Groundwater contamination and its effect on health in Turkey

The sources of groundwater pollution in Turkey are identified, and pathways of contaminants to groundwater are first described. Then, the effects of groundwater quality on health in Turkey are evaluated. In general, sources of groundwater contamination fall into two main categories: natural and anthropogenic sources. Important sources of natural groundwater pollution in Turkey include geological formations, seawater intrusion, and geothermal fluid(s). The major sources of anthropogenic groundwater contamination are agricultural activities, mining waste, industrial waste, on-site septic tank systems, and pollution from imperfect well constructions. The analysis results revealed that natural contamination due to salt and gypsum are mostly found in Central and Mediterranean regions and arsenic in Aegean region. Geothermal fluids which contain fluoride poses a danger for skeleton, dental, and bone problems, especially in the areas of Denizli, Isparta, and Ayd?n. Discharges from surface water bodies contaminate groundwater by infiltration. Evidence of such contamination is found in Upper K?z?l?rmak basin, Gediz basin, and Büyük Melen river basin and some drinking water reservoirs in ?stanbul. Additionally, seawater intrusion causes groundwater quality problems in coastal regions, especially in the Aegean coast. Industrial wastes are also polluting surface and groundwater in industrialized regions of Turkey. Deterioration of water quality as a result of fertilizers and pesticides is another major problem especially in the regions of Mediterranean, Aegean, Central Anatolia, and Marmara. Abandoned mercury mines in the western regions of Turkey, especially in ?anakkale, ?zmir, Mu?la, Kütahya, and Bal?kesir, cause serious groundwater quality problems.     

基于多元统计方法的某地浅层地下水污染来源分析

为查明某地农田灌溉水井水质污染致使作物生长受损事件的污染来源,对研究区10眼水井进行了水质检测分析,并采用多元统计方法判断污染来源。结果表明:研究区水样中全盐量普遍超过农田灌溉水质标准,总硬度、硫酸盐、氨氮和氰化物等也存在不同程度的超标;水样中全盐量、氨氮与氰化物的含量之间存在显著正相关,具有共同的来源,且与河流A补给关系密切;地下水中盐分过高是造成作物受损的主要原因;地下水中全盐量、氨氮及氰化物等主要污染物来源于上游的焦化企业。基于多元统计方法的地下水污染来源分析结果可为当地地下水污染防治及管控提供环境管理依据。     

Does irrigation with reclaimed water significantly pollute shallow aquifer with nitrate and salinity? An assay in a perurban area in North Tunisia

In Tunisia, reclaimed water is increasingly used for irrigation in order to mitigate water shortage. However, few studies have addressed the effect of such practice on the environment. Thus, we attempted in this paper to assess the impact of irrigation with reclaimed water on the nitrate content and salinity in the Nabeul shallow aquifer on the basis of satellite images and data from 53 sampled wells. Ordinary and indicator kriging were used to map the spatial variability of these groundwater chemical parameters and to locate the areas where water is suitable for drinking and irrigation. The results of this study have shown that reclaimed water is not an influential factor on groundwater contamination by nitrate and salinity. Cropping density is the main factor contributing to nitrate groundwater pollution, whereas salinity pollution is affected by a conjunction of factors such as seawater interaction and lithology. The predictive maps show that nitrate content in the groundwater ranges from 9.2 to 206 mg/L while the electric conductivity ranges from 2.2 to 8.5 dS/m. The high-nitrate concentration areas underlie sites with high annual crop density, whereas salinity decreases gradually moving away from the coastline. The probability maps reveal that almost the entire study area is unsuitable for drinking with regard to nitrate and salinity levels. Appropriate measures, such as the elaboration of codes of good agricultural practices and action programs, should be undertaken in order to prevent and/or remediate the contamination of the Nabeul shallow aquifer.     

