Infiltration Of Contaminants Research Articles

Partially coated TiO2 on Al2O3 membrane for high water flux and photodegradation by novel filtration strategy in photocatalytic membrane reactors

Partially coated TiO2 (pc-TiO2) layer on the porous Al2O3 membrane substrate was developed by using low-cost poly (vinyl chloride) (PVC) to generate interstitial voids to be applied in a photocatalytic membrane reactor for the treatment of organic dye contaminant. The combination of dead-end filtration with cross-flow filtration under intermittent UV irradiation onto a developed composite ceramic membrane was suggested to reduce the membrane fouling effectively. Our study showed that the water flux and anti-fouling properties of the pc-TiO2/Al2O3 composite membrane was much higher than those of uniformly coated TiO2 (uc-TiO2)/Al2O3. Cross-flow membrane filtration provided a much greater synergistic impact on photocatalytic activity for both uc- and pc-TiO2/Al2O3 composite membranes than Al2O3 bare membrane substrate. Less fouling caused by hydrodynamic shear along the membrane surface is thought to be associated with better accessibility of UV irradiation by the reactive surface of the TiO2/Al2O3 composite membrane, promoting the photodegradation of the organic dye contaminant in water filtration.

Micropollutants related to human activity in groundwater resources in Barbados, West Indies

Several micropollutants, including caffeine, artificial sweeteners, pharmaceuticals, steroid hormones and a current-use pesticide were analyzed in water samples collected from five groundwater pumping stations in Barbados. The presence of caffeine and three artificial sweeteners (i.e. acesulfame, sucralose, saccharin) in groundwater samples indicated that groundwater was being contaminated by infiltration of wastewater into the karst aquifer. An estrogen (i.e. estrone), three pharmaceuticals (i.e. carbamazepine, trimethoprim, ibuprofen) and a transformation product of the fungicide, chlorothalonil (i.e. 4-hydroxychlorothalonil) were also detected at ng/L concentrations in groundwater collected from two or more pumping sites. The concentrations of carbamazepine and trimethoprim were correlated with the concentrations of caffeine (R2 values of 0.70 to 0.80), indicating pharmaceutical contamination of groundwater by infiltration from domestic wastewater. The concentrations of caffeine were generally higher in groundwater samples collected in June during the wet season relative to the concentrations in samples collected in February during the dry season, indicating that infiltration of contaminants is higher during periods of heavy rainfall. Rapid rates of degradation and relatively slow rates of infiltration may explain why several target analytes were not detected in groundwater. Elevated concentrations of 4-hydroxychlorothalonil > 0.1 μg/L in samples collected at two of the monitoring sites warrant further studies on the sources and the distribution of this compound and other pesticides used in agriculture and for turf-treatment (e.g. golf courses). Overall, more data are needed in order to implement mitigation strategies that are effective in reducing chemical contamination in groundwater in Barbados.

Combinational Biomimicking of Lotus Leaf, Mussel, and Sandcastle Worm for Robust Superhydrophobic Surfaces with Biomedical Multifunctionality: Antithrombotic, Antibiofouling, and Tissue Closure Capabilities.

Surface wetting occurring in daily life causes undesired contaminations, which are critical issues in various fields. To solve these problems, the nonwetting property of a superhydrophobic (SH) surface has proven its utility by preventing contaminant infiltration, serious infections, or malfunction. However, the application of SH surfaces in the biomedical field has been limited due to the weak durability and toxicity of the related components. To overcome these limitations, we developed a robust and biocompatible SH surface through combinational biomimicking of three natural organisms, lotus leaf, mussel, and sandcastle worm, for the first time. Using the water-immiscible and polycationic characteristics of mussel adhesive protein (iMglue), an SH iMglue-SiO2(TiO2/SiO2)2 coating was fabricated by solution-based electrical charge-controlled layer-by-layer growth of nanoparticles (NPs). The fabricated iMglue-SiO2(TiO2/SiO2)2 SH surface showed excellent durable nonwetting properties and was applied to an intracatheter tube coating to develop antithrombotic catheters under blood flow. Furthermore, we developed a iMglue-employed SH patch for a tissue closure bandage by spraying hydrophobic SiO2 NPs on the iMglue-covered cotton pads. The prepared iMglue-employing SH patch showed perfect bifunctionality with excellent antibiofouling and tissue closure capabilities. Our work presents a novel, useful strategy for fabricating a biomedically multifunctional, robust SH surface through combinational mimicking of natural organisms.

