Academia Journal of Environmental Science 5(6): 095-101, June 2017 DOI: 10.15413/ajes.2017.0113 ISSN: ISSN 2315-778X ©2017 Academia Publishing Research Paper Groundwater quality assessment using water quality index (WQI) in Liaquatabad Town, Karachi, Pakistan Accepted 22nd June, 2017 ABSTRACT The aim of the present study is to evaluate the groundwater quality of Liaquatabad Town using water quality index (WQI) measured through physico- chemical parameters. For this purpose, groundwater samples (n = 31) were randomly collected through boring wells from various sites of study area. Data revealed that TDS content of groundwater is very high (mean: 1045.55 mg/L) which is double the WHO limit for drinking purpose. Elevated concentrations of Ca, Na, Cl, and HCO3 is reported in 85, 33, 40 and 70% wells respectively, which exceeded the corresponding WHO guideline for drinking purpose. Very high concentration of these major ions (Ca, Na, Cl, and HCO3) is indicative of sewage Adnan Khan* and Yusra Rehman mixing with groundwater in Liaquatabad. The calculated value of water quality index (WQI = 66.1) shows that groundwater in Liaquatabad town is not suitable Department of Geology, University of for drinking purpose but can be used for industrial and irrigation purpose. Karachi, Karachi, Pakistan. *Corresponding author. Email: Keywords: Groundwater quality, physio-chemical parameters, water quality [email protected]. index, Liaquatabad town. INTRODUCTION Water is an essential component of all forms of life; no the modern civilization, industrialization, urbanization, organism can survive without water. Daily demand of increase in population and improper waste management drinking water of a man is normally 7% of his body weight are agents of degradation of groundwater quality (Iqbal and Gupta, 2009) but this water can become a threat (Agarwal, 2009). to the continuation of life if it gets polluted with harmful or Karachi is the biggest and densely populated (more than toxic substances (Abbasi and Vinithan, 1999). Water is 20 million population) city of Pakistan which is facing the mainly obtained from two sources, that is, surface water acute shortage of municipally supplied water since many which includes rivers, canals, fresh water lakes and decades. It is the main reason that residents of Karachi are streams etc and ground water like well and borehole water rapidly switching over to groundwater for drinking and (McMurry and Fay, 2004). In the present scenario, water other domestic uses. Despite of such drastic switch over no demand is increasing all over the world due to rapid detailed work has been carried out so far to assess the growth in population and more than half of the world status of groundwater quality in Karachi. Thus, the present depends on groundwater for survival (UNESCO, 1992). In study aimed at screening the groundwater for its quality to Asia alone, about 1 billion people are directly relying on ensure its potential use in one of the core residential areas. groundwater source (Foster, 1995). According to World Liaquatabad town is selected for this purpose due to the Health Organization, about 80% of all the diseases in fact that it is a densely populated town where middle to human beings are caused by water (Al-Hadithi, 2012). lower middle class of the society is settled since birth of Usually the groundwater is considered less polluted as Pakistan. Another objective of this study is to apply Water compared to the surface water due to less exposure to the quality index (WQI) method to classify the groundwater of external environment (Iqbal and Gupta, 2009). However, Liaquatabad town for various purposes. Academia Journal of Environmental Science; Khan and Rehman. 096 Figure 1: Geological map of Liaquatabad town, Karachi. Study area MATERIALS AND METHODS Sample collection Liaquatabad town is located in the central district of Karachi which lies between latitude 24.8880° to 24.9223° Thirty-one groundwater samples were randomly collected N and longitude 67.0177° to 67.0644° E (Figure 1). The from depth range of 16 to 78 m. Groundwater was study area is mainly residential which is spread over 11.28 electrically pumped for 2 to 3 min to get representative km2 area with dense population of 985,581 (KSMP, 2007). sample from the aquifer. Location of each well was marked Liaquatabad town is bordered by Lyari River in the South with the help of Global Positioning System (GPS) on the and Orangi nala in the west. Similarly, Gujjar nala passes google earth image (Figure 2). Groundwater samples were through the center of Liaquatabad town (Figure 1). collected in plastic bottles of 1.5 L capacity for physico- Geologically, this town is completely covered with chemical analysis. Bottles were properly washed and alluvium. Sub-surface rocks belong to Nari and Gaj rinsed thoroughly with distilled water and then with formations of Oligocene and Miocene age respectively. groundwater at each sampling site. For nitrate Nari Formation consist of sandstones with interbedded determination, groundwater samples were collected in