Contaminant Flow Research Articles

MATHEMATICAL ANALYSIS OF 2-D STEADY SEEPAGE FLOW AND THE BEHAVIOR OF CONTAMINATES TRANSPORTATION THROUGH HOMOGENEOUS EARTH DAM USING COMSOL SOFTWARE

Seepage is a flow that happens through / under hydraulic structures or through the porous media such as in the case of earth dams from upstream to downstream due to difference in the hydraulic head. Study of seepage flow is important for hydraulic engineering. Before the structures being built, the behaviors of the seepage flows must be predicted because the seepage flow causes harmful to hydraulic structures. In this paper, a homogenous earth dam with sand material is proposed and constructed with horizontal bed filter at the Toe of the dam is taken as a case study. Through this Comsol is used to interpret the seepage of flow and contaminants transportation through the dam. The general objective of this paper is thus to present a prediction model aimed at quantifying a selected concentration of contaminants in the reservoir, and then predicted in the body of the dam, and at the exit from the dam. Computation Fluid Dynamics (CFD) Module (Comsol version 4.2) with its sub-programs named (Free and Porous Media Flow and Species Transport through Porous Media) was used in the analysis and study the seepage flow and of the contaminants transportation. This software is based on the finite element techniques that were used for solving the governing equations of flow and transportation of contaminant through porous media. Also, it was used to determine the phreatic line, amount of seepage within the dam, the pressure head, the total head, and the amount of contaminates transported through the dam body. From the comsol software, it is deduced that when the water level is at the maximum height (20m), it needs 12 days and (18) hr, at normal height (15m) it needs 29 days, while at a minimum height (8 m) it needs 81 days to reach the drain zone.

Geochemistry of Lakes in a Zone Impacted by an Arctic Iron-Producing Enterprise

The paper presents data on the chemical composition of waters and bottom sediments in lakes variably affected by liquid wastes from facilities of the Olkon Joint-Stock Company in Olenegorst, Murmansk oblast, which mines and processes iron ores. Since Olkon started operating, the composition of water in nearby water bodies has underwent significant changes. The mineralization (TDS) and pH of the lacustrine waters have increased (to 100 mg/L and 7.6 respectively). The qualitative composition of the water has also changed (the water type has changed from hydrocarbonate to sulfate), as also have the proportions of the dominant cations. The waters of the lakes have enriched in nitrogen-group compounds. The $${\text{NO}}_{3}^{ - }$$ concentrations in some of the lakes are higher than the concentrations of the dominant ions (Na+, K+, and Cl–) recalculated into equivalent concentrations. The inflow of contaminants with the waste waters has suppressed biological productivity and reduced concentrations of organic compounds in the lacustrine waters. The waters of the lakes that received waste waters form the iron-producing facilities contain the highest Ni, Cu, Co, Al, and Sr concentrations, whereas the Fe concentrations are the lowest, which is reportedly explained by a decrease in the concentrations of organic compounds and an increase in pH of the lacustrine waters (and a corresponding decrease in the Fe solubility). The paper reports data on the speciation of metals in the lacustrine waters: Fe and Cu occur in them mostly in compounds with organic ligands Fe(III)–L and Cu(II)–L; Mn is contained as Mn(II)– $${\text{SO}}_{4}^{{2 - }}$$ /Cl–/OH– compounds; and Ni, Co, and Zn form compounds with hydroxyl groups Ni(II)–OH, Co(II)–OH, and Zn(II)–OH. Concentrations of heavy metals in the lacustrine bottom sediments depend on the dominant form of their occurrence in the waters. The surface layers of the bottom sediments are significantly enriched in heavy metals (Ni, Cu, Co, Cd, Pb, As, Hg, Fe, and Mn), which are tens of times higher than the background concentrations. The highest values of the contamination factor (Cf) and degree of contamination (Cd) were found in the lakes contaminated with waste waters from the facilities.

Collaborative research to support urban agriculture in the face of change: The case of the Sumida watercress farm on O'ahu.

