Journal articles on the topic 'Water source mixing'
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Zdon, Andy, Keith Rainville, Nicholas Buckmaster, Steve Parmenter, and Adam Love. "Identification of Source Water Mixing in the Fish Slough Spring Complex, Mono County, California, USA." Hydrology 6, no. 1 (March 20, 2019): 26. http://dx.doi.org/10.3390/hydrology6010026.
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While the desert ecosystem is highly dependent on the water resources that sustain it, the Fish Slough spring complex is an arid, spring-dependent wetland undergoing a multidecadal decline in spring outflow. This evaluation updates the source water forensics of the Fish Slough Spring complex, a substantial spring complex in the northern Owens Valley of the Basin and Range geomorphic provinces, in order to better understand the nature of the spring flow decline. The source of spring flow at Fish Slough was evaluated through an integration of the established geologic setting with measured groundwater elevations, and water quality and isotope chemistry compiled from both previously published sources and collection of new samples. While previous efforts to source the Fish Slough springs only considered potential source areas within the local geography, this evaluation considered a larger geographic extent for potential source areas to the spring water. The results infer that Fish Slough springs are sourced from multiple source water areas in hydraulic communication: a basin fill aquifer and warm, sodic spring systems with distinctive chemical signatures. Mixing from these sources occurs along two hypothesized flow paths, one from the northeast through the Tri-Valley area and one from the north and northwest through the Volcanic Tablelands. Northeast Spring has the strongest signature for Tri-Valley area waters, whereas the remaining Fish Slough Springs are comprised of a mixture of both flow paths. These conclusions have important implications for water management activities that have the potential to impact the desert ecosystem supported by these springs.
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Pierrehumbert, R. T. "Lateral mixing as a source of subtropical water vapor." Geophysical Research Letters 25, no. 2 (January 15, 1998): 151–54. http://dx.doi.org/10.1029/97gl03563.
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Sun, Xin, Li Li Ye, and Ting Lin Huang. "Theoretical Analysis of the Energy Required for Destratification of a Stratified Source Reservoir." Applied Mechanics and Materials 295-298 (February 2013): 1066–69. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.1066.
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The minimum energy required for destratification of a source water reservoir is important to determine the design capacity of mixing system used to improve the source water quality. Taking Jinpen Reservoir in Xi’an, as a study case, the water volumes under different water levels of the reservoir were numerically calculated using the geometry data obtained with a RTK system. The total potential energy (PE) was determined by integrating the PE in each thin sub-layer over the water depth with density dependent on the water temperature. The average water temperature after complete mixing was calculated based on the heat exchange theory, and was consistent with the numerical result of temperature simulation. The difference of total potential energy before and after mixing was calculated for each month with the data of water temperature, water density and water volume. The minimum energy required for destratification increasing with the temperature gradient, was relatively high during the period from June to October, and reached a peak of 2412.92 kW·h in July.
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Viennet, David, Guillaume Lorette, David Labat, Matthieu Fournier, Mathieu Sebilo, Olivier Araspin, and Pierre Crançon. "Mobile Sources Mixing Model Implementation for a Better Quantification of Hydrochemical Origins in Allogenic Karst Outlets: Application on the Ouysse Karst System." Water 15, no. 3 (January 18, 2023): 397. http://dx.doi.org/10.3390/w15030397.
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On the edge of sedimentary basins, karst aquifers can be fed by several water sources from both autogenic and allogenic recharge. In some cases, assessing water origins can be hard and cause some difficulties for water resource management. The main goal of this study is to show the implementation of the mobile sources mixing model approach. More precisely, this research develops how a monitoring method using a multi-proxy approach can be used to quantify waters sources contributions from several origins at the outlets of a karst system. The study site is the Ouysse karst system, located in western France. The site offers the opportunity to understand the mixing processes between allogenic and autogenic water recharges. The karst system covers a 650 km² watershed, and is fed by three different chemical facies: (i) Autogenic water from the direct infiltration on the karstified limestones with high HCO3− values (median: 436 mg.L−1); (ii) Water coming from sinking rivers fed by spring coming from igneous rocks with low mineralization but relatively higher K+ values (median: 4.2 mg.L−1); (iii) Highly mineralized water coming from deep evaporitic layers and feeding another sinking river with very high sulfate concentrations (median: 400 mg.L−1). Sliding window cross-correlation analyses and hydrochemical analyses during a flood event are performed to implement a mobile source mixing model approach. This approach shows significant differences with a simple fixed source mixing model and appears more reliable but requires more time and money to carry out. The results and conclusion of this study will be used for forecasting and managing operational actions for resource management.
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Zhou, Zizhen, Tinglin Huang, Weijin Gong, Yang Li, Yue Liu, Shilei Zhou, and Meiying Cao. "Water Quality Responses during the Continuous Mixing Process and Informed Management of a Stratified Drinking Water Reservoir." Sustainability 11, no. 24 (December 11, 2019): 7106. http://dx.doi.org/10.3390/su11247106.
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Aeration and mixing have been proven as effective in situ water quality improvement methods, particularly for deep drinking water reservoirs. While there is some research on the mechanism of water quality improvement during artificial mixing, the changes to water quality and the microbial community during the subsequent continuous mixing process is little understood. In this study, we investigate the mechanism of water quality improvement during the continuous mixing process in a drinking water reservoir. During this period, we found a reduction in total nitrogen (TN), total phosphorus (TP), ammonium-nitrogen (NH4-N), iron (Fe), manganese (Mn), and total organic carbon (TOC) of 12.5%–30.8%. We also measured reductions of 8.6% and 6.2% in TN and organic carbon (OC), respectively, in surface sediment. Microbial metabolic activity, abundance, and carbon source utilization were also improved. Redundancy analysis indicated that temperature and dissolved oxygen (DO) were key factors affecting changes in the microbial community. With intervention, the water temperature during continuous mixing was 15 °C, and the mixing temperature in the reservoir increased by 5 °C compared with natural mixing. Our research shows that integrating and optimizing the artificial and continuous mixing processes influences energy savings. This research provides a theoretical basis for further advancing treatment optimizations for a drinking water supply.
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Ali, Geneviève A., André G. Roy, Marie-Claude Turmel, and François Courchesne. "Source-to-stream connectivity assessment through end-member mixing analysis." Journal of Hydrology 392, no. 3-4 (October 2010): 119–35. http://dx.doi.org/10.1016/j.jhydrol.2010.07.049.
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Zhu, Hai, Shengjie Lu, Lingling Wang, Jieru Xu, and Saiyu Yuan. "Numerical Study of Mixing Process by Point Source Pollution with Different Release Positions in a Sinuous Open Channel." Water 14, no. 12 (June 13, 2022): 1903. http://dx.doi.org/10.3390/w14121903.
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The process of pollutant mixing is significantly influenced by secondary flow and turbulence in meandering rivers. To investigate the influence of different point source release positions on the pollutant mixing process in sinuous open channel flows, a 3D large-eddy simulation (LES) model based on OpenFOAM was established to simulate the process of passive scalar transport in a sinuous channel with a rectangular cross-section. After verification by a flume experiment, two sets of cases in which the point sources were arranged at identical intervals in spanwise and streamwise directions were configured to evaluate the mixing efficiency. The effect of flow structure, secondary motion, and the turbulent viscosity on the scalar transport and mixing was discussed. The distribution of scalar as well as the scalar flux was analyzed in detail, and the fluctuation characteristics were also described. The results demonstrate that due to the existence of secondary flow in the sinuous channel, different transverse and streamwise release positions of the point source have significant influence on mixing efficiency and spatial distribution of the pollutant. The point source placed near the center of the cross-section in transverse or near the apex of the bend in streamwise result in higher mixing efficiency. Mixing efficiency calculated by different indices can be different, which requires comprehensive assessment.
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Zhang, Jing, and Xing Li Sun. "Calculation Methods and Application of a Hydrodynamic-Based Marine Pollution Mixing Zone." Advanced Materials Research 610-613 (December 2012): 1546–50. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.1546.
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In water environment management, a mixing zone is an area within which the concentration of pollutants are allowed to be higher than the water quality standards and beside which the water quality should satisfy the standards. A reasonable range of a mixing zone is important for the water function and environment manage. At present, there is no agreed method for mixing zone calculation. In this paper, a new calculation method of a hydrodynamic-based marine pollution mixing zone was proposed; it comprehensively considered both the source intensity and the specific hydrodynamic conditions. The example results showed that the method could really reflect the mixed state after sewage entering into the sea water and could be used in a mixing zone calculation.
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Rothfuss, Youri, and Mathieu Javaux. "Reviews and syntheses: Isotopic approaches to quantify root water uptake: a review and comparison of methods." Biogeosciences 14, no. 8 (May 2, 2017): 2199–224. http://dx.doi.org/10.5194/bg-14-2199-2017.
