




































 
 

 

9 
© 2020 by the authors; licensee Asian Online Journal Publishing Group 
 

Asian Review of Environmental and Earth Sciences 
Vol. 7, No. 1, 9-17, 2020 

ISSN(E) 2313-8173/ ISSN(P) 2518-0134 
DOI: 10.20448/journal.506.2020.71.9.17 

© 2020 by the authors; licensee Asian Online Journal Publishing Group 

   
 

 
 
 
Assessment of Groundwater Quality in Coastal Region a Case Study of 
Qayyumabad, Karachi, Pakistan 

 
Adnan Khan1 

 Syed Asad Raza2 

 Afrida Fatima3 

 Syed Wasi Haider4 

 
 

( Corresponding Author) 
 
1,2,3Department of Geology, University of Karachi, Pakistan. 

 
4Institute of Space Science and Technology, University of Karachi, Pakistan. 

 

 
Abstract 

The aim of present study is to assess groundwater quality of Qayyumabad area for drinking 
purpose. Groundwater samples (n = 20) were collected from wellbores from variable depths (12-
300 feet) occurring on both banks of the Malir River near study area. Water quality was assessed 
through estimation of physical parameters including, pH, Eh, TDS, EC, hardness, temperature, 
aesthetic character (taste, color and odor) and chemical parameters including major cations (Na, K, 

Ca, Mg), anions (Cl, NO₃, SO₄, HCO₃) and minor/trace elements (Fe, As). Data revealed that 
groundwater of study area has very high TDS content (range: 805-40340 mg/l) and positive Eh (-
180 to +125 mV), suggesting the recent recharge. The pH varies in the range of 6.55-7.75 which 
comply with WHO limit (6.5-8.5) for drinking water. Major solutes varied in the order of Na 
(mean: 2587 mg/l) > Mg (433mg/l) > Ca (231mg/l) > K (91 mg/l) while anions in the order of Cl 

(mean: 3385 mg/l) > SO₄ (mean: 580 mg/l) > HCO₃ (mean: 343 mg/l) > NO₃ (11.43 mg/l). Both 
arsenic and iron contents occur within the WHO permissible limits except two samples which 
showed elevated Fe (4950 ppb) and As (100 ppb) respectively. These results suggest that 
groundwater in study area is unfit for drinking purpose. Principal component analysis (PCA) 
explained four factors where F1 suggests the salts leaching mechanism and F2 indicated anoxia 
prevalence due to organic matter decomposition. On the other hand, F3 confirmed water rock 
interaction and F4 supported the prevalence arsenic release associated with anoxia. 

 
Keywords: Groundwater, Shallow aquifers, Drinking quality, Coastal part, Karachi. 

 
Citation | Adnan Khan; Syed Asad Raza; Afrida Fatima; Syed Wasi 
Haider (2020). Assessment of Groundwater Quality in Coastal 
Region a Case Study of Qayyumabad, Karachi, Pakistan. Asian 
Review of Environmental and Earth Sciences, 7(1): 9-17. 
History:  
Received: 22 October 2019 
Revised: 25 November 2019 
Accepted: 30 December 2019 
Published: 12 February 2020 
Licensed: This work is licensed under a Creative Commons 

Attribution 3.0 License  
Publisher:  Asian Online Journal Publishing Group 
 

Acknowledgement: Authors are highly thankful to Chairperson, Department 
of Geology, University of Karachi for providing analytical facilities. 
Funding: This study received no specific financial support. 
Competing Interests: The authors declare that they have no conflict of 
interests. 
Transparency: The authors confirm that the manuscript is an honest, 
accurate, and transparent account of the study was reported; that no vital 
features of the study have been omitted; and that any discrepancies from the 
study as planned have been explained. 
Ethical: This study follows all ethical practices during writing.   

 

 

Contents 
1. Introduction ...................................................................................................................................................................................... 10 
2. Materials and Methods ................................................................................................................................................................... 10 
3. Results and Discussion ................................................................................................................................................................... 11 
4. Conclusion ......................................................................................................................................................................................... 16 
References .............................................................................................................................................................................................. 16 
 

 
 
 

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Contribution of this paper to the literature 
This paper will integrate the knowledge of groundwater sources occurring in coastal parts of the world 
where dense population is a common demographic manifestation. It will also provide the insights about 
river systems occurring in the proximity of sea on groundwater characteristics.  

