Impact of polluted canal water on adjacent soil and groundwater systems

Received, 12 May 1999 · Accepted, 2 August 1999     

Groundwater pollution in Quaternary aquifer of Vitoria – Gasteiz (Basque Country, Spain)

 As a result of diverse changes in land use and in water-resource management in the high basin of the Zadorra River (Basque Country), an important loss of water resources and an intense contamination by nitrogen compounds has taken place. The purpose of this paper is to detail the land transformations that have taken place on the aquifer since the 1950s: increase of drainage network, change from dry to irrigated farming, and diversion of rivers at the aquifer unit inlet. Furthermore, we analyze the impact of these transformations on the hydrodynamics and water quality of this aquifer system. Received: 12 January 1996 · Accepted: 10 March 1996     

The relationship between the water table and the surface flow of a losing stream, lower Medano Creek, Great Sand Dunes National Monument, Colorado

 Proposed groundwater withdrawals in the San Luis Valley of Colorado may lower the water table in Great Sand Dunes National Monument. In response, the National Park Service initiated a study that has produced a generalized conceptual model of the hydrologic system in order to assess whether a lowering of the water table might decrease the surface flow of lower Medano Creek. Based upon information obtained during the drilling of several boreholes, there appear to be five important hydrostratigraphic units underlying lower Medano Creek within the upper 30 m of the ground surface: 1. a perched aquifer overlying an aquitard located between about 5 and 6 m below the ground surface; 2. the aquitard itself; 3. an unconfined aquifer located between the upper and lower aquitards; 4. an aquitard located between about 27 and 29 m below the ground surface; and 5. a confined underlying the lower aquitard. Because the areal extent of the aquitards cannot be determined from the borehole data, a detailed conceptual model of the hydrogeologic system underlying lower Medano Creek cannot be developed. However, a generalized conceptual model can be envisioned that consists of a complex system of interlayered aquifers and leaky aquitards, with each aquifer having a unique hydraulic head. Water levels in the perched aquifer rise rapidly to their annual maximum levels in response to the arrival of the flow terminus of Medano Creek during the spring runoff event, and the location of the flow terminus is directly dependent upon the discharge of the creek. Water levels in the deeper, non-perched aquifers do not appear to fluctuate significantly in response to the arrival of the flow terminus, demonstrating that it is unlikely that the proposed groundwater withdrawals will decrease the surface flow of lower Medano Creek. Received: 27 December 1995 · Accepted: 20 February 1996     

Mass transport modelling to assess contamination of a water supply well in Sabarmati river bed aquifer, Ahmedabad City, India

 Drinking water supply wells were constructed in the Sabarmati river bed aquifer of Ahmedabad city using radial pipes and are known as French Collector wells. Contamination of groundwater from one of the French wells near Sabarmati railway bridge was noticed in 1992. The suspected pollution sources are Duff-nala of Shahibaug and two other sources from slum dwellings on either side of Sabarmati river. A combined groundwater flow, pathlines and a mass transport model was constructed covering an area of 9 km² to analyse the capture zone of the French well under two different scenarios. Aquifer parameters of the river bed aquifer were available. Dry river bed condition was simulated under scenario I and controlled flow in the river bed was simulated under scenario II. The groundwater velocity and migration of contaminant particles from sources was analysed in the pathline model. Total dissolved solids (TDS) concentration contours originating from sources in the mass transport model (MT3D) were computed by solving an advection-dispersion equation. The computed pathlines and TDS concentration contours indicate likely migration of contaminant plume from pollutant sources to the French well during 365 days under two scenarios. The model results confirm the tracer injection studies carried out to know the likely migration of contaminants towards the French well. The modelling study emphasised the necessity of controlled release of surface water in Sabarmati river bed from Dharoi reservoir throughout the year. Received: 28 October 1998 · Accepted: 17 June 1999     

The chemical composition of the surface system of Peneos river, Thessaly/Central Greece