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Abstract. Plant root water uptake (RWU) has been documented for the past five decades from water stable isotopic analysis. By comparing the (hydrogen or oxygen) stable isotopic compositions of plant xylem water to those of potential contributive water sources (e.g., water from different soil layers, groundwater, water from recent precipitation or from a nearby stream), studies were able to determine the relative contributions of these water sources to RWU. In this paper, the different methods used for locating/quantifying relative contributions of water sources to RWU (i.e., graphical inference, statistical (e.g., Bayesian) multi-source linear mixing models) are reviewed with emphasis on their respective advantages and drawbacks. The graphical and statistical methods are tested against a physically based analytical RWU model during a series of virtual experiments differing in the depth of the groundwater table, the soil surface water status, and the plant transpiration rate value. The benchmarking of these methods illustrates the limitations of the graphical and statistical methods while it underlines the performance of one Bayesian mixing model. The simplest two-end-member mixing model is also successfully tested when all possible sources in the soil can be identified to define the two end-members and compute their isotopic compositions. Finally, the authors call for a development of approaches coupling physically based RWU models with controlled condition experimental setups.
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Somaratne, N., K. Smettem, J. Lawson, K. Nguyen, and J. Frizenschaf. "Hydrological functions of sinkholes and characteristics of point recharge in groundwater basins." Hydrology and Earth System Sciences Discussions 10, no. 9 (September 6, 2013): 11423–49. http://dx.doi.org/10.5194/hessd-10-11423-2013.
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Abstract. Karstic limestone aquifers are hydrologically and hydrochemically extremely heterogeneous and point source recharge via sinkholes and fissures is a common feature. We studied three groundwater systems in karstic settings dominated by point source recharge in order to assess the relative contributions to total recharge from point sources using chloride and δ18O relations. Preferential groundwater flows were observed through an inter-connected network of highly conductive zones with groundwater mixing along flow paths. Measurements of salinity and chloride indicated that fresh water pockets exist at point recharge locations. A measurable fresh water plume develops only when a large quantity of surface water enters the aquifer as a point recharge source. The difference in chloride concentrations in diffuse and point recharge zones decreases as aquifer saturated thickness increases and the plumes become diluted through mixing. The chloride concentration in point recharge fluxes crossing the watertable plane can remain at or near surface runoff chloride concentrations, rather than in equilibrium with groundwater chloride. In such circumstances the conventional chloride mass balance method that assumes equilibrium of recharge water chloride with groundwater requires modification to include both point and diffuse recharge mechanisms.
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Ombaki, Richard, and Joash Kerongo. "Formulated Mathematical Model for Delayed Particle Flow in Cascaded Subsurface Water Reservoirs with Validation on River Flow." Journal of Applied Mathematics 2022 (November 10, 2022): 1–11. http://dx.doi.org/10.1155/2022/3438200.
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Migration of pollutant particles into subsurface water reservoirs through point sources is largely involved mixing processes within the system of water flow. Possible potential sources of pollution to these point sources include municipal wastes, septic loads, landfills, uncontrolled hazardous wastes, and sewage storage tanks. The mixing processes of pollutant significantly alter their predictive rate of flow in the water reservoirs, and therefore the time inherent in mixing processes need to be accounted for. In this study, pollution of subsurface water reservoirs mainly rivers and streams through contaminated water point sources (CWPS) was studied through a conceptual perspective of mixing problem processes in water tanks. The objective was to formulate a discrete time delay mathematical model which describes the dynamics of water reservoir pollution that involve single species contaminants such as nitrates, phosphorous, and detergents injecting from a point source. The concentration x t of pollutants was expressed as a function of the inflow and outflow rates using the principle for the conservation of mass. The major assumption made in modeling of mixing problems using tanks is that mixing is instantaneous. Practical realities dictate that mixing cannot occur instantaneously throughout the tank. So as to accommodate these realities, the study refined the systems of ordinary differential equations (ODEs) generated from principles of mixing problems in cascading tanks, into a system of delayed differential equations (DDEs) so that the concentration of pollutant leaving the reservoir at time t would be equal to the average concentration at some earlier instant, t − τ for the delay τ > 0 . The formulated model is a mathematical discrete time delay model which can be used to describe the dynamics of subsurface water reservoir pollution through a point source. The model was simulated on municipal River Nyakomisaro in Kisii County, Kenya. Physical and kinematic parameters of the river (cross-sectional lengths, depths, flow velocities) at three river sectional reservoirs were measured and the obtained parameter values were then used to evaluate coefficients of the formulated model equation. The system of DDEs from this simulation was solved numerically on MATLAB using dde23 software. From the graphical views generated for concentration of pollutant x t versus time t , it was established that the developed DDEs cover longer time series solutions (characteristic curves) than that from the corresponding ODEs in the same reservoir indicating that time necessary for particle flow through water reservoirs is underestimated if ODEs are used to describe particle flow. Also, the graphical views indicated similar tendencies (characteristics) in particle flow with time elapse even though initial values of concentration x t were different for every potentially recognized single species pollutant considered in each river reservoir. Hence, longer values of time t will imply more pollution in the water reservoir and vice versa. By introducing time delays due to constituent mixing processes in water quality simulation models that make use of advection-diffusion equation such as Qual2kw, the findings of this study can help for better understanding of the contaminant’s accumulation levels and their rate of transport in water resource. These will assist, for example, water-quality protection agencies such as Environmental Protection Agency (EPA), World Health Organization (WHO), and National Environmental Management Authority (NEMA) for the need to generate efficient and effective remedial strategies to control or mitigate hazardous or risks arising from water pollution.
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Nogueira, Guilherme E. H., Christian Schmidt, Daniel Partington, Philip Brunner, and Jan H. Fleckenstein. "Spatiotemporal variations in water sources and mixing spots in a riparian zone." Hydrology and Earth System Sciences 26, no. 7 (April 13, 2022): 1883–905. http://dx.doi.org/10.5194/hess-26-1883-2022.
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Abstract. Riparian zones are known to modulate water quality in stream corridors. They can act as buffers for groundwater-borne solutes before they enter the stream at harmful, high concentrations or facilitate solute turnover and attenuation in zones where stream water (SW) and groundwater (GW) mix. This natural attenuation capacity is strongly controlled by the dynamic exchange of water and solutes between the stream and the adjoining aquifer, creating potential for mixing-dependent reactions to take place. Here, we couple a previously calibrated transient and fully integrated 3D surface–subsurface numerical flow model with a hydraulic mixing cell (HMC) method to map the source composition of water along a net losing reach (900 m) of the fourth-order Selke stream and track its spatiotemporal evolution. This allows us to define zones in the aquifer with more balanced fractions of the different water sources per aquifer volume (called mixing hot spots), which have a high potential to facilitate mixing-dependent reactions and, in turn, enhance solute turnover. We further evaluated the HMC results against hydrochemical monitoring data. Our results show that, on average, about 50 % of the water in the alluvial aquifer consists of infiltrating SW. Within about 200 m around the stream, the aquifer is almost entirely made up of infiltrated SW with practically no significant amounts of other water sources mixed in. On average, about 9 % of the model domain could be characterized as mixing hot spots, which were mainly located at the fringe of the geochemical hyporheic zone rather than below or in the immediate vicinity of the streambed. This percentage could rise to values nearly 1.5 times higher following large discharge events. Moreover, event intensity (magnitude of peak flow) was found to be more important for the increase in mixing than event duration. Our modeling results further suggest that discharge events more significantly increase mixing potential at greater distances from the stream. In contrast near and below the stream, the rapid increase in SW influx shifts the ratio between the water fractions to SW, reducing the potential for mixing and the associated reactions. With this easy-to-transfer framework, we seek to show the applicability of the HMC method as a complementary approach for the identification of mixing hot spots in stream corridors, while showing the spatiotemporal controls of the SW–GW mixing process and the implications for riparian biogeochemistry and mixing-dependent turnover processes.
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Diez, F. J., L. P. Bernal, and G. M. Faeth. "Self-Preserving Mixing Properties of Steady Round Nonbuoyant Turbulent Jets in Uniform Crossflows." Journal of Heat Transfer 127, no. 8 (March 1, 2005): 877–87. http://dx.doi.org/10.1115/1.1991868.
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The self-preserving mixing properties of steady round nonbuoyant turbulent jets in uniform crossflows were investigated experimentally. The experiments involved steady round nonbuoyant fresh water jet sources injected into uniform and steady fresh water crossflows within the windowed test section of a water channel facility. Mean and fluctuating concentrations of source fluid were measured over cross sections of the flow using planar-laser-induced-fluorescence (PLIF). The self-preserving penetration properties of the flow were correlated successfully similar to Diez et al. [ASME J. Heat Transfer, 125, pp. 1046–1057 (2003)] whereas the self-preserving structure properties of the flow were correlated successfully based on scaling analysis due to Fischer et al. [Academic Press, New York, pp. 315–389 (1979)]; both approaches involve assumptions of no-slip convection in the cross stream direction (parallel to the crossflow) and a self-preserving nonbuoyant line puff having a conserved momentum force per unit length that moves in the streamwise direction (parallel to the initial source flow). The self-preserving flow structure consisted of two counter-rotating vortices, with their axes nearly aligned with the crossflow (horizontal) direction, that move away from the source in the streamwise direction due to the action of source momentum. Present measurements extended up to 260 and 440 source diameters from the source in the streamwise and cross stream directions, respectively, and yielded the following results: jet motion in the cross stream direction satisfied the no-slip convection approximation; geometrical features, such as the penetration of flow boundaries and the trajectories of the axes of the counter-rotating vortices, reached self-preserving behavior at streamwise distances greater than 40–50 source diameters from the source; and parameters associated with the structure of the flow, e.g., contours and profiles of mean and fluctuating concentrations of source fluid, reached self-preserving behavior at streamwise (vertical) distances from the source greater than 80 source diameters from the source. The counter-rotating vortex structure of the self-preserving flow was responsible for substantial increases in the rate of mixing of the source fluid with the ambient fluid compared to corresponding axisymmetric flows in still environments, e.g., transverse dimensions in the presence of the self-preserving counter-rotating vortex structure were 2–3 times larger than transverse dimensions in self-preserving axisymmetric flows at comparable conditions.
