field is important only close to the river. We conclude that over-simplistic analytical models can introduce substantial errors if vertical heat exchange at the aquifer boundaries is not accounted for. This has to be considered when using seasonal temperature fluctuations as a natural tracer for bank infiltration.
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Affiliation(s)
- Nelson Molina-Giraldo
- Center for Applied Geoscience (ZAG), University of Tübingen, Sigwartstraße 10, 72076 Tübingen, Germany.
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Mastrocicco M, Prommer H, Pasti L, Palpacelli S, Colombani N. Evaluation of saline tracer performance during electrical conductivity groundwater monitoring. JOURNAL OF CONTAMINANT HYDROLOGY 2011; 123:157-166. [PMID: 21324545 DOI: 10.1016/j.jconhyd.2011.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 10/22/2010] [Accepted: 01/13/2011] [Indexed: 05/30/2023]
Abstract
Saline solutions are the most commonly used hydrological tracers, because they can be easily and economically monitored by in situ instrumentation such as electrical conductivity (EC) loggers in wells or by geoelectrical measurements. Unfortunately, these low-cost techniques only provide information on the total concentration of ions in solution, i.e., they cannot resolve the ionic composition of the aqueous solution. This limitation can introduce a bias in the estimation of aquifer parameters where sorption phenomena between saline tracers and sediments become relevant. In general, only selected anions such as Cl(-) and Br(-) are recognised to be transported unretarded and they are referred to as conservative tracers or mobile anions. However, cations within the saline tracer may interact with the soil matrix through a range of processes such as ion exchange, surface complexation and via physical mass-transfer phenomena. Heterogeneous reactions with minerals or mineral surfaces may not be negligible where aquifers are composed of fine alluvial sediments. The focus of the present study was to examine and to quantify the bias between the aquifer parameters estimated during model-based interpretation of experimental data of EC measurements of saline tracer relative to the aquifer parameters found by specific measurements (i.e. via ionic chromatography, IC) of truly conservative species. To accomplish this, column displacement experiments with alluvial aquifer materials collected from the Po lowlands (Italy) were performed under water saturated conditions. The behaviour of six selected, commonly used saline tracers (i.e., LiCl, KCl, and NaCl; LiBr, KBr, and NaBr) was studied and the data analysed by inverse modelling. The results demonstrate that the use of EC as a tracer can lead to an erroneous parameterisation of the investigated porous media, if the reactions between solute and matrix are neglected. In general, errors were significant except for KCl and KBr, which is due to the weak interaction between dissolved K(+) and the sediment material. The study shows that laboratory scale pre-investigations can help with tracer selection and to optimise the concentration range targeted for in situ multilevel monitoring by unspecific geoelectrical instrumentation.
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Newman BD, Osenbrück K, Aeschbach-Hertig W, Solomon DK, Cook P, Rózański K, Kipfer R. Dating of 'young' groundwaters using environmental tracers: advantages, applications, and research needs. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2010; 46:259-78. [PMID: 20845177 DOI: 10.1080/10256016.2010.514339] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Many problems related to groundwater supply and quality, as well as groundwater-dependent ecosystems require some understanding of the timescales of flow and transport. For example, increased concern about the vulnerabilities of 'young' groundwaters (less than ~1000 years) to overexploitation, contamination, and land use/climate change effects are driving the need to understand flow and transport processes that occur over decadal, annual, or shorter timescales. Over the last few decades, a powerful suite of environmental tracers has emerged that can be used to interrogate a wide variety of young groundwater systems and provide information about groundwater ages/residence times appropriate to the timescales over which these systems respond. These tracer methods have distinct advantages over traditional approaches providing information about groundwater systems that would likely not be obtainable otherwise. The objective of this paper is to discuss how environmental tracers are used to characterise young groundwater systems so that more researchers, water managers, and policy-makers are aware of the value of environmental tracer approaches and can apply them in appropriate ways. We also discuss areas where additional research is required to improve ease of use and extend quantitative interpretations of tracer results.
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Affiliation(s)
- Brent D Newman
- Water Resources Programme, International Atomic Energy Agency, Vienna International Centre, Vienna, Austria.
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