Laxman Kumar Duvva1, Thirupathi Bookya2 and Sriramulu Theegala3 1Department of Applied Geochemistry, Osmania University, Hyderabad 23Department of Geology, Osmania University, Hyderabad Corresponding authors Email [email protected] ABSTRACT The Maheshwaram area of Ranga Reddy district and its groundwater quality evaluates for its suitability for drinking and agricultural purposes. Forty two groundwater samples were collected from pre and post-monsoon seasons and analyzed for chemical parameters such as pH, Electrical Conductivity, Total Dissolved Solids (TDS), TH, Na, K, Ca2, Mg2, Cl-, HCO3-, CO32-, and, SO42-. To assessed the groundwater quality based on Gibbs Ratio, Sodium Adsorption Ratio (SAR), Sodium Percentage (Na ), Chloro Alkaline Indices (CAI), Kelleys Ratio (KR), Magnesium Hazard (MH) and Permeability Index (PI) were calculated. The hydrogeochemical facies distribution which indicates the water types Na – Ca2 – HCO3- – Cl- and mixed Na – Ca2 – Mg2 – HCO3- – Cl-, the plot shows that the groundwater samples fall under the subdivision of alkaline earths (Ca2 Mg2) exceeds Alkalis (Na K) dominated over the strong acids (Cl- SO42-) exceeds Weak acids (HCO3- CO32-) in pre and post-monsoon seasons. The high concentration of total hardness and TDS in a few places identify the unsuitability of groundwater for drinking and agriculture, such areas require special care to provide adequate drainage. Keywords Groundwater quality, Drinking, Irrigation and Maheshwaram area INTRODUCTION Groundwater is the alternate source in absence of surface water bodies for its utility for different purposes. Unfortunately due to technological advancement, urbanization, population growth and mismanagement in proper utilization of available resources resulted in deterioration of groundwater both in terms of quality and quantity. Under normal conditions the quality of groundwater influenced by geochemical processes such as weathering of minerals, precipitation, dissolution, ion exchange, oxidation, reduction and residence time of groundwater (Rina et al., 2013). Groundwater quality comprises physical, chemical and biological qualities. Human activities alter the natural composition of groundwater through the disposal of industrial wastewater, sanitary landfills, storage piles, household septic tanks, improperly constructed wastewater disposal wells and application of chemicals on agricultural lands. Hydrochemical evaluation of groundwater systems is base on the availability of a significant amount of information concerning groundwater chemistry (Aghazadeh and Mogadam 2004 Hossien 2004 Purushotham 2011 Machender 2014 Satyanarayana 2017). Quality of groundwater is equally essential to its quantity owing to the suitability of water for various purposes (Schiavo et al., 2006 Subramani et al., 2005). Groundwater chemistry, in turn, depends on many factors, such as general geology, the degree of chemical weathering of the various rock types, quality of recharge water and inputs from sources other than water-rock interaction. Such factors and their interactions result in a complex groundwater quality (Domenico and Schwartz 1990 Guler and Thyne 2004 Vazquez et al., 2005 Purushotam et al., 2011). The groundwater quality and human health are closely related and consumption of contaminated water has adverse effect on human health. Determination of physical, chemical and bacteriological properties is essential for evaluation of the quality of groundwater for different purposes as per water quality standards laid by different agencies (CGWB, 2010). Assessment of groundwater quality has prompted the author to take study related to the quality variations in Maheshawaram area of Ranga Reddy district, forty two groundwater samples were collected from hand pumps and bore wells in the vicinity of cultivated agricultural land, hand pumps in a densely populated area in pre and post-monsoon seasons. In this paper, an attempt is made to evaluate the quality indices of groundwater to understand the geochemical relationships of water quality for the suitability of groundwater resources. In view, an extensive survey conducted to know the quality of water for domestic and irrigation use. The Study Area The Maheswaram area of Ranga Reddy district, Telangana state which is locates 35 km from Hyderabad, India on Srisailam highway covering an area of 246 km2. The study area lies in between Latitudes 17 02 