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Noone, D., C. Risi, A. Bailey, M. Berkelhammer, D. P. Brown, N. Buenning, S. Gregory, et al. "Determining water sources in the boundary layer from tall tower profiles of water vapor and surface water isotope ratios after a snowstorm in Colorado." Atmospheric Chemistry and Physics Discussions 12, no. 7 (July 4, 2012): 16327–75. http://dx.doi.org/10.5194/acpd-12-16327-2012.
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Abstract. The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H2O and CO2 mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every 15 min during four winter days near Boulder, Colorado. Coeval analysis of the D/H ratios and CO2 concentrations find these two variables to be complementary with the former being sensitive to daytime surface fluxes and the latter particularly indicative of nocturnal surface sources. Together they capture evidence for strong vertical mixing during the day, weaker mixing by turbulent bursts and low level jets within the nocturnal stable boundary layer during the night, and frost formation in the morning. The profiles are generally not well described with a gradient mixing line analysis because D/H ratios of the end members (i.e., surface fluxes and the free troposphere) evolve throughout the day which leads to large uncertainties in the estimate of the D/H ratio of surface water flux. A mass balance model is constructed for the snow pack, and constrained with observations to provide an optimal estimate of the partitioning of the surface water flux into contributions from sublimation, evaporation of melt water in the snow and evaporation from ponds. Results show that while vapor measurements are important in constraining surface fluxes, measurements of the source reservoirs (soil water, snow pack and standing liquid) offer stronger constraint on the surface water balance. Measurements of surface water are therefore essential in developing observational programs that seek to use isotopic data for flux attribution.
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Noone, D., C. Risi, A. Bailey, M. Berkelhammer, D. P. Brown, N. Buenning, S. Gregory, et al. "Determining water sources in the boundary layer from tall tower profiles of water vapor and surface water isotope ratios after a snowstorm in Colorado." Atmospheric Chemistry and Physics 13, no. 3 (February 8, 2013): 1607–23. http://dx.doi.org/10.5194/acp-13-1607-2013.
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Abstract. The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H2O and CO2 mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every 15 min during four winter days near Boulder, Colorado. Coeval analysis of the D/H ratios and CO2 concentrations find these two variables to be complementary with the former being sensitive to daytime surface fluxes and the latter particularly indicative of nocturnal surface sources. Together they capture evidence for strong vertical mixing during the day, weaker mixing by turbulent bursts and low level jets within the nocturnal stable boundary layer during the night, and frost formation in the morning. The profiles are generally not well described with a gradient mixing line analysis because D/H ratios of the end members (i.e., surface fluxes and the free troposphere) evolve throughout the day which leads to large uncertainties in the estimate of the D/H ratio of surface water flux. A mass balance model is constructed for the snow pack, and constrained with observations to provide an optimal estimate of the partitioning of the surface water flux into contributions from sublimation, evaporation of melt water in the snow and evaporation from ponds. Results show that while vapor measurements are important in constraining surface fluxes, measurements of the source reservoirs (soil water, snow pack and standing liquid) offer stronger constraint on the surface water balance. Measurements of surface water are therefore essential in developing observational programs that seek to use isotopic data for flux attribution.
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Diez, F. J., L. P. Bernal, and G. M. Faeth. "Self-Preserving Mixing Properties of Steady Round Buoyant Turbulent Plumes in Uniform Crossflows." Journal of Heat Transfer 128, no. 10 (July 7, 2006): 1001–11. http://dx.doi.org/10.1115/1.2345424.
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The self-preserving mixing properties of steady round buoyant turbulent plumes in uniform crossflows were investigated experimentally. The experiments involved salt water sources injected into fresh water crossflows within the windowed test section of a water channel. Mean and fluctuating concentrations of source fluid were measured over cross sections of the flow using planar-laser-induced fluorescence which involved seeding the source fluid with Rhodamine 6G dye and adding small concentrations of ethanol to the crossflowing fluid in order to match the refractive indices of the source flow and the crossflow. The self-preserving penetration properties of the flow were correlated successfully based on the scaling analysis of Diez, Bernal, and Faeth (2003, ASME J. Heat Transfer, 125, pp. 1046–1057) whereas the self-preserving structure properties of the flow were correlated successfully based on the scaling analysis of Fischer et al. (1979, Mixing in Inland and Coastal Waters, Academic Press, New York, pp. 315–389); both approaches involved assumptions of no-slip convection in the cross stream (horizontal) direction (parallel to the crossflow) and a self-preserving line thermal having a conserved source specific buoyancy flux per unit length that moves in the streamwise (vertical) direction (parallel to the direction of both the initial source flow and the gravity vector). The resulting self-preserving structure consisted of two counter-rotating vortices having their axes nearly aligned with the crossflow direction that move away from the source in the streamwise (vertical) direction due to the action of buoyancy. Present measurements extended up to 202 and 620 source diameters from the source in the streamwise and cross stream directions, respectively. The onset of self-preserving behavior required that the axes of the counter-rotating vortex system be nearly aligned with the crossflow direction. This alignment, in turn, was a strong function of the source/crossflow velocity ratio, uo∕v∞. The net result was that the onset of self-preserving behavior was observed at streamwise distances of 10–20 source diameters from the source for uo∕v∞=4 (the smallest value of uo∕v∞ considered), increasing to streamwise distances of 160–170 source diameters from the source for uo∕v∞=100 (the largest value of uo∕v∞ considered). Finally, the counter-rotating vortex system was responsible for substantial increases in the rate of mixing of the source fluid with the ambient fluid compared to axisymmetric round buoyant turbulent plumes in still environments, e.g., transverse dimensions in the presence of the self-preserving counter-rotating vortex system were 2–3 times larger than the transverse dimensions of self-preserving axisymmetric plumes at similar streamwise distances from the source.
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Yan, Zhongyue, Jing Xu, and Xiaohong Ruan. "An improved source apportionment mixing model combined with a Bayesian approach for nonpoint source pollution load estimation." Hydrology Research 50, no. 3 (February 26, 2019): 849–60. http://dx.doi.org/10.2166/nh.2019.076.
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Abstract A nonpoint source (NPS) loads evaluation method based on the Bayesian source apportionment mixing model was established in this research. The model assumed that (1) the pollutant concentration from each source mixed with the others in the monitoring section during transport, (2) transport only considered first-order attenuation, (3) point source pollution had relatively stable emissions, and (4) the measurement error was random, unrelated, and consistent with a normal distribution (mean of 0). All unknown parameters in the model were taken as random variables, and their posterior distributions were derived by Markov chain Monte Carlo procedures based on historical data, literature, and empirical information. The outflow system of the Huaihe River was adopted as a case study to verify the feasibility of the model. Gelman–Rubin, automatic frequency control statistics, and the determination coefficient (R2) verified the reliability. The results showed that the total loads of ammonia nitrogen (NH4+), chemical oxygen demand, total nitrogen, and total phosphorus from NPSs accounted for 16.35–27.58%, 18.78–25.69%, 21.68–29.71%, and 42.11–52.09%, respectively. The parameter sensitivity analysis showed that prior distribution of NPS concentration was the most sensitive one, which should be determined reasonably based on the empirical or historical information.
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Larsen, Daniel, Justin Paul, and Randy Cox. "Geochemical and isotopic evidence for upward flow of saline fluid to the Mississippi River Valley alluvial aquifer, southeastern Arkansas, USA." Hydrogeology Journal 29, no. 4 (March 31, 2021): 1421–44. http://dx.doi.org/10.1007/s10040-021-02321-3.
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AbstractGroundwater from the Quaternary Mississippi River Valley Alluvial (MRVA) aquifer in southeastern Arkansas (SE AR), USA, has higher salinity compared to other MRVA groundwater. Previous studies have argued for infiltration of evaporated soil water as a primary source for the elevated salinity, although seepage from local rivers and deep groundwater sources also have been considered. Geochemical and isotope data from irrigation, public supply, and industrial wells, as well as subsurface geologic data, are used to demonstrate that upward flow of saline water along regional faults is the primary source of salinity in MRVA aquifer groundwater in SE AR. Sodium, chloride (Cl-) and bromide (Br-) concentrations illustrate mixing relationships between MRVA aquifer groundwater and Jurassic Smackover Formation brine, with mixing percentages of <1% Smackover brine being the source of anomalously high Cl-, Br-, and other ions in MRVA groundwater with elevated salinity. Stable oxygen and hydrogen isotope data suggest substantial mixing of Paleogene Wilcox Formation water with that of the MRVA aquifer groundwater and varying degrees of evaporative concentration. Radiocarbon and helium isotope data argue for contributions of chloride-rich, pre-modern and relatively fresh modern water for recharge to the MRVA aquifer. Chloride concentration in MRVA aquifer waters closely follows the spatial distribution of earthquake-induced liquefaction features and known or suspected geologic faults in SE AR and northeastern Louisiana. A conceptual model is developed where deep-seated basinal fluids in overpressured reservoirs migrate upward along faults during and following Holocene earthquakes into the overlying MRVA over 100s to 1,000s of years
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Bryjak, Marek, Nalan Kabay, Enver Güler, and Barbara Tomaszewska. "Concept for energy harvesting from the salinity gradient on the basis of geothermal water." WEENTECH Proceedings in Energy 4, no. 2 (December 13, 2018): 88–96. http://dx.doi.org/10.32438/wpe.6118.