As urban areas expand around the world, there are growing efforts to restore and protect natural and agricultural systems for the multitude of ecosystem services they provide to urban communities. This study presents a researcher-farmer collaboration in a highly urbanized area of O'ahu focused on understanding the historical and current challenges and opportunities faced by a culturally and socially valued spring-dependent urban farm, Sumida Farm, which produces the majority of the state of Hawai'i's watercress. We conducted a long-term trend analysis (25 years) of factors identified by the farmers to be important historical drivers of crop yield, including groundwater pumping, pest outbreaks, temperature, Oceanic Niño Index, and precipitation. We combined this analysis with a year of intensive spring water sampling on the farm to evaluate nutrient and contaminant composition and flow to understand water-related stressors, as well as evaluate the potential of the farm to provide nutrient retention services. We found negative correlations between historical crop yields and increases in the Oceanic Niño Index, temperature thresholds, and pest outbreaks. Despite the surrounding urbanization, we found on-farm water quality to be very high, and microbial analyses revealed an abundance of denitrifiers (nirS gene) suggesting that the farm provides a nutrient retention service to downstream systems. Finally, we found that socio-cultural values including heritage value, aesthetic value, and educational value are increasingly important for the Sumida family and surrounding community. These socio-cultural benefits alongside highly valued local food production and nutrient retention services are essential for continued community and political support. Collectively, our study demonstrates that challenges facing urban agricultural systems shift through time, and that recognition of the beyond crop-yield benefits of these systems to urban communities is essential to their long-term survival.

Imaging contamination surrounding a wastewater dumpsite using 2 terrain conductivity meters

Terrain conductivity meters are effective tools for imaging shallow groundwater and soil contamination; however, the capability of different meters as well as the comparability of their results is a controversial issue. We used the EMP-400 Profiler and EM-31 terrain conductivity meters to investigate the soil and groundwater contamination around a wastewater lake in Wadi Uranah, western Saudi Arabia. Both devices are used simultaneously to collect apparent conductivity data along 19 profiles with a total length of 40 kilometers and the collected data are subjected to similar processing routines and plotting parameters. The results show that despite differences in the absolute conductivity values acquired by both meters, they produce significantly comparable subsurface images of apparent conductivity distribution. The results also show that each meter has a set of advantages and disadvantages. The EMP-400 Profiler is lighter, smaller, and easier to handle and operate in field and has the capability to operate at 3 different frequencies, yielding images at variable depth slices. On the other hand, subsurface apparent conductivity images provided by the EM-31 show apparent conductivity images with more details those of the EMP-400 Profiler. The apparent conductivity maps, collected by both meters, confirm that the flow and accumulation of contaminants in the area are structurally controlled and trending the northeast-southwest direction.

Multi-pollutant approach to model contaminants flow in surface and groundwater: A review

Pollution of surface and groundwater is largely caused by anthropogenic activities and the natural geogenic processes. Most of the contaminants in surface and groundwater have a common origin. The aim of this review is to highlight the importance of multi-approach modeling of pollutants which is required for various reasons, owing to the availability of different types and sources of water pollutants. We attempted a systematic review to assess the current progress in modeling water pollution using multi-approach methods. Results showed that (9) out of the eleven (11) chosen studies have applied some forms of multi-approach modeling methods to examine pollutants in surface and groundwater. Results also suggest that there is an increased concern on understanding how pollutants are transported from sources to surface water and how impurities are transported to groundwater aquifers by infiltering surface flows. A major limitation of water quality models is that models assumed a uniform environmental setting and can simulate contaminants only in the gas and aqueous states. The rationality of contaminant modeling using multi-pollutant approaches is mostly problematical to validate because suitable field data is wanting for comparison. Therefore, the model output must be scrutinized within the context of the uncertainty of the model inputs, data limitations and consistently essential application of established standards from the literature.

β-Cyclodextrin Polymerized in Cross-Flowing Channels of Biomass Sawdust for Rapid and Highly Efficient Pharmaceutical Pollutants Removal from Water.