 Peneos is the mainstream for the drainage of Thessaly's basin. It contributes significantly in recharging the aquifers, as well as to the direct irrigation water, since there is intense agricultural activity in the basin of Thessaly. The investigation of the hydrochemical conditions of the surface water system of Peneos showed that the chemical composition is related to the lithology of the aquifers of the basin, the anthropogenic influence and the biological activity. The chemical composition of this system changes in time and space. The salinity decreases during the winter period, in contrast to the summer period when it increases drastically. The lower values of TDS appear in the upstream part of the river (95–124 mg/l) whereas downstream, the values of TDS increase significantly (400–632 mg/l). The hydrochemical type Ca-Mg-HCO₃ dominates the largest part of the river while it changes to NA-Cl in the estuary. The concentrations of the dissolved species in the main Peneos river are higher than in the spring waters. Peneos is the most polluted river in Greece. The concentration of the pollutants is higher at the downstream part of the river, but is lower than the accepted upper limits. The use of the surface water of the system of Peneos river for irrigation purposes based on the SAR factor is acceptable because the absorption ratio for Na and salinity are low and medium respectively. Received: 27 October 1997 · Accepted: 21 September 1998     

Experimental study of impact of a certain polluted river on groundwater along river bank in Southeast China

Based on the large scale land and resources survey project--groundwater contamination survey in southeast China, a certain polluted river and its typical sites along its bank were selected as research objectives. Such river is a comprehensive sewage channel for certain provincial capital city, with complicated types of pollutants. Based on the analysis on water level of horizonal and vertical hydrogeologic profile and water quality monitoring data, the impact and range of the polluted river on local groundwater were evaluated. Data show that the polluted river supplies water to underground aquifers throughout the year, which has great impact on groundwater horizontally, but different ions have different responses. Major influential indexes such as inorganic component 3-nitrogen, sulphate, chloride etc. present an obvious relevance, while iron, manganese, fluoride, arsenic and heavy metal and so on are less impacted. The first four indexes in groundwater are less impacted by the surface sewage because of their protogenesis, and heavy metal components become less due to sediment filtration. Data also show that deep groundwater is less influenced, on the contrary, ammonia nitrogen ion is obviously impacted. On the basis of influence degree as well as range of evaluation, some factors that caused the existing influence were discussed and proposes feasible study direction.     

Groundwater nitrate pollution in an alluvium aquifer, Eskişehir urban area and its vicinity, Turkey

 A large amount of the water requirement (municipal, industrial, etc.) of Eskişehir city, Turkey, is supplied from groundwater via wells in the urban area. The groundwater in the Eskişehir Plain alluvium has been polluted by municipal and industrial wastewater, and agricultural activities. The nitrate concentrations at nine sampling points on Porsuk River, the main water course in the plain, ranged from 1.5 to 63.3 mg/l during the period from July 1986 to August 1988. In the same period, the nitrate concentrations measured in water from 51 wells ranged between 2.2–257.0 mg/l. The nitrate content of the groundwater samples was 34.2% above 45 mg/l, the upper limit for nitrate in drinking water standards. High nitrate levels were observed in water from wells in the central and eastern parts of the urban area. The nitrate content of the well water is subject to seasonal fluctuation. In general, low nitrate concentrations were observed in wet seasons, and high ones in dry seasons. Received: 16 April 1996 · Accepted: 2 October 1996     

Groundwater flow rate and contaminant migration in fissure-karstic aquifer of Opole Triassic system southwest Poland

 This paper presents hydrogeological problems occurring during municipal water exploitation and mine dewatering. These activities result in groundwater quantity and quality changes in the fissure-karstic aquifer. Increase of nitrate concentration up to 12 mg NNO₃/l due to intensive fertilizer use, and high tritium concentration, show water system impact up to 100 m depth. Intensive water exploitation produces large cones of depression with over 40-m water-level depletion in the Opole region. Flow rates of major components and isotopes have been verified by chemical migration history. Some aspects of the protection policy of this type of aquifer are also discussed. Received: 7 March 1997 · Accepted: 17 November 1998     