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The use of renewable energy resource is usually directed to solar, wind or hydroelectric stations. However, there are other sources for getting the ‘green energy’. One of them is geothermal source, the energy stored in the underground fluids. In the world, geothermal water is used mostly for heating purposes, greenhouses, agriculture, for generation of warm water, therapeutic and recreational purposes and to generate electricity in power stations. After these uses, geothermal water is usually seen as waste water. This research presents the idea for innovative energy harvesting from the salinity gradient on the basis of waste geothermal water. Two methods are analyzed to be used: capacitive mixing (CAPMIX) and reverse electrodialysis (RED). The aim of the research concept is analysis for testing the applicability of both methods in energy harvesting from mixing of saline geothermal water and RO brine with water, before its re-injection to underground reservoirs.
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Yevenes-Burgos, M. A., and C. M. Mannaerts. "Untangling hydrological pathways and nitrate diffusive sources by chemical appraisal in a stream network of a reservoir catchment." Hydrology and Earth System Sciences Discussions 8, no. 2 (March 2, 2011): 2289–322. http://dx.doi.org/10.5194/hessd-8-2289-2011.
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Abstract. Stable water isotopes and water hydrochemistry of a catchment in the Alentejo region, south Portugal, were analysed to investigate source origins of water and nitrate flows towards a reservoir. The 353 km2 headwater catchment of Roxo river, is strongly influenced by agricultural impacts, and high variations in water and chemical inflows into an important drinking and irrigation water supply (108 m3) are observed. This leads to regular disputes on water quantity and quality amongst local authorities and population. Three sampling campaigns in different seasons were used to address the temporal and spatial variations in stream and groundwater hydrochemistry and water isotopic signatures. A total of 27 sampling points from the stream network, shallow groundwater and reservoir were used. Isotopic signatures and chemistry of precipitation were obtained from local data of the Global Network of Isotopes in Precipitation (GNIP) and the Global Atmosphere Watch (GAWSIS) network. Other meteorological, hydrological and environmental datasets were obtained from local authorities. The stable water isotopes deuterium (δ2H), oxygen-18 (δ18O) together with chloride (Cl–) and sulphate (SO42–) were used as environmental tracers in the hydrological pathways. Water pathways were then related with nitrate concentrations to elucidate potential relationships between the water and nutrient sources. Interpretation of isotope signatures showed a high degree of isotope enrichment in both surface (stream flow) and shallow groundwater. For the entire period, most of stream waters were located right of the global meteoric water line or GMWL and plotted along a local evaporation line (LEL) established for the study area. The LEL showed slopes similar to stream systems in other dry environments. Monthly stream flow and precipitation, seasonal isotope compositions and major ion chemistry data were used for an evaluation of the relative contribution of water sources using an end-member mixing analysis. An extensive PCA or principal component analysis preceded the mixing analysis. Contributions of the three water end-members in the catchment: groundwater, surface runoff and precipitation to stream flow could be identified based on their 2H, 18O and Cl– signatures. Also two hydro chemical data outliers for Cl– and NO3– from two sample points were identified by the analysis and could be related to local waste water outfalls, giving the method also diagnostic value for pollution source allocation. The shallow groundwater source could be related to stream nitrate concentrations during the wet seasons, indicating a linkage between hydrological flow paths, nitrate sources and season. Conversely, weak links between precipitation, and surprisingly also surface water runoff and nitrate levels were found. In this catchment, we found a consistent pattern of the particular groundwater end member, being main source of nitrate to the stream water and reservoir, based on conservative mixing of the different water sources.
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Osman, Ola, Oluwajinmi Daniel Aina, and Farrukh Ahmad. "Chemical fingerprinting of saline water intrusion into sewage lines." Water Science and Technology 76, no. 8 (June 23, 2017): 2044–50. http://dx.doi.org/10.2166/wst.2017.374.
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High salinity in sewage sludge can affect not only the operation of wastewater treatment plants (WWTPs) but also the quality of treated water generated, thereby limiting its downstream reuse. Using data on geochemical parameters, both for the central WWTP in Abu Dhabi, UAE, and literature values for potential regional saline water sources (e.g., shallow groundwater and regional Arabian Gulf seawater), a variety of chemical fingerprinting diagnostic ratios were calculated and plotted in order to determine the source of salinity in the municipal sewage. Data were compared with data from a regional WWTP that was not impacted by salinity. Monitoring data demonstrated persistently elevated levels of salinity in the municipal wastewater arriving at the central WWTP from the city. Dilution/concentration analysis using a conductivity vs. chloride plot showed both potential sources, i.e. Arabian Gulf seawater and coastal hypersaline groundwater, as feasible sources of wastewater salinization. Further diagnostic analysis using a Panno Plot indicated that coastal groundwater was the only likely source of salinization of municipal sewage. Additional confirmation of the identity of the source and the extent of mixing using different lines of evidence like stable isotope ratios is recommended for future study.
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Beria, Harsh, Joshua R. Larsen, Anthony Michelon, Natalie C. Ceperley, and Bettina Schaefli. "HydroMix v1.0: a new Bayesian mixing framework for attributing uncertain hydrological sources." Geoscientific Model Development 13, no. 5 (May 27, 2020): 2433–50. http://dx.doi.org/10.5194/gmd-13-2433-2020.
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Abstract. Tracers have been used for over half a century in hydrology to quantify water sources with the help of mixing models. In this paper, we build on classic Bayesian methods to quantify uncertainty in mixing ratios. Such methods infer the probability density function (PDF) of the mixing ratios by formulating PDFs for the source and target concentrations and inferring the underlying mixing ratios via Monte Carlo sampling. However, collected hydrological samples are rarely abundant enough to robustly fit a PDF to the source concentrations. Our approach, called HydroMix, solves the linear mixing problem in a Bayesian inference framework wherein the likelihood is formulated for the error between observed and modeled target variables, which corresponds to the parameter inference setup commonly used in hydrological models. To address small sample sizes, every combination of source samples is mixed with every target tracer concentration. Using a series of synthetic case studies, we evaluate the performance of HydroMix using a Markov chain Monte Carlo sampler. We then use HydroMix to show that snowmelt accounts for around 61 % of groundwater recharge in a Swiss Alpine catchment (Vallon de Nant), despite snowfall only accounting for 40 %–45 % of the annual precipitation. Using this example, we then demonstrate the flexibility of this approach to account for uncertainties in source characterization due to different hydrological processes. We also address an important bias in mixing models that arises when there is a large divergence between the number of collected source samples and their flux magnitudes. HydroMix can account for this bias by using composite likelihood functions that effectively weight the relative magnitude of source fluxes. The primary application target of this framework is hydrology, but it is by no means limited to this field.
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Griffis, Timothy J., Jeffrey D. Wood, John M. Baker, Xuhui Lee, Ke Xiao, Zichong Chen, Lisa R. Welp, et al. "Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer." Atmospheric Chemistry and Physics 16, no. 8 (April 25, 2016): 5139–57. http://dx.doi.org/10.5194/acp-16-5139-2016.
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Abstract. Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle – an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m) in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL) over a 3-year period (2010 to 2012). These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from −40.2 to −15.9 ‰ and δ2Hv ranged from −278.7 to −113.0 ‰) and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv) of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( > 25 mmol mol−1) indicate that regional evaporation can account for 40 to 60 % of the PBL water vapor. These estimates are in relatively good agreement with that derived from numerical weather model simulations. This relatively large fraction of evaporation-derived water vapor implies that evaporation has an important impact on the precipitation recycling ratio within the region. Based on multiple constraints, we estimate that the summer season recycling fraction is about 30 %, indicating a potentially important link with convective precipitation.
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Holland, Paul R. "Oscillating Dense Plumes." Journal of Physical Oceanography 41, no. 8 (August 1, 2011): 1465–83. http://dx.doi.org/10.1175/2011jpo4532.1.
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Abstract The flow of dense polar shelf waters down continental slopes is a critical component of the global ocean circulation. Recent observations suggest that such plumes can be heavily impacted by tidal variability, and many of the world’s important dense-water sources are located in tidally active areas. Tides affect the source of dense water (by modulating the location of hydrographic gradients) and control the subsequent plume mixing and flow path. In an effort to separate these effects, dense plumes are modeled here by extending a classical one-dimensional plume model to two unsteady scenarios in which the plume path is fixed. The first case features a pulsed release of dense water into a stagnant ambient, and the model predicts that gravity waves propagate down the plume. Advective waves in plume density travel with the mean velocity of the current and thus have a wavelength of , the product of plume velocity and the oscillation period P. The second case is of a steady-sourced plume flowing through an ambient that has uniformly oscillating flow. This drives fluctuating shear at the plume–ambient interface (and/or seabed) that leads to variable entrainment of ambient fluid into the plume. Perturbed properties are subsequently advected by the plume, leading to standing “entrainment waves” that also have a wavelength of . Pulsed-source effects may be distinguished from variable-entrainment effects by the phase difference between waves in the different state variables of each plume. Both effects are maximized when the ratio , where L is the plume length. This condition is satisfied in the Ross Sea, Antarctica, where observations show dense plumes that are strongly affected by tides. Modeled pulsed-source effects qualitatively agree with the observations, implying that hydrographic variability in Ross Sea plumes is associated with variability in their dense-water source rather than unsteady plume mixing. These results might help inform the gathering and interpretation of oceanographic data in tidally active dense-water source regions.