Evaluation of groundwater quality and its suitability for drinking and agricultural use in Thanjavur city, Tamil Nadu, India

As groundwater is a vital source of water for domestic and agricultural activities in Thanjavur city due to lack of surface water resources, groundwater quality and its suitability for drinking and agricultural usage were evaluated. In this study, 102 groundwater samples were collected from dug wells and bore wells during March 2008 and analyzed for pH, electrical conductivity, temperature, major ions, and nitrate. Results suggest that, in 90% of groundwater samples, sodium and chloride are predominant cation and anion, respectively, and NaCl and CaMgCl are major water types in the study area. The groundwater quality in the study site is impaired by surface contamination sources, mineral dissolution, ion exchange, and evaporation. Nitrate, chloride, and sulfate concentrations strongly express the impact of surface contamination sources such as agricultural and domestic activities, on groundwater quality, and 13% of samples have elevated nitrate content (>45 mg/l as NO₃). PHREEQC code and Gibbs plots were employed to evaluate the contribution of mineral dissolution and suggest that mineral dissolution, especially carbonate minerals, regulates water chemistry. Groundwater suitability for drinking usage was evaluated by the World Health Organization and Indian standards and suggests that 34% of samples are not suitable for drinking. Integrated groundwater suitability map for drinking purposes was created using drinking water standards based on a concept that if the groundwater sample exceeds any one of the standards, it is not suitable for drinking. This map illustrates that wells in zones 1, 2, 3, and 4 are not fit for drinking purpose. Likewise, irrigational suitability of groundwater in the study region was evaluated, and results suggest that 20% samples are not fit for irrigation. Groundwater suitability map for irrigation was also produced based on salinity and sodium hazards and denotes that wells mostly situated in zones 2 and 3 are not suitable for irrigation. Both integrated suitability maps for drinking and irrigation usage provide overall scenario about the groundwater quality in the study area. Finally, the study concluded that groundwater quality is impaired by man-made activities, and proper management plan is necessary to protect valuable groundwater resources in Thanjavur city.     

The Impact of Urbanization and Protection of Water Resources in Owerri and Environs SE, Nigeria

Untreated sewage and agriculture are the most important sources of contamination. The study was carried out by conducting a short-term surface water and groundwater pollution survey of the Owerri Urban area and its environs, in order to establish the current levels of pollution. An attempt has been made to show the relationships between pollution levels, population density, industrial and agricultural activities. The spatial distribution of pollutants due to a poor land use system and to human activities was investigated. This emphasises integrated planned development as a preventive measure for arresting pollution levels in fast growing urban centres. The total groundwater stored in the area amounts to 7.87 × 10⁹ m³. Twenty five percent of this is released as base flow into the adjacent rivers (Otamiri and Nworie). The annual groundwater recharge is 3.4 × 10⁹ m³. The enormous volume of groundwater stored and the comparatively low cost of development makes groundwater an excellent alternative supply source for the area (Uma et al., 1984).     

Natural and anthropogenic factors affecting the shallow groundwater quality in a typical irrigation area with reclaimed water,North China Plain

In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO₃ type in grass land to Ca·Na-Cl (+NO₃) type and Na (Ca)-Cl (+NO₃+SO₄) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO₃) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area.     

A Fuzzy Logic Approach to Assess Groundwater Pollution Levels Below Agricultural Fields

A fuzzy logic approach has been developed to assess the groundwater pollution levels below agricultural fields. The data collected for Kumluca Plain of Turkey have been utilized to develop the approach. The plain is known with its intensive agricultural activities, which imply excessive application of fertilizers. The characteristics of the soils and underlying groundwater for this plain were monitored during the years 1999 and 2000. Additionally, an extensive field survey related to the types and yields of crops, fertilizer application and irrigation water was carried out. Both the soil and groundwater have exhibited high levels of nitrogen, phosphorus and salinity with considerable spatial and temporal variations. The pollution level of groundwater at several established stations within the plain were assessed using Fuzzy Logic. Water Pollution Index (WPI) values are calculated by Fuzzy Logic utilizing the most significant groundwater pollutants in the area namely nitrite, nitrate and orthophosphate together with the groundwater vulnerability to pollution. The results of the calculated WPI and the monitoring study have yielded good agreement. WPI indicated high to moderate water pollution levels at Kumluca plain depending on factors such as agricultural age, depth to groundwater, soil characteristics and vulnerability of groundwater to pollution. Fuzzy Logic approach has shown to be a practical, simple and useful tool to assess groundwater pollution levels.     