Hydrogeological investigation of Antalya basin concerning the future domestic water needs of Antalya City (Turkey)

A hydrogeological study has been carried out in Antalya travertine basin for the future domestic water supply of Antalya. Geological formations that could be used as an aquifer have been identified, and a hydrogeological map has been prepared. Water-quality analyses show that groundwater has been and is being contaminated by sewage discharge, industrial works, and other activities that create an ever-expending impact to the only available aquifer. Something should be done immediately to protect the aquifer from additional degradation. Received: 28 April 1998 · Accepted: 18 August 1998     

Conceptual model of the evolution of groundwater quality at the wet zone in Sri Lanka

 The evolution of groundwater quality at a wet zone in Sri Lanka was made clear using field investigation, chemical and isotopic analyses methods. In the wet zone, the concentrations of major ions and electrical conductivity (EC) in the groundwater are low with small seasonal change. Except for sodium, silica and chloride, the EC and other major ion concentrations increase along the groundwater flow direction. The contributions of bicarbonate and calcium ions to the increase in EC are the largest among the major ions. The groundwater quality shows calcium-bicarbonate type, the initial stage of the Chebotarev series. There is a seasonal change in isotopic composition. The isotopically lighter groundwater was found at the valley bottom in the rainy season. Under the very heavy precipitation conditions, the slope of the regression line between δD and δ¹⁸O and deuterium excess for groundwater are close to 8 and 10, respectively. In other cases, the slopes of the regression lines and deuterium excess are, less than 8 and 10, respectively. Received: 5 August 1998 · Accepted: 19 October 1998     

Application of a groundwater contamination index in Finland and Slovakia

A methodology is presented for evaluating and mapping the degree of groundwater contamination by applying the contamination index C _d . The applicability of the contamination index was tested in two distinctly different geological regions: the area between Uusikaupunki and Yläne in southwestern Finland and the Brezno area in central Slovakia. The index takes into account both the number of parameters that exceed the upper permissible concentrations of contaminants or potentially harmful elements and the part of the concentrations exceeding those values. The water-quality parameters reflect the effect of diverse natural (topographical, climatical, geological, biological) and anthropogenic (type of land use, local pollution) environmental factors on groundwater quality. In Finland, technical-aesthetic contamination was found over more than half the test area. These quality problems were most often related to acidity and high concentrations of organic carbon and Al and Fe in wells. Health-risk-based contamination, mainly caused by elevated concentrations of fluoride, radon, or nitrate, was found in only a few separate areas. In Slovakia, naturally contaminated and anthropogenically polluted groundwaters could be distinguished. The geogenic pollution is mainly derived from sulfide mineralizations. In both countries the strongest anthropogenic pollution was found in intensively cultivated areas.     

Assessment of the geological and hydrogeological environment at a site of government-level conflict in Incheon, Korea

 The natural environment of an environmental conflict site in Incheon, Korea was assessed with a focus on the hydrogeological environment. Residents had made claims against a company because of health problems, including skin tumors. More specifically, the residents suspected that their drinking groundwater had been contaminated by glass fibers which had caused the health problems. Air, soil, and groundwater samples were analyzed to estimate whether environmental pollution could have caused the problems claimed by the residents. No specific evidence was found from this study to support the groundwater contamination by glass fibers, but groundwater contamination by leaked fuel oils was confirmed in the course of evaluating the glass fiber problem. Received: 16 May 1997 · Accepted: 18 August 1997     

The impact of human activities in the Malia coastal area (Crete) on groundwater quality

The evaluation of the long-term effects of seawater intrusion into the aquifers due to negative water balance and nitrate pollution of drinking-water quality due to human activities requires detailed knowledge of both the transport of the chemical constituents and the geochemical processes within aquifers. Hydrogeological and hydrochemical studies in the unconfined aquifer of Malia have provided the necessary data to define the areas at increased risk from these phenomena. The solution of the second Fick's low under given boundary conditions gave an estimate of the propagation of groundwater pollution by NO₃ ^–. Additionally, in order to simulate the ion concentration changes during a period, for example a period of positive water balance or refreshening, groundwater transport and cation exchange reactions were modelled using the code PHREEQM. Received: 25 July 1997 · Accepted: 4 November 1997     

