Eğirdir Lake basin was selected as the study area because the lake is the second largest freshwater lake in Turkey and groundwater in the basin is used as drinking water. In the present study, 29 groundwater samples were collected and analyzed for physico-chemical parameters to determine the hydrochemical characteristics, groundwater quality, and human health risk in the study area. The dominant ions are Ca2+, Mg2+, HCO32−, and SO42. According to Gibbs plot, the predominant samples fall in the rock–water interaction field. A groundwater quality index (WQI) reveals that the majority of the samples falls under good to excellent category of water, suggesting that the groundwater is suitable for drinking and other domestic uses. The Ca-Mg-HCO3, Ca-HCO3, Ca-SO4-HCO3, and Ca-Mg-HCO3-SO4 water types are the dominant water types depending on the water–rock interaction in the investigation area. Risk of metals to human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adults and children. It was indicated that As with HQ ingestion >1 was the most important pollutant leading to non-carcinogenic concerns. It can be concluded that the highest contributors to chronic risks were As and Cr for both adults and children.
INTRODUCTION
Groundwater and surface waters are the major sources of water around the world. The economic development and ecological stability of many countries heavily depends on clean and adequate water. Groundwater is a valuable natural resource and is believed to be comparatively much cleaner and free from pollution than surface water (Armon & Kott 1994; Arya et al. 2012; Boateng et al. 2016). Also, due to a lack of surface water, groundwater has played a major role in meeting drinking and irrigation demands in arid and semi-arid regions (Khosravi et al. 2016). The need for groundwater is greater than ever before, related to industrial and agricultural developments (Kaviarasan et al. 2016). Groundwater quality is an important factor for drinking, domestic, industrial, and agricultural usages (Babiker et al. 2007). The quality of groundwater is affected by natural sources or numerous types of human activity (Kavaf & Nalbantçılar 2007; Nas & Berktay 2010; Varol & Davraz 2015a). Point and non-point pollution sources such as fertilizers, effluent run-off from industries, chemical dumping sites, and domestic sewage cause groundwater to become polluted and to create health problems (Rohul-Amin et al. 2012; Nalbantçılar & Pınarkara 2015). Therefore, systematic monitoring of the water quality parameters controlling hydrochemical processes are essential for sustainable usage of the water.
Hydrochemical studies of groundwater are providing a better understanding of possible changes in quality as development progresses (Varol & Davraz 2015a). A knowledge of hydrochemistry is important to assess the groundwater quality in any area in which groundwater is used for both irrigation and drinking needs (Srinivas et al. 2013). The conventional techniques such as trilinear plots, statistical techniques are widely accepted methods to determine the quality of water (Kumar et al. 2015). In addition, numerous water quality indices have been formulated all over the world, such as the US National Sanitation Foundation Water Quality Index (NSFWQI) (Brown et al. 1970), Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI) (Khan et al. 2003), British Columbia Water Quality Index (BCWQI), and Oregon Water Quality Index (OWQI) (Abbasi 2002; Debels et al. 2005; Kannel et al. 2007) to assess water quality. These indices are one of the most effective ways for water quality information provision to the public, concerned authorities, or policy-makers for water quality management and are considered to be one of the simplest methods used for overall water quality assessment (Shabbir & Ahmad 2015).
Groundwater contamination by inorganic and organic compounds of natural or anthropogenic origin represents a serious global environmental problem since groundwater is used as a significant drinking water source worldwide. The identification and characterization of associated human health risks are important problems that need to be addressed by environmental and medical geochemistry (Rapant & Krêmová 2007). It is known that water pollution may become a significant threat to human health (Davies 1983). Nearly 25,000 people die of such water pollution problems every day and one-third of urban inhabitants in developing countries cannot access safe drinking water (Yin & Deng 2006; Li & Ling 2006). Generally, drinking water containing different anions and heavy metals has significant adverse effects on human health either through deficiency or toxicity due to excessive intake (Varol & Davraz 2015b). For example, arsenic represents one of the most potentially toxic inorganic contaminants of groundwater worldwide (Focazio et al. 1999; Smith et al. 2000; Lin et al. 2002; Ahmed et al. 2004; Bundschuh et al. 2004; Tollestrup et al. 2005; Li et al. 2007; Rapant & Krêmová 2007; Kavcar et al. 2009; Phan et al. 2010). Fluoride, which generally occurs in nature, is beneficial to human health in trace amounts, but can be toxic in excess (Varol & Davraz 2015b). Risk assessment is the methodological approach in which the toxicity of a chemical is identified, characterized, and analyzed. Current knowledge of element and compound toxicity enables a descriptive (qualitative) risk assessment based on the identification of adverse effects (chronic, carcinogenic) and the quantitative assessment of risk level (calculation and map presentation of health risk) (Rapant & Krêmová 2007).
The geographic information system (GIS), a high performance computer-based tool, is playing a critical role in water resource management and pollution study. GIS represents a technological advancement in terms of overlay mapping techniques (Igboekwe & Akankpo 2011). Also, many studies have indicated that GIS is a powerful tool to assess water quality (Butler et al. 2002; Skubon 2005; Asadi et al. 2007; Babiker et al. 2007; Yammani 2007; Rangzan et al. 2008; Jeihouni et al. 2014; Krishnaraj et al. 2015; Varol & Davraz 2015a). GIS applications are used widely in groundwater studies, such as site suitability analyses, managing site inventory data, estimating vulnerability of groundwater to pollution potential from non-point sources of pollution, modeling groundwater movement, modeling solute transport and leaching, and integrating groundwater quality assessment models with spatial data to create spatial decision support systems (Engel & Navulur 1999). Additionally, mapping water quality indices within a GIS framework will be a useful tool for water quality management (Shabbir & Ahmad 2015).
The present study was carried out to evaluate the hydro-chemical characteristics, groundwater quality, and human health risk in Eğirdir Lake basin, which is one of the important drinking water basins in Turkey. In the study area, groundwater is used as drinking and irrigation water. There are several point and non-point pollution sources and groundwater quality is under threat in the region. Hence, this study has great importance for the identification of management options for the sustainable usages of the groundwater.