Modeling interactions between saturated and un-saturated zones by Hydrus-1D in semi-arid regions (plain of Kairouan,Central Tunisia)

In semi-arid areas like the Kairouan region, salinization has become an increasing concern because of the constant irrigation with saline water and over use of groundwater resources, soils, and aquifers. In this study, a methodology has been developed to evaluate groundwater contamination risk based on the unsaturated zone hydraulic properties. Two soil profiles with different ranges of salinity, one located in the north of the plain and another one in the south of plain (each 30 m deep) and both characterized by direct recharge of the aquifer, were chosen. Simulations were conducted with Hydrus-1D code using measured precipitation data for the period 1998–2003 and calculated evapotranspiration for both chosen profiles. Four combinations of initial conditions of water content and salt concentration were used for the simulation process in order to find the best match between simulated and measured values. The success of the calibration of Hydrus-1D allowed the investigation of some scenarios in order to assess the contamination risk under different natural conditions. The aquifer risk contamination is related to the natural conditions where it increased while facing climate change and temperature increase and decreased in the presence of a clay layer. Hydrus-1D was a useful tool to predict the groundwater level and quality in the case of a direct recharge and in the absence of any information related to the soil layers except for the texture.     

典型水源地地下水污染风险评价

地下水污染是由含水层本身的脆弱性与人类活动产生的污染负荷造成的。污染物的荷载可以控制或改变,但是含水层的敏感性是本质的、天然的特性。污染风险不仅取决于相对稳定、不宜改变的含水层天然特征,还取决于主观的污染活动。因此,从地下水天然防污性能、地下水污染源荷载以及地下水社会效益3个方面评价了典型水源地地下水受污染的风险。     

Groundwater geochemistry and identification of hydrogeochemical processes in a hard rock region, Southern India

Hydrogeochemical investigations were carried out in Chithar River basin, Tamil Nadu, India to identify the major geochemical processes that regulate groundwater chemistry. For this study, long-term (1991–1997) and recent water quality data (2001–2002) for 30 groundwater wells spread over the study area were used to understand the groundwater geochemistry and hydrogeochemical process regulating groundwater quality. Groundwater quality data obtained from more than 400 water samples were employed. Results of electrical conductivity and chloride express large variation between minimum and maximum values and high standard deviation, which suggests that the water chemistry in the study region is not homogeneous and influenced by complex contamination sources and geochemical process. Nitrate and depth to water table expose the influences of surface contamination sources, whereas dissolved silica, fluoride and alkalinity strongly suggest the effect of rock–water interaction. In the study region, weathering of carbonate and silicate minerals and ion exchange reactions predominantly regulate major ion chemistry. Besides, the concentrations of sulphate, chloride and nitrate firmly suggest the impact of agricultural activities such as irrigation return flow, fertiliser application, etc on water chemistry in the study region.     

Tailoring groundwater quality monitoring to vulnerability: a GIS procedure for network design