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Stanley, S. J., and D. W. Smith. "Modelling chlorinated discharges from water treatment plants: a case study." Canadian Journal of Civil Engineering 18, no. 6 (December 1, 1991): 985–94. http://dx.doi.org/10.1139/l91-121.
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Virtually all water treatment plants have the ability to discharge chlorinated water back to the source stream. Such water may originate from an emergency bypass, filter backwash water or other diversions. The discharge of chlorinated water to receiving water bodies has caused concern because of its toxicity effects to aquatic biota and potential health hazards. This paper demonstrates the use of a transverse mixing model that incorporates both mixing and pollutant decay in assessing the environmental impact of these discharges. The results of such an analysis can be used to base control measures on, such that environmental impact is minimized and guidelines met. Presented is an impact assessment of chlorinated wastewater discharges from two water treatment plants in Edmonton, Alberta. Key words: environmental impacts, mixing, stream pollution, chlorine decay, water treatment.
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Yevenes, M. A., and C. M. Mannaerts. "Untangling hydrological pathways and nitrate sources by chemical appraisal in a stream network of a reservoir catchment." Hydrology and Earth System Sciences 16, no. 3 (March 8, 2012): 787–99. http://dx.doi.org/10.5194/hess-16-787-2012.
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Abstract. The knowledge of water source contributions to streamflow is important for understanding chemical contamination origins and the status of biogeochemical cycling in stream networks of catchments. In this study, we evaluated whether a limited number of spatially distributed geochemical tracer data sampled during different hydrological seasons were sufficient to quantify water flow pathways and nitrate sources in a catchment. Six geochemical water constituents (δ2H, δ18O, Cl−, SO2−4, Na+, NO−3 and K+) of precipitation, stream water, alluvial sediment pore water and shallow groundwater of a 352 km2 agricultural catchment in the Alentejo region of Portugal were analysed. Exploratory data analysis and end-member mixing analysis (EMMA) were performed to estimate the water source mixing proportions. Residual analysis of principal components was used to identify the appropriate geochemical tracers and the number of end-members (water sources and flow paths), and their proportional contributions to streamflow were quantified. Spearman's rank correlation analysis was further used to identify nitrate origins in the streamflow. Results showed that, when using data from both wet and dry seasons, streamflow chemistry was strongly influenced by shallow groundwater. When only wet season data were modelled, streamflow chemistry was controlled and generated by three end-members: shallow groundwater, alluvial sediment pore water and precipitation. Isotope signatures of stream water were located mostly below the local meteoric water line (LMWL) and plotted along a local evaporation line (LEL), reflecting the permanence in the streamflow of shallow groundwater subjected to prior evaporation. Interpretation of isotope signatures during summer showed an isotopic enrichment in both streamflow and shallow groundwater. Measured and historical stream nitrate concentrations appeared to be strongly related to shallow groundwater. In addition, two hydrochemical data outliers for almost every solute from two sample points were identified by the analysis and could be related to local waste water outfalls. The results of this study have improved our understanding of water source contributions to streamflow in the catchment, and also yielded indications of nitrate consumption related to biogeochemical processes in the streamflow network. Moreover, we could conclude that the relatively limited geochemical spatial sample database used in this study was an adequate input for the end-member mixing analysis and diagnostic tools to quantify water sources and nitrate origins in the streamflow of the catchment.
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Sharma, H., and Z. Ahmad. "Transverse mixing of pollutants in streams: a review." Canadian Journal of Civil Engineering 41, no. 5 (May 2014): 472–82. http://dx.doi.org/10.1139/cjce-2013-0561.
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Spilling or release of foreign particles in the flowing water is considered as pollution of water, and due to the inherent property of water to dissolve the substance, the particulate is well mixed in water. To monitor the extent of pollution in a stream it is essential to know how the pollutants mix in the river. It is observed that vertical mixing of pollutants is a very rapid process in the vertical directions and longitudinal mixing occurs very far from source of pollutant, which is generally out of reach of observations. Thus intermediate or transverse mixing zone is considered very important for water quality modeling. This paper is an attempt to summarize the phenomenon behind pollutant transport, reduction of three-dimensional advection–dispersion equation to two-dimensional equation, and factors causing and affecting transverse mixing of pollutants.
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Chen, Song, and Herong Gui. "Calculating groundwater mixing ratios in multi-aquifers based on statistical methods: a case study." Water Practice and Technology 16, no. 2 (March 19, 2021): 621–32. http://dx.doi.org/10.2166/wpt.2021.027.
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Abstract Samples of river water and groundwater from Quaternary (QA), sandstone (SA), Taiyuan formation (TA), and Ordovician limestone (OA) aquifers in the Suxian coal-mining district, Anhui Province, China were collected. Their physicochemical properties, and major ion and isotopic compositions were determined. The samples were alkaline, with pH values exceeding 8, and the total dissolved solids concentrations depended on the water source. The δD and δ18O contents were highest in the river water samples and lowest in the SA groundwater. The isotopic characteristics of the QA and OA groundwaters suggest recharge by rainfall and surface water. The isotopic characteristics of river water were controlled mainly by evaporation. Water–rock interactions, the flow rate, and the main water sources were the most important influences on groundwaters in QA, OA, and TA, but the properties of SA groundwater were controlled by static reserves. Two discriminant functions, explaining more than 98.2% of the total variances, indicated that QA, TA, and OA were hydraulically connected. Three groundwater sources were identified as end-members, and a conceptual model was established to calculate water mixing ratios.
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Abiye, Tamiru A., Molla B. Demlie, and Haile Mengistu. "An Overview of Aquifer Physiognomies and the δ18O and δ2H Distribution in the South African Groundwaters." Hydrology 8, no. 2 (April 19, 2021): 68. http://dx.doi.org/10.3390/hydrology8020068.
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A comprehensive assessment of the stable isotope distribution in the groundwater systems of South Africa was conducted in relation to the diversity in the aquifer lithology and corresponding hydraulic characteristics. The stable isotopes of oxygen (18O) and hydrogen (2H) in groundwater show distinct spatial variation owing to the recharge source and possibly mixing effect in the aquifers with the existing water, where aquifers are characterized by diverse hydraulic conductivity and transmissivity values. When the shallow aquifer that receives direct recharge from rainfall shows a similar isotopic signature, it implies less mixing effect, while in the case of deep groundwater interaction between recharging water and the resident water intensifies, which could change the isotope signature. As aquifer depth increases the effect of mixing tends to be minimal. In most cases, the isotopic composition of recharging water shows depletion in the interior areas and western arid zones which is attributed to the depleted isotopic composition of the moisture source. The variations in the stable isotope composition of groundwater in the region are primarily controlled by the isotope composition of the rainfall, which shows variable isotope composition as it was observed from the local meteoric water lines, in addition to the evaporation, recharge and mixing effects.
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Lee, Taeho, Jinho Cho, and Jeekeun Lee. "Mixing Properties of Emulsified Fuel Oil from Mixing Marine Bunker-C Fuel Oil and Water." Journal of Marine Science and Engineering 10, no. 11 (November 1, 2022): 1610. http://dx.doi.org/10.3390/jmse10111610.
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Alternative marine fuels are needed to help reduce the exhaust emissions of ships. In this study, we performed an analysis to verify the potential applicability of a fuel based on Bunker-C oil, a low-grade marine heavy oil, as a novel alternative marine fuel. Bunker-C oil and water were mixed in the presence of a 0.8–1.2% emulsifier in four steps from 0% to 25% to produce a special type of emulsified fuel oil. Confocal microscopy images of samples after stabilization for approximately three days at room temperature showed no variation in the pattern at the 0% condition with no water, but a relatively homogenous mixed state of water droplets was found across all domains at the 5–25% conditions. The open-source software Image-J indicated the extraction of 166, 3438, and 5636 water droplets with mean diameters of 1.57, 1.79, and 2.08 μm, as well as maximum diameters of 7.31, 21.41, and 25.91 μm, at the 5%, 15%, and 25% conditions, respectively. For all three conditions, the mean particle diameter was approximately 2 μm, below the 20 μm reported in previous studies, with uniform distributions. This suggests that the mixed state was adequately homogenous.
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Wang, Jian, Nan Lu, and Bojie Fu. "Inter-comparison of stable isotope mixing models for determining plant water source partitioning." Science of The Total Environment 666 (May 2019): 685–93. http://dx.doi.org/10.1016/j.scitotenv.2019.02.262.
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Preul, Herbert C. "Analysis of source control for domestic wastewaters." Water Science and Technology 32, no. 1 (July 1, 1995): 153–59. http://dx.doi.org/10.2166/wst.1995.0035.