MATERIALS AND METHODOLOGY
Study area
There are two main groundwater basins, Uluborlu-Senirkent and Yalvaç-Gelendost, with a combined area of 525 km2. Yalvaç-Gelendost basin is located in the east of Eğirdir Lake and covers catchments of the Hoyran and Yalvaç rivers which are discharged to the lake. The most important settlements are Gelendost and Yalvaç, and there are many villages and municipalities connected to these districts. Senirkent-Uluborlu basin is located in the northwest of the lake and besides the Senirkent and Uluborlu districts, Büyükkabaca, Küçükkabaca, İleydağı, Yassıören, Ortayazı, Garip, Dereköy, Uluğbey, Başköy, and Gençali settlements are located in the basin. According to meteorological data obtained from the State Meteorology Works, the main rainfall varies from 348 to 788 mm in the study area (Şener & Davraz 2013). In recent years, surface and groundwater quality has been under threat in the basin due to many pollution sources, such as open dumps, fertilizer and pesticides practices in agricultural areas, uncontrolled sewerage system, mining activities, etc. (Şener 2010). Agricultural production takes place in approximately 1,147 km2 of the Eğirdir Lake basin. In these regions, natural and synthetic fertilizers and agricultural pesticides have been used in large amounts, and this is the main cause of the degradation of groundwater quality in the study area (Şener et al. 2009).
Geological and hydrogeological settings
Seven hydrogeologic units were determined in the study area based on hydrogeological properties of the lithological units. The Quaternary alluvium and the Mesozoic carbonate rocks are classified as aquifer units in the basin. Pyroclastic units and Neogene deposits were identified as semi-permeable units. In addition, ophiolite complex, flysch, and metamorphic rocks were identified as impermeable units due to having low permeability. Alluvium is the most important aquifer due to the porous structures and groundwater is taken from alluvial aquifer in the basin. According to groundwater level data, the groundwater depth varies from 3 to 36 m in the Senirkent-Uluborlu basin, 1–21.6 m in the Yalvaç basin, and 0.15–51.2 m in the Gelendost basin (Şener & Davraz 2013). The groundwater flow direction of the alluvium aquifer is toward the Eğirdir Lake in the basin. The amount of groundwater discharge to the east side of Eğirdir Lake by means of the karstic aquifer was determined as 114 hm3/year using the MODFLOW model (Soyaslan 2004). Yalvaç and Hoyran streams discharge 26.38 and 3.42 m3/s to Eğirdir Lake, respectively (Şener 2010). In the west of the lake, the amount of groundwater discharge from alluvium aquifer to Eğirdir Lake has been calculated as 7.8 hm3/year (Seyman 2005). Pupa Stream is the most important surface water flowing through the basin and it discharges 12.84 m3/year to Eğirdir Lake (Seyman 2005; Tay 2005). Hydraulic conductivity determined in the west of the study area varies between 8.72 × 10−6 and 2.24 × 10−4 m/s in alluvium. Hydraulic conductivity was calculated as 1.18 × 10−5 to 5.6 × 10−7 m/s in the east of the basin (Şener & Davraz 2013).
Pollution sources
Groundwater contamination can be classified into two groups: natural (geogenic) and man-made (anthropogenic) sources. Natural groundwater contamination is primarily caused by water–rock interaction, geothermal field effects and/or infiltration from low quality rivers, lakes, or seawater.
Sampling and analytical procedure
Groundwater samples were collected during October 2014 representing the dry season in accordance with United States Environmental Protection Agency methodologies (USEPA 2000). A total of 29 water samples taken from wells/springs and the coordinates of these locations were loaded in the Magellan eXplorist 600 Manual Global Positioning System (GPS). Samples were stored in two polyethylene bottles. One of the bottles was acidified with suprapure HNO3 for determination of cations and another was kept unacidified for anion analyses. Bottles labeled to avoid misidentification were rinsed in clear spring water several times and then filled to the top to minimize the entrapment of air in water samples (Larsen et al. 2001), then stored at 4 °C in a refrigerator.
The pH, temperature (T, °C), electrical conductivity (EC, μS/cm), total dissolved solids (TDS, mg/L), and dissolved oxygen (DO, mg/L), were measured in situ with YSI Professional Plus handheld multi-parameter instruments that were calibrated with standard solutions. The major chemical constituents were analyzed at the ACME Laboratory (Canada-ISO 9002 Accredited Co.). The major cation (Ca, Mg, K, Na) and trace metal (Al, As, B, Ba, Cr, Cu, Fe, Mn, Ni, Pb, Zn) amounts were determined by inductively coupled plasma mass spectrometry within group 2C-MS in the ACME Laboratory. Chloride, bicarbonate, sulfate, and nitrate analyses were performed in the Eğirdir Fisheries Research Institute Laboratory (Isparta/Turkey). The bicarbonate concentrations were determined by titrimetric method. The argentometric method based on titration of a sample with silver nitrate was used for the determination of chloride (AWWA 1995). Sulfate was determined spectrophotometrically by barium sulfate turbidity method (Clesceri et al. 1998; AOAC 1995). In addition, determination of nitrate was performed by using spectrophotometer reagents and WTW photoLab Spectral-12 Spektrophotometre. The calculated charge–balance error of the water samples is <5%, and this ratio is within the limits of acceptability.
Water quality index calculation
<50: excellent water
50–100: good water
100–200: poor water
200–300: very poor water
>300: unsuitable for drinking
Mapping
The advancement of GIS and spatial analysis helps to integrate the laboratory analysis data with the geographic data and to model the spatial distributions of water quality parameters, most robustly and accurately (Shabbir & Ahmad 2015). In the present study, the distribution maps of the water quality indices were prepared by using GIS techniques. First, the coordinates of the sampling points were determined using a hand-held GPS device and the locations were imported into GIS software through point layer. The database file including sample codes and all analyses results of the chemical parameters was prepared and this geodatabase was used to generate the spatial distribution map of the WQI. For this, ArcGIS software, Spatial Analyst extension, and inverse distance weight (IDW) interpolation methods were applied in the study. IDW is most suitable in the formulation of the interpolation of isodynamic contours. It also produces smooth and continuous surface changes between observations (Mantzafleri 2007).