Monitoring networks aiming to assess the state of groundwater quality and detect or predict changes could increase in efficiency when fitted to vulnerability and pollution risk assessment. The main purpose of this paper is to describe a methodology aiming at integrating aquifers vulnerability and actual levels of groundwater pollution in the monitoring network design. In this study carried out in a pilot area in central Italy, several factors such as hydrogeological setting, groundwater vulnerability, and natural and anthropogenic contamination levels were analyzed and used in designing a network tailored to the monitoring objectives, namely, surveying the evolution of groundwater quality relating to natural conditions as well as to polluting processes active in the area. Due to the absence of an aquifer vulnerability map for the whole area, a proxi evaluation of it was performed through a geographic information system (GIS) methodology, leading to the so called “susceptibility to groundwater quality degradation”. The latter was used as a basis for the network density assessment, while water points were ranked by several factors including discharge, actual contamination levels, maintenance conditions, and accessibility for periodical sampling in order to select the most appropriate to the network. Two different GIS procedures were implemented which combine vulnerability conditions and water points suitability, producing two slightly different networks of 50 monitoring points selected out of the 121 candidate wells and springs. The results are compared with a “manual” selection of the points. The applied GIS procedures resulted capable to select the requested number of water points from the initial set, evaluating the most confident ones and an appropriate density. Moreover, it is worth underlining that the second procedure (point distance analysis [PDA]) is technically faster and simpler to be performed than the first one (GRID?+?PDA).     

Soil salinity evolution and its relationship with dynamics of groundwater in the oasis of inland river basins: case study from the Fubei region of Xinjiang Province, China

Soil salinization is an important worldwide environmental problem, especially in arid and semi-arid regions. Knowledge of its temporal and spatial variability is crucial for the management of oasis agriculture. The study area has experienced dramatic change in the shallow groundwater table and soil salinization during the 20th century, especially in the past two decades. Classical statistics, geostatistics and geographic information system (GIS) were applied to estimate the spatial variability of the soil salt content in relation to the shallow groundwater table and land use from 1983 to 2005. Consumption of reservoir water for agricultural irrigation was the main cause of a rise in the shallow groundwater table under intense evapotranspiration conditions, and this led indirectly to soil salinization. The area of soil salt accumulation was greater in irrigated than in non-irrigated landscape types with an increasing of 40.04% from 1983 to 2005 in cropland at ∼0.43 t ha⁻¹ year⁻¹, and an increase at ∼0.68 t ha⁻¹ year⁻¹ in saline alkaline land. Maps of the shallow groundwater table in 1985 and 2000 were used to deduce maps for 1983 and 1999, respectively, and the registration accuracy was 99%.     

A methodology for rapid assessment of the environmental status of the shallow aquifer of ��Tavoliere di Puglia�� (Southern Italy)

Anticipating the European Water Framework Directive (2000/60/EC), the Italian Government issued Legislative Decree n.152/99 which sets out rules for classifying the environmental status of national water bodies in order to achieve specific qualitative objectives by 2016. The most recent European Groundwater Directive (2006/118/EC), which was only recognized by Italy in early 2009 (Legislative Decree 30/09), requires such resources to be characterized from a qualitative standpoint and the risk of their being polluted by individual pollutants or groups of pollutants to be evaluated. This paper reports a simple methodology, based on easy-to-apply rules, for the rapid classification of groundwater, and the results of its application to the shallow aquifer of the plain of Tavoliere delle Puglie located in south Italy. Data collected during well-water monitoring campaigns carried out from 2002 to 2003 made it possible to assess the environmental status of the Tavoliere which, unfortunately, was found to be characterized by ??significant anthropic pressures on quality and/or quantity of groundwater and necessitating specific improvement actions??.     

Indexing method for assessment of pollution potential of leachate from non-engineered landfill sites and its effect on ground water quality