 
1. Introduction 

Water is fundamental need of each individual and it is a privilege of individual to approach drinking safe water. 
Life essentially depends on water and its quality being used on regular basis for different purposes. The water we 
use is either the river driven which is treated in different plants or the wellbore water which we directly suck from 
specific depth. However, recently the increasing population is resulting in the acute shortage of municipally 
supplied water. In order to overcome the demand of water, groundwater is used as an alternative. According to 
world health organization (WHO) about 80% diseases are water borne. Pakistan is becoming water stressed 
country and is likely to be water scarce in near future [1]. Pakistan positions at number 80 among 122 countries 
with respect to drinking water quality. Drinking water sources, both surface and groundwater are polluted with 
coliforms, dangerous metals and pesticides all through the nation. 

Major factors of groundwater chemistry are regional geology, geochemical process and land use patterns [2]. 
The quality of water is greatly influenced by its composition.  The major part of dissolved elements in groundwater 
comes from dissolved minerals in soil and sedimentary rocks. Natural filtration through soil and sediments makes 
the groundwater free from organic impurities [3].On the other hand, seawater intrusion in coastal settings 
deteriorates the quality by increasing the salt content in groundwater. It becomes a menace where surface water is 
polluted and the municipal water supply is abandoned or irregular. 

Like many big cities of developing countries, Karachi is a coastal city which is expanding every day. The city 
has a large number of industrial units generating approximately 1.3 million liters of effluents per day with only 
about 5% of the industrial and domestic waters receiving significant treatment and the rest untreated waste is 
discharged directly into Malir and Lyari rivers [4]. Coastal part of Karachi is by far, the most populous (~10 
million inhabitants, as per 1998 census) and the largest industrial (more than 1000 large industrial units) base of 
Pakistan, with a coastline extending up to about 80 km.  

Geomorphically, Karachi city lies on Hub and Malir River basins. Shallow aquifers of Karachi are mainly 
recharged by these two rivers. Presently, drinking water supply to the Metropolitan Karachi is maintained through 
three main sources including (i) Indus River (Keenjhar Lake) (ii) Hub River (Hub Dam) and (iii) groundwater 
through boring wells. However, increasing population, over-exploitation of groundwater and limited recharge of 
aquifer system has caused severe decline in water table during the last two decades. The three large industrial areas 
known as Sindh Industrial Trading Estate (SITE), Korangi Industrial Trading Estate (KITE) and Landhi 
Industrial Trading Estate (LITE) are discharging huge quantities of effluents comprising of organic matter, heavy 
metals, oil, greases, liquid and solid wastes into Malir and Lyari rivers. This malpractice is causing severe 
environmental degradation in various ecosystems of the city. The toxic metals and organic dye containing waste is 
directly poured into the Lyari and Malir rivers without any treatment. Malir River basin is very important in terms 
of agricultural activity, transporting municipal and industrial waste to the sea. Besides, Malir River is main water 
source recharging the shallow aquifers occurring in its surroundings. It is hypothesized that industrial effluents 
and municipal wastes being disposed off through Mali River is causing the contamination of shallow groundwater 
by infiltration through aquifer depths. This may lead to hamper the health of resident around Mali River. 
Therefore, it is imperative to screen the groundwater around Malir River for its quality determination. For this 
purpose, Qayyumabad area was selected as study site due to the fact that it lies at the terminus of Malir River 
where high accumulation of trace elements and other contaminates is expected as compared to the corresponding 
concentration upstream. Moreover, seawater intrusion is also likely to reduce groundwater potability due to 
excessive salt content. 
 

2. Materials and Methods 
2.1. Study Area  

Qayyumabad is located (latitude: 24º 49´ 32´´ N, longitude: 67º 05´ 02´´ E) on the western bank of Malir River 
in Korangi creek area Figure 1. It is a suburb of Korangi which is spread over an area of about 109 Acre with a 
dense population (more than 7000 people) of multiple ethnic backgrounds. The residents are provided with 
municipally supplied water through pipelines but water supply is sporadic and occasionally available. Due to over 
population and damage to water supply line and water theft the problem of fresh water availability is aggravating. 
As a result, people have switched over to groundwater sources for domestic uses. The area under study lies on 
south eastern corner of Karachi Figure 1. Geologically, it is marking the southernmost extension of the Pab Range. 
Gaj Formation of Miocene age is exposed in study area.   The catchment area of Malir River is situated in the 
north of study area [5]. Generally water is present at very shallow depth (12-40 feet) due to the fact that water-
saturated zones are present within the weathered profile of the rocks or in the recent windblown sands. Stable 
aquifers are present in the terrace deposits of Mali River which are 150-200 meters thick.   



Asian Review of Environmental and Earth Sciences, 2020, 7(1): 9-17 

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Figure1. Sample location map of study area. 