RESULTS AND DISCUSSION
The qualities of a water resource depend on the management of anthropogenic discharges as well as the natural physicochemical characteristics of the catchment areas (Efe et al. 2005). The statistical summary of the physicochemical parameters and limit values for drinking waters is presented in Table 1. The chemical composition of the water samples (n = 29) in the study region shows a wide range. The temperature variation ranges from 10.16 to 20 °C with a mean value of 13.7 °C. pH is one of the most important operational water quality parameters, with the optimum pH required often being in the range of 6.5–9.5 (WHO 2004). It is controlled by carbon dioxide, carbonate, and bicarbonate equilibrium (Hem 1985). The minimum and maximum values of pH were measured as 8.2 and 8.68, respectively, with a mean value of 8.4. This shows that the groundwater of the study area is slightly alkaline due to the presence of carbonates and bicarbonates from karstic rocks. EC is a measure of water capacity to convey electric current. The presence of various dissolved salts is responsible for the EC of water. The EC in the study region varied from 175 to 692 μS/cm with an average of 425.90 μS/cm. TDS is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized, or microgranular suspended form (Saravanakumar & Ranjithkumar 2011). Concentrations of TDS in water vary considerably in different geological regions owing to differences in the solubilities of minerals (WHO 2004). TDS ranged from 222.2 to 794.9 mg/L with a mean value of 465.1 mg/L. The permissible limit of TDS of drinking water is 500 mg/L (WHO 2008). The observation shows that the TDS exceeded the maximum permissible limit in 12 locations. In addition, Todd (1980) suggested that groundwater be classified using TDS into very fresh (0–250 mg/L), fresh (250–1,000 mg/L), brackish (1,000–10,000 mg/L), and saline (10,000–100,000 mg/L) (Boateng et al. 2016). According to this categorization, all the groundwater samples fell under the fresh water type in the study area. DO is an essential parameter for the survival of all aquatic organisms and oxygen is the most well established indicator of water quality (Said et al. 2004). The optimum value for good water quality is 4 to 6 mg/L of DO, which ensures healthy aquatic life in a water body (Alam et al. 2007; Avvannavar & Shrihari 2008). The in situ measured DO values of the water samples ranged from 7.1 to 10.7 mg/L with a mean value of 8.9 mg/L.
Statistical summary of the physical and chemical parameters of the groundwater
Parameters . | Minimum . | Maximum . | Mean . | Standard deviation . | WHO (2008) . | TS-266 (2005) . |
---|---|---|---|---|---|---|
EC (μS/cm) | 175.00 | 692.00 | 425.90 | 148.51 | ||
pH | 8.20 | 8.68 | 8.40 | 0.14 | 6.5–8.5 | 6.5–9.5 |
Temperature (°C) | 10.16 | 20.07 | 13.70 | 2.26 | ||
DO (mg/L) | 7.10 | 10.70 | 8.90 | 1.06 | ||
TDS (mg/L) | 222.2 | 794.9 | 465.1 | 176.9 | 500 | |
HCO32− (mg/L) | 169.58 | 606.34 | 386.25 | 112.00 | 500 | |
Cl− (mg/L) | 8.87 | 26.95 | 13.88 | 4.50 | 250 | 250 |
SO42− (mg/L) | 7.11 | 495.50 | 138.67 | 159.31 | 250 | 250 |
Na+ (mg/L) | 1.20 | 25.76 | 10.76 | 6.21 | 200 | 200 |
Ca2+ (mg/L) | 43.86 | 198.21 | 108.31 | 46.28 | 300 | 200 |
K+ (mg/L) | 0.36 | 28.76 | 4.13 | 6.88 | 12 | |
Mg2+ (mg/L) | 5.87 | 46.01 | 25.71 | 11.28 | 30 | 150 |
NO3− (mg/L) | 0.87 | 3.87 | 2.34 | 0.85 | 50 | |
Al (mg/L) | 0.0010 | 0.4310 | 0.0441 | 0.1109 | 0.2 | 0.2 |
As (mg/L) | 0.0040 | 0.0128 | 0.0079 | 0.0023 | 0.01 | 0.01 |
B (mg/L) | 0.0090 | 0.0910 | 0.0422 | 0.0238 | ||
Ba (mg/L) | 0.0056 | 0.5560 | 0.1425 | 0.1327 | 0.7 | |
Cr (mg/L) | 0.0009 | 0.0545 | 0.0102 | 0.0133 | 0.05 | 0.05 |
Cu (mg/L) | 0.0007 | 0.0341 | 0.0052 | 0.0086 | 2 | 2 |
Fe (mg/L) | 0.0090 | 0.5810 | 0.0468 | 0.1403 | 0.2 | |
Mn (mg/L) | 0.00004 | 0.0485 | 0.0050 | 0.0121 | 0.4 | 0.05 |
Ni (mg/L) | 0.0001 | 0.0036 | 0.0006 | 0.0006 | 0.07 | 0.02 |
Pb (mg/L) | 0.0001 | 0.0035 | 0.0006 | 0.0011 | 0.01 | 0.01 |
U (mg/L) | 0.0003 | 0.0101 | 0.0030 | 0.0025 | 0.03 | |
Zn (mg/L) | 0.0009 | 0.0741 | 0.0137 | 0.0198 |
Parameters . | Minimum . | Maximum . | Mean . | Standard deviation . | WHO (2008) . | TS-266 (2005) . |
---|---|---|---|---|---|---|
EC (μS/cm) | 175.00 | 692.00 | 425.90 | 148.51 | ||
pH | 8.20 | 8.68 | 8.40 | 0.14 | 6.5–8.5 | 6.5–9.5 |
Temperature (°C) | 10.16 | 20.07 | 13.70 | 2.26 | ||
DO (mg/L) | 7.10 | 10.70 | 8.90 | 1.06 | ||
TDS (mg/L) | 222.2 | 794.9 | 465.1 | 176.9 | 500 | |
HCO32− (mg/L) | 169.58 | 606.34 | 386.25 | 112.00 | 500 | |
Cl− (mg/L) | 8.87 | 26.95 | 13.88 | 4.50 | 250 | 250 |
SO42− (mg/L) | 7.11 | 495.50 | 138.67 | 159.31 | 250 | 250 |
Na+ (mg/L) | 1.20 | 25.76 | 10.76 | 6.21 | 200 | 200 |
Ca2+ (mg/L) | 43.86 | 198.21 | 108.31 | 46.28 | 300 | 200 |
K+ (mg/L) | 0.36 | 28.76 | 4.13 | 6.88 | 12 | |
Mg2+ (mg/L) | 5.87 | 46.01 | 25.71 | 11.28 | 30 | 150 |
NO3− (mg/L) | 0.87 | 3.87 | 2.34 | 0.85 | 50 | |