Estudo da vulnerabilidade à contaminação na porção norte da Bacia Hidrográfica do Ribeirão Claro, SP

Pelo fato de o Aquífero Rio Claro ser um aquífero livre e de estar relativamente próximo da superfície, acaba se tornando susceptível à infiltração de contaminantes das mais variadas fontes. O presente artigo apresenta um estudo sobre a vulnerabilidade das camadas superficiais dos perfis de alteração da Formação Rio Claro na porção norte da Bacia Hidrográfica do Ribeirão Claro. Como produto principal, foi gerado um mapa de vulnerabilidade à contaminação, na escala 1:50.000, que correlaciona a geologia e o uso e ocupação do solo na área. Além disso, foram realizados ensaios geotécnicos in situ com o permeâmetro de Guelph e a coleta de amostras deformadas e indeformadas de solos pertencentes à Formação Rio Claro para a realização de ensaios geotécnicos para obtenção dos índices físicos e de granulometria e sedimentação. Com os resultados obtidos foi possível observar uma heterogeneidade nos valores de condutividade hidráulica nos solos da Formação Rio Claro, reflexo de sua composição também variada. A vulnerabilidade à contaminação observada neste estudo foi, em geral, alta para toda a área do aquífero.

Litho-stratigraphic and hydrogeological evaluation of groundwater system in parts of Benin Metropolis, Benin City Nigeria: The key to groundwater sustainability

Previous studies revealed that soil properties play a significant role in aquifer contamination. Consequently, it is necessary to understand the nature and properties of soil in carrying out groundwater evaluation. This study evaluates the subsurface geology and groundwater flow direction in Okpagha, Iguomo, Ikhueniro and Okhuahe suburbs in Benin City, Nigeria. Six boreholes were drilled by means of manual (rotary) method in different parts of the study area and each borehole was logged in order to understand the lithology, depth to water table, static water level as well as flow direction. The results obtained show that aquifer within the study areas were confined, semi confined to unconfined and was dominated by sands with minor clay and lignite interbed. It was observed that aquifer becomes shallower towards eastern portion of the study areas with increase in sand and decrease in clay materials. It was also observed that groundwater flow map revealed a flow direction of North-West to South-East from North West to South East. The decrease in the depth of aquifer and increase in sand material could be explained by the closeness to sea level. This phenomenon can enhance the infiltration of contaminants into aquifer thereby contaminating the groundwater bodies. It is therefore necessary to constantly monitor the groundwater quality in this suburbs in order to be aware of the quality of water resources being consumed because poor water quality can impact public health negatively. Furthermore, the authors advise that boreholes should be drilled in the direction of groundwater flow for maximum yield Keywords : Groundwater, lithology, borehole, aquifer, water quality and contaminants

Assessment of Hydrocarbons (C10-C50), Polycyclic Aromatic Hydrocarbons (PAHs), and Trace Metals (TMs) Contamination in the Riverbanks of the Chaudière River Three Years after the Lac-Mégantic Railway Disaster (Southern Québec, Canada)

ABSTRACTOn July 6, 2013, in downtown Lac-Mégantic (southern Québec, Canada), several tank cars carrying crude oil derailed. This resulted in a series of explosions and a huge fire that led to the terrible Lac-Mégantic disaster. This study deals with the characterization of the Chaudière River banks and bed in order to determine the current state of contamination by hydrocarbons (C10-C50), polycyclic aromatic hydrocarbons (PAHs), and trace metals (TMs). The highest concentrations of hydrocarbons found in the Chaudière River are respectively 960 mg kg−1 dry weight in soil and 760 mg kg−1 dry weight in river sediment. Over half of the all samples were under the detection threshold (i.e. > 300 mg kg−1 in soil and > 832 mg kg−1 in sediment). The concentration in river sediment PAH concentrations were low, with values below the detection threshold. TM concentrations in the soil and sediment are also very low, rarely exceeding class A and B thresholds and chronic effect reference values (164 mg kg−1) which constitute the criteria for soil quality and the protection of aquatic life established by the Québec Environment Ministry. These low levels are largely due to the efforts deployed by government authorities to limit the infiltration and dispersal of contaminants along the river, and to the hydrological conditions that also favoured the dispersal and dilution of pollutants.