Water pollution arising from pharmaceuticals has raised great concerns about the potential risks for biosphere and human health. However, rapid and efficient removal of pharmaceutical contaminants from water remains challenging. Wood sawdust, a byproduct of the wood-processing industry, is an abundant, cost-effective, and sustainable material with a unique hierarchically porous microstructure. These features make wood sawdust quite interesting as a filtration material. Here, we report a novel cross-flow filtration composite based on β-cyclodextrin-polymer-functionalized wood sawdust (β-CD/WS) in which the pharmaceutical contaminant water flows through the sawn-off vessel channels and the micropores on the surface of the cell walls, generating the turbulence. Such water flow characteristics ensure full contact between pharmaceutical pollutants and β-CD grafted on the cellulose backbone of wood sawdust, thereby enhancing the water treatment efficiency. Consequently, the β-CD/WS filter device shows a high removal efficiency of over 97.5% within 90 s for various pharmaceutical contaminants including propranolol, amitriptyline, chlortetracycline, diclofenac, and levofloxacin, and a high saturation uptake capacity of 170, 156, 257, 159, and 185 mg g-1, respectively. The high-performance wood-sawdust-based cross-flow filtration opens new avenues for solving the global water pollution issues, especially those caused by pharmaceutical contaminants.

Micro-Physics of Discipline: Spaces of the Self in Middle Eastern Women Life Writings

Contemporary life narratives by or about Middle Eastern women often portray the female body as the object of oppressive ethical and political governmentalities. This article focuses on the writings of a generation of secular and Muslim women, whose works describe the condition of women as subjugated by sovereign states and disciplinary governments, to examine the politics of space in the workings of the complex interactions between gender and power. To this end, Erving Goffman’s spatial theories on the territories of the self and the modalities of contamination are used to examine the function of political spaces in Jean P. Sasson’s Princess, Azar Nafisi’s Reading Lolita in Tehran, Zainab Salbi’s Between Two Worlds, and Manal al-Sharif’s Daring to Drive. The findings indicate that three modes of violations strategically contaminate the female subjects’ spaces of the self: informational preserve, physical and interpersonal. Of all the three modes, physical contamination—such as mandatory veiling/deveiling, corporeal exposure, forced exposure to dirt and appropriation of personal possessions—proves to be the most common. The study concludes that even though space is used as a strategy of regulating the female body, the subjugated women constantly struggle to re-construct different spaces to disrupt the flow of contamination..

Analysis of the relation between pollutant loading and water depth flowrate changes in a constructed wetland for agricultural nonpoint source pollution management

When stormwater runoff flows into a constructed wetland, the water level changes inside, and the volume of the wetland changes accordingly. In this study, the relationship between pollutant removal and water depth flowrate changes was analyzed with velocity phase analysis, using the concepts of horizontal velocity and vertical velocity. A constructed wetland located in an agricultural area was used for the velocity phase analysis. Analysis results revealed that all four ponds and Phases I and III accounted for over 90% of the pollutant load. In particular, Phase III, where vertical and horizontal velocities were reduced, was responsible for approximately twice the load on average. The reason for the highest load in Phase III was due to the inflow of contaminants into the constructed wetland through the first flush effect occurred at the time when the flow rate decreased due to the difference in runoff strength. Therefore, it is necessary to maximize Phases I and III in the velocity phase when designing multi-stage wetlands to make the flow of water more natural. Furthermore, considering pollutant load levels, a design review is needed to expand the size of downstream wetlands, so that they can optimize water quality management functions.

Three-dimensional velocity and concentration measurements and simulations of a scaled Jack Rabbit II mock urban array

Abstract Magnetic resonance (MR) techniques provide non-invasive, three-dimensional measurements of velocity and concentration fields. Applying MR techniques to measure flows of contaminants through urban arrays provides a wealth of information that is difficult to obtain with large-scale field tests. In this project, a 1:188 scaled model of the phase 1 Jack Rabbit II field test was replicated and studied using a water tunnel with properties chosen to mimic field conditions. Three-dimensional, time-averaged flow data was measured using magnetic resonance velocimetry (MRV) and magnetic resonance concentration (MRC) techniques. The scaled flow was also modeled with large-eddy simulations (LES) to provide a dataset for comparison with the MR based measurements. Despite a complex, three-dimensional flow field, both velocity and concentration show good agreement between the experimental measurements and simulation data. Measurement uncertainty was estimated to be ± 5 % of each of the measured velocity components at each location for MRV and ± 4 % of the measured concentration at each location for MRC.