Al (mg/L) | 0.0010 | 0.4310 | 0.0441 | 0.1109 | 0.2 | 0.2 |
As (mg/L) | 0.0040 | 0.0128 | 0.0079 | 0.0023 | 0.01 | 0.01 |
B (mg/L) | 0.0090 | 0.0910 | 0.0422 | 0.0238 | ||
Ba (mg/L) | 0.0056 | 0.5560 | 0.1425 | 0.1327 | 0.7 | |
Cr (mg/L) | 0.0009 | 0.0545 | 0.0102 | 0.0133 | 0.05 | 0.05 |
Cu (mg/L) | 0.0007 | 0.0341 | 0.0052 | 0.0086 | 2 | 2 |
Fe (mg/L) | 0.0090 | 0.5810 | 0.0468 | 0.1403 | 0.2 | |
Mn (mg/L) | 0.00004 | 0.0485 | 0.0050 | 0.0121 | 0.4 | 0.05 |
Ni (mg/L) | 0.0001 | 0.0036 | 0.0006 | 0.0006 | 0.07 | 0.02 |
Pb (mg/L) | 0.0001 | 0.0035 | 0.0006 | 0.0011 | 0.01 | 0.01 |
U (mg/L) | 0.0003 | 0.0101 | 0.0030 | 0.0025 | 0.03 | |
Zn (mg/L) | 0.0009 | 0.0741 | 0.0137 | 0.0198 |
The major anions abundance in the study area was in the order of HCO32− > SO42− > Cl− > NO3−. The concentration of carbonates in natural waters is a function of dissolved carbon dioxide, temperature, pH, cations, and other dissolved salts. Bicarbonate is present in considerable amounts according to carbonate ions. Also, bicarbonate concentration of natural waters generally held within a moderate range by the effects of the carbonate equilibrium (Kumar et al. 2015). The bicarbonate concentration varied between 169.58 and 606.34 mg/L with a mean of 386.25 mg/L. The concentration of bicarbonate in the study area was mostly within the WHO (2008) standards except for four samples, Y20, Y21, Y22, and Y24. Sulfate occurs naturally in numerous minerals and is used commercially, principally in the chemical industry (Nas & Berktay 2010). It is one of the least toxic anions, even though dehydration is observed at high concentrations (Varol & Davraz 2015b). According to WHO (2008) and TS-266 (2005) the highest desirable and maximum permissible limit of sulfate is 250 mg/L. The sulfate concentration in the groundwater samples varied between 7.11 and 495.5 mg/L with a mean concentration of 138.67 mg/L. Sulfate exceeded the maximum permissible limit in six locations, Y21, Y23, Y24, Y27, Y28, and Y29.
The chloride in groundwater may be from diverse sources such as weathering, leaching of sedimentary rocks and soil, domestic and municipal effluents (SarathPrasanth et al. 2012). No health-based guideline value is proposed for chloride in drinking water. However, high concentrations of chloride give a salty taste to water and beverages (WHO 2004). The concentration of chloride ion in groundwater of the study area varied between 8.87 and 26.95 mg/L with a mean of 13.88 mg/L. All groundwater samples were within the maximum permissible limit of 250 mg/L. Nitrate is the product of nitrogenous material conversion and aerobic stabilization of organic nitrogen (Shabbir & Ahmad 2015). The nitrate concentration in groundwater and surface water is normally low but can reach high levels as a result of leaching or run-off from agricultural and/or contamination from human or animal wastes as a consequence of the oxidation of ammonia and similar sources (WHO 2004). The nitrate concentration ranged from 0.87 to 3.87 mg/L with a mean value of 2.34 mg/L in the study area; the permissible limit of nitrate is given as 50 mg/L by the TS-266 and WHO for drinking water. According to analysis results, all of the groundwater samples were within the maximum permissible limit.
The order of the major cation trend was Ca2+ > Mg2+ > Na+ > K+ and Ca2+ is the dominant ion among the cations in the study area. Calcium and magnesium are directly related to hardness of the water and these ions are the most abundant elements in the surface and groundwater, and exist mainly as bicarbonates and, to a lesser degree, in the form of sulfate and chloride (Kumar et al. 2015). Ca can be derived from dissolution of carbonate minerals (e.g., calcite, dolomite, aragonite) as well as carbonate cement within formations. The primary source of Mg in natural water is ferromagnesian minerals (olivine, diopside, biotite, hornblend) within igneous and metamorphic rocks and magnesium carbonate (dolomite) in sedimentary rock (Singh et al. 2012). The Ca and Mg concentrations of water samples vary from 43.86 to 198.21 mg/L and 5.87 to 46.01 mg/L, respectively. Calcium concentrations of all groundwater samples were within the maximum permissible limit of 300 mg/L. However, magnesium exceeded the maximum permissible limit in ten locations, Y3, Y4, Y8, Y9, Y11, Y12, Y19, Y20, Y21, and Y26. The Na concentration ranged from 1.2 to 25.76 mg/L with a mean value of 10.76 mg/L in the study area; the permissible limit of sodium is given as 200 mg/L by the TSE and WHO for drinking water. According to analysis results, groundwater samples were within the maximum permissible limit. Potassium is a naturally occurring element and the amount of potassium varied between 0.36 and 28.76 mg/L with an average value of 4.13 mg/L. It was found that all the samples with potassium content within the permissible limit, except for sample Y14.