土壤-含水层侧渗系统在净化河水中的应用——以郑州市索须河工程为例

由于降水较少以及地下水超采,北方地区大部分河流基流匮乏,河水主要来自未经深度处理的城市生活污水和工业废水,河水水质难以达标.在这些地区,利用河流漫滩土壤和含水层的天然净化能力,建立近自然土壤-含水层侧渗系统是净化河水的有效途径之一.在介绍侧渗系统净化机理及适用条件的基础上,通过室内试验和野外示范工程研究索须河土壤-含水层对河水中氨氮的去除效果.室内试验表明该处土壤及浅部含水层对氨氮的去除主要通过稀释、吸附和微生物等作用;通过对示范工程典型剖面上的监测井观测表明该系统对氨氮的去除效果良好,受降水补给的土壤和含水层使得河水中的氨氮硝化为亚硝酸盐和硝酸盐.硝酸盐在地下水中很难被去除,只有少部分通过反硝化作用转化成N2.土壤-含水层侧渗系统行之有效,可应用于类似索须河的北方河流.     

Adsorption of arsenic by natural aquifer material in the San Antonio-El Triunfo mining area, Baja California, Mexico

 Several experiments of arsenic (As) adsorption by aquifer material of the San Antonio-El Triunfo (SA-ET) mining area were conducted to test the feasibility of this material acting as a natural control for As concentrations in groundwater. This aquifer material is mineralogically complex, composed of quartz, feldspar, calcite, chlorite, illite, and magnetite/hematite. The total iron content (Fe₂O₃) in the fine fraction is ∼12%, whereas Fe₂O₃ in the coarse fraction is <10 wt%. The experimental percent total As adsorbed vs. pH curves obtained match the topology of total As adsorbed onto iron oxi-hydroxides surface (arsenate + arsenite; high adsorption at low pH, low adsorption at high pH). A maximum of about 80% adsorbed in the experiments suggests the presence of arsenite in the experimental solutions. The experimental adsorption isotherm at pH 7 indicates saturation of surface sites at high solute concentrations. Surface titration of the aquifer material indicates a point of zero charge (PZC) for the adsorbent of about 8 to 8.5 (PZC for iron oxyhydroxides =7.9–8.2). Comparison between experimental and modeled results (using the MICROQL and MINTEQA2 geochemical modeling and speciation computer programs) suggests that As is being adsorbed mostly by oxyhydroxides surfaces in the natural environment. Based on an estimated retardation factor (R), the travel time of the As plume from the SA-ET area to La Paz and Los Planes is about 700 to 5000 years. Received: 17 March 1997 · Accepted: 8 September 1997     

Water resources development and management in the Cuddapah district, India

 Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological (surface and groundwater) and geochemical aspects have been studied for the development and management of water resources in drought-prone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About 91 000 ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about 47 000 ha is irrigated by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators for the irrigation practices. Groundwater assessment studies revealed that 584 million m³ of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or the application of fertilisers. Received: 10 June 1998 · Accepted: 15 November 1998     

Hydrochemical evolution and environmental features of Salso River catchment, central Sicily (Italy)

 A hydrogeochemical study of the Salso River highlighted the chemical and isotopic space-time evolution along its flow path and the main contamination processes. Within the basin, three different hydrogeochemical facies have been individuated: (1) Ca-Mg-HCO₃, (2) Ca-Mg-SO₄ and (3) Na-Cl. The first facies reflects the chemical composition of the groundwaters hosted in the carbonate reliefs that belong to the Madonie Mountains. The second and the third facies are the result of the interaction processes between surface waters and the gypsum and salty clays, respectively. Two pollution sources have been also located in the basin downstream from the salt mine and downstream from a discharge area of wastewater from the town of Gangi. On the basis of the location of natural and anthropogenic pollution sources, the waters available for drinking and irrigation use are also indicated. Received: 16 July 1999 · Accepted: 22 December 1999     