                      

 
2.2. Sample Collection  

Groundwater samples (n=20) were collected from boring wells at variable depth range (12-300 feet). Water 
samples were collected in plastic bottles of about 1.5 liter by using electrical pumps to run water for 1-2 minutes to 
get fresh samples of the groundwater for physicochemical analysis. Bottles were properly washed and rinsed 
thoroughly with distilled water and then with groundwater at sampling site to minimize any impurity. Locations of 
the wells were marked on the map with the help of Global Positioning System (GPS).  
 

2.3. Sample Analysis  
 Aesthetic characters (color, taste, odor,) and physical parameters including temperature, and turbidity were 

measured by thermometer and turbidity meter respectively. The pH and Eh of collected samples were measured by 
using pH meter (ADWA AD 111) while TDS and EC were determined by using EC meter (ADWA AD 330).  
Sodium and potassium were estimated by flame photometer (JENWAY EFP7) while calcium, magnesium, chloride, 
and bi-carbonate were determined by standard titration method. Gravimetric method was used for sulphate 
determination. Nitrate content was estimated by using spectrophotometer (HACH-8171) and iron by atomic 
absorption spectrometer (Analyst 400, Perkin Elmer). Arsenic content was determined by colorimetric method 
using arsenic testing Kit (Merck). Statistical analysis was carried out by using SPSS software (Version 16.00).  
PCA analysis was employed on data set of groundwater parameters including well depth, temperature, pH, Eh, 

TDS, EC, hardness, Na, K, Ca, Mg, Cl, NO₃, SO₄, HCO₃, Fe, and As.  
 

3. Results and Discussion 
3.1. Physical Parameters 

Physical characteristics of collected groundwater samples have been summarized in Table 1. Well depth of 
collected samples ranges between 12-300 feet with a mean of 90 feet Table 1. Tapping the water from such variable 
depths is due to various factors including affordability, geological variation of aquifers characteristics and 
recharging tendency of aquifers. Data revealed that a few samples have shown light yellow to brown color, which 
suggest presence of organic matter or metals such as iron in those groundwater samples. The color of water is also 
dependent on the degree of oxidation i.e. darker the color of groundwater, higher the degree of oxidation. All 
samples are saline to highly saline in taste which is due to high TDS content (range: 805-40340 mean; 7820 ppm). 
Saline taste of groundwater is reported from all depth ranges (12-300 feet) which suggest that salinity of 
groundwater in study area is free from depth variation. Generally, it is observed that high TDS is found in both 
shallow and deeper wells, but wells with more depth have relatively low TDS content. It suggests that saline 
source is transmitting its salt content from shallow to deeper wells. Water is not considered suitable for drinking if 
the quantity of dissolved minerals exceeds 1,000 mg/L [6].The groundwater temperature of collected samples 
ranges between 26-32˚C with a mean of 30˚C Table 4, but most of the samples (n=15) have 30˚C or above 
suggesting that water is infiltrating from surface runoffs.  



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 The pH of groundwater in study area varies from 6.55 to 7.75 with a mean of 7.03 Table 4. The suitable pH for 
drinking water ranges between 6.5–8.5 [6]. About half of the collected samples are acidic making these water wells 
unfit for drinking due to possible chemical reactivity. Though pH has no direct effect on human health, its higher 
range accelerates the scale formations in water heating apparatus [7]. On the other hand it indirectly affects water 
quality and its parameters such as metal ion solubility and pathogen existence [8]. TDS content of the collected 
samples ranges between 800-40340 ppm with a mean value of 7820 ppm Table 4. All the samples have TDS above 
desirable limit of WHO (500 ppm) for drinking purpose. TDS content from natural sources vary from less than 30 
mg/liter to as much as 6000 mg/liter [9] depending on the relative solubility of minerals in different geological 
regions. High TDS content in groundwater of study area may rise due to the influx of natural saline water such as 
sea water intrusion [10] which is consistent with the fact that study area lies in the proximity of Karachi coast 
where Malir River channel is invaded by sea water.  

 
Table-1. Summary of physical parameters determined in collected groundwater samples of study area. 

Physical Parameters 

Sample 
no 

Well 
age 

Well 
depth 

(ft) 
Color Taste 

Temperature 

(Ċ) 

Hardness 
mg/l 

PH 
Eh 

(mv) 
TDS 
(ppm) 

EC 
(µS/
cm) 

Latitude 
Longi
tude 

Q1 1 year 250 colorless saline 32 600 6.91 76 3000 6000 
24°52'16.

19"N 

67° 
5'31.2
1"E 

Q2 
15 

years 
22 

light 
yellow 

saline 32 1200 7.21 57 4210 8420 
24°51'43.

69"N 

67° 
5'30.0
6"E 

Q3 3 years 130 colorless saline 29 1500 6.79 38 2100 4200 
24°51'39.