Trace metals are the most persistent and dangerous pollutants in aquatic ecosystems. They disturb the natural balance of ecosystems that have been formed evolutionarily over a long period of time (Arnason & Fletcher 2003; Bai et al. 2011). Trace metal accumulations determined in waters and sediment indicate the presence of natural (geogenic) or anthropogenic sources. Water–rock interaction within drainage basins is the primary source for the lithogenic contribution of heavy metals into an aquatic system. Also, anthropogenic sources such as urban and industrial waste water, mining and smelting operations, combustion of fossil fuels, processing and manufacturing industries, waste disposal including dumping are primary pollutants for aquatic systems (Pardo et al. 1990; Şener et al. 2014). Al, As, B, Ba, Cr, Cu, Fe, Mn, Ni, Pb, U, and Zn analyses were performed in water samples and it was found that the concentrations of the Ba, Cu, Mn, Ni, Pb and U parameters were within the permissible limit given by the TSE and WHO for drinking water. However, there is no limit value for B and Zn parameters. The minimum, maximum, and mean values of the trace metal parameters can be seen in Table 1. The Al and As contents of water samples were determined as a range 0.001–0.431 mg/L and 0.004–0.0128 mg/L, respectively. According to analysis results, all of the groundwater samples were within the maximum permissible limit in terms of Al except for sample Y8. However, As concentrations were over the permissible limit of the WHO (2008) and TS-266 (2005) in six locations, Y1, Y4, Y5, Y6, Y7, and Y8. The B and Ba contents of water samples were determined as a range 0.009–0.0910 mg/L and 0.005–0.556 mg/L, respectively and all of the groundwater samples were within the maximum permissible limit for Ba. The concentration of Cr ranges from 0.0009 to 0.054 mg/L in groundwater and was mostly within the TSE and WHO standards except for one sample (Y3). The concentration of Cu was within the maximum permissible limits with minimum and maximum of 0.0007 and 0.0341 mg/L, respectively.
The Fe concentration in the groundwater samples varied between 0.009 and 0.581 mg/L with an average concentration of 0.0468 mg/L, and the concentration of Fe was within the WHO standards except for only one water sample (Y8). The trace metal results indicated that sample Y8 has high Al, As, and Fe content and sample Y3 has high Cr content. Both of them are located in the Senirkent-Uluborlu basin and the main reason for this excessive dosage is pesticide and fertilizer usage during agricultural activities and also water–rock interaction with volcanic units. The Mn and Ni contents of water samples were determined as a range 0.00004–0.0485 mg/L, and 0.0001–0.0036 mg/L, respectively. In addition, the Pb, U, and Zn contents of water samples were determined as a range 0.0001–0.0035 mg/L, 0.0003–0.0101 mg/L, and 0.0009–0.0741 mg/L, respectively (Table 1).
Hydrochemical types
Water chemistry is mainly influenced by water–rock interaction taking place from the recharge area to sampling location (Purushothaman et al. 2014). In addition, hydrogeochemical types reflect the effects of chemical reactions occurring between the minerals within the lithologic framework and groundwater (Varol & Davraz 2015a). In the present study, the groundwater samples were classified hydrochemically using major cations and anions with conventional Piper trilinear diagram (Piper 1944) to determine the similarities between groundwater in the basin. Also, a Gibbs diagram was used to understand the genesis of groundwater.
Gibbs diagram
Piper trilinear diagram
WQI
Relative weight of chemical parameters
Parameters . | WHO (2008) standards . | Weight (wi) . | Relative weight (Wi) . |
---|---|---|---|
pH | 6.5–8.5 | 4 | 0.0727 |
TDS | 500 | 5 | 0.0909 |
HCO3 | 500 | 3 | 0.0545 |
Cl | 250 | 4 | 0.0727 |
SO4 | 250 | 4 | 0.0727 |
NO3 | 50 | 5 | 0.0909 |
Ca | 300 | 3 | 0.0545 |
Mg | 30 | 3 | 0.0545 |
Na | 200 | 2 | 0.0364 |
As | 0.01 | 5 | 0.0909 |
Cr | 0.05 | 4 | 0.0727 |
Mn | 0.40 | 4 | 0.0727 |
Pb | 0.01 | 3 | 0.0545 |
Ni | 0.07 | 3 | 0.0545 |
U | 0.03 | 3 | 0.0545 |
∑wi = 55 | ∑Wi = 1 |
Parameters . | WHO (2008) standards . | Weight (wi) . | Relative weight (Wi) . |
---|---|---|---|
pH | 6.5–8.5 | 4 | 0.0727 |
TDS | 500 | 5 | 0.0909 |
HCO3 | 500 | 3 | 0.0545 |
Cl | 250 | 4 | 0.0727 |
SO4 | 250 | 4 | 0.0727 |
NO3 | 50 | 5 | 0.0909 |
Ca | 300 | 3 | 0.0545 |
Mg | 30 | 3 | 0.0545 |
Na | 200 | 2 | 0.0364 |
As | 0.01 | 5 | 0.0909 |
Cr | 0.05 | 4 | 0.0727 |
Mn | 0.40 | 4 | 0.0727 |
Pb | 0.01 | 3 | 0.0545 |
Ni | 0.07 | 3 | 0.0545 |
U | 0.03 | 3 | 0.0545 |
∑wi = 55 | ∑Wi = 1 |
WQI values and water types of the samples
Sample no. . | WQI . | Water type . |
---|---|---|
1 | 31.8 | Excellent water |
2 | 21.7 | Excellent water |
3 | 37.8 | Excellent water |
4 | 39.1 | Excellent water |
5 | 30.3 | Excellent water |
6 | 33.3 | Excellent water |
7 | 30.0 | Excellent water |
8 | 37.8 | Excellent water |
9 | 26.4 | Excellent water |
10 | 26.1 | Excellent water |
11 | 32.9 | Excellent water |
12 | 26.3 | Excellent water |
13 | 36.0 | Excellent water |
14 | 28.7 | Excellent water |
15 | 24.7 | Excellent water |
16 | 28.3 | Excellent water |
17 | 26.3 | Excellent water |
18 | 26.3 | Excellent water |
19 | 34.2 | Excellent water |
20 | 41.1 | Excellent water |
21 | 50.8 | Good water |
22 | 38.7 | Excellent water |
23 | 48.8 | Excellent water |
24 | 54.6 | Good water |
25 | 31.1 | Excellent water |
26 | 32.4 | Excellent water |
27 | 45.5 | Excellent water |
28 | 50.9 | Good water |
29 | 43.7 | Excellent water |
Sample no. . | WQI . | Water type . |
---|---|---|
1 | 31.8 | Excellent water |
2 | 21.7 | Excellent water |
3 | 37.8 | Excellent water |
4 | 39.1 | Excellent water |
5 | 30.3 | Excellent water |
6 | 33.3 | Excellent water |
7 | 30.0 | Excellent water |
8 | 37.8 | Excellent water |
9 | 26.4 | Excellent water |
10 | 26.1 | Excellent water |
11 | 32.9 | Excellent water |
12 | 26.3 | Excellent water |
13 | 36.0 | Excellent water |
14 | 28.7 | Excellent water |
15 | 24.7 | Excellent water |
16 | 28.3 | Excellent water |
17 | 26.3 | Excellent water |
18 | 26.3 | Excellent water |
19 | 34.2 | Excellent water |
20 | 41.1 | Excellent water |
21 | 50.8 | Good water |
22 | 38.7 | Excellent water |
23 | 48.8 | Excellent water |
24 | 54.6 | Good water |
25 | 31.1 | Excellent water |
26 | 32.4 | Excellent water |
27 | 45.5 | Excellent water |
28 | 50.9 | Good water |
29 | 43.7 | Excellent water |
The computed WQI for the groundwater samples values ranged from 21.7 to 54.6 in the study and the groundwater quality of the study area is in the ‘excellent’ to ‘good’ range. 89.66% of the groundwater samples represented ‘excellent water’ and 10.34% of the samples fell into ‘good water’ category. According to the WQI distribution map of the study area, the samples taken from the Yalvaç-Gelendost basin have lower WQI values compared with samples taken from the west of the lake. Domestic, agricultural, and/or industrial pollutants are the main reason for the poor water quality in the Yalvaç-Gelendost basin.
