Introduction

Groundwater which is in aquifers beneath the earth surface is considered the most important natural resource to mankind. It is the primary source for human consumption, agriculture, and industrial purposes. In the past few decades, due to population growth, rapid urbanization, and industrialization, ground-water quantity and quality has been deteriorated especially in the developing countries, such as India. As the groundwater is an important part of the hydrological cycle, it is more prone to various sources of contamination according to Soujanya (2016). In general, the quality of groundwater varies with the location, geology, type, and quantity of dissolved ions present in it. According to Fatta et al. (1999), landfills have been identified as one of the major threats of ground-water resources. Most importantly, the groundwater located near the landfills or dumpsites is highly polluted due to the leachate produced from it. The toxic leachate rich in organic and inorganic constituents negatively influence the parametric composition of the groundwater making it unsuitable for the human sustenance. Several scientific studies were conducted worldwide to study the impact of leachate on ground-water chemistry (Longe and Balogun 2010; Vasanthi et al. 2008; Sabahi et al. 2009; Jhamnani and Singh 2009). In India, as the groundwater is the main source for drinking and irrigation, regular monitoring of the wells is required to check for various anthropogenic sequences for wellbeing and sustainability. Therefore, in the present study, physico-chemical characteristics of groundwater (dry and wet seasons) located around the municipal open dumpsite of Jawaharnagar village were analyzed for drinking water suitability as per WHO (2011) and various irrigation water quality determining factors, such as sodium adsorption ratio (SAR), sodium percentage (Na%), permeability index (PI), soluble sodium percentage (SSP), and Kelley’s ratio (KR) (Fig. 1).

Fig. 1
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Conception framework of the study

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Materials and methods

Study location

Hyderabad is the capital city of Telangana and Andhra Pradesh and is the sixth largest city in India. Currently, 5000 metric tons (MT) of municipal solid waste are generated in the city. This waste is collected by the waste collectors with the help of tricycle cart and dumped into the three major collection points in Hyderabad city which are located in Yousufguda, Imlibun, and Lower Tank bund. Waste from all the three collection points eventually gets collected and dumped into the Municipal Dumpsite of Jawaharnagar village without a proper segregation and recycling process. The percentage composition of the municipal solid waste generated in Hyderabad city according to Gowtham Raj et al. (2015) is shown in Fig. 2.

Fig. 2
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Percentage composition of municipal solid waste in Hyderabad (after Gowtham Raj et al. 2015)

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Municipal dump site is situated in Jawaharnagar Village, Shameerpet Mandal, Rangareddy District of Telangana. It is located just outside the limits of GHMC (Greater Hyderabad Municipal Corporation) and inside the HMDA (New limits of Hyderabad). The site is 35 km from Hyderabad city and 105 km away from the state highway connecting Hyderabad and Nagpur in west direction from boundary of project site. It is an open dumpsite which was established in the year 2002. The total area of Jawaharnagar village dumpsite is 350 dekar (da) from which the area occupied by the waste at present is 182 da. It is located between 7030′01″N to 17032′03″N latitude and 78034′13″E to 78037′47″E longitude (Fig. 3). At Jawaharnagar village dumpsite, ground-water table is located at 120 cm below ground level. The annual mean temperature is 26 °C. Summers (March–June) are hot with maximum temperatures of 40 °C. Winter (December–January) has temperatures varying from 14.7 to 28.6 °C. Heavy rain from the south-west summer monsoon falls between June and September, supplying Rangareddy with most of its annual rainfall of 812.5 mm (32 in). Monthly rainfall distribution of the sampling year (2015) in Rangareddy district is presented in Fig. 4.

Fig. 3
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Location map of study area

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Fig. 4
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Source: (Ground Water Department, Telangana State (2015)

Monthly rainfall distribution of Ranga reddy District

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Sample collection

One leachate sample (from leachate pond) and 15 ground-water samples were collected during dry and wet period (2015) around the dumpsite as per availability. Sampling was done in 1 L pre-cleaned high-density polyethylene bottles (HDPE) with dilute HNO3 and was stored in the laboratory at 4 °C for 2 days until analyzes. Geographic locations of the sampling points were collected with the help of TRIMBLE GPS. The leachate and ground-water samples were analyzed for 12 parameters viz., pH, total dissolves solids (TDS), total hardness (TH), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chlorides (Cl), carbonates (CO3), bicarbonates (HCO3), nitrates (NO3), and sulphates (SO4) using the standard procedures recommended by APHA standards (2005).