Risk assessment of groundwater environmental contamination: a case study of a karst site for the construction of a fossil power plant.

This paper presents a demonstration of an integrated risk assessment and site investigation for groundwater contamination through a case study, in which the geologic and hydrogeological feature of the site and the blueprint of the fossil power plant (FPP) were closely analyzed. Predictions for groundwater contamination in case of accidents were performed by groundwater modeling system (GMS) and modular three-dimensional multispecies transport model (MT3DMS). Results indicate that the studied site area presents a semi-isolated hydrogeological unit with multiplicity in stratum lithology, the main aquifers at the site are consisted of the filled karst development layer with a thickness between 6.0 and 40.0m. The poor permeability of the vadose zone at the FPP significantly restricted the infiltration of contaminants through the vadose zone to the subsurface. The limited influence of rarely isotropic porous karstified carbonate rocks on the groundwater flow system premised the simulate scenarios of plume migration. Analysis of the present groundwater chemistry manifested that that the groundwater at the site and the local area are of the HCO3-Ca, HCO3, and SO4-Ca types. A few of the water samples were contaminated by coliform bacteria and ammonia nitrogen as a result of the local cultivation. Prediction results indicate that the impact of normal construction and operation processes on the groundwater environment is negligible. However, groundwater may be partly contaminated within a certain period in the area of leakage from the diesel tanks, the industrial wastewater pool, and the cooling tower water tank in case of accidents. On a positive note, none of the plumes would reach the local sensitive areas for groundwater using. Finally, an anti-seepage scheme and a monitoring program are proposed to safeguard the groundwater protection. The integrated method of the site investigation and risk assessment used in this case study can facilitate the protection of groundwater for the construction of large-scale industrial project.

Mathematical modelling and computer simulation of toxic gas building infiltration

Abstract A toxic gas release, e.g. H2S, from pipeline accidents or sour wells, although improbable, may lead to serious consequences for the health of people and the environment. Such incidents might also jeopardize occupants of nearby indoor environments via infiltration of toxic contaminants. Despite that risk, there is still a lack of data and of comparative studies concerning the appropriate models and mitigation methods. The purpose of this work is, therefore, the improved modelling of toxic gas building infiltration, by a combination of tools and approaches. Using a realistic release scenario, the present comprehensive analysis demonstrates the need to consider the detailed building characteristics and meteorology. Significant deviations are observed between simple and advanced building ingress models. Furthermore, the consequences assessment leads to contradicting conclusions depending on the employed dose-response approaches. The proposed methodology could serve as a guide for the improvement of relevant risk-assessment tools and of future studies.

Comparison of Potential Risk on Two Managed Aquifer Recharge Sites from River Basin

Drinking water production facilities are designed to filter contaminants that are ever-present in raw water. These facilities, however, pose risks of tap water contamination or water supply discontinuation in the event of a massive chemical spill. A managed aquifer recharge (MAR) offers the advantage of purifying surface water as well as maintaining water underground for extended periods of time, thus securing sufficient time for a response to contaminant infiltration and dramatically increasing consumer safety. However, contaminated aquifers are difficult to recover; accordingly, it is important that MAR sites engage in preemptive responses to chemical spills in order to protect their aquifers. This study assesses potential risks in order to quantify the detrimental impacts of chemical spills in cities located in river basins on drinking water supply facilities. The targets of analysis are two MAR sites in South Korea. The potential risk analysis offers grounds upon which aggressive basin management can be implemented to ensure water supply facility operation safety. The lack of data for available for analysis is addressed using a stochastic methodology that ranks cities in which MAR sites are endangered based on the cities’ potential risk probability distributions. The results of the analysis show that water supply facilities surrounded by larger cities have relatively higher potential risks, and would, therefore, need to handle more management targets to prevent chemical spills. Furthermore, the proposed methodology contributes not only to potential risk management of existing water supply facilities, but also to MAR site selection.