Risk assessment on human health
A human health risk assessment is the process to estimate the nature and probability of adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future. On a global scale, pathogenic contamination of drinking water poses the most significant health risk to humans. However, significant risks to human health may also result from exposure to non-pathogenic, toxic contaminants that are often ubiquitous in water. In this section, the hazard index (HI) method was used to assess the overall potential for non-carcinogenic effects of metals and nitrate contaminants in groundwater in the Eğirdir Lake basin. To assess the overall potential for non-carcinogenic effects posed by more than one chemical, an HI approach is developed based on USEPA (1986a) Guidelines for Health Risk Assessment of Chemical Mixtures.
Hazard identification is to estimate the hazardous effect of the contaminant. In the first step, the hazard level is examined by physical and chemical properties of contaminants such as mobility and contaminant levels at the point of exposure where the contaminants are exposed to the environment. The second step is exposure assessment, estimated by average daily dose (ADD) using the identification of intensity, frequency, exposure period, and pathway of contaminants. In the third step, dose–response assessment examines the relationship between adverse effects and exposure levels of carcinogenic and non-carcinogenic chemicals. The two principal toxicity indices are known as SF (cancer slope factor) and reference dose (RfD). The SF and RfD values can be obtained from the EPA Integrated Risk Information System (IRIS) on-line database and EPA Health Effects Assessment Summary Tables (USEPA 1994). Risk characterization is the final step that predicts the level of risk. The results of exposure assessment and dose–response assessment are integrated to derive quantitative estimates of cancer risk and HI (USEPA 1986a, 1986b, 1989; Lee et al. 2006).
The default values used to estimate potential exposure from drinking contaminated water and the default values (USEPA 2001) that are used to estimate dermal ADD for adults and children are given in Table 4. Kp is dermal permeability coefficient in water, unit in cm/h. The default permeability constants for all other inorganic compounds are provided in USEPA (2004) and Kp values for several inorganic compounds are given in Table 5.
Default values for drinking water and dermal routine
Variables . | Adults . | Children . |
---|---|---|
L (L/day) | 2 | 1 |
EF (days/year) | 365 oral; 350 dermal | 365 oral; 350 dermal |
ED (year) | 30 | 6 |
BW (kg) | 70 | 15 |
AT (in day) | 10,950 | 2,190 |
SA (cm2) | 18,000 | 6,600 |
ET (h/day) | 2.6 | 1 |
Variables . | Adults . | Children . |
---|---|---|
L (L/day) | 2 | 1 |
EF (days/year) | 365 oral; 350 dermal | 365 oral; 350 dermal |
ED (year) | 30 | 6 |
BW (kg) | 70 | 15 |
AT (in day) | 10,950 | 2,190 |
SA (cm2) | 18,000 | 6,600 |
ET (h/day) | 2.6 | 1 |
Kp, RfD, SF values and HI for each element
. | Kp (cm/h) . | RfD-oral (mg/kg/d) . | RfD-dermal (mg/kg/d) . | SF (kg d/mg) . | HQingestion . | HQdermal . | HI = ΣHQs . | Cancer riskingestion . | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Adult . | Child . | Adult . | Child . | Adult . | Child . | Adult . | Child . | |||||
Al | 1 × 10−3 | 1 | 0.1 | 1.23 × 10−2/8.57 × 10−5 | 1.00 × 10−2/6.67 × 10−5 | 2.76 × 10−3/6.41 × 10−6 | 1.82 × 10−3/8.44 × 10−6 | 1.51 × 10−2/7.00 × 10−5 | 1.06 × 10−2/7.09 × 10−5 | |||
As | 1 × 10−3 | 3 × 10−4 | 1.23 × 10−4 | 1.5 | 1.22 × 100/3.81 × 10−1 | 2.84 × 100/8.89 × 10−1 | 2.08 × 10−2/6.67 × 10−2 | 1.37 × 10−2/4.08 × 10−2 | 1.29 × 100/4.02 × 10−1 | 2.89 × 100/9.03 × 10−1 | 1.71 × 10−4/5.49 × 10−4 | 1.01 × 10−3/9.90 × 10−4 |
B | 1 × 10−3 | 0.2 | 1.4 × 10−2 | 1.01 × 10−2/9.71 × 10−3 | 1.00 × 10−2/7.33 × 10−3 | 1.01 × 10−3/9.62 × 10−4 | 1.08 × 10−3/9.95 × 10−4 | 1.00 × 10−2/9.43 × 10−4 | 1.09 × 10−2/8.00 × 10−3 | |||
Ba | 1 × 10−3 | 0.2 | 1.4 × 10−2 | 1.16 × 10−2/8.06 × 10−4 | 1.85 × 10−1/6.4 × 10−3 | 1.16 × 10−2/8.79 × 10−4 | 1.68 × 10−2/5.78 × 10−4 | 1.05 × 10−1/9.84 × 10−3 | 2.02 × 10−1/6.97 × 10−3 | |||