21"N 

67° 
4'53.1
9"E 

Q4 
25 

years 
40 colorless saline 30 800 6.9 97 3100 6200 

24°51'13.
67"N 

67° 
5'7.19

"E 

Q5 
20 

years 
12 colorless saline 30 900 7.42 16 805 1610 

24°50'44.
04"N 

67° 
5'7.44

"E 

Q6 3 years 20 
light 

yellow 
saline 31 1100 7.37 40 4100 8200 

24°50'47.
40"N 

67° 
4'39.2
9"E 

Q7 3 years 35 colorless saline 30 3000 6.88 51 7830 1560 
24°49'30.

80"N 

67° 
4'59.3
2"E 

Q8 dna dna 
light 

yellow 
saline 30 400 7.75 -70 1100 2300 

24°49'16.
89"N 

67° 
5'5.03

"E 

Q9 3 years 180 
light 

brown 
saline 26 920 7.37 -120 4000 8000 

24°50'4.5
8"N 

67° 
4'48.8
0"E 

Q10 dna dna 
light 

yellow 
saline 26 620 6.8 125 1020 2040 

24°50'26.
05"N 

67° 
4'20.9
6"E 

Q11 
6 

months 
150 colorless saline 30.1 10000 6.57 -126 30200 

6040
0 

24°50'39.
01"N 

67° 
6'1.96

"E 

Q12 9 years dna 
light 

yellow 
saline 30.5 900 7.3 -65 7230 

1446
0 

24°50'50.
24"N 

67° 
6'15.2
3"E 

Q13 3 years 30 colorless saline 30 10000 6.63 -180 40340 
8068

0 
24°49'43.

45"N 

67° 
6'17.5
5"E 

Q14 5 years 16 colorless saline 29.4 1000 7.1 -15 3600 7200 
24°49'30.

63"N 

67° 
6'26.5
0"E 

Q15 15 days 15 colorless saline 31.3 1300 6.98 16 5310 
1062

0 
24°49'15.

68"N 

67° 
6'17.6
2"E 

Q16 2 years 25 colorless saline 30.1 1400 7.18 -101 1020 2040 
24°48'51.

63"N 

67° 
6'25.3
0"E 

Q17 7 years 100 colorless saline 31.1 500 6.55 86 20340 
4068

0 
24°50'21.

78"N 

67° 
6'22.5
0"E 

Q18 
2 

months 
dna smoky saline 30 6000 6.83 33 11010 

2202
0 

24°51'0.5
0"N 

67° 
6'35.4
6"E 

Q19 
6 

months 
117 colorless saline 30.8 3000 7.23 38 2900 5800 

24°51'20.
87"N 

67° 
6'48.7
2"E 

Q20 
7 

months 
300 colorless saline 28 700 7.02 98 3180 6360 

24°51'27.
43"N 

67° 
7'29.3
2"E 

WHO LIMITS 
 

500 
6.5-
8.5  

500 
 

dna=data not available 

 



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Elevated content of TDS produces gastro-intestinal irritation in human body [11]. According to Prakash and 
Soma [12] classification only 5% of the total samples (n=20) are found non-saline, 30% are slightly saline, 45% are 
moderately saline and 20% are very saline Table 2 The variation in TDS of collected groundwater samples is quite 
higher (800-40340 ppm), which is mainly attributed to anthropogenic activities and to geochemical process [13] 
prevailing in the study area. The hardness of groundwater samples ranges between 400-10000 mg/L with a mean 
of 2292 mg/L Table 4. About 95% samples have hardness above permissible limit (500 mg/l) prescribed by World 
Health Organization (WHO) [6] for drinking purpose. The oxidation reduction potential of collected samples 
varies from -180 to +125 mV with a mean of +4.7 mV where about 65% samples showed positive Eh suggesting 
the recent recharge.  

 
Table 2. TDS classification of study area groundwater (after Prakash and Soma [12]). 

Classification TDS in mg/l No. of Samples 

Non – saline < 1000 1 
Slightly saline 1000 – 3000 6 

Moderately saline 3000 – 10000 9 
Very saline > 10000 4 

                                           Source: Prakash and Soma [12]. 

 

3.2. Chemical Characteristics 
Chemical parameters include major cations (Na, K, Ca, Mg), anions (Cl, NO₃, SO₄, HCO₃) and minor/trace 

elements (Fe, As) have been summarized in Table 3. 
 