Assessment of intrinsic vulnerability to the contamination of karst aquifer using the COP method in the Carste Lagoa Santa Environmental Protection Unit, Brazil

This study addresses the intrinsic groundwater vulnerability by using the COP method index and GIS technology on the karst-fissured aquifer of the Carste Lagoa Santa Protection Unit, located in the state of Minas Gerais, Brazil. This area has a great importance due to its rich paleontology, archeology and speleology. The region is groundwater dependent, and it has been suffering pressure by economic development. Therefore, it is important to identify vulnerable areas in which infiltration of contaminants is likely to happen. The main goal of this study was to create an intrinsic groundwater contamination vulnerability map (scale 1:50.000), which will be used to assist the implantation of groundwater monitoring net project in the area. The index vulnerability was evaluated by analyzing COP model parameters through geoprocessing techniques. However, in order to adapt the method to the studied area conditions, changes in frame and values of input parameter weights (lithology and slope/vegetation) were necessary. The outcomes showed five categories of groundwater contamination vulnerable zones: high to the highest vulnerability level (10.95%), moderated (58.77%) and low to the lowest vulnerability (30.28%). Despite the low percentage of high to the highest vulnerably level area, they must be considered by environmental managers due to strong relationship between superficial and groundwater in the area.

Assessment of groundwater vulnerability to pollution using the Kherici’s method in the Talezza plain, Collo region (NE Algeria)

Abstract The intrinsic vulnerability of groundwater aquifers refers to their sensitivity to all contamination coming from soil surface irrespective of the nature of the polluting. In order to improve the protection of groundwater, there must be a reduction in the infiltration of contaminants towards the reservoir through the impacting factors determination of this phenomenon by means of research. There are collected models that include particular number of factors which allow the determination of a sign of groundwater vulnerability of all superficial pollutions. The goal of the study centers on ascertaining the state of vulnerability and the risk of groundwater pollution of the Collo region with a new proposed method by Kherici. Generally, assessment methods of vulnerability and the danger of groundwater pollution employ parametric systems with numerical quotation, cartographic superposition where the analytical methods are based on equations. In this study, we consider the combination of criteria dependent on natural factors (thickness of the unsaturated zone, geologic facies, degree of auto-purification) and the causes of groundwater vulnerability to man-made pollution (anthropogenic factors).

Investigation of Possible Impact of 2, 4, 6-Trinitrotoluene (TNT) Explosive Seismic Energy Source on the Nitrate Content of Groundwater in Sagbama Area, Niger Delta, Nigeria

The impact of 2, 4, 6-trinitrotoluene (TNT) high explosive seismic blasting operations on the nitrate content of groundwater in Sagbama area, Niger Delta, Nigeria was investigated. A total amount of 116, 349.2 kg 2, 4, 6trinitrotoluene (TNT) was detonated in 60, 398 source point in an area of 771.26 square kilometers of Sagbama area. Eleven boreholes was used to study the impact of the TNT shots in Sagbama area. Ultraviolet spectroscopic method was used in the determination of nitrate in the groundwater. A control sample was taken from the borehole stations by sampling a day before detonation of TNT. Subsequently, sampling was carried out a day after TNT detonation and then, on a fourth-nightly basis. The average nitrate value of the control (water before detonation) was 2.53 mg/l. After dynamite detonation, the average measured nitrate values ranged from 2.56 to 2.65 mg/l. These variations of the water sample test values in comparison with the values of the control samples were not significant enough to be said that there was any groundwater contamination. Computation of the grain size distribution curve parameters yielded a permeability value of 3.24 cm/sec. The representative litho logy of Sagbama area as revealed by the borehole logging showed that they are mainly non-plastics also categorized as cohensionless sands. The presence of silty sands at 4 to 5m depths could be an obstruction to infiltration of contaminants from dynamite detonation. However, the nitrate content of the groundwater was below 10 mg/l compliance limit of U.S. Environmental Protection Agency (EPA) standards.