Dumping of solid waste in a non-engineered landfill site often leads to contamination of ground water due to leachate percolation into ground water. The present paper assesses the pollution potential of leachate generated from three non-engineered landfill sites located in the Tricity region (one each in cities of Chandigarh, Mohali and Panchkula) of Northern India and its possible effects of contamination of groundwater. Analysis of physico-chemical properties of leachate from all the three landfill sites and the surrounding groundwater samples from five different downwind distances from each of the landfill sites were collected and tested to determine the leachate pollution index (LPI) and the water quality index (WQI). The Leachate Pollution Index values of 26.1, 27 and 27.8 respectively for landfill sites of Chandigarh (CHD), Mohali (MOH) and Panchkula (PKL) cities showed that the leachate generated are contaminated. The average pH values of the leachate samples over the sampling period (9.2 for CHD, 8.97 for MOH and 8.9 for PKL) show an alkaline nature indicating that all the three landfill sites could be classified as mature to old stage. The WQI calculated over the different downwind distances from the contamination sites showed that the quality of the groundwater improved with an increase in the downwind distance. Principal component analysis (PCA) carried out established major components mainly from natural and anthropogenic sources with cumulative variance of 88% for Chandigarh, 87.1% for Mohali and 87.8% for Panchkula. Hierarchical cluster analysis (HCA) identifies three distinct cluster types for the groundwater samples. These clusters corresponds to a relatively low pollution, moderate pollution and high pollution regions. It is suggested that all the three non-engineered landfill sites be converted to engineered landfill sites to prevent groundwater contamination and also new sites be considered for construction of these engineered landfill sites as the present dumpsites are nearing the end of their lifespan capacity.     

Design of National Groundwater Quality Monitoring Network in Egypt

In the Nile Valley and Delta the protection of groundwater resources is high priority environmental concern. Many groundwater quality problems are already dispersed and may be widespread and frequent in occurrence. Examples include problems associated with the extensive application of chemical fertilizers in agricultural specially in the new reclaimed areas, leaks in sewers, septic tanks, the aggregate effects of many different points source pollution in urban areas and natural, geologically related water quality problems. A national groundwater quality monitoring has been designed and implemented based on the stepwise procedure. The national groundwater quality monitoring network is used to quantify the quality changes in long run, either caused by pollution activities or by salt water intrusion and to describe the overall current groundwater quality status on a national scale of the main aquifers. The monitoring tools and methodologies developed in this research can be used to assure protection of public health and determine the sustainability of groundwater in various purposes. This national monitoring network plays important roles for decision makers in developing the groundwater resources management plans in different aquifers systems in Egypt.     

Suitability assessment of groundwater for drinking, irrigation and industrial use in some North Indian villages

The study comprised suitability assessment of groundwater for drinking, irrigation, and industrial use. A total of 34 groundwater samples were collected from Rewari town and its perimeter from the land chiefly used for agriculture. Physico-chemical characterization of the samples revealed that groundwater from most of the sources was not fit for drinking owing to a high concentration of calcium, magnesium, hardness and fluoride. Suitability for irrigation, too, was low since most of the sources had high value of sodium adsorption ratio (SAR), residual sodium carbonate (RSC), soluble sodium percentage (SSP) and magnesium hazard which can render salinity and alkali hazard to soils on long term use in irrigation. No source of water was found to be suitable for industrial application since it had high concentration of calcium carbonate which can precipitate very easily. It was observed that sodium, sulphate, and chloride were the chief ions present in water and based on the abundance of ions and their correlation type, most of the groundwater samples are of sodium sulphate and/or sodium chloride type. The high concentration of the chemical constituents is attributed to the lithologic composition of the area. It was observed that the water of deep meteoric percolation type was of sodium sulphate type and the shallow of sodium chloride type.     

Groundwater quality and hydrogeochemical properties of Torbalı Region, Izmir, Turkey

The large demand for drinking, irrigation and industrial water in the region of Torbali (Izmir, Turkey) is supplied from groundwater sources. Almost every factory and farm has private wells that are drilled without permission. These cause the depletion of groundwater and limiting the usage of groundwater. This study investigates spatial and temporal change in groundwater quality, relationships between quality parameters, and sources of contamination in Torbali region. For this purpose, samples were collected from 10 different sampling points chosen according to their geological and hydrogeological properties and location relative to factories, between October 2001 and July 2002. Various physical (pH, temperature, EC), chemical (calcium, magnesium, potassium, sodium, chloride, alkalinity, copper, chromium, cadmium, lead, zinc) and organic (nitrate, nitrite, ammonia, COD and cyanide) parameters were monitored. It was observed that the groundwater has bicarbonate alkalinity. Agricultural contamination was determined in the region, especially during the summer. Nitrite and ammonia concentrations were found to be above drinking water standard. Organic matter contamination was also investigated in the study area. COD concentrations were higher than the permissible limits during the summer months of the monitoring period.     