3.2.1. Major Cations  
Sodium is the major cation which has highly variable concentration (range: 205-14810 mg/L; mean 2587 

mg/L). All samples have sodium concentration above permissible limit (200 mg/L) prescribed by WHO [14] for 
drinking purpose Table 3. High level of sodium in collected samples is due to the involvement of seawater as the 
study area lies in the proximity (8 km approximately) of Arabian Sea. Similar is true about potassium content 
(range 24-160 mg/L; mean: 90.7 mg/L). It is observed that all the collected samples are exceeding the safe limit of 
potassium (12 mg/L) Table 3. Main reason of increasing potassium in groundwater seems due to agricultural 
activities [15] and the sewage mixing. Moreover, K might have come from the weathering of feldspar and clay 
minerals from the aquifer matrix as feldspars are more susceptible to weathering and alteration than quartz in 
silicate rocks [16].Calcium and magnesium contents range between 75-800 and 48.6-2217 mg/L respectively. The 
mean value of calcium (231 mg/L) is double of the permissible limit by WHO 100 mg/L Table 3. Likewise, the 
mean concentration of Mg is thrice the prescribed limit (150 mg/L). All samples have Mg concentration above the 
WHO limit for drinking purpose except four samples (Q3, Q5, Q12, and Q15). About 70% of the total samples 
show relatively high Mg concentration than Ca. Generally Ca dominates over Mg in groundwater but reverse 
occurs due groundwater interaction with dolomitic rocks [17] seawater intrusion or the cation exchange on clay 
surfaces.  
 

Table-3. Summary of chemical parameters determined in collected groundwater samples of study area. 

Chemical Parameters 

  Major Cations Major Anions 
Minor/trace 

elements 

Sample no Na K Ca Mg Cl NO3  SO4 HCO3 Fe As 

Q1 900 24 120 72.9 1100 8.03 230 290 8 bdl 
Q2 1300 83 150 200.48 1700 13.8 980 200 bdl 5 
Q3 560 35 350 151.88 460 4.01 660 380 4 bdl 
Q4 1070 106 230 54.68 180 18.88 320 300 bdl bdl 
Q5 205 71 100 157.95 1600 4.6 106 490 bdl 5 
Q6 1450 131 120 194.4 600 10 250 260 25 bdl 
Q7 4500 125 90 674.32 190 9.06 650 224 35 5 
Q8 220 79 80 48.6 200 12.9 190 220 102 bdl 
Q9 1200 106 200 102.06 2100 8.48 120 550 4950 25 

Q10 260 64 80 102.06 604 4.19 66 335 776 5 
Q11 14810 144 350 2217.38 2000 8.66 2050 700 65 5 
Q12 2830 100 100 157.95 3019 7.6 740 210 208 5 
Q13 980 160 800 1944 30600 16 500 370 315 5 

Q14 1170 82 150 151.87 1700 9.28 310 340 7 5 
Q15 2616 96 160 218.7 1900 11.67 360 360 5 5 
Q16 380 69 190 224.78 260 3.37 680 270 65 100 
Q17 8620 142 600 85.05 12700 8.42 495 380 bdl 5 
Q18 5850 109 400 1215 5600 16.78 210 390 194 5 

Q19 1300 50 276 561.33 980 25.21 2010 280 4 bdl 

Q20 1520 38 75 124.53 200 27.69 680 310 6 bdl 
WHO LIMIT 200 12 75 150 250 10 250 300 300 10 
All values are in (mg/l), except Fe & As which are in (µg/l) 
bdl=below detection level 

 

3.2.2. Major Anions 
The concentration of chloride (range 180-30600 mg/L; mean: 3384.5 mg/L) and sulphate (range: 66-

2050 mg/L; mean: 580.35 mg/L) are highly variable. About 80% of the total collected samples have chloride 
concentration above WHO standard (250 mg/L) for drinking water. Strong positive correlation of Cl with Ca (r² = 
0.955) followed by TDS and EC (r² = 0.786) suggest that the evaporative concentration of major salts is increasing 



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in the study area due to aridity and sewage infiltration. Moreover, high concentrations of Cl- may be due to the 
effect of sea tides in the Qayyumabad area as suggested by Mashiatullah, et al. [18]. Lusczynski and Swarzenski 
[19] considers chloride content above 50 mg/L as an indication of salt water intrusion, the groundwater of study 
area contains chloride concentration far above the limits suggested by Lusczynski and Swarzenski [19] confirming 
the salt water intrusion. Similarly, mean concentration of sulphate is twice the permissible limit (250 mg/L) of 
WHO for drinking water Table 4. Very high sulphate content in the groundwater of study area suggests the 
gypsum dissolution, use of inorganic fertilizer and the recent recharge of saline water [20, 21]. High concentration 
of sulphate in study area is consistent with the study of Mashiatullah, et al. [18] in Ghizri creek which is 5.6 km 
away from Qayyumabad. It is also complimenting the seawater intrusion mechanism as an agent of high sulphate 
and chloride contents in groundwater of study area.  

