scholarly journals Identification of aquifer pollution’s point sources with the Reciprocity Principle

2021 ◽  
Author(s):  
Nejla T. Hariga ◽  
Rachida Bouhlila
Keyword(s):  
High Efficiency ◽  
Linear Equations ◽  
Water Flux ◽  
Rocky Mountain ◽  
Point Sources ◽  
Polluted Water ◽  
Water Fluxes ◽  
Reciprocity Principle ◽  
Transient Transport ◽  
Transport Problems

Abstract The principle of reciprocity, called Maxwell-Bettitheorem, initially used in mechanics in an elastic structure, establishes a relation of equality between two distinct strains under different loads. In this paper, we extend and apply this principle to flow and solute transport equations in porous media, in order to perform the pollution sources identification in aquifers. We developed general 2D expressions of the reciprocity principle for transient transport problems. This model leads to a linear equations set, with point sources coordinates, concentrations and associated water fluxes as unknowns. The proposed model is then applied to the Rocky Mountain Arsenal aquifer, where polluted water is injected into a well in the domain. The proposed inverse technique successfully recovered the position and the pollutant concentration in addition to the associated water flux. Moreover, we developed and implemented the inverse method for different knowledge levels of the degrees of the aquifer contamination, i.e. more or less data available in the field. Multiple pollution point sources and noisy data situations are also developed and tested with high efficiency. The proposed method would be easy and useful to be implemented in the modeling software now widely used by researchers and groundwater managers. It can thus be applied in real case studies, to help authorities and regulators to efficiently identify the polluters and the contamination process i.e. its location, onset, duration and the associated mass and water fluxes.

Linking soil water and solutes fluxes to soil properties and vegetation types: insights from a case-study in the high tropical Andes of Ecuador

2021 ◽  
Author(s):  
Sebastián Páez-Bimos ◽  
Veerle Vanacker ◽  
Marcos Villacis ◽  
Marlon Calispa ◽  
Oscar Morales ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Conservation ◽  
Water Flux ◽  
Water Fluxes ◽  
Vegetation Types ◽  
Tropical Andes ◽  
Conservation Area ◽  
Solute Fluxes ◽  
Doc Concentration ◽  
Water Conservation Area

<p>The high tropical Andes ecosystem, known as páramo, provides important hydrological services to densely populated areas in the Andean region. In order to manage these services sustainably, it is crucial to understand the biotic and abiotic processes that control both water quality and fluxes. Recent research in the páramo highlights a knowledge gap regarding the role played by soil-vegetation interactions in controlling soil-water processes and resulting water and solute fluxes.</p><p>Here, we determine the hydrological and geochemical fluxes in four soil profiles in the páramo of the Antisana´s water conservation area in northern Ecuador. Water fluxes were measured biweekly with field fluxmeters in the hydrological year Apr/2019- Mar/2020 under two contrasting vegetation types: tussock-like grass (TU) and cushion-forming plants (CU). Soil solution was collected in parallel with wick samplers and suction caps for assessing the concentrations of dissolved cations, anions and organic carbon (DOC). In addition, soil moisture was measured continuously in the upper meter of the soil profile, i.e. first three horizons (A, 2A and 2BC), using water content reflectometers. The vertical water flux in the upper meter of each soil profile was simulated using the 1D HYDRUS model. We carried out a Sobol analysis to identify sensitive soil hydraulic parameters. We then derived water fluxes by inverse modeling, based on the measured soil moisture. We validated the calculated water fluxes using the fluxmeter data. Solute fluxes were estimated by combining the water fluxes and the soil solution compositions.</p><p>Our preliminary results suggest that water fluxes and DOC concentration vary under different vegetation types. The fluxmeter data from the 2A horizon indicates that the cumulative water flux under TU (2.8 - 5.7 l) was larger than under CU (0.8 – 1.1 l) during the dry season (Aug-Sep and Dec-Jan). However, the opposite trend was observed in the wet season for maximum water fluxes. Moreover, the DOC concentration in the uppermost horizon was higher under CU (47.3 ±2.2 mg l<sup>-1</sup>) than under TU (3.1 ±0.2 mg l<sup>-1</sup>) vegetation during the monitoring period. We associate the water and solute responses under different vegetation types to the contrasting soil hydro-physical and chemical properties (e.g., saturated hydraulic conductivity and organic carbon content) in the uppermost soil horizon. Our study illustrates the existence of a spatial association between vegetation types, water fluxes and solute concentrations in Antisana´s water conservation area. By modelling the hydrological balance of the upper meter of the soil mantle, the water and solute fluxes will be estimated for soils with different vegetation cover.</p><p> </p>