shales and subordinate limestones (Pithawalla and Martin- bottles of 100 ml capacity in which 1 ml boric acid solution Kaye, 1946) which is overlain by the Gaj Formation having was injected through sterile syringe to cease any further 50 m thick bed in the Karachi region comprising reaction. predominantly soft to hard sandstone and argillaceous limestone (Shah, 2009). Based on the thickness of Gaj Formation, it is assummed that most of the wells (depth Groundwater analysis range: 16 to 46 m) of study area are tapping groundwater from the aquifers of Gaj Formation. Similarly, the rest of The pH and total dissolved solids (TDS) of collected the wells are installed in the Nari Formation aquifers samples (n =31) were measured with the glass electrode (Table 1). pH meter (Adwa AD 111) and EC meter (Adwa AD 330) Academia Journal of Environmental Science; Khan and Rehman. 097 Figure 2: Sample location map using Google Earth Image. respectively. Concentration of sodium and potassium were quality (Bad and Poor). Weighted arithmetic index method determined by using flame photometer (Model No. of WQI proposed by Brown et al. (1970) was applied to JENWAY PFP7). Sulphate content was tested by evaluate the groundwater quality status in Liaquatabad gravimetric method, while bicarbonate by titration and town. Physicochemical parameters including pH, TDS and chloride was estimated by argentometric titration method. major cations (Ca, Mg, Na and K) and anions (HCO3, Cl, SO4 The method used for the analysis of calcium was EDTA and NO3) were used to calculate WQI of groundwater in titration standard method (1992). Magnesium was Liaquatabad town. WQI is calculated using the formula: estimated as the difference between hardness and calcium with the help of standard formula. Groundwater samples WQI=∑QnWn/ ∑Wn preserved in the boric acid were analyzed to determine the nitrate concentration by cadmium reduction method Where: (HACH-8171) on spectrophotometer. Qn is the quality rating of nth water quality parameter; Wn is the unit weight of nth water quality parameter; The quality rating Qn is calculated using the equation: Water quality index (WQI) Qn=100*[(Vn – Vi) / (Vs- Vi)] WQI is one of the most effective tools to communicate Where: information on the quality of water to the concerned citizens and policy makers (Yisa and Jimoh, 2010). It was Vn is the actual amount of nth parameter present; first proposed by Horton (1965) which was later on Vi is the ideal value of the parameter, Vi = 0, except for pH generalized by Brown et al. (1970). According to Bharti (Vi = 7); (2011), WQI is a single number that rates the water quality Vs is the standard permissible value for the nth water by aggregating several water quality parameters and quality parameter. usually the higher score alludes to the better quality (Excellent and Good) and the lower score to degraded Unit weight (Wn) is calculated using the formula: Academia Journal of Environmental Science; Khan and Rehman. 098 Table 1: Physico-chemicals parameters determined in groundwater of Liaquatabad Town. Physical parameters Major cations Major anions S/No Depth TDS Ca Mg Na K HCO3 Cl SO4 NO3 pH (m) (mg/L) (mg/L) mg/L 1 55 8.02 3710 42 67.92 950 9 550 691.28 252.3 6.18 2 40 7.94 786 102 67.92 210 6 250 228.65 89.54 15.43 3 24 7.73 665 104 88.45 120 7 350 194.98 122.1 6.206 4 - 7.51 730 118 98.54 126 9 350 182.57 97.68 6.182 5 30 7.62 773 127 107.73 135 9 350 196.75 122.1 6.668 6 78 7.95 877 100 110.57 178 7 337.5 257.01 97.68 15.19 7 37 7.57 818 154 106.07 172 6 325 212.7 73.26 15.47 8 - 7.64 801 102 99.10 162 8 250 207.38 130.2 13.9 9 34 7.36 929 88 67.55 272 6 375 294.24 81.4 6.574 10 53 7.54 762 93 91.53 152 8 337.5 246.38 122.1 13.54 11 46 7.22 1270 92 85.13 325 6 550 478.58 130.2 5.017 12 37 7.66 1820 97 85.21 460 10 412.5 973.10 73.26 10.08 13 43 7.32 1120 90 100.24 240 9 325 428.95 170.9 13.51 14 - 7.36 1680 106 88.33 470 7 350 886.25 73.26 7.634 15 24 7.38 663 70 79.58 118 4 275 53.175 40.7 4.981 16 43 7.25 920 84 90.88 158 6 350 100.44 114 11.54 17 46 7.26 732 83 76.38 130 6 275 85.08 73.26 6.356 18 37 7.45 653 92 94.04 111 6 250 173.71 130.2 4.131 19 46 7.15 1130 108 125.87 162 13 312.5 414.77 40.7 5.526 20 70 7.29 784 86 99.27 120 7 300 223.34 16.28 4.532 21 24 7.69 724 100 83.84 120 5 312.5 200.29 16.28 5.652 22 46 7.39 840 68 59.05 179 5 350 223.34 138.4 5.112 23 43 7.21 1710 144 130.98 322 10 300 762.18 146.5 7.716 24 61 7.48 1600 100 110.57 326 11 300 671.78 146.5 19.17 25 26 7.61 798 156 67.07 160 6 332.5 230.43 73.26 5.072 26 16 7.59 508 98 71.81 93 15 332.5 115.21 56.98 2.48 27 18 7.41 715 88 96.71 112 14 322.5 212.7 40.7 7.936 28 70 7.56 848 70 101.45 150 6 335 272.97 65.12 7.208 29 18 7.55 716 68 97.93 175 7 377.5 210.93 81.4 15.22 30 - 7.29 1800 138 176.3 330 13 352.5 1049.3 114 7.32 31 58 7.99 530 98 73.02 110 8 290 154.21 97.68 3.084 WHO Limit - 6.5-8.5 500 75 150 200 12 300 250 250 10 Mean 41.59 7.52 1045.6 98.9 93.52 220.9 8.03 338.06 342.99 97.68 8.54 Min 16 7.15 508 42 59.05 93 4 250 53.18 16.28 2.48 Max 78 8.02 3710 156 176.30 950 15 550 1049.3 252.3 19.17 Std.