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Arsenic in groundwater and its health risk assessmentin drinking water of Mailsi, Punjab, PakistanAtta Rasoola, Abida Farooqia, Sajid Masoodb & Khadim Hussainc

a Environmental hydro-geochemistry Laboratory, Department of Environmental Sciences,Quaid-i-Azam University, 45320-Islamabad, Pakistanb Department of Plant Sciences, Quaid-i-Azam University, 45320-Islamabad, Pakistanc Geoscience Advanced Research Laboratories, Chak Shehzad, Islamabad,Accepted author version posted online: 29 Jun 2015.

To cite this article: Atta Rasool, Abida Farooqi, Sajid Masood & Khadim Hussain (2015): Arsenic in groundwater and its healthrisk assessment in drinking water of Mailsi, Punjab, Pakistan, Human and Ecological Risk Assessment: An International Journal,DOI: 10.1080/10807039.2015.1056295

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Arsenic in drinking water of Mailsi area, Pakistan.

Arsenic in groundwater and its health risk assessment in drinking water of Mailsi, Punjab,

Pakistan

Atta Rasool1, Abida Farooqi

1, Sajid Masood

2 and Khadim Hussain

3

1Environmental hydro-geochemistry Laboratory, Department of Environmental Sciences, Quaid-

i-Azam University, 45320-Islamabad, Pakistan

2Department of Plant Sciences, Quaid-i-Azam University, 45320-Islamabad, Pakistan

3Geoscience Advanced Research Laboratories, Chak Shehzad, Islamabad

Corresponding Author: Dr. Abida Farooqi, Phone: 0092-51-90644139, E-mail:

abida.farrukh@gmail.com

Abstract

The present study was aimed to assess drinking water quality regarding arsenic (As) and its

impact on health from Mailsi (Punjab), Pakistan. Forty four groundwater samples were collected

from two sites Sarganaand Mailsi. Arsenic and other cations were determined by atomic

absorption spectrophotometer, whereas the anions were determined either through titration or

spectrophotometer. The results revealed that dominant anions were HCO3-and Cl

- and Ca

+2was

the dominant cation andoverall water chemistry of the area was CaMgHCO3- type. Arsenic

concentrations were high, rangedfrom 11 to 828 µg/L that crossed the World Health

Organization permissible limits. Likewise, higher SO4-2

concentrations ranging from 247 to 1053

mg/L were observed. The health risk index was higher in Sargana site which employed the

differences in terms of higher Average Daily Dose,,Hazard Quotient , and Carcinogenic Risk of

arsenic. which is unsuitable for drinking purpose. The area seems to be at high risk due to arsenic

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pollution and wells have never been tested for arsenic concentrations earlier, therefore necessary

measures should be taken to test the wells with respect to arsenic.

Key words

Arsenic, drinking water, risk assessment, health risk, Mailsi, Pakistan

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1. Introduction

Quality of water is a vital concern for mankind since it is directly linked to human welfare. More

than 50% of the world’s population is dependent on groundwater for drinking. Groundwater is

the only source of drinking for many rural and small communities.This groundwater becomes

polluted mainly through improper urbanization, industrialization, agricultural practices and

domestic waste (Patil and Patil 2010).

Arsenic (As) is one of the harmful metalloids present in the groundwater resulting from both

anthropogenic and natural sources (Baig et al. 2010).Natural and anthropogenic activities such as

weathering, erosion, biological activities, petroleum refining, the use of wood preservatives,

pesticides, semi-conductors, paints, dyes, metals, soaps, drugs and herbicides significantly

contaminate the ground water (Gecol et al. 2004).

All over the world more than 70 arsenic affected countries have been recognized and majority of

these nations belong to South East Asia and South Asia. Worldwide 150million people are

affected by consumption of As contaminated water (Ravenscroft et al. 2009). It is frequently

found in different regions of the world, as by inference, in the groundwater ofthe USA,

Argentina, Taiwan, China, Hungary and Ganges Plains of India(Smedley and Kinniburgh

2002).South Asian countries like India and Bangladesh are facing severe health problems due to

As contamination of drinking water(Muhammad et al. 2010; Halim et al. 2009; Xie et al. 2009;

Gupta et al. 2009).

In Pakistan, As in groundwater is now an emerging threat in different areas of the country such

as Jamshoro (Baiget al. 2010),MancharLake (Arain et al. 2009), Lahore and Kasur(Farooqi et al.

2007a), Muzaffargarh (Nickson et al. 2005), DG Khan(Malana and Khosa 2011