Real Continuation Method and its Application in Kinematic Synthesis

2000 ◽  
Author(s):  
Liu Anxin ◽  
Yang Tingli
Keyword(s):  
High Efficiency ◽  
Continuation Method ◽  
Linear Equations ◽  
Path Generation ◽  
Kinematic Synthesis ◽  
Real Solutions ◽  
Non Linear ◽  
Four Bar Linkage ◽  
Non Linear Equations

Abstract Real continuation method for finding real solutions to non-linear equations is proposed. Synthesis of planar four-bar linkage for path generation with nine precision points is studied using this method. The proposed method has high efficiency and can best be used for solving synthesis problems.

scholarly journals Development of load duration curve system in data-scarce watersheds based on a distributed hydrological model

2019 ◽  
Vol 50 (3) ◽  
pp. 886-900
Author(s):  
Jia Wang ◽  
Xin-hua Zhang ◽  
Chong-Yu Xu ◽  
Hao Wang ◽  
Xiao-hui Lei ◽  
...  
Keyword(s):  
Hydrological Model ◽  
Assessment Tool ◽  
Swat Model ◽  
River Basins ◽  
Point Sources ◽  
Guizhou Province ◽  
Polluted Water ◽  
Distributed Hydrological Model ◽  
Load Duration ◽  
Load Duration Curve

AbstractMany developing countries and regions are currently facing serious water environmental problems, especially the lack of monitoring systems for medium- to small-sized watersheds. The load duration curve (LDC) is an effective method to identify polluted waterbodies and clarify the point sources or non-point sources of pollutants. However, it is a large challenge to establish the LDC in small river basins due to the lack of available observed runoff data. In addition, the LDC cannot yet spatially trace the specific sources of the pollutants. To overcome the limitations of LDC, this study develops a LDC based on a distributed hydrological model of the Soil and Water Assessment Tool (SWAT). First, the SWAT model is used to generate the runoff data. Then, for the control and management of over-loaded polluted water, the spatial distribution and transportation of original sources of point and non-point pollutants are ascertained with the aid of the SWAT model. The development procedures of LDC proposed in this study are applied to the Jian-jiang River basin, a tributary of the Yangtze River, in Duyun city of Guizhou province. The results indicate the effectiveness of the method, which is applicable for water environmental management in data-scarce river basins.

scholarly journals Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation

2011 ◽  
Vol 15 (11) ◽  
pp. 3495-3510 ◽  
Author(s):  
M. Munz ◽  
S. E. Oswald ◽  
C. Schmidt
Keyword(s):  
Water Flux ◽  
Subsurface Water ◽  
Pass Band ◽  
Time Lags ◽  
Water Fluxes ◽  
Amplitude Ratios ◽  
Flux Calculation ◽  
Temperature Probe ◽  
Sand Box ◽  
Flow Velocities

Abstract. Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux.

scholarly journals Stationary and Nonstationary Ion and Water Flux Interactions in Kidney Proximal Tubule: Mathematical Analysis of Isosmotic Transport by a Minimalistic Model

2019 ◽  
pp. 101-147 ◽  
Author(s):  
Erik Hviid Larsen ◽  
Jens Nørkær Sørensen
Keyword(s):  
Water Uptake ◽  
Time Course ◽  
Epithelial Transport ◽  
Water Flux ◽  
Experimental Studies ◽  
Physiological Parameter ◽  
Water Fluxes ◽  
Fluid Absorption ◽  
Knock Out ◽  
Osmotic Permeability

AbstractOur mathematical model of epithelial transport (Larsen et al. Acta Physiol. 195:171–186, 2009) is extended by equations for currents and conductance of apical SGLT2. With independent variables of the physiological parameter space, the model reproduces intracellular solute concentrations, ion and water fluxes, and electrophysiology of proximal convoluted tubule. The following were shown: Water flux is given by active Na+ flux into lateral spaces, while osmolarity of absorbed fluid depends on osmotic permeability of apical membranes. Following aquaporin “knock-out,” water uptake is not reduced but redirected to the paracellular pathway. Reported decrease in epithelial water uptake in aquaporin-1 knock-out mouse is caused by downregulation of active Na+ absorption. Luminal glucose stimulates Na+ uptake by instantaneous depolarization-induced pump activity (“cross-talk”) and delayed stimulation because of slow rise in intracellular [Na+]. Rate of fluid absorption and flux of active K+ absorption would have to be attuned at epithelial cell level for the [K+] of the absorbate being in the physiological range of interstitial [K+]. Following unilateral osmotic perturbation, time course of water fluxes between intraepithelial compartments provides physical explanation for the transepithelial osmotic permeability being orders of magnitude smaller than cell membranes’ osmotic permeability. Fluid absorption is always hyperosmotic to bath. Deviation from isosmotic absorption is increased in presence of glucose contrasting experimental studies showing isosmotic transport being independent of glucose uptake. For achieving isosmotic transport, the cost of Na+ recirculation is predicted to be but a few percent of the energy consumption of Na+/K+ pumps.