The pH was measured with digital pH meter (HANNA Inst. Italy) and conductivity with conductivity meter. Total dissolved solids (TDS) were calculated from Electrical Conductivity (EC) using an empirical equation. Total alkalinity, total hardness, calcium, magnesium, and chlorides were estimated by titrimetry using the standard EDTA. Carbonates and bicarbonates were determined by titration with H2SO4. Sodium and potassium were determined by flame photometry. Nitrate determination was carried out using Ion-Selective Electrode (Model-Orion4star). Sulphates were measured by Spectrophotometer (Model-Spectronic 21). The analytical data thus obtained could be used for different classifications for various suitability purposes and decision making.

Results and discussion

Leachate chemistry

The physico-chemical characteristics of collected leachate around the dumpsite during dry and wet seasons were analyzed and presented in Table 1. The color of the leachate was dark brownish which can be mainly attributed to the oxidation of ferrous to ferric form and the formation of ferric hydroxide colloids and complexes with fulvic/humic substance (Chu et al. 1994). Leachate pH is highly alkaline in nature. Alkaline pH is normally encountered at landfills, 10 years after disposal according to El-Fadel et al. (2002). Other analyzed parameters, such as TDS, TH, Ca2+, Mg2+, Na+, K+, Cl−, CO3 2−, HCO3 −, NO3 −, and SO4 2−, were found to have higher concentrations in the leachate collected during dry season when compared to wet season leachate sample which could be due to the dilution process of the contaminating ions. However, the high values of EC 55,000 µS/cm and TDS 34,775 mg/l recorded during dry season is mainly contributed by the major ions in larger concentrations indicating the presence of inorganic material.

Table 1 Physico-chemical characteristics of leachate (dry and wet) seasons
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Major ion chemistry of groundwater

Drinking suitability

Ground-water samples (No. 15) collected from the study area during dry and wet seasons were analyzed using APHA standards (2005) and compared with the drinking water quality standards (WHO 2011), and statistical information, such as minimum, maximum, mean, and standard deviation, was presented in Tables 2 and 3. The pH of groundwater ranged from 7.1 to 7.8 and 6.1 to 7.7 during dry and wet seasons, respectively. The pH results indicate that all the ground-water samples fall within the permissible limits and are in alkaline state according to WHO standards. The EC values of the groundwater ranged from 600 to 2200 and 825 to 2000 µS/cm during dry and wet seasons, respectively. The EC values of all the ground-water samples fall within the permissible levels of WHO standards except for few collected near the dumpsite indicating the impact of leachate on groundwater which may contain more soluble salts. The TDS values of groundwater ranged from 384 to 1408 and 528 to 1280 mg/l during dry and wet seasons indicating that almost all the samples exceeded the permissible levels of WHO standards. The calcium (Ca2+) values of the groundwater ranged from 65 to 335 and 44 to 300 mg/l during dry and wet seasons. All the ground-water samples exceeded the permissible levels of WHO standards except for few magnesium (Mg2+) values of the groundwater ranged from 27 to 115 and 5 to 92 mg/l. Most of the samples fall within the permissible limits of WHO standards except for few. The highest value of magnesium (115 mg/l) was recorded in GW15 collected during dry season. The TH values of the groundwater ranged from 200 to 1000 and 199 to 664 mg/l during dry and wet seasons. All the ground-water samples exceeded the permissible levels of WHO standards. According to Sawyer and McCarthy 1967 classification based on TH, all the ground-water samples in the study area collected during dry and wet seasons fall under hard to very hard category. The Na+ values ranged from 27 to 155 and 15 to 110 mg/l during dry and wet seasons. All the ground-water samples fall within the permissible limits of WHO standards. Potassium values of the groundwater ranged from 2 to 6 and 3 to 10 mg/l during dry and wet seasons. All the samples fall within permissible limits of WHO standards. The nitrate values of the ground-water samples ranged from 13 to 196 and 19 to 204 mg/l during dry and wet seasons. All the ground-water samples exceeded the permissible limits of WHO standards except for few. Major sources for nitrate in groundwater include domestic sewage, runoff from agricultural fields, and leachate from landfill sites. Higher concentration of nitrates (>50 mg/l) in water causes a disease called ‘‘Methaemoglobinaemia’’ also known as ‘‘Blue-baby Syndrome’’. This disease particularly affects infants that are up to 6-month-old Kapil et al. (2009). The sulphate values of groundwater ranged from 106 to 250 and 49 to 183 mg/l collected during dry and wet seasons. All the samples of the study area fall within the permissible limits of WHO standards. The chloride values of the ground-water samples ranged from 78 to 1100 and 50 to 998 mg/l collected during dry and wet seasons. Most of the ground-water samples exceeded the permissible limits of WHO standards except for few. The highest chloride value was recorded in GW6 in both the seasons, which is located at 1.2 km away from the dumpsite. High concentrations of chlorides are added to the groundwater from the municipal wastes, which clearly indicate the impact of landfill leachate. Other sources include farm drainage and sewage effluents. The abundance of major cations and anions of groundwater collected during dry and wet seasons is as follows: Ca2+ > Na+ > Mg2+ > K+>Cl− > HCO3 − > SO4 2− > NO3 − > CO3 2− and Ca2+ > Mg2+ > Na+ > K+>HCO3 − > Cl− > NO3 − > SO4 2− > CO3 2−, respectively.