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In a large number of urban watersheds, a combination of upstream approaches for the control of the major CSO pollution sources may be more cost-effective than current end-of-pipe solutions. Source control has been directed largely at the control of rainfall runoff and stormwater flows. This paper concentrates on the control of domestic wastewater as a part of integrated source control by preventing its mixing with storm water in combined sewer systems during rainfall runoff periods, thereby avoiding or reducing CSOs. CSO data from a typical urban watershed of approximately 100 hectares in Cincinnati are used as a prototype for illustration purposes.
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Barbeta, Adrià, Sam P. Jones, Laura Clavé, Lisa Wingate, Teresa E. Gimeno, Bastien Fréjaville, Steve Wohl, and Jérôme Ogée. "Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest." Hydrology and Earth System Sciences 23, no. 4 (April 26, 2019): 2129–46. http://dx.doi.org/10.5194/hess-23-2129-2019.
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Abstract. We investigated plant water sources of an emblematic refugial population of Fagus sylvatica (L.) in the Ciron river gorges in south-western France using stable water isotopes. It is generally assumed that no isotopic fractionation occurs during root water uptake, so that the isotopic composition of xylem water effectively reflects that of source water. However, this assumption has been called into question by recent studies that found that, at least at some dates during the growing season, plant water did not reflect any mixture of the potential water sources. In this context, highly resolved datasets covering a range of environmental conditions could shed light on possible plant–soil fractionation processes responsible for this phenomenon. In this study, the hydrogen (δ2H) and oxygen (δ18O) isotope compositions of all potential tree water sources and xylem water were measured fortnightly over an entire growing season. Using a Bayesian isotope mixing model (MixSIAR), we then quantified the relative contribution of water sources for F. sylvatica and Quercus robur (L.) trees. Based on δ18O data alone, both species used a mix of top and deep soil water over the season, with Q. robur using deeper soil water than F. sylvatica. The contribution of stream water appeared to be marginal despite the proximity of the trees to the stream, as already reported for other riparian forests. Xylem water δ18O could always be interpreted as a mixture of deep and shallow soil waters, but the δ2H of xylem water was often more depleted than the considered water sources. We argue that an isotopic fractionation in the unsaturated zone and/or within the plant tissues could underlie this unexpected relatively depleted δ2H of xylem water, as already observed in halophytic and xerophytic species. By means of a sensitivity analysis, we found that the estimation of plant water sources using mixing models was strongly affected by this δ2H depletion. A better understanding of what causes this isotopic separation between xylem and source water is urgently needed.
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Duan, Xueliang, Fengshan Ma, Jie Guo, Haijun Zhao, Hongyu Gu, Shuaiqi Liu, and Qihao Sun. "Source Identification and Quantification of Seepage Water in a Coastal Mine, in China." Water 11, no. 9 (September 7, 2019): 1862. http://dx.doi.org/10.3390/w11091862.
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The Sanshandao gold mine, which is the largest coastal mine in China, is under threat from seawater intrusion and water inrush. The objective of this study is to determine the water end-members (seawater, freshwater, and brine) of the seepage water in the mine and quantify the proportion of end-members. Non-conservative ions and ion exchange were identified by using hydrogeochemical analysis. Then, the principal component analysis (PCA) was used to identify the end-members of mine water. Three end-members were identified, so a ternary mixture model was applied to compute the mixing ratios. The potential water flow channels and the prevailing supply patterns were inferred by combining the results of mixing ratios with the tectonic and engineering geological conditions. The results indicate that the proportion of seawater in mine water is about 57%, the freshwater is about 16% and the brine is about 27% for the entire mine area, the prevailing supply pattern of seawater was lateral recharge, the water samples which were located in −510 m sublevel or in the northeast of prospecting line 2260 had high proportions of seawater, the freshwater supplied the groundwater mainly through the secondary fractures developed area in a vertical recharge and the influence depth was about −500 m, and F3 was the largest tensile-shear fault in the study area and it was both a watercourse for seawater and fresh water.
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Nagode, Klara, Tjaša Kanduč, Tea Zuliani, Branka Bračič Železnik, Brigita Jamnik, and Polona Vreča. "Daily Fluctuations in the Isotope and Elemental Composition of Tap Water in Ljubljana, Slovenia." Water 13, no. 11 (May 21, 2021): 1451. http://dx.doi.org/10.3390/w13111451.
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The isotope and elemental composition of tap water reflects its multiple distinct inputs and provides a link between infrastructure and the environment over a range of scales. For example, on a local scale, they can be helpful in understanding the geological, hydrogeological, and hydrological conditions and monitor the proper functioning of the water supply system (WSS). However, despite this, studies examining the urban water system remain limited. This study sought to address this knowledge gap by performing a 24 h multiparameter analysis of tap water extracted from a region where the mixing of groundwater between two recharge areas occurs. This work included measurements of temperature and electrical conductivity, as well as pH, δ2H, δ18O, d, δ13CDIC, and 87Sr/86Sr ratios and major and trace elements at hourly intervals over a 24 h period. Although the data show only slight variations in the measured parameters, four groups were distinguishable using visual grouping, and multivariate analysis (Spearman correlation coefficient analysis, hierarchical cluster analysis, and principal components analysis). Finally, changes in the mixing ratios of the two sources were estimated using a linear mixing model. The results confirm that the relative contribution from each source varied considerably over 24 h.
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Sorooshian, A., S. M. Murphy, S. Hersey, H. Gates, L. T. Padro, A. Nenes, F. J. Brechtel, H. Jonsson, R. C. Flagan, and J. H. Seinfeld. "Comprehensive airborne characterization of aerosol from a major bovine source." Atmospheric Chemistry and Physics Discussions 8, no. 3 (June 3, 2008): 10415–79. http://dx.doi.org/10.5194/acpd-8-10415-2008.
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Abstract. We report an extensive airborne characterization of aerosol downwind of a massive bovine source in the San Joaquin Valley (California) on two flights during July 2007. The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed chemical composition, particle size distribution, mixing state, sub- and supersaturated water uptake behavior, light scattering properties, and the interrelationship between these parameters and meteorology. Total PM1.0 levels and concentrations of organics, nitrate, and ammonium were enhanced in the plume from the source as compared to the background aerosol. Organics dominated the plume aerosol mass (~56–64%), followed either by sulfate or nitrate, and then ammonium. Particulate amines were detected in the plume aerosol by a particle-into-liquid sampler (PILS) and via mass spectral markers in the Aerodyne cToF-AMS. Amines were found to be a significant atmospheric base even in the presence of ammonia; particulate amine concentrations are estimated as at least 14–23% of that of ammonium in the plume. Enhanced sub- and supersaturated water uptake and reduced refractive indices were coincident with lower organic mass fractions, higher nitrate mass fractions, and the detection of amines. Kinetic limitations due to hydrophobic organic material are shown to have likely suppressed droplet growth. After removing effects associated with size distribution and mixing state, the normalized activated fraction of cloud condensation nuclei (CCN) increased as a function of the subsaturated hygroscopic growth factor, with the highest activated fractions being consistent with relatively lower organic mass fractions and higher nitrate mass fractions. Subsaturated hygroscopic growth factors for the organic fraction of the aerosol are estimated based on employing the Zdanovskii-Stokes Robinson (ZSR) mixing rule. Representative values for a parameterization treating particle water uptake in both the sub- and supersaturated regimes are reported for incorporation into atmospheric models.
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Sorooshian, A., S. M. Murphy, S. Hersey, H. Gates, L. T. Padro, A. Nenes, F. J. Brechtel, H. Jonsson, R. C. Flagan, and J. H. Seinfeld. "Comprehensive airborne characterization of aerosol from a major bovine source." Atmospheric Chemistry and Physics 8, no. 17 (September 12, 2008): 5489–520. http://dx.doi.org/10.5194/acp-8-5489-2008.
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Abstract. We report an extensive airborne characterization of aerosol downwind of a massive bovine source in the San Joaquin Valley (California) on two flights during July 2007. The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed chemical composition, particle size distribution, mixing state, sub- and supersaturated water uptake behavior, light scattering properties, and the interrelationship between these parameters and meteorology. Total PM1.0 levels and concentrations of organics, nitrate, and ammonium were enhanced in the plume from the source as compared to the background aerosol. Organics dominated the plume aerosol mass (~56–64%), followed either by sulfate or nitrate, and then ammonium. Particulate amines were detected in the plume aerosol by a particle-into-liquid sampler (PILS) and via mass spectral markers in the Aerodyne C-ToF-AMS. Amines were found to be a significant atmospheric base even in the presence of ammonia; particulate amine concentrations are estimated as at least 14–23% of that of ammonium in the plume. Enhanced sub- and supersaturated water uptake and reduced refractive indices were coincident with lower organic mass fractions, higher nitrate mass fractions, and the detection of amines. The likelihood of suppressed droplet growth owing to kinetic limitations from hydrophobic organic material is explored. After removing effects associated with size distribution and mixing state, the normalized activated fraction of cloud condensation nuclei (CCN) increased as a function of the subsaturated hygroscopic growth factor, with the highest activated fractions being consistent with relatively lower organic mass fractions and higher nitrate mass fractions. Subsaturated hygroscopic growth factors for the organic fraction of the aerosol are estimated based on employing the Zdanovskii-Stokes Robinson (ZSR) mixing rule. Representative values for a parameterization treating particle water uptake in both the sub- and supersaturated regimes are reported for incorporation into atmospheric models.