Nitrate concentration ranges between 3.37-27.69 mg/L with a mean of 11.43 mg/L Table 4. About 50% of 
total collected samples are unfit for drinking in terms of nitrate content as against WHO compliance (10 mg/L). It 
indicates that nitrate reducing bacteria are active in the groundwater of the study area, which is supported by 
exceptionally high bicarbonate content (mean: 346.9 mg/L) suggesting that organic matter decomposition is 
followed by nitrate reduction in the groundwater [22]. Bicarbonate content in collected groundwater samples 
ranges between 200-700 mg/L with a mean of 342.95 mg/L. About 55% of total collected samples have 
bicarbonate content above permissible limit (300 mg/l). Bicarbonate may be released from the dissolution of 
carbonate minerals via biodegradation of organic matter [23-25].  
 

3.2.3. Minor and Trace Elements   
Iron concentration in collected groundwater samples ranges between 4-4950 µg/L with a mean of 423 µg/L 

Table 4. It is observed that, all samples have iron concentration within permissible limit (300 µg/l) set by WHO 
except three samples (Q9, Q10 and Q13) which have high iron concentration (4950, 776 and 315 µg/l respectively). 
Iron in these samples may have come from some additional sources or due to prevalence of reducing conditions. 
Sample 9 contains rise value of both Fe and As but vice versa of this happens in sample 16 where extremely high 
value of arsenic As is present regardless of iron Fe. About 95% of the total samples (n=20) have very low 
correlation between Fe and As. It supports the notion that reduction of iron oxyhydroxide is necessary but not a 
sufficient condition for elevated arsenic concentration in groundwater of Holocene aquifers [26]. Arsenic content 
in collected samples varied between 5-100 µg/L with a mean of 13.84 µg/L Table 4. Only two samples (9 and 16) 
showed the abnormally high concentration of As i.e. 25 and 100 µg/l respectively, Arsenic is naturally occurring 
element available in the soil and sediments [27-29]. However Arsenic can be introduced to a groundwater system 
through various means, including surface water and precipitation as well as anthropogenic and naturally occurring 
sources [30, 31]. There is a relationship between the degree of reduction of the groundwater and the arsenic 
concentration; the more groundwater reduction, the more will be the arsenic concentration [32]. Since the 
groundwater of study area is mostly oxic as indicated by positive Eh values for most of the samples, the occurrence 
of low arsenic content is consistent with the redox rule.  
 

Table-4. Statistics of physicochemical parameters. 

Parameters Minimum Maximum Mean STD deviation 

Hardness 400 10000 2292 2930.099 
Well depth(ft) 12 300 90.12 90.88 

Temperature (C) 76 37 79.86 1.619 
pH 6.55 7.75 7.05 0.314 

Eh (mv) -180 +125 +4.7 +86.309 
TDS (ppm) 805 40340 7819.8 105.18 

EC 1610 80680 14939.5 21267.8 
Na 205 14810 2587 3.58E+07 
K 24 160 90.7 38.267 
Ca 75 800 231.05 190.349 
Mg 48.6 2217.38 432.99 629.069 
Cl 180 30190 3384.65 7.01E+03 

NO3 3.37 27.69 11.43 6.689 
SO4 66 2050 580.35 554.697 

HCO3 200 700 342.9 122.969 
Fe 4 4950 423 1.22E+03 
AS 5 100 13.84 26.46 

 
3.3. Ionic Interrelationship 

Strong positive correlation of well depth with bicarbonate (r = 0.851) and iron (r = 0.731) suggest that 
reducing conditions are increasing with depth Table 5. It is well established that bicarbonate may be released from 
dissolution of carbonate minerals via biodegradation of organic matter [23-25]. There is very weak negative 
relation of Na with Cl (r=-0.212) Table 5 but this can be increases with time. The Na/Cl relation has often been 
used to identify the mechanism for salinity distribution and saline intrusion [33-35]. If   Na and Cl ions enter in 
solution in equal quantity during the dissolution of halite, a linear relationship may be observed between these ions 
[36]. This relation is observed in our sample 17 and 18 Table 3. Abnormally high value of chloride concentration 
in sample Q13 (30600 mg/l) is observed regardless of sodium concentration. This concentration pattern suggests 
that sodium and chloride are not strongly correlated with each other. This pattern cannot rule out the same source 
of Na and Cl due to the fact that a part of Na is adsorbed onto the clays through cation exchange mechanism while 
chloride still remains in the mobile phase due to its conservative behavior.  