Table 2 Physico-chemical parameters, descriptive statistics of analyzed ground-water samples compared with WHO (2011) (dry)
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Table 3 Physico-chemical parameters, descriptive statistics of analyzed ground-water samples compared with WHO (2011) (wet)
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Hydrochemical facies

The hydrochemical evolution of groundwater can be understood using the analytical data obtained from groundwater samples as a result of plotting the major cations and anions in the piper trilinear diagram (Piper 1944). The piper diagram consists of three distinct fields: cation ternary field (left), anion ternary field (right), and diamond field (centre). Leachate samples and ground-water samples of both seasons (dry and wet) were plotted on the piper diagram so as to understand their relationship, as it reveals the similarities and differences in the quality. Similar studies were carried out (Syafalni et al. 2014; Akudo et al. 2010; Akpoborie et al. 2015). According to the piper diagrams (Fig. 5a, b; Table 4), the leachate samples collected during dry and wet seasons fall in Na+/K+ and Cl− class type which can be observed from anion and cation ternary fields. The majority of the ground-water samples fall in Cl− class type along with leachate both in dry and wet seasons which can be observed from the anion ternary field and are a clear indication of leachate pollution. According to Panno et al. (2006); Uma (2004); Hanchar (1991); Baedecker and Back (1979), dumpsite, landfill leachate, and sewage are indeed known sources of chloride, bicarbonate, calcium, and magnesium loading to native groundwater. From the plot, alkaline earth (Ca2+ and Mg2+) exceed alkalies (Na+ and K+), while the strong acids (Cl− and SO4 2−) exceed the weak acids (CO3 2− and HCO3 −). Therefore, the dominant ground-water type of the study area can be observed as CaCl2 type.

Fig. 5
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a Piper diagram of Leachate and groundwater of the study area (dry). b Piper diagram of leachate and groundwater of the study area (wet)

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Table 4 Ground-water type based on piper diagram for Jawaharnagar dumpsite
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Irrigation suitability

The suitability assessment of groundwater for irrigation purpose is essential to provide good quality water for a proper growth of crop plants. The classification systems used to evaluate the suitability of groundwater for irrigation purpose can be determined through the indices, such as percentage sodium (Na%), sodium adsorption ratio (SAR), Kelley’s ratio (KR), and permeability index (PI), sodium soluble percentage (SSP) and USSL classification.

Salinity

Electrical conductivity (EC) is a measure of the dissolved ionic salts present in the groundwater. EC is a good measure of salinity hazard to crops, as it reflects the TDS in groundwater (Subramani et al. 2005). During dry season, 80 % of the ground-water samples fall under “permissible” category, 13 % fall under “good” category, and 7 % fall in “doubtful” category for irrigation purpose. During wet season, 100 % of ground-water samples fall in “permissible” category for irrigation purpose (Table 5). Excessive high salinity can affect the plants causing specific toxicity of sodium and higher osmotic pressure around the roots, thus preventing an efficient water absorption by the plants.

Table 5 Irrigation water quality based on EC values
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According to Wilcox (1955), in all natural waters, Na% is a common parameter to assess its suitability for irrigational purposes. The sodium in irrigation water in usually denoted as % Na and can be determined using the formula:

$$\% {\text{Na}} = \frac{{({\text{Na}}^{ + } ) \times 100}}{{({\text{Ca}}^{2 + } + {\text{Mg}}^{2 + } + {\text{Na}}^{ + } + {\text{K}}^{ + } )}}.$$

From Table 6, it can be observed that the ground-water samples of the study area collected during dry and wet seasons fall under ‘‘excellent” to “permissible’’ limits for irrigation.

Table 6 Irrigation water quality based on % Na
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Sodium adsorption ratio (SAR)

The SAR is the most useful parameter for determining the suitability of groundwater for irrigation purposes, because it measures the alkali/sodium hazard to crops (Subrahmanyam and Yadaiah 2000). It can be determined using the following formula introduced by Karanth (1987) (Table 7):

$${\text{SAR}} = \frac{{{\text{Na}}^{ + } }}{{\sqrt {({\text{Ca}}^{2 + } + {\text{Mg}}^{2 + } )/2} }}$$

where sodium, calcium, and magnesium are in meq/L.The results of the SAR values indicated that all the ground-water samples of the study area collected during dry and wet seasons fall in “excellent” category for irrigation. US Salinity diagram was also used to determine irrigation water suitability by plotting SAR against EC. The USSL (1954) plot indicated that 86 % of the ground-water samples collected during dry season fall in C3S1 field, which indicates high salinity and low-sodium type and 14 % of the samples fall in C2S1 field which indicates medium salinity and low-sodium type, whereas 100 % of the samples collected during wet season fall in C3S1 category indicating high salinity and low-sodium type (Fig. 6a, b). High salinity water can be used only on the soils with adequate drainage and salt tolerant plants must be selected. Low-sodium-type water can be used for irrigation purpose on almost all the types of soils with little danger of exchangeable sodium (Hem 1989).

Table 7 Irrigation water quality based on SAR (after Karanth 1987)
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Fig. 6
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a USSL classification of groundwater of the study area (dry). b USSL classification of groundwater of the study area (wet)

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Sodium Soluble Percentage (SSP)

It is also to evaluate the sodium hazard. The SSP is calculated as follows (Todd 1995):

$${\text{SSP}} = \frac{{({\text{Na}}^{ + } + {\text{K}}^{ + } ) \times 100}}{{({\text{Na}}^{ + } + {\text{K}}^{ + } + {\text{Ca}}^{2 + } + {\text{Mg}}^{2 + } )}}.$$

All ions are expressed in meq/L. Based on the calculated values (Table 8), all the ground-water samples of the study area fall in “excellent” class suitable for irrigation. Positive correlation between SAR and SSP (R 2 = 0.9477) is shown in Fig. 7.

Table 8 Irrigation water quality based on SSP (after Todd 1995)
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Fig. 7
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SAR vs SSP for irrigation water

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Kelley’s Ratio (KR)

The KR values are calculated by the formula given by Kelly (1963):

$${\text{KR}} = \frac{{({\text{Na}}^{ + } )}}{{({\text{Ca}}^{2 + } + {\text{Mg}}^{2 + } )}}.$$

KR values of 1 or <1 indicate suitability, while KR values of >1 indicate unsuitability for irrigation purpose. Based on this classification, all the ground-water samples collected during dry and wet seasons fall in “good” category for irrigation purpose, i.e., below (<1 or 1) (Table 9).

Table 9 Irrigation water quality based on KR (after Kelly 1963)
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Permeability Index (PI)

The PI values also indicate the suitability of groundwater for irrigation. This index is used to evaluate the effects of water quality on the physical properties of the soil. It is calculated by the following equation which was developed by Doneen (1964):

$${\text{PI}} = \frac{{({\text{Na}}^{ + } + \sqrt {{\text{HCO}}_{3}^{ - } } ) \times 100}}{{({\text{Ca}}^{2 + } + {\text{Mg}}^{2 + } + {\text{Na}}^{ + } )}},$$

where all ions are expressed in meq/L. During dry season, the majority of the samples (80 %) fall in “good to permissible” category and 20 % of the samples fall in “doubtful to unsuitable” category. During wet season, most of the samples (87 %) fall in “good to permissible” and 13 % of the samples fall in “excellent” category for irrigation purpose (Table 10).

Table 10 Irrigation water quality based on PI (after Doneens 1964)
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Conclusion

The leachate characteristics studied reveal that almost all the parameters carried out were found to have higher concentrations during dry season with slight dilutions in wet season. The interpretations of the hydrochemical analyses of the groundwater collected in both the seasons reveal the unsuitability for drinking purpose considering drinking water quality standards. Hydrochemical facies studies reveal that most of the ground-water samples fall in the Cl type along with the leachate which can be witnessed from piper diagram plotted for both the seasons. It can be observed that the groundwater having higher concentrations of Ca+2, Cl−, and NO3 − can be used as an indication of leachate percolation into the groundwater which can have deleterious effects to humans if consumed. According to the irrigation water quality classification limits, most of the ground-water samples of the study area are suitable for various irrigation needs. However, salt tolerant plants/crops are appropriate, as the water is highly saline in nature which can be witnessed from the USSL diagram. Finally, it can be concluded that leachate emanating from the dumpsite is causing an environmental risk which has to curb immediately, as it is highly dangerous in every aspect of the life.