to 17 14 North and Longitudes 78 18 to 78 34 East and in the Survey of India Topographical maps 56 K/8 and 56 K/12 (Fig. 1). The major rock types in the study area are peninsular gneiss and calc gneiss, which are the main granites and granitic gneisses rocks are composed of quartz, feldspar, biotite, and hornblende (Fig. 2). The Study area receives annual average rainfall (738 mm) from northeast and southwest monsoons, the average temperature in summer is 400C and winter is 140C. Materials and Methods In order to assess the groundwater quality, forty two groundwater samples have been collected in pre-cleaned polyethylene containers for pre and post-monsoon seasons. They were analyzed for pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Calcium (Ca2), Magnesium (Mg2), Sodium (Na), Potassium (K), Carbonate (CO32-), Bicarbonate (HCO3-), Chloride (Cl-), Sulphate (SO42-), Nitrate (NO3-) and Fluoride (F-) for all physico-chemical parameter using standard methods (APHA 1995), The pH was measured with Digital pH Meter (Model 802 Systronics) and Electrical Conductivity was measured with Conductivity Meter (Model 304 Systronics). Total Dissolved Solids were estimated by calculation method. Sodium and Potassium was measured with Flame photometer (Model Systronics 130). The TH (as CaCO3) and Ca were analyzed volumetrically using standard EDTA. The concentration Mg is difference between the TH and Ca2. CO32- and HCO3- were estimated by titrating with standard HCl using phenolphthalein and Methyl orange as acid-base indicators. The Cl- is estimated by titrating with standard AgNO3. Sulphates and Nitrates were measured with Spectronics 21 (Model BAUSCH LOMB). Fluoride concentration was measured with Orion ion analyzer with fluoride ion selective electrode. RESULTS AND DISCUSSION Groundwater Chemistry The statistical summary of the chemical analysis of groundwater of the study area given in (Table 1). The pH value of groundwater in the study area is varying between 6.70 8.80 and 6.60 8.60 during pre and post-monsoon seasons, which is indicating slightly acidic to alkaline. The EC values varying from 525 3922 S/cm and 425 2910 S/cm in pre and post-monsoon seasons. The high concentration of Electrical Conductivity indicates enrichment of salts in the groundwater. The HCO3- varying from 55 567 mg/L and 78 708 mg/L in pre and post-monsoon seasons. The Cl- varying from 24 344 mg/L and 36 687 mg/L in pre and post-monsoon seasons. The high concentration of Chloride in groundwater may be from diverse sources such as weathering, leaching of rocks and soil, domestic and municipal effluents (Sarath Prasanth et al., 2012). The SO42- varying from 16 249 mg/L and 19 249 mg/L in pre and post-monsoon seasons. Excess sulphate concentration is due to breaking of organic substances from topsoil and water leachable sulfate present in fertilizer (Miller 1979 Craig and Anderson 1979). The NO3- values varied from 3.0 200 mg/L and 4 128 mg/L in pre and post-monsoon seasons. The high concentration of nitrates are due to leaching of organic substances from the weathered soil. The Ca2 values ranges from 18 180 mg/L and 14 176 mg/L and Mg2 values varying from 2.0 74 mg/L and 10 103 mg/L in pre and post-monsoon seasons. The Na values range from 16 189 mg/L and 28 276 mg/L. K values varying from 01 10 mg/L and 01 – 08 mg/L in pre and post-monsoon seasons. Fluoride in the study area varies in the range of 0.31 3.03 mg/L and 0.28 – 2.58 mg/L in pre and post-monsoon seasons. Highest fluoride level at YCLIN Clinical Reference Lab (3.03mg/L), towards Amirpet in pre-monsoon and post-monsoon seasons at Subhanpur village (2.58 mg/L), lowest at K.C. Cheruvu Tanda (0.31 mg/L) and (0.28 mg/L) in pre and post-monsoon seasons, respectively. The maximum tolerance limit fluoride in groundwater is 1.5 mg/L. Ingestion of high fluoride water with more than tolerance limit results in Fluorosis (Madhnure et al., 2007). Hydrogeochemical facies of Groundwater Major ion chemistry of groundwater examined by using (Piper 1994) trilinear diagram to identify the chemical alteration in groundwater. The Piper diagram consists of two lower triangular fields and a central diamond-shaped field. Three field have incorporation of major ions only, which are cations like (Ca2 Mg2) alkaline earths, (Na K) alkalis, HCO3- weak acid, and (SO42- Cl-) strong acid. Water facies identified by the projection of plots in the central