scholarly journals Selective Cesium Adsorptive Removal on Using Crosslinked Tea Leaves

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 412 ◽  
Author(s):  
Dan Yu ◽  
Shintaro Morisada ◽  
Hidetaka Kawakita ◽  
Keisuke Ohto ◽  
Katsutoshi Inoue ◽  
...  
Keyword(s):  
Alkali Metals ◽  
High Efficiency ◽  
Polluted Water ◽  
Batch Adsorption ◽  
Hydroxyl Groups ◽  
Radioactive Cesium ◽  
Tea Leaves ◽  
Inorganic Ion ◽  
Langmuir Isotherm Model ◽  
Cationic Exchange

To remove the radioactive cesium from the polluted environment, tea leaves were chosen as cheap, and abundantly available environment-friendly bio-adsorbents to investigate the alkali metals adsorption. Fresh and used tea leaves (FT and UT) were found to have high efficiency and selectivity for cesium adsorption, after the crosslinking with concentrated sulfuric acid. Calculation of the proton-exchanged amount suggested adsorption mechanism of three alkali metals on crosslinked tea leaves involve a cationic exchange with a proton from the hydroxyl groups of the crosslinked tea leaves, as well as coordination with ethereal oxygen atoms to form the chelation. Further, considering the practical application of the polluted water treatment, the competitive adsorption of Cs+ and Na+ ions was investigated by the batch-wise method and column chromatography separation. Unlike the conventional ion exchange and chelate resins with less selectivity for Cs+ coexisting cations, both crosslinked fresh tea leaves (CFT) and crosslinked used tea leaves (CUT) exhibited Cs selectivity over Na. In addition, batch adsorption studies revealed that the cesium adsorptions were driven by the Langmuir isotherm model; the capacity of both crosslinked tea leaves for cesium adsorption was determined to be around 2.5 mmol g−1. The adsorption capacities are sufficiently higher in comparison with those of synthetic polymers, inorganic ion-exchangers, and other bio-adsorbents.

scholarly journals PREPARATION OF AN ORGANOSILICA-BASED MEMBRANE FROM TEOS-MTES AND ITS APPLICATION FOR DESALINATION OF WETLAND SALINE WATER

Konversi ◽  
2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Lilis Septyaningrum ◽  
Rahmawati Rahmawati ◽  
Fitri Ria Mustalifah ◽  
Aulia Rahma ◽  
Dewi Puspita Sari ◽  
...  
Keyword(s):  
Saline Water ◽  
Sol Gel ◽  
Water Flux ◽  
Water Desalination ◽  
Clean Water ◽  
Water Fluxes ◽  
Salt Rejection ◽  
Membrane Performance ◽  
Wetland Water ◽  
Hot Season

When hot season, South Kalimantan society which especially, in Muara Halyung village frequently go through clean water lacking. It becomes worst by water dirtied on wetland aquifer aftermath the seawater intrusion. Wetland water sources become saline and cannot be used for household needs. Organosilica membrane technology is one of methods can be used to remove salt contain in water. This study aims are to investigate the functionalization and organosilica membrane performance from TEOS-MTES which calcined on particularly temperature for wetland saline water desalination. Synthesis of organosilica sol was conducted by sol-gel method. Then the dried sol was calcined at 350°C and 600 °C, and characterized by FTIR (Fourier Transform InfraRed). Subsequently organosilica membrane was applicated for wetland saline water desalination via pervaporation. The result shows organosilica membrane performance was obtained the water flux 10,55 and 0,87 kg.m-2h-1 which calcined at 350 and 600 °C. The salt rejection in all membrane exhibits extremely high over 99%. It evinces the organosilica membrane from TEOS-MTES which calcined at 350 °C is great to applicated for wetland saline water desalination by both of water fluxes and salt rejection showed high.

The investigation on Fe3O4 magnetic flocculation for high efficiency treatment of oily micro-polluted water

2019 ◽  
Vol 244 ◽  
pp. 399-407 ◽  
Author(s):  
Juan Tang ◽  
Jie Wang ◽  
Hui Jia ◽  
Haitao Wen ◽  
Juan Li ◽  
...  
Keyword(s):  
High Efficiency ◽  
Polluted Water
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