Omni-Gravity Nanophotonic Heating and Leidenfrost-Driven Water Recovery System

Abstract Recycling systems aboard spacecraft are currently limited to approximately 80% water recovery from urine. To address challenges associated with odors, contamination, and microgravity fluid flow phenomena, current systems use toxic pretreatment chemicals, filters, and rotary separators. Herein, a semipassive and potentially contaminant- and biofouling-free approach to spacecraft urine processing is developed by combining passive liquid–gas separation, nanophotonic pasteurization, and noncontact Leidenfrost droplet distillation. The system aims to achieve >98% water recovery from wastewater streams in zero, Lunar, Martian, and terrestrial gravitational environments. The surfaces of the phase separator are coated with carbon black nanoparticles that are irradiated by infrared light-emitting diodes (LEDs) producing hyperlocal heating and pasteurization during urine collection, separation, and storage. For the prescribed flow rate and timeline, the urine is then introduced into a heated 8.5-m-long helical hemicircular aluminum track. The low pitch and the high temperature of the track combine to establish weakly gravity-driven noncontact Leidenfrost droplet distillation conditions. In our technology demonstrations, salt-free distillate and concentrated brine are successfully recovered from saltwater feed stocks. We estimate equivalent system mass metrics for the approach, which compare favorably to the current water recovery system aboard the International Space Station.

Investigation of the dependence of small rivers on the state of bottom sediments by mathematical methods

Emergency inflow of contaminants into river waters, construction of various hydraulic engineering structures can have an adverse impact on the river ecosystem. Water quality assessment is necessary for operative water resources management, development of engineering solutions for water streams rehabilitation. In this work, application of genetic algorithms for selection of significant indicators of bottom sediments quality for water quality indicators of small rivers in the Republic of Bashkortostan (Russia) has been tested. Selection of significant parameters for indicators of water quality of small rivers was conducted from input parameters: hydrochemical indicators of water quality, indicators of quality of bottom sediments.

Infiltration of surface water through subsidence failure assessment applying electric prospecting, case Aguascalientes Valley, Mexico

Abstract. Land subsidence is an anthropogenic hazard triggered by different causes, one of them is groundwater overexploitation over aquifer systems composed for granular compressible sedimentary fill. One of the effects of this phenomenon is the generation and reactivation of ground failures, becoming risk points for aquifer pollution through the fast infiltration of contaminated water. A system of failures and fractures has developed in the Aguascalientes valley since 1980's when groundwater overexploitation became intensive. Currently, the entire valley present regional subsidence and several ground failures have developed; many of them crossing surficial water flows and sewage pipes, thus, inducing filtering of domestic wastewater to the subsoil and increasing the environmental hazard for the aquifer system. In this work, we present the results of a study to assess the surficial water infiltrations through a subsidence related ground failure crossing a small stream, which carries domestic wastewater. Additionally, we investigate the acquisition method of Electrical Resistivity Tomography (ERT) and the electrode placement more suitable to detect the flow of contaminated water through the studied ground failure. To find out the potential leakage, we use electric geophysical methods, applying Schlumberger, Wenner and dipole-dipole arrangements with electrode separations from 2.5 to 10 m in order to explore a depth from 9 to 30 m. The obtained results showed that the Schlumberger configuration appears to be more helpful to detect changes in the stratigraphy toward depth, while dipole-dipole and Wenner are more suitable to detect lateral variations such as the vertical wastewater leakage in the first 6 to 8 m depth. Resulted resistivity models showed that in the first 10 m depth, the contaminant flow follow with a vertical path through the ground failure, then, the it becomes horizontal, flowing through the more permeable soil strata. Therefore, for the studied sites, the filtration of domestic wastewater through ground failure does not represent an immediate hazard to the aquifer system. Nevertheless, ground failures crossing damaged wastewater pipes or contaminated surficial water flows in Aguascalientes Valley, could induce the infiltration of polluted water to the near surface strata, favoring a potential aquifer pollution in a long term.