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Schlitzer, Reiner. "14C in the Deep Water of the East Atlantic." Radiocarbon 28, no. 2A (1986): 391–96. http://dx.doi.org/10.1017/s0033822200007505.
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The renewal of east Atlantic deep water and its large-scale circulation and mixing have been studied in observed distributions of temperature, silicate, ΣCO2, and 14C. 14C variations in northeast Atlantic deep water below 3500m depth are small. Δ14C values range from − 100‰ to −125‰. 14C bottom water concentrations decrease from Δ14C =−117‰ in the Sierra Leone Basin to Δ14C = − 123‰ in the Iberian Basin and are consistent with a mean northward bottom water flow. The characteristic of the water that flows from the west Atlantic through the Romanche Trench into the east Atlantic was determined by inspection of θ/Δ14C and θ/SiO2 diagrams. A mean potential temperature of θ = 1.50 ± .05°C was found for the inflowing water. A multi-box model including circulation, mixing, and chemical source terms in the deep water has been formulated. Linear programing and least-squares techniques have been used to obtain the transport and source parameters of the model from the observed tracer fields. Model calculations reveal an inflow through the Romanche Trench from the west Atlantic, which predominates over any other inflow, of (5 ± 2) Sv (potential temperature 1.50°C), a convective turnover of (150 ± 50) years and a vertical apparent diffusivity of (4 ± 1) cm2/s. Chemical source terms are in the expected ranges.
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Jameel, Yusuf, Simon Brewer, Richard P. Fiorella, Brett J. Tipple, Shazelle Terry, and Gabriel J. Bowen. "Isotopic reconnaissance of urban water supply system dynamics." Hydrology and Earth System Sciences 22, no. 11 (November 28, 2018): 6109–25. http://dx.doi.org/10.5194/hess-22-6109-2018.
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Abstract. Public water supply systems (PWSS) are critical infrastructure that is vulnerable to contamination and physical disruption. Exploring susceptibility of PWSS to such perturbations requires detailed knowledge of supply system structure and operation. The physical structure of the distribution system (i.e., pipeline connections) and basic information on sources are documented for most industrialized metropolises. Yet, most information on PWSS function comes from hydrodynamic models that are seldom validated using observational data. In developing regions, the issue may be exasperated as information regarding the physical structure of the PWSS may be incorrect, incomplete, undocumented, or difficult to obtain in many cities. Here, we present a novel application of stable isotopes in water (SIW) to quantify the contribution of different water sources, identify static and dynamic regions (e.g., regions supplied chiefly by one source vs. those experiencing active mixing between multiple sources), and reconstruct basic flow patterns in a large and complex PWSS. Our analysis, based on a Bayesian mixing model framework, uses basic information on the SIW and production volumes of sources but requires no information on pipeline connections in the system. Our work highlights the ability of stable isotopes in water to analyze PWSS and document aspects of supply system structure and operation that can otherwise be challenging to observe. This method could allow water managers to document spatiotemporal variation in flow patterns within PWSS, validate hydrodynamic model results, track pathways of contaminant propagation, optimize water supply operation, and help monitor and enforce water rights.
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Franz, P., and T. Röckmann. "High-precision isotope measurements of H<sub>2</sub><sup>16</sup>O, H<sub>2</sub><sup>17</sup>O, H<sub>2</sub><sup>18</sup>O, and the Δ <sup>17</sup>O-anomaly of water vapor in the southern lowermost stratosphere." Atmospheric Chemistry and Physics 5, no. 11 (November 7, 2005): 2949–59. http://dx.doi.org/10.5194/acp-5-2949-2005.
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Abstract. We report the first high-precision measurements of δ 18O and Δ 17O at high southern latitudes that can resolve changes in the isotopic composition of water vapor in the lowermost stratosphere and upper troposphere. A strong increase of δ 18O with decreasing mixing ratio above the tropopause is evident in the data. Since also the water vapor mixing ratio decreases above the tropopause, the effect seen in the isotope data can be explained by mixing of moist air from the tropopause with dry stratospheric air. However, the source of this dry stratospheric air is not known; both fast transport from the extratropical tropopause or mixing with air from the dehydrated polar vortex are likely. The magnitude of the Δ 17O-anomaly (departure from mass-dependent fractionation (MDF)) was below 2 per mil for each datapoint, and a zero anomaly in lower level stratospheric water vapor is possible. Various transport histories for the stratospheric data are discussed based on the mixing ratio and isotope data.
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Birt, David, Danielle Wain, Emily Slavin, Jun Zang, Robert Luckwell, and Lee D. Bryant. "Stratification in a Reservoir Mixed by Bubble Plumes under Future Climate Scenarios." Water 13, no. 18 (September 8, 2021): 2467. http://dx.doi.org/10.3390/w13182467.
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During summer, reservoir stratification can negatively impact source water quality. Mixing via bubble plumes (i.e., destratification) aims to minimise this. Within Blagdon Lake, a UK drinking water reservoir, a bubble plume system was found to be insufficient for maintaining homogeneity during a 2017 heatwave based on two in situ temperature chains. Air temperature will increase under future climate change which will affect stratification; this raises questions over the future applicability of these plumes. To evaluate bubble-plume performance now and in the future, AEM3D was used to simulate reservoir mixing. Calibration and validation were done on in situ measurements. The model performed well with a root mean squared error of 0.53 °C. Twelve future meteorological scenarios from the UK Climate Projection 2018 were taken and down-scaled to sub-daily values to simulate lake response to future summer periods. The down-scaling methods, based on diurnal patterns, showed mixed results. Future model runs covered five-year intervals from 2030 to 2080. Mixing events, mean water temperatures, and Schmidt stability were evaluated. Eight scenarios showed a significant increase in water temperature, with two of these scenarios showing significant decrease in mixing events. None showed a significant increase in energy requirements. Results suggest that future climate scenarios may not alter the stratification regime; however, the warmer water may favour growth conditions for certain species of cyanobacteria and accelerate sedimentary oxygen consumption. There is some evidence of the lake changing from polymictic to a more monomictic nature. The results demonstrate bubble plumes are unlikely to maintain water column homogeneity under future climates. Modelling artificial mixing systems under future climates is a powerful tool to inform system design and reservoir management including requirements to prevent future source water quality degradation.
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Kasajima, Y., and T. Johannessen. "Role of cabbeling in water densification in the Greenland Basin." Ocean Science Discussions 5, no. 3 (September 12, 2008): 507–43. http://dx.doi.org/10.5194/osd-5-507-2008.
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Abstract. The contribution of cabbeling mixing to water mass modification in the Greenland Sea was explored from hydrographic observation across the Greenland Basin in summer 2006. Neutral surface was chosen as a reference frame, and the strength of cabbeling mixing was determined by the dianeutral velocity magnitude. Water types in the area were classified into North Atlantic Water (NAW), modified North Atlantic Water (mNAW), water from Barents Sea near Bear Island (BIW), Arctic Intermediate Water (AIW) and Deep Water (DW), and significant cabbeling-induced velocity (>1 m/day) appeared at the interfaces of these water types below the seasonal pycnocline. The mixing between BIW and NAW in the eastern periphery was the most vigorous, where mixing-induced velocity reached 7.5 m/day which accompanied NAW production of 123 m3/day through transformation of BIW. Cabbeling in the Arctic Frontal Zone was found of two types; mixing within NAW in the upper layer and mixing within mNAW in the lower layer with a maximum velocity of 3 m/day. Source waters in the central Greenland Basin were AIW and mNAW and produced a vertical velocity of 4 m/day. In the western part of the Greenland Basin, the areas of active cabbeling were widely separated and each mixing point appeared rather weak, with a maximum velocity of 2.5 m/day. The average density gain in the eastern periphery was 0.003 kg/m3 while it was 0.001 kg/m3 in the other areas, though the impact of cabbeling on the bulk buoyancy change was highest in the western Greenland Sea. The frontal areas occupied approximately 50% of the whole analysis area and the total density gain due to cabbeling mixing in the Greenland Basin as a whole was estimated as 6.7×10−4 kg/m3.
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Kasajima, Y., and T. Johannessen. "Role of cabbeling in water densification in the Greenland Basin." Ocean Science 5, no. 3 (July 14, 2009): 247–57. http://dx.doi.org/10.5194/os-5-247-2009.
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Abstract. The effects of cabbeling mixing on water mass modification in the Greenland Sea were explored by hydrographic observations across the Greenland Basin in summer 2006. The neutral surface was chosen as a reference frame, and the strength of cabbeling mixing was quantified by the dianeutral velocity magnitude. Active cabbeling spots were detected with the criterion of the velocity magnitude >1 m/day, and four active cabbeling areas were identified; the west of Bear Island (SB), the Arctic Frontal Zone (AFZ), the central Greenland Sea (CG) and the western Greenland Sea (WG). The most vigorous cabbeling mixing was found at SB, where warm North Atlantic Water (NAW) mixed with cold water from the Barents Sea, inducing a maximum velocity of 7.5 m/day and a maximum density gain of 4.7×10−3 kg/m3. At AFZ and CG, the mixing took place between NAW, modified NAW and Arctic Intermediate Water (AIW), and the density gain at these fronts were 1.5×10−3 kg/m3 (AFZ) and 1.3×10−3 kg/m3 (CG). In the western Greenland Sea, the active cabbeling spots were widely separated and mixing appeared to be rather weak, with a maximum velocity of 2.5 m/day. The mixing source waters at WG were modified NAW, AIW and even denser water, and the density gain in this area was 0.4×10−3 kg/m3. The deepest mixing produced water whose density is equivalent to that of the dense water of the basin, indicating that cabbeling in the western Greenland Sea contributed directly to basin-scale water densification. The water mass modification rate was the highest at AFZ (about 8.0 Sv), suggesting that cabbeling may play an important role in water transformation in the Greenland Basin.