Strong positive correlation of Na with SO4, Mg, and HCO3 (r = 0.936) (r = 0.666) (r = 0.691) Table 5suggest 
that seawater intrusion. The negative correlation between nitrate and arsenic (r = -0.747) Table 5 suggest that 
there is inverse relation between these two. Negative correlation between As and NO3 does not exclude a common 



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source. Under anaerobic conditions NO3 is a very conservative ion whereas As is highly immobile at best in a near-
neutral pH range.There is a relationship between the degree of reduction of the groundwater and the arsenic 
concentration; the more groundwater reduction, the more will be the arsenic concentration [32]. High 
concentration of nitrate in some samples suggests that the conditions are sub-oxic to anoxic. The reducing nature 
of the groundwater has led to the reduction of some of the arsenic to As (III) and possible desorption of arsenic 
since As (III) is normally less strongly sorbed by the iron oxides than As(V) under near-neutral pH conditions of 
groundwater [27, 37]. Further reduction will lead to the partial dissolution of the poorly crystallized ferric oxide 
with subsequent release of iron and additional arsenic [38]. 
 

Table-5. Correlation matrix of physicochemical parameters determined in collected Groundwater samples of study area. 

Correlation matrix 

  
Well 
depth 

Hard
ness 

Temp
eratu

re 
PH Eh TDS Ec Na K Ca Mg Cl NO3 SO4 

HCO
3 

Fe 
A
s 

Well 
depth 

1                                 

Hardness 0.206 1                               
Temperat

ure 
-0.707 0.257 1                             

PH 0.093 -0.898 -0.593 1                           

Eh -0.45 -0.595 0.324 0.206 1                         
TDS 0.147 0.975 0.211 -0.857 -0.624 1                       

Ec 0.147 0.975 0.211 -0.857 -0.625 1 1                     
Na 0.487 0.595 0.211 -0.634 -0.088 0.436 0.436 1                   

K 0.286 0.879 0.058 -0.798 -0.407 0.902 0.902 0.481 1                 

Ca 0.002 0.802 0.095 -0.606 -0.758 0.897 0.897 0.023 0.722 1               
Mg 0.232 0.995 0.274 -0.913 -0.546 0.952 0.951 0.666 0.872 0.74 1             

Cl -0.18 0.646 0.094 -0.5 -0.598 0.786 0.786 -0.212 0.657 0.955 0.571 1           
NO3 -0.161 0.505 0.167 -0.536 -0.157 0.661 0.661 -0.054 0.693 0.685 0.457 0.78 1         

SO4 0.349 0.674 0.334 -0.683 -0.245 0.5 0.5 0.936 0.429 0.148 0.735 -0.11 -0.161 1       
HCO3 0.851 0.468 -0.356 -0.239 -0.528 0.408 0.409 0.691 0.394 0.21 0.493 -0.029 0.053 0.582 1     

Fe 0.731 -0.278 -0.942 0.599 -0.312 -0.215 -0.215 -0.222 -0.037 -0.084 -0.3 -0.081 -0.083 -0.378 0.394 1   

As -0.097 -0.339 -0.055 0.475 -0.231 -0.406 -0.406 -0.333 -0.594 -0.189 -0.351 -0.242 -0.747 -0.071 -0.27 0.04 1 
This matrix is not positive 
definite 

                              

 
3.4. Principal Component Analysis (PCA) 

To accurately identify the main processes governing the hydrochemistry of groundwater in the system, a factor 
analysis was performed using a subset of variables including the physical parameter (Well depth, Temperature, 
Hardness, pH, Eh, Total dissolved solids, Electrical conductivity) while chemical parameters (sodium, potassium, 
calcium, magnesium, chloride, nitrate, sulphate, bicarbonate), and minor/trace elements (Iron, Arsenic). Four 
factors where extracted which have Eigen values greater than 1 and these factors are discussed separately in detail. 
The PCA was performed on 20 groundwater samples where four principal components were extracted. The first 
four principal components together account for about 97.62% of the total variance in the data set, in which the first 
principal component explains 50.94% of the total data set variance, the second component explained the 20.43% 
while third component explained 16.89% and the fourth component explains the 9.37% Table 6. 
 

Table-6. Principal components analysis (PCA). 