Cr | 1 × 10−3 | 3 × 10−3 | 7.5 × 10−5 | 7.3 × 10−3 | 1.33 × 10−2/8.57 × 10−3 | 1.21 × 100/8.00 × 10−2 | 1.20 × 10−2/8.80 × 10−2 | 1.02 × 10−1/9.56 × 10−3 | 1.08 × 10−1/9.40 × 10−2 | 1.00 × 10−1/9.19 × 10−2 | 1.14 × 10−5/7.51 × 10−7 | 1.30 × 10−5/8.27 × 10−7 |
Cu | 1 × 10−3 | 3.7 × 10−2 | 8 × 10−3 | 1.38 × 10−2/9.03 × 10−3 | 1.17 × 10−2/8.83 × 10−3 | 1.04 × 10−4/7.21 × 10−5 | 1.80 × 10−3/8.44 × 10−5 | 1.29 × 10−2/9.97 × 10−3 | 1.21 × 10−2/9.09 × 10−3 | |||
Fe | 1 × 10−3 | 0.3 | 0.14 | 5.53 × 10−2/8.57 × 10−4 | 1.29 × 10−1/5.56 × 10−3 | 2.66 × 10−3/9.16 × 10−5 | 1.75 × 10−3/7.53 × 10−5 | 5.80 × 10−2/8.98 × 10−4 | 1.31 × 10−1/5.63 × 10−3 | |||
Mn | 1 × 10−3 | 0.14 | 1.84 × 10−3 | 1.23 × 10−3/8.16 × 10−6 | 1.04 × 10−2/5.24 × 10−5 | 1.69 × 10−2/8.01 × 10−5 | 1.11 × 10−2/9.17 × 10−6 | 1.21 × 10−2/6.08 × 10−5 | 1.02 × 10−3/7.76 × 10−5 | |||
Ni | 2 × 10−4 | 2 × 10−2 | 5.4 × 10−3 | 1.00 × 10−3/1.43 × 10−4 | 1.07 × 10−2/3.33 × 10−4 | 1.66 × 10−5/2.37 × 10−6 | 1.09 × 10−5/1.56 × 10−6 | 1.02 × 10−3/1.45 × 10−4 | 1.07 × 10−2/3.35 × 10−4 | |||
Pb | 1 × 10−4 | 3.6 × 10−3 | 5.5 × 10−2 | 2.78 × 10−2/7.94 × 10−4 | 1.11 × 10−2/7.41 × 10−3 | 1.26 × 10−6/9.43 × 10−7 | 1.28 × 10−5/7.33 × 10−7 | |||||
U | 1 × 10−3 | 3 × 10−3 | 0.4 | 1.30 × 10−2/9.14 × 10−3 | 1.22 × 10−1/9.91 × 10−2 | 1.15 × 10−4/9.26 × 10−6 | 1.02 × 10−4/6.67 × 10−6 | |||||
Zn | 6 × 10−4 | 0.3 | 6 × 10−2 | 1.07 × 10−3/8.57 × 10−5 | 1.09 × 10−3/9.78 × 10−4 | 1.63 × 10−4/8.98 × 10−6 | 1.78 × 10−4/7.17 × 10−6 | 1.14 × 10−3/9.15 × 10−5 | 1.68 × 10−2/9.96 × 10−4 | |||
NO3 | 1.6 | 0.8 | 6.52 × 10−2/1.55 × 10−2 | 1.01 × 10−1/9.67 × 10−2 | 1.01 × 10−3/7.93 × 10−4 | 1.10 × 10−3/8.81 × 10−4 | 1.62 × 10−2/6.81 × 10−2 | 1.02 × 10−1/9.83 × 10−2 |
. | Kp (cm/h) . | RfD-oral (mg/kg/d) . | RfD-dermal (mg/kg/d) . | SF (kg d/mg) . | HQingestion . | HQdermal . | HI = ΣHQs . | Cancer riskingestion . | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Adult . | Child . | Adult . | Child . | Adult . | Child . | Adult . | Child . | |||||
Al | 1 × 10−3 | 1 | 0.1 | 1.23 × 10−2/8.57 × 10−5 | 1.00 × 10−2/6.67 × 10−5 | 2.76 × 10−3/6.41 × 10−6 | 1.82 × 10−3/8.44 × 10−6 | 1.51 × 10−2/7.00 × 10−5 | 1.06 × 10−2/7.09 × 10−5 | |||
As | 1 × 10−3 | 3 × 10−4 | 1.23 × 10−4 | 1.5 | 1.22 × 100/3.81 × 10−1 | 2.84 × 100/8.89 × 10−1 | 2.08 × 10−2/6.67 × 10−2 | 1.37 × 10−2/4.08 × 10−2 | 1.29 × 100/4.02 × 10−1 | 2.89 × 100/9.03 × 10−1 | 1.71 × 10−4/5.49 × 10−4 | 1.01 × 10−3/9.90 × 10−4 |
B | 1 × 10−3 | 0.2 | 1.4 × 10−2 | 1.01 × 10−2/9.71 × 10−3 | 1.00 × 10−2/7.33 × 10−3 | 1.01 × 10−3/9.62 × 10−4 | 1.08 × 10−3/9.95 × 10−4 | 1.00 × 10−2/9.43 × 10−4 | 1.09 × 10−2/8.00 × 10−3 | |||
Ba | 1 × 10−3 | 0.2 | 1.4 × 10−2 | 1.16 × 10−2/8.06 × 10−4 | 1.85 × 10−1/6.4 × 10−3 | 1.16 × 10−2/8.79 × 10−4 | 1.68 × 10−2/5.78 × 10−4 | 1.05 × 10−1/9.84 × 10−3 | 2.02 × 10−1/6.97 × 10−3 | |||
Cr | 1 × 10−3 | 3 × 10−3 | 7.5 × 10−5 | 7.3 × 10−3 | 1.33 × 10−2/8.57 × 10−3 | 1.21 × 100/8.00 × 10−2 | 1.20 × 10−2/8.80 × 10−2 | 1.02 × 10−1/9.56 × 10−3 | 1.08 × 10−1/9.40 × 10−2 | 1.00 × 10−1/9.19 × 10−2 | 1.14 × 10−5/7.51 × 10−7 | 1.30 × 10−5/8.27 × 10−7 |
Cu | 1 × 10−3 | 3.7 × 10−2 | 8 × 10−3 | 1.38 × 10−2/9.03 × 10−3 | 1.17 × 10−2/8.83 × 10−3 | 1.04 × 10−4/7.21 × 10−5 | 1.80 × 10−3/8.44 × 10−5 | 1.29 × 10−2/9.97 × 10−3 | 1.21 × 10−2/9.09 × 10−3 | |||
Fe | 1 × 10−3 | 0.3 | 0.14 | 5.53 × 10−2/8.57 × 10−4 | 1.29 × 10−1/5.56 × 10−3 | 2.66 × 10−3/9.16 × 10−5 | 1.75 × 10−3/7.53 × 10−5 | 5.80 × 10−2/8.98 × 10−4 | 1.31 × 10−1/5.63 × 10−3 | |||
Mn | 1 × 10−3 | 0.14 | 1.84 × 10−3 | 1.23 × 10−3/8.16 × 10−6 | 1.04 × 10−2/5.24 × 10−5 | 1.69 × 10−2/8.01 × 10−5 | 1.11 × 10−2/9.17 × 10−6 | 1.21 × 10−2/6.08 × 10−5 | 1.02 × 10−3/7.76 × 10−5 | |||
Ni | 2 × 10−4 | 2 × 10−2 | 5.4 × 10−3 | 1.00 × 10−3/1.43 × 10−4 | 1.07 × 10−2/3.33 × 10−4 | 1.66 × 10−5/2.37 × 10−6 | 1.09 × 10−5/1.56 × 10−6 | 1.02 × 10−3/1.45 × 10−4 | 1.07 × 10−2/3.35 × 10−4 | |||
Pb | 1 × 10−4 | 3.6 × 10−3 | 5.5 × 10−2 | 2.78 × 10−2/7.94 × 10−4 | 1.11 × 10−2/7.41 × 10−3 | 1.26 × 10−6/9.43 × 10−7 | 1.28 × 10−5/7.33 × 10−7 | |||||