Simulated Moving Bed Purification for Flavonoids from Tartary Buckwheat Shell.

Tartary buckwheat shell is an important by-product of Tartary buckwheat production. Previous studies shown that Tartary buckwheat shells are rich in flavonoids, which are responsible for their antioxidant properties. Due to lack of advanced separation technologies, the purification for Tartary buckwheat shell is still in the laboratory scale, and could not realize the industrialization production. According to the results of static adsorption experiment, AB-8 resin was selected for Tartary buckwheat shell flavonoids (TBSF) adsorption. The adsorption isotherm, resin adsorption thermodynamic and dynamic adsorption parameters were studied. And the adsorption of AB-8 resin for TBSF was determined as an endothermic process. Results of preparative chromatography experiment showed that TBSF could be efficiently purified by AB-8 resin. And the optimal parameters were: feed concentration 25mg/mL, desorption flow rate 2.5mL/min. Under these conditions, the TBSF were separated effectively. Results of liquid chromatography-mass spectrometer (LC-MS) indicated that there were seven kinds of flavonoids in Tartary buckwheat shell, which were mainly from the 40 and 60% of ethanol elution. Simulated moving bed (SMB) was applied for TBSF purification the first time in this study. The optimal conditions of SMB were as following: adsorption zone flow rate 7.0mL/min, contaminant removal zone flow rate 17.9mL/min, product elution zone flow rate 22.3mL/min, regeneration zone flow rate 21.5mL/min, water washing zone flow rate 27.5mL/min, switching time 1260S, and the purity and yield of TBSF was 90±0.22% and 85±0.28%, respectively. The IC50 values of α-glucosidase inhibition activities and DPPH scavenging activity of the purified TBSF were 57.09±0.15 and 7.92±0.23μg/mL, respectively. The constituents of TBSF showed higher α-glucosidase inhibition activities and antioxidant than raw TBSF and rutin. The results suggest that SMB is a proper method for industrial production of TBSF, and SMB could be applied for other natural products purification.

On the backlayering flow of the buoyant contaminants in a tunnel with forced longitudinal ventilation

In a longitudinally ventilated tunnel, the backlayering flow of buoyant contaminants appears when the ventilation velocity is lower than the critical velocity. In this study, we use brine-water experiments to investigate the backlayering length and the flow structure of the backlayering flow. It is found that the “seemingly stagnant” backlayering flow actually consists of two sub-layers moving towards opposite directions. The distribution of the reduced gravity in the entire model tunnel is measured using a light attenuation technique. The contaminant concentration in the backlayering flow is significantly larger than that in the downstream current. A dimensionless parameter is proposed to normalize the density distribution in different backlayering flows. In the scenario without boundary heat transfer, the mass exchange between the buoyant fluid and ambient fluid also can reduce the buoyancy force of the backlayering flow. A model is proposed to estimate the backlayering length without boundary heat loss. Because both boundary heat loss and mass exchange contribute to the buoyancy attenuation of smoke backlayering flow, the effect of the boundary heat transfer on the backlayering length is quantitatively analyzed by comparing the present model with previous models of smoke backlayering. The results are helpful for understanding the buoyant backlayering flow in longitudinally ventilated tunnels.

Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-based Electrical Insulation.

Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better thermal conductivity and thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.

Numerical Simulation of the Flow Field and Pollutant Dispersion around a Hill under Different Thermal Stratifications

AbstractThis paper applied a commercial computational fluid dynamics code, STAR-CD, with the renormalization group k–ε turbulence model to simulate the flow and dispersion of contaminants released from a source on the windward side of a hill under different thermal stratifications. In the wake region, the influence of atmospheric stratification on the flow field is inconspicuous under neutral and unstable conditions because of the effect of mechanical disturbance. However, this influence becomes slightly conspicuous under stable conditions. When atmospheric stratification is stable, in the range of z/H < 1.0 (where z is height above the surface and H is height of the hill), the velocity deficits are smaller than those under neutral and unstable conditions. The maximum turbulence kinetic energy (TKE) appears in the wake regions, and the variation in TKE is significantly lower than that under neutral and unstable conditions. When atmospheric stratification is unstable, the vertical and horizontal spread of the plume is slightly greater than that under neutral and stable conditions and the maximum concentration is less than that under neutral conditions. When the Froude number is large (~11; Brunt–Väisälä frequency = 0.52), atmospheric stratification is slightly stable, the structure of flow around the hill is generally similar to that under neutral conditions, and the high-concentration regions are large on the windward side of the hill. Smaller high-concentration regions just appear on the windward side of the hill under unstable conditions. The pollutant concentrations in the wake region of the hill increase as a result of the effect of thermal stability, and the vertical spreading range of the plume along the downwind axis (x axis) is larger than that under neutral and stable conditions.