Geophysical monitoring of subsurface contamination in two-phase porous media

We have explored a new technology based on using low-frequency strain attenuation data to monitor the infiltration of contaminants into two-fluid phase porous materials. The attenuation mechanism is related to the loss of energy due to the hysteresis of resistance to meniscus movement (changes in surface tension and wettability) when a pore containing two fluids is stressed at very low frequencies. This phenomenon was verified in our laboratory experiments and applied to a field study near Maricopa, Arizona. In the field study we conducted controlled experiments with the aim of detecting and monitoring the infiltration of a contaminant – a biosurfactant – into groundwater. Three sets of geophysical instruments, each consisting of a 3-component seismometer and a tiltmeter, were installed near an irrigation site. The experiment lasted about 3years with controlled irrigations of initially water only and then water with contaminant into the vadose zone. We used naturally occurring signals of microseisms for our seismic sources and solid Earth tides as sources for the tilt signals.To process the tilt data we extracted the tidal signal from the raw data, and then compared the measured tidal signals with site-specific theoretical data. Changes in tidal signals indicate a strong anomaly associated with the irrigation when a 150ppm concentration of a biosurfactant was present. No such anomaly was detected when only water was used. Further data processing with an automated procedure shows that the anomalies still persisted. Furthermore, the microseismic results from the seismic data suggest that there may also be a detectable anomaly.

Galvanic corrosion of aircraft bonded joints as a result of adhesive microcracks

This paper studies the root causes of a corrosion failure found in the Airbus A320 CFM56-5b intakes. This failure occurs in a dissimilar materials joint and is strongly related to the adhesive loss of integrity at very low temperatures. The ductility reduction of the adhesive at low temperatures promotes the microcracks formation within the adhesive layer of the bonded joint, which in turn sparks the corrosion process. These microcracks allow the infiltration of dust, moisture, contaminants and salt water in the interface between the adhesive and adherents, which promotes the creation of a dielectric between the joint adherents and consequently their galvanic corrosion. Results show that the thermal strains of the dissimilar joint materials at very low temperatures significantly reduces the adhesive load margin reserved for drag loads. Some remarks are drawn in order to improve the joint corrosion resistance.

Groundwater Vulnerability and Risk Mapping Based on Residence Time Distributions: Spatial Analysis for the Estimation of Lumped Parameters

Specific vulnerability estimations for groundwater resources are usually geographic information system-based (GIS) methods that establish spatial qualitative indexes which determine the sensitivity to infiltration of surface contaminants, but with little validation of the working hypothesis. On the other hand, lumped parameter models, such as the Residence Time Distribution (RTD), are used to predict temporal water quality changes in drinking water supply, but the lumped parameters do not incorporate the spatial variability of the land cover and use. At the interface between these two approaches, a GIS tool was developed to estimate the lumped parameters from the vulnerability mapping dataset. In this method the temporal evolution of groundwater quality is linked to the vulnerability concept on the basis of equivalent lumped parameters that account for the spatially distributed hydrodynamic characteristics of the overall unsaturated and saturated flow nets feeding the drinking water supply. This vulnerability mapping method can be validated by field observations of water concentrations. A test for atrazine specific vulnerability of the Val d’Orleans karstic aquifer demonstrates the reliability of this approach for groundwater contamination assessment.

Multiple, isotopically heterogeneous plagioclase populations in the Bushveld Complex suggest mush intrusion

The Bushveld Complex and other layered intrusions show significant initial isotopic heterogeneity, both between and within co-existing cumulate minerals. Various processes have been proposed to account for this, including (i) intrusion of variably contaminated crystal mushes from deeper staging chambers, (ii) blending of semi-consolidated crystal mushes as a result of subsidence during cooling, (iii) variable infiltration of contaminants into a partially solidified crystal mush, (iv) density-driven mixing of minerals from isotopically distinct magma pulses, (v) contamination of crystals at the roof of the intrusion and mechanical incorporation of such contaminated crystals into the lower crystallisation front as a result of gravitational instability at the upper crystallisation front, and (vi) late-stage metasomatic processes. In order to assess the likely process(es) responsible for initial isotopic heterogeneities within the Bushveld Complex, we analysed core and rim domains of 12 plagioclase crystals from the Main and Upper zones of the Bushveld Complex for their Sr-isotopic compositions. The data show the presence of multiple, isotopically heterogeneous populations of plagioclase occurring within the same rocks. The data presented here are best explained through the intrusion of variably contaminated crystal mushes derived from a sub-compartmentalized, sub-Bushveld staging chamber that underwent different degrees of contamination with crustal rocks of the Kaapvaal craton.

Potential Efficiency of Riparian Vegetated Buffer Strips in Intercepting Soluble Compounds in the Presence of Subsurface Preferential Flows.