diamond-shaped field as per the classifications made by (Karanth 1987). Aquachem 4.0 scientific software used for the plotting of piper trilinear diagram. The piper diagram reflects the dominated water type in the study area is Na – Ca2 – HCO3- – Cl- and mixed Na – Ca2 – Mg2 – HCO3- – Cl- (Fig. 3a and b). This process which indicates that the groundwater samples fall under the subdivision of alkaline earths (Ca2 Mg2) exceeds Alkalis (Na K) dominated over the strong acids (Cl- SO42) exceeds Weak acids (HCO3- CO32-) in pre and post-monsoon seasons (Table 3). Gibbs diagram To establish the relationship of water composition and aquifer lithological characteristics, the data plotted on Gibbs diagram. The major distinct fields such as precipitation, rock and evaporation dominances types in the Gibbs plot (Gibbs, 1970). Gibbs ratios are calculated with the formulae given below and expressed in meq/L. Gibbs ratio I (for anion) Cl- /(Cl- HCO3-) (1) Gibbs ratio II (for cation) (Na K) / (Na K Ca2) (2) Gibbs ratio I of the study area values ranges from 0.15 0.85 meq/L with an average of 0.46 meq/L and 0.31 0.90 meq/L with an average of 0.57 meq/L in pre and post-monsoon season (Table 1). Gibbs ratio II for the study area values ranges from 0.18 – 0.79 with an average of 0.46 meq/L and 0.16 0.86 meq/L with an average of 0.48 meq/L in pre and post-monsoon seasons (Table 1). The study area the groundwater samples are fall in rock dominance and evaporation dominance field in pre and post-monsoon seasons (Fig. 4a and b). Drinking water quality Drinking water quality the analytical results of physical and chemical parameters of groundwater were compared with the standard guideline values as recommended by the World Health Organization for drinking and public health purposes (WHO 2011) (Table 1). The table shows the most desirable limits and maximum allowable limits of various parameters. The concentrations of cations such as Na, Ca2, and Mg2, K and anions such as HCO3-, CO32-, Cl- and SO42- are within the maximum allowable limits for drinking except for a few samples.
Total dissolved solids and Total hardness To ascertain the suitability of groundwater for any purposes, it is essential to classify the groundwater depending upon their hydrochemical properties based on their TDS values (Carroll 1962, Todd 2001). The TDS of groundwater in the study area varying between 165 2510 mg/L with an average of 928.08 mg/L and 272 1862 mg/L with an average of 824.38 mg/L, during pre and post-monsoon seasons (Table 1). The highest desirable limit TDS up to 500 mg/L (WHO 2011). Based on this classification fresh water is 67 and brackish water 33 in pre-monsoon seasons and post-monsoon season 69 is fresh water and 31 is brackish water of the study area (Table 2). The high concentration of TDS is due to the influence of anthropogenic sources, such as domestic sewage, septic tanks, and agricultural activities. The Total Hardness of groundwater in the study area varying between 117 725 mg/L with an average of 365.40 mg/L and 76 863 mg/L with an average of 304.39 mg/L, during pre and post-monsoon seasons (Table 1). According to WHO specification TH is 500 mg/L is the maximum allowable limit. Based on this classification of the total hardness about 64, 26 and 10 of the groundwater samples are fall in the very hard, moderate to hard and hard water category in pre-monsoon season. In post-monsoon season, the groundwater samples are fall in very hard 33, hard 30 and moderate to hard 07 (Table 2), which indicates the hardness of the water is due to the presence of alkaline earth such as calcium and magnesium. IRRIGATION WATER QUALITY Salinity and alkalinity hazard Electrical conductivity is a good measure of salinity hazard to crops as it reflects the TDS in groundwater. Eight and four out of 42 samples in pre and post-monsoon seasons exceeded (Table 2) the permissible limit for irrigation (Ragunath 1987). Based on the this classification excess salinity reduces the osmotic activity of plants and thus interferes with the absorption of water and nutrients from the soil (Saleh et al., 1999). Sodium Adsorption Ratio (SAR) Ca and Mg in the proper proportion with sodium maintain soil in the good state. In irrigation water, often represented by a parameter called Sodium Adsorption Ratio (SAR) which can be calculated by the formula taking individual values of Na, K, Ca2 and Mg2 in milliequivalent per liter.