Principle Component Matrixa 

  Component 

  F1 F2 F3 F4 

TDS 0.99 -0.031 -0.121 0.062 
EC 0.99 -0.03 -0.121 0.062 
Hardness 0.986 0.017 0.082 0.124 
Mg 0.975 0.034 0.172 0.099 
K 0.914 0.069 -0.106 -0.247 
PH -0.896 0.319 -0.297 0.061 
Ca 0.829 -0.087 -0.489 0.248 

Cl 0.698 -0.249 -0.659 0.131 

NO₃ 0.632 -0.301 -0.498 -0.481 

Eh -0.566 -0.461 0.373 -0.553 
Well depth 0.197 0.965 0.093 -0.111 
Fe -0.238 0.818 -0.474 -0.165 
Temperature 0.241 -0.816 0.441 0.113 

HCO₃ 0.476 0.768 0.239 -0.1 

Na 0.552 0.301 0.765 -0.14 

SO₄ 0.591 0.191 0.759 0.194 

As -0.459 0.076 0.023 0.871 
Eigen values 8.66 3.474 2.871 1.592 
Variance % 50.939 20.435 16.888 9.365 
Cumulative 50.939 71.374 88.262 97.626 

Extraction Method: Principal Component Analysis. 



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3.4.1. Factor 1 (F1) 
F1 accounts for 50.94% of the total variance and strongly positive loaded with TDS (0.99), EC (0.99), hardness 

(0.98), magnesium (0.97), potassium (0.91), calcium (0.83), chloride (0.7), nitrate (0.63), sodium (0.55) and sulphate 
(0.59) while strong negatively loaded with pH (-0.89) and Eh (-0.56) Table 6. This clustering of variables 
associated with F1 suggest that the conditions are reducing with acidic pH which is leading to dissolve higher 
amount of salts and minerals in the groundwater of the area. Comparing the role of pH and Eh, it is observed that 
pH has dominating role in mineral dissolution and leaching of ions from their corresponding salts. About 50% of 
total samples have pH value less than 7 which are considered acidic Table 1. 
 

3.4.2. Factor 2 (F2) 
F2 accounts for 20.43% of total variance and strongly positive loaded with well depth (0.96), Iron Fe (0.82) and 

bicarbonate HCO₃ (0.77) while negatively loaded with temperature (-0.82) Table 6. This clustering of variables 

associated with F2 suggests that Fe and HCO₃ are increases with increasing depth. Due to the reducing condition 

leading to increase in concentration of HCO₃ and Fe in groundwater of study area. The correlation of 
concentration of bicarbonate and iron is(r = 0.4) Table 5 though the relationship between these two is not very 
significant because decomposition of oxygen by bacteria is not reach the stage of iron but as far as the bacterial 
activity present in the groundwater relationship between these two becomes stronger and stronger.  
 

3.4.3. Factor 3 (F3) 
F3 accounts for 16.88% of total variance which shows strong positive loading with sodium (0.76), sulphate 

(0.76) while negative with chloride (-0.66) Table 6. This cluster pattern of variables suggests that ion exchange of 
sodium is happening in groundwater of study area. Generally the source of sodium and chloride is same, but 
sodium has a tendency to ion exchange, so when the saline source transmit its concentration towards the depth 
sodium replace itself with available cation while the chloride concentration were kept constant because it is 
conservative and thereby reported in groundwater samples regardless of Na. 
 

3.4.4. Factor 4 (F4) 
F4 accounts for 9.36% of the total variance and showing strong positive loading with arsenic As (0.87) while 

negatively loaded with nitrate NO3 (-0.48) and Eh (-0.55) Table 6. This cluster of variable loadings clearly shows 
that the nitrate reducing bacteria are responsible for arsenic dissolution as arsenic is mobilized in reducing 
conditions [39]. Under anoxic conditions, nitrate reducing bacteria use nitrate instead of oxygen to oxidize 
organic material. This process of denitrification results in decrease of nitrate concentration in groundwater [40]. 
Reducing condition is very important for arsenic mobilization [39], but in present study the weak correlation of 
ORP with the arsenic indicates that there is recent inflow of nitrate in the system. On the other hand the principal 
component analysis has shown the Factor 4 as important one which caters the major role of reducing conditions, 
nitrate and arsenic.  
 

4. Conclusion 
The groundwater of study area is physically, chemically and biologically contaminated. Both natural process 

and anthropogenic activities are responsible for polluting the groundwater. High salinity, hardness and bacterial 
contamination are major water quality deteriorating factors. Most of the physiochemical parameters are against 
WHO compliance. The main parameters deteriorating the quality of groundwater are TDS, Na, K, Ca, Mg, Cl, 

NO₃, SO₄ and HCO₃. Water rock interaction is prime driver in study area which is leading to salt leaching 
followed by anoxia prevalence due to sewage mixing. Reducing environment is responsible for leaching of As from 
river bed sediments and alluvium forming the similar to aquifers in other river basins of the world. Seawater 
intrusion is also evident in the groundwater of study area. It is concluded that groundwater of Qayyumabad is unfit 
for drinking purpose and its long term intake may cause serious health consequences. 
 

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