Buffer strips have been widely recognized as to promote infiltration, deposition and sorption of contaminants for protecting surface water against agricultural contamination. However, such strips do not intercept all contaminants, particularly soluble ones. Although preferential flow (PF) has been suggested as one factor among several decreasing the efficiency of buffer strips, the mechanisms involved are not well understood. This project examines buffer strip efficiency at intercepting solutes when subsurface PF occurs. Two soluble sorbed tracers, FD&C Blue #1 and rhodamine WT, were applied on an agricultural sandy loam soil to evaluate the ability of a naturally vegetated buffer strip to intercept soluble contaminants. Rhodamine was applied about 15 m from the creek, while the Blue was applied 15 m to 165 m from the creek. Tracer concentration was measured over a two-year period in both the creek and the buffer strip through soil and water samples. Although the tracers traveled via different pathways, they both quickly moved toward the creek, passing beneath the buffer strip through the soil matrix. Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used. The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed.

A three-dimensional mesh-free model for analyzing multi-phase flow in deforming porous media

Fully coupled flow-deformation analysis of deformable multiphase porous media saturated by several immiscible fluids has attracted the attention of researchers in widely different fields of engineering. This paper presents a new numerical tool to simulate the complicated process of two-phase fluid flow through deforming porous materials using a mesh-free technique, called element-free Galerkin (EFG) method. The numerical treatment of the governing partial differential equations involving the equilibrium and continuity equations of pore fluids is based on Galerkin’s weighted residual approach and employing the penalty method to introduce the essential boundary conditions into the weak forms. The resulting constrained Galerkin formulation is discretized in space using the same EFG shape functions for the displacements and pore fluid pressures which are taken as the primary unknowns. Temporal discretization is achieved by utilizing a fully implicit scheme to guarantee no spurious oscillatory response. The validity of the developed EFG code is assessed via conducting a series of simulations. According to the obtained numerical results, adopting the appropriate values for the EFG numerical factors can warrant the satisfactory application of the proposed mesh-free model for coupled hydro-mechanical analysis of applied engineering problems such as unsaturated soil consolidation and infiltration of contaminant into subsurface soil layers.

Effect of biochar on leaching of organic carbon, nitrogen, and phosphorus from compost in bioretention systems

Compost is used in bioretention systems to improve soil quality, water infiltration, and retention of contaminants. However, compost contains dissolved organic matter, nitrate, and phosphorus, all of which can leach out and potentially contaminate ground and surface waters. To reduce the leaching of nutrients and dissolved organic matter from compost, biochar may be mixed into the bioretention systems. Our objective was to test whether biochar and co-composted biochar mixed into mature compost can reduce the leaching of organic carbon, nitrogen, and phosphorus. There was no significant difference between the effects of biochar and co-composted biochar amendments on nutrient leaching. Further, biochar amendments did not significantly reduce the leaching of dissolved organic carbon, nitrate, and phosphorus as compared to the compost only treatment. The compost–sand mix was the most effective in reducing nitrate and phosphorus leaching among the media.

Assessment of Groundwater Quality in the Dogger Aquifer of Poitiers, Poitou-Charentes Region, France

The Poitou-Charentes, located in the Center-West of France, is a region where economy is based mainly on agriculture. This region, made up of 4 Departments (Vienne, Charente, Charente Maritime, Deux-Sevres), is supplied largely by groundwater exploitation, both for consumption and for irrigation. This resource is thus vital to the region and its preservation is a major issue. The objective of this study is the determination of the groundwater quality in the Dogger aquifer of Poitiers (Vienne Department), which is the main water resource for this area and to achieve a better understanding of the factors influencing groundwater mineralization. Sixty-six wells, distributed over the study area, were sampled and analyzed for major ions (Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, SO42-, NO3-). Data were interpreted using graphical (Piper diagram, binary diagrams) and statistical methods (correlation matrix, principal components analysis). Saturation and chloro-alkaline indices were also computed. It is shown that the groundwater mineralization is mainly associated with Ca2+, K+, HCO3-, Cl-, SO42-, and NO3-. Hydrochemistry of groundwater is determined by both natural processes, and anthropogenic factors. Natural factors are dissolution of carbonate and dolomitic minerals, and cation exchanges with clays, while anthropogenic factors are contaminant infiltration with waste waters and agricultural fertilizers. Nitrate is the main contaminant found in the groundwater and makes this resource unsuitable for consumption at some places.