The influence of karst features on environmental studies in Turkey

 The carbonate rocks of Turkey, which underlie about one third of the country, possess major water resources with great potential for electricity generation and water supplies. The ongoing development of karst features, especially in the southern part of Turkey, demonstrates specific environmental problems that occur in many karst water supply projects. Karst aquifers, springs, sinkholes, dolines, poljes and other karst features are of great importance from the standpoint of karst water resources and environmental research studies. In karst regions, conservation and protection of groundwater resources for both qualitative and quantitative evaluations is possible only when the catchment area is determined accurately. Since the catchment area in karst terrains is not limited by the surface drainage boundaries and the groundwater flows through well-developed coduits or fissures, the equations used in non-karstic areas cannot be applied to such karstic regions. Studies on the development of karst features and its environmental impacts in Turkey are of recent origin. Therefore, many unreliable methods are being applied in karstic areas. For example, the use of "shallow holes or sinkholes and fault zones" for septic water waste disposal or as sewage by those who are not familiar with karst, sometimes causes very serious problems of extensive groundwater pollution. This paper discusses the development of different karstic features in Turkey and case studies on its environmental impacts. Received: 27 December 1995 · Accepted: 10 July 1996     

Impact of liquid waste disposal on potable groundwater resources near Perth,Western Australia

 Drilling of 15 boreholes at a disused liquid waste disposal site near Perth, Western Australia, has indicated that a contamination plume extends about 1000 m in a southerly direction from the site in the direction of groundwater flow. The plume is up to 600 m wide and 5–40 m thick. Chemical and microbiological analyses have indicated that contaminated groundwater contains high concentrations of ammonia, iron, and bacteria at levels that commonly exceed national drinking water guidelines. It is likely that a proposed water supply production well in the path of the contamination plume will have to be abandoned, and additional wells may have to be abandoned if the plume continues to extend in the direction of groundwater flow. There is currently insufficient information to indicate whether the plume is continuing to expand, but studies on similar plumes in the Perth metropolitan area have indicated that contaminated groundwater can move at rates up to 100 m yr^–1. Several other liquid waste disposal sites are now located in residential areas of Perth where wells are used for garden irrigation. Further work is required to ensure that there is no potential impact of groundwater contamination on public health in these areas. Received: 31 July 1995 · Accepted: 18 September 1995     

Impacts of at-site wastewater disposal systems on the groundwater aquifer in arid regions: case of Sfax City, Southern Tunisia

Groundwater in Sfax City (Tunisia) has been known since the beginning of the century for its deterioration in quality, as a result of wastewater recharge into the aquifer. An average value of 12 × 10⁶ m³ of untreated wastewater reaches the groundwater aquifer each year. This would result not only in a chemical and biological contamination of the groundwater, but also in an increase of the aquifer piezometric level. Quantitative impacts were evaluated by examining the groundwater piezometric level at 57 surface wells and piezometers. The survey showed that, during the last two decades, the groundwater level was ever increasing in the urban area with values reaching 7 m in part; and decreasing in Sidi Abid (agricultural area) with values exceeding −3 m. Groundwater samples for chemical and microbial analysis were collected from 41 wells spread throughout the study area. Results showed significantly elevated levels of sodium, chlorides, nitrates and coliform bacteria all over the urban area. High levels (NO₃: 56–254 mg/l; Na >1,500 mg/l; Coliforms >30/100 ml) can be related to more densely populated areas with a higher density of pit latrine and recharge wells. Alternatively results showed a very variable chemical composition of groundwater, e.g. electrical conductivity ranges from 4,040 to19,620 μs/cm and the dry residual varies between 1.4 and 14 g/l with concentrations increasing downstream. Furthermore a softening of groundwater in Set Ezzit (highly populated sector) was observed.