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Gabriel, Oliver, Katerina Ruzicka, and Norbert Kreuzinger. "Upgrading Vienna's wastewater treatment plant – linking point source emissions to Environmental Quality Standards." Water Science and Technology 65, no. 7 (April 1, 2012): 1290–97. http://dx.doi.org/10.2166/wst.2012.010.
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The new water quality protection approach of the EU combines the control of emissions with instream Environmental Quality Standards (=EQS). Since 1 April 2006 and actually relevant in the version of 2010 in Austria, priority substances from list A of the EUROPEAN DIERECTIVE 76/464 and further EQS of relevant chemical substances (list B), identified by a national risk assessment, have to be reached to achieve a good ecological state in the surface water (Edict for Water Quality Standards, 2006; changes to the Edict for Water Quality Standards 2010). The practical assessment of these substances after point source emissions is prescribed in the Edict, but rarely carried out. In this paper, two substances, namely: (1) ammonium (list B); and (2) nonylphenol, an endocrine disrupting compound (list A) are presented to discuss: (i) the improvement of treatment efficiency due to the upgrade of a large Waste Water Treatment Plant (=WWTP); (ii) the relevance of mixing processes and modelling as a method to control EQS after point source emissions; and (iii) the improvement of water quality in the ambient surface waters. It is shown that the improved treatment in the case of nonylphenol leads to emission values which fall below the EQS, making an assessment unnecessary. In the case of ammonium emission, values are significantly reduced and violation of EQS is avoided, while mixing modelling is shown to be a suitable instrument to address the resulting instream concentrations at different border conditions.
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Singh, Sarbjit, Zulfequar Ahmad, and Umesh C. Kothyari. "Two-dimensional mixing of pollutants in streams with transverse line source." Journal of Hydraulic Research 47, no. 1 (January 2009): 90–99. http://dx.doi.org/10.3826/jhr.2009.3171.
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Akhtar, Shehnaz, Haider Ali, and Cheol Woo Park. "Complete Evaluation of Cell Mixing and Hydrodynamic Performance of Thin-Layer Cascade Reactor." Applied Sciences 10, no. 3 (January 21, 2020): 746. http://dx.doi.org/10.3390/app10030746.
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Microalgae are a great source of food and supplements as well as a potential source for the production of biofuels. However, the operational cost must be reduced to allow viable productions of bulk chemicals such as biofuels from microalgae. One approach to minimize the cost is to increase the efficiency of the photobioreactor. Photobioreactor efficiency is correlated to hydrodynamic mixing, which promotes single cell exposure to sunlight, keeps algae cells in suspension, and homogenizes the distribution of nutrients. Thus, a possible route to enhance the efficiency of the photobioreactor can be identified through an improved understanding of the mixing phenomenon. Therefore, for the current thin-layer cascade reactor, two aspects of its performance—namely, cell mixing and hydrodynamic characteristics—are evaluated under varying mass flow rates, slope angles, water depths, and aspect ratios of the channel by using computational fluid dynamics. The resulting model is validated with experimental data. Results reveal that limited cell mixing is achieved in the thin-layer cascade reactor with increased water depth and large aspect ratios. However, cell mixing is significantly increased at high mass flow rates. The increase in the mass flow rate and slope angle results in increased flow velocity and power consumption.
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Abrha, Biniam, and Avi Ostfeld. "Analytical Solutions to Conservative and Non-Conservative Water Quality Constituents in Water Distribution System Storage Tanks." Water 13, no. 24 (December 8, 2021): 3502. http://dx.doi.org/10.3390/w13243502.
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Water storage tanks are one of the primary and most critical components of water distribution systems (WDSs), which aim to manage water supply by maintaining pressure. In addition, storage provides a surplus source of water in case of an emergency. To gain the mentioned advantages, storage tanks are incorporated in most WDSs. Despite these advantages, storage can also pose negative impacts on water quality, thereby affecting water utilities. Water quality problems are a result of longer residency times and inadequate water mixing. This study aimed to construct a model of a tank’s water quantity and quality by formulating and solving governing equations based on inlet/outlet configurations and processes that influence the movement of water and chemical substances inside it. We used a compartment model to characterize the mixing behavior inside a tank. A water quality simulation model with different compartment arrangements was explored for extended filling and draining of storage, which was further validated using a previously published case study.
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Pradiko, Hary, Evi Afiatun, and Evan Fabian. "Influence of Mixing and Detention Time in Electro Coagulation Process to Treat Raw Water at Badak Singa Water Treatment Plant." INDONESIAN JOURNAL OF URBAN AND ENVIRONMENTAL TECHNOLOGY 1, no. 2 (May 2, 2018): 137. http://dx.doi.org/10.25105/urbanenvirotech.v1i2.2823.
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Source of raw water used at Badak Singa Water Treatment Plant come from surface water such as Cisangkuy River. This source of raw water is affected by conditions in the upstream, pollution along the stream, climate and weather. In the drinking water supply system, turbidity is one important factor for several reasons such as aesthetic factor, burden to filtration, and interfere the disinfection process. Electro coagulation is one of water treatment method that combines the process of coagulation, flotation, and electrochemical. <strong>Aims:</strong><strong> </strong>This research aims to see at the ability of the electro coagulation process in reducing turbidity as an alternative to substitute the conventional coagulation system. <strong>Methodology and results: </strong>This research carried out by testing electro coagulation with variations in mixing, current density produced by voltage 10, 20 and 30 volt and detention time 5, 10, 20 and 30 minute to reduce the initial turbidity of 100 NTU. The result are that: the efficiency of electro coagulation with mixing is better than electro coagulation without mixing to reduce the initial turbidity of 100 NTU; the final turbidity value of the processing result is better as the length of detention time used and meet the quality standard from detention time of 10 minute; the higher the current density given and the longer the detention time used, the higher the processing efficiency and the formed flock volume is deposited. <strong>Conclusion, significance and impact study: </strong>A good turbidizing removal process using electrocoagulation requires the agitation process and long detention time.<strong></strong>
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Shaheen, Mohamed N. F., and Elmahdy M. Elmahdy. "Environmental monitoring of astrovirus and norovirus in the Rosetta branch of the River Nile and the El-Rahawy drain, Egypt." Water Supply 19, no. 5 (January 2, 2019): 1381–87. http://dx.doi.org/10.2166/ws.2019.004.
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Abstract Sewage discharge is considered to be the primary source of viral contamination in aquatic environments. This study was conducted to evaluate the impact of El-Rahawy wastewater on the water quality of the Rosetta branch of the River Nile (Rosetta River Nile) through detection of astrovirus (AstV) and norovirus (NoV) in the water and sediments of both sites. For this purpose, we collected 72 wastewater and 12 sediment samples from El-Rahawy drain, and 12 river water and 12 sediment samples from Rosetta River Nile before and after mixing with El-Rahawy wastewater between April 2017 and March 2018. AstVs and NoVs were identified in wastewater (40.2% versus 25%), El-Rahawy sediment (41.6% versus 20.8%), river water after mixing with wastewater (25% versus 16.6%), river water before mixing with wastewater (8.3% versus 0%), river sediment after mixing with wastewater (16.6% versus 8.3%), and no viruses were found in river sediments before mixing with wastewater. AstV genogroup B and NoV genogroup GI were the most frequently detected genotypes in the analyzed samples, with a peak incidence in the winter months. Increasing detection rates of both viruses in El-Rahawy drain samples and river water taken from the Rosetta branch after receiving El-Rahawy wastewater reflect the impact of this drain on the water quality of this stretch of the River Nile.
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White, Joseph C., and William K. Smith. "Seasonal variation in water sources of the riparian tree species Acer negundo and Betula nigra, southern Appalachian foothills, USA." Botany 93, no. 8 (August 2015): 519–28. http://dx.doi.org/10.1139/cjb-2015-0003.
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Determining which water sources a plant accesses throughout a year is an important step in understanding how changes in source characteristics affect utilization by plants. Water sources of Acer negundo L. and Betula nigra L. of the foothills of the southern Appalachians Mountains were examined during one full year, including the phenological stages of leaf bolt, flowering, and leaf senescence and abscission. Source utilization was monitored, comparing the isotopic composition of water samples from woody tissue with those of possible water sources at the site. Species used deep ground and shallow soil water, with a greater reliance on deeper sources during the late growing season. Betula nigra was typically more depleted in δ2H than all water sources measured, while values from A. negundo were more variable throughout the study. Intraspecifically, isotopic values did not vary monthly or seasonally for either species (P > 0.56), while interspecific values were different for December, January, and July samplings (P < 0.02). Positive relationships occurred between air temperature and isotopic values of both species (P < 0.04), and may reflect increased evaporation from the upper soil layers at warmer temperatures, which both species appeared to use. An inability to sample all sources prevented the application of mixing models and may weaken conclusions.