U | 1 × 10−3 | 3 × 10−3 | 0.4 | 1.30 × 10−2/9.14 × 10−3 | 1.22 × 10−1/9.91 × 10−2 | 1.15 × 10−4/9.26 × 10−6 | 1.02 × 10−4/6.67 × 10−6 | |||||
Zn | 6 × 10−4 | 0.3 | 6 × 10−2 | 1.07 × 10−3/8.57 × 10−5 | 1.09 × 10−3/9.78 × 10−4 | 1.63 × 10−4/8.98 × 10−6 | 1.78 × 10−4/7.17 × 10−6 | 1.14 × 10−3/9.15 × 10−5 | 1.68 × 10−2/9.96 × 10−4 | |||
NO3 | 1.6 | 0.8 | 6.52 × 10−2/1.55 × 10−2 | 1.01 × 10−1/9.67 × 10−2 | 1.01 × 10−3/7.93 × 10−4 | 1.10 × 10−3/8.81 × 10−4 | 1.62 × 10−2/6.81 × 10−2 | 1.02 × 10−1/9.83 × 10−2 |
Carcinogenic risk of As through oral intake for child exceeded the target risk of 1 × 10−4 (Table 5) and indicated that the ingestion of water over a long lifetime could increase the probability of cancer. The risk assessment indicated that As was the most important pollutant in the Eğirdir Lake basin. Previous studies reported adverse health effects including hypertension, neuropathy, diabetes, skin lesions, and cardiovascular diseases through high arsenic intake (Avani & Rao 2007; Bhattacharya et al. 2007; Wu et al. 2009). Therefore, special attention should be paid to arsenic for local residents, particularly for sensitive children, and measures need to be taken to sustain a healthy aquatic ecosystem.
CONCLUSIONS
The hydrochemical characteristics, groundwater quality, and human health risk in Eğirdir Lake basin was evaluated in the present study. Eğirdir Lake is an indispensable water source for the region due to usage aims such as drinking/irrigation water, tourism, and fishing. The groundwater is used as drinking and irrigation water in the study area. A total of 29 samples were taken from wells within the study area and analyzed for hydrochemical and quality evaluation. The order of anion and cations are HCO32− > SO42− > Cl− > NO3− and Ca2+ > Mg2+ > Na+ > K+ in groundwater samples and HCO3 and Ca2+ are the dominant ions among the anions and cations in the study area. According to Piper trilinear diagram, Ca-Mg-HCO3, Ca-HCO3, Ca-SO4-HCO3, and Ca-Mg-HCO3-SO4 are the dominant water types related to water–rock interaction. Carbonate weathering plays an active role in development of the water type. Also, Gibbs plot indicates that all the samples fall in the rock–water interaction dominance zone. The results of the analyses were compared with drinking water limit values determined by WHO (2008) and TS-266 (2005) to assess the potability of groundwater. The results show that HCO32−, SO4−2, Mg2+, Al, As, Cr, and Fe are a little over the WHO (2008) and TS-266 (2005) limit values. All the other parameters are within the permissible limit for drinking water. In the study area, groundwater quality is slowly reaching an unsuitable stage for drinking water due to industrial and agricultural activities. Moreover, water–rock interaction affects the water quality adversely. According to the WQI classification, the water samples fall into the excellent to good water category. In general, groundwater quality in Yalvaç-Gelendost basin is lower than Senirkent-Uluborlu basin. However, high Al, As, and Fe content was determined in Senirkent-Uluborlu basin related to water–rock interaction and agricultural activities.
Risk assessment is an attempt to identify and quantify potential risks to human health resulting from exposure to various contaminants. In this study, oral ingestion and dermal route were taken into consideration for adults and children. HQingestion of As for adults was more than 1 in three locations. However, HQingestion of As for children was more than 1 in all of the locations except for two samples in the Eğirdir Lake basin, indicating serious health concerns. In addition, HQingestion of Cr for child was more than 1 at only one location. It can be concluded that the highest contributors to chronic risks were As and Cr for both adults and children. This indicated that As posed serious health concerns for local residents via oral intake, while other metals via oral intake and all the elements via dermal absorption posed no or little health threat.