Use of multivariate indicator kriging methods for assessing groundwater contamination extents for irrigation

Multivariate geostatistical approaches have been applied extensively in characterizing risks and uncertainty of pollutant concentrations exceeding anthropogenic regulatory limits. Spatially delineating an extent of contamination potential is considerably critical for regional groundwater resources protection and utilization. This study used multivariate indicator kriging (MVIK) to determine spatial patterns of contamination extents in groundwater for irrigation and made a predicted comparison between two types of MVIK, including MVIK of multiplying indicator variables (MVIK-M) and of averaging indicator variables (MVIK-A). A cross-validation procedure was adopted to examine the performance of predicted errors, and various probability thresholds used to calculate ratios of declared pollution area to total area were explored for the two MVIK methods. The assessed results reveal that the northern and central aquifers have excellent groundwater quality for irrigation use. Results obtained through a cross-validation procedure indicate that MVIK-M is more robust than MVIK-A. Furthermore, a low ratio of declared pollution area to total area in MVIK-A may result in an unrealistic and unreliable probability used to determine extents of pollutants. Therefore, this study suggests using MVIK-M to probabilistically determine extents of pollutants in groundwater.     

Irrigation Efficiency and Quality of Irrigation Return Flows in the Ebro River Basin: An Overview

The review analysis of twenty two irrigation efficiency (IE) studies carried out in the Ebro River Basin shows that IE is low (average IE)_avg(= 53%) in surface-irrigated areas with high-permeable and shallow soils inadequate for this irrigation system, high (IE)_avg(= 79%) in surface-irrigated areas with appropriate soils for this system, and very high (IE)_avg(= 94%) in modern, automated and well managed sprinkler-irrigated areas. The unitary salt (total dissolved solids) and nitrate loads exported in the irrigation return flows (IRF) of seven districts vary, depending on soil salinity and on irrigation and N fertilization management, between 3–16 Mg salt/ha⋅ year and 23–195 kg NO)₃ ⁻-N/ha⋅ year, respectively. The lower nitrate loads exported from high IE districts show that a proper irrigation design and management is a key factor to reduce off-site nitrogen pollution. Although high IE’s also reduce off-site salt pollution, the presence of salts in the soil or subsoil may induce relatively high salt loads (≥14 Mg/ha⋅ year) even in high IE districts. Two important constrains identified in our revision were the short duration of most surveys and the lack of standards for conducting irrigation efficiency and mass balance studies at the irrigation district level. These limitations {emphasize the need for the establishment of a permanent and standardized network of drainage monitoring stations for the appropriate off-site pollution diagnosis and control of irrigated agriculture.     

Impact of storm water on groundwater quality below retention/detention basins

Groundwater from 33 monitoring of peripheral wells of Karachi, Pakistan were evaluated in terms of pre- and post-monsoon seasons to find out the impact of storm water infiltration, as storm water infiltration by retention basin receives urban runoff water from the nearby areas. This may increase the risk of groundwater contamination for heavy metals, where the soil is sandy and water table is shallow. Concentration of dissolved oxygen is significantly low in groundwater beneath detention basin during pre-monsoon season, which effected the concentration of zinc and iron. The models of trace metals shown in basin groundwater reflect the land use served by the basins, while it differed from background concentration as storm water releases high concentration of certain trace metals such as copper and cadmium. Recharge by storm water infiltration decreases the concentration and detection frequency of iron, lead, and zinc in background groundwater; however, the study does not point a considerable risk for groundwater contamination due to storm water infiltration.