EMBED Equation.3 In the study area, sodium adsorption ratio values range from 0.49 6.52 meq/L with an average of 2.24 mg/L and 1.30 8.64 meq/L with an average of 4.16 mg/L in pre and post-monsoon seasons (Table 1). All samples fall in the excellent class in pre and post-monsoon seasons (Table 2), implies that no alkali hazard is anticipated to the crops.
The U.S. salinity laboratory (USDA 1954) proposed a diagram for studying the suitability of groundwater for irrigation purposes based on SAR. The chemical parameters of the groundwater of the area are represented in the USSL diagram (Fig. 5 and 6). Based on this classification about 83 of the groundwater samples are fall under C3S1 class indicating high salinity low sodium waters, 10 of the groundwater samples are fall under C2S1 class indicates medium salinity and low sodium waters, 5 of the groundwater samples fall under C4S1 class indicating very high salinity and low sodium water and 2 of the groundwater sample fall under C3S2 class indicating high salinity medium sodium waters in pre and post-monsoon seasons. This implies that the groundwater quality can be used for irrigation on all types of soil.
Sodium percentage (Na ) Irrigation water containing large amounts of sodium is of special concern due to sodiums effects on soil and poses a sodium hazard. Excess sodium in water produces the undesirable effects of changing soil properties and reducing soil permeability (Subba Rao 2006). Hence, the assessment of sodium percentage is necessary while considering the suitability for irrigation, which is calculated using the formula and expressed in meq/L. EMBED Equation.3 (4) The sodium percentage values vary from 9.14 – 75.17 meq/L with an average of 36.76 meq/L in pre-monsoon season and 21.04 68.79 meq/L with an average of 44.78 mg/L in the post-monsoon season (Table 1). Based on this classification, about 14, 17 of the groundwater samples are excellent to good category, 64, 40 of the groundwater samples are good to permissible, 10, 26 of the samples are doubtful to unsuitable category in pre and post-monsoon seasons respectively for irrigation purposes. About 5 of the groundwater samples fall in the field of unsuitable for irrigation in post-monsoon season. Residual Sodium Carbonate (RSC) Residual sodium carbonate has been used to determine the hazardous effect of carbonate and bicarbonate on the quality of water for agricultural purpose (Eaton 1950) and is determined by the formula and expressed in meq/L. EMBED Equation.3 (5) The RSC values range from -10.19 3.26 meq/L with an average of -2.64 meq/L in pre-monsoon season and -10.50 4.20 meq/L with an average of -1.27 meq/L in post-monsoon season respectively (Table 1), The classification of irrigation water according to RSC values containing greater than 2.5 meq/L of RSC are not suitable for irrigation. The study area which is classified on the basis of RSC values is presented in (Table 2) about 90, 83 of groundwater samples are fall in the safe category for irrigation in pre and post-monsoon seasons, about 5, 7 of groundwater sample are in marginal for irrigation in pre and post-monsoon seasons and about 5, 10 of groundwater sample are in unsuitable for irrigation in pre and post-monsoon seasons. Chloro Alkaline Indices (CAI) It is essential to know the changes in chemical composition of groundwater during its travel in the sub-surface (Aastri 1994). The Chloro-alkaline indices CAI 1, 2 are suggested by (Schoeller 1977) which indicate the ion exchange between the groundwater and its host environment. The Chloro-alkaline indices are calculated using the formula given below and expressed in meq/L). 1) Chloro Alkaline Indices EMBED Equation.3 (6) 2) Chloro Alkaline Indices EMBED Equation.3 (7) If there is ion exchange of Na and K from water with magnesium and calcium in the rock, the exchange is known as direct when the indices are positive. If the exchange reversed, then the exchange is indirect, and the indices are found to be negative. The CAI-1 was calculated for the groundwater of the study area varying between -3.71 0.86 meq/L with an average of -0.21 meq/L and – 4.09 to 0.56 meq/L with an average of -0.39 meq/L in pre and post-monsoon seasons (Table 1). The CAI-2 are calculated for the waters of the study area varying from -0.67 -1.25 meq/L with an average of 0.10 meq/L and -0.58 1.90 meq/L with an average of 0.01 meq/L in pre and post-monsoon seasons (Table 1). In the pre-monsoon season, CAI-1 and 2 graph