Explicit finite difference solution for contaminant transport problems with constant and oscillating boundary conditions

For constant and oscillating boundary conditions, the 1-D advection-diffusion equation with constant coefficients, which describes a contaminant flow, is solved by the explicit finite difference method in a semi-infinite medium. It is shown how far the periodicity of the oscillating boundary carries on until diminishing to below appreciable levels a specified distance away, which depends on the oscillation characteristics of the source. Results are tested against an analytical solution reported for a special case. The explicit finite difference method is shown to be effective for solving the advection-diffusion equation with constant coefficients in semi-infinite media with constant and oscillating boundary conditions.

Spatial disturbance synchrony alters the association of food chain length and ecosystem size

AbstractThe origin of variation in food chain length (FCL) has long been a central topic of ecology due to its influences on trophic control, energy flow and bioaccumulation of environmental contaminants. The positive association of FCL and ecosystem size has been consistently supported in natural systems. Recent studies, however, have begun to report no effects of ecosystem size on FCL. The emerging inconsistency among previous studies implies the existence of overlooked factors that can modulate the relationship between FCL and ecosystem size. Here, we developed a mathematical model describing metacommunity dynamics to show that large ecosystems do not necessarily support long food chains in the presence of spatially correlated disturbance. Our simple model predicted that the effect of ecosystem size was strongly dependent on the spatial extent of disturbance synchrony. When the spatial correlation of disturbance was weak, the positive association between FCL and ecosystem size appeared. However, the relationship of FCL and ecosystem size became more complex, including hump‐shaped and multimodal forms, as the spatial extent of disturbance synchrony increases. This pattern emerged because larger ecosystems have wider aerial coverage, so more chances exist that an episodic disturbance hits some of the habitat patches and spreads across the landscape. Our finding highlights the important role of spatial disturbance synchrony in driving FCL, providing insights into why ecosystem size effects are variable across systems.

Effects of ontogeny and invasive crayfish on feeding ecology and mercury concentrations of predatory fishes

Lake food web structure dictates the flow of energy and contaminants to top predators, and addition of invasive species can shift these flows. We examined trophic position (TP), proportional reliance on the littoral zone (Proplittoral), and mercury (Hg) concentrations across the life-span of two predatory fishes, walleye (Sander vitreus) and northern pike (Esox lucius), in lakes with and without invasive virile crayfish (Faxonius virilis). The littoral zone was the dominant foraging zone for both species regardless of size, accounting for 59% and 80% of the diet of walleye and pike, respectively. Both species increased in TP and Hg with body size, as did crayfish. Walleye in crayfish-present lakes had lower Proplittoral, TP, and Hg concentrations compared with non-present lakes, but trophic magnification of Hg through the food web was consistent across all six lakes. These findings underscore a strong role for the littoral zone in channeling energy and contaminants to higher trophic levels and how invasive species can occupy new habitats at low abundance while altering food web structure and contaminant bioaccumulation.

1 D contaminant transport through unsaturated stratified media using EFGM

In the present study, analysis of contaminant transport through one dimensional unsaturated stratified media using element free Galerkin method has been presented. Element free Galerkin method is a meshfree method. A FORTRAN code has been developed for the same. The developed model is compared with the results available in the literature and are found in good agreement. Further a parametric study has been conducted to examine the effects of various parameters like velocity, dispersivity, retardation factor and effect of saturation on the contaminant flow. The results presented conclude that transport of contaminant is retarded in unsaturated zone in comparison with the saturated zone.