sample values are showing that 25 samples positive (60) and 17 samples show negative (40). The post-monsoon season CAI-1 and 2 graph sample values are shows that 17 positive and 25 negatives. The chloro-alkaline indices also support the fact that reverse ion exchange is the main hydrochemical process controlling the groundwater chemistry in the region (Fig. 8). Kelleys Ratio The level of Na measured against Ca2 and Mg2 is known as Kellys ratio, based on which irrigation water can be rated (Kelly 1946 Paliwal 1967 1972). The concentration of Na in irrigation water is considered to be one of the prime roles in making the water unsuitable. The Kellys ratio is 1 suitable, marginal is 1-2 and unsuitable is 2. The Kellys ratio is calculated using the formula given below and expressed in meq/L. EMBED Equation.3 (8) The Kelly ratio values range from 0.10 3.02 meq/L with an average of 0.69 meq/L and 0.28 2.18 meqL with an average of 0.89 meq/L in pre and post-monsoon seasons (Table 1), which indicates that 79 and 62 suitable for pre and post-monsoon seasons, marginal is 19 pre-monsoon, 36 post-monsoon seasons, unsuitable 2 in pre-monsoon and post-monsoon seasons for irrigation purposes (Table 2). Magnesium Hazard (MH) Alkaline earth is in the equilibrium state in groundwater. If soils have more alkaline earths, they reduce crop yield. Szaboles and Darab (1964) proposed a magnesium hazard with the alkaline earth for irrigation. This hazard is expressed in terms of Magnesium Hazard (MH), which is computed by (Eq. 9), using the values of ions in meq/L. (9) The Magnesium hazard values in the study area values range from 3.16 69.55 meq/L with an average of 37.17 meq/L and 18.35 75.38 meq/L with an average of 40.75 meq/L in pre and post-monsoon seasons (Table 1). According to the classification of MH values containing greater than 50 are considered harmful and unsuitable for irrigation. Based on this classification about 7 of the groundwater samples are greater than 50 in pre-monsoon season and remaining groundwater samples are less than 50 in pre and post-monsoon seasons. Permeability Index (PI) The Permeability Index (PI) values also depict suitability of groundwater for irrigation purposes, since long-term use of irrigation water can affect the soil permeability, influenced by the Na, Ca2, Mg2, and HCO3-contents of the soil. The PI can be expressed as Eq. 10 EMBED Equation.3 (10) The concentrations are reported in meq/l. Doneen (1964) developed a criterion for assessing the suitability of water for irrigation based on PI, where waters can be classified as classes I, II, and III. The PI values of the study area varied from 20 100 meq/L with an average of 57 meq/L and 37 96 meq/L with an average of 65 meq/L in pre and post-monsoon seasons (Table 1). According to the classification PI values about 2, 83 and 15 groundwater samples fall in class I, II and III categories in pre-monsoon season. About 21, 64 and 15 of groundwater samples fall in categories respectively I, II and III classes of a post-monsoon season (Fig. 9). Conclusions The present study of hydrochemical analysis reveals that the groundwater in Maheshwaram area is hard, fresh to brackish and alkaline in nature. The chemical relationships in Piper diagram identify Na – Ca2 – HCO3- – Cl- and mixed Na – Ca2 – Mg2 – HCO3- – Cl- prevent water type, which indicates that alkaline and strong acids dominated over the alkalis earth and weak acids. According to Gibbs plot, groundwater samples are fall in the rock dominance and evaporation dominance. Total Hardness is high in the groundwater thereby, causing the groundwater in one-fourth of the study area to be unsuitable for drinking. Based on this classification of TDS values about fresh water is 67 and brackish water 33 in pre-monsoon season and about 69 is fresh water and 31 is brackish water in post-monsoon season. According to irrigation assessment of chemical parameter such as Na, Wilcox, RSC, CAI, KR, MH and PI, based on the these classification of the groundwater samples are identified to be unsuitable for irrigation. Focuses on individual chemical parameters are reveals that groundwater quality for irrigation and drinking, contradictory locations exist which are majorly caused by the anthropogenic activities such as industrial effluents, sewage discharge and agricultural activities. Thus the study suggests appropriate remedial measures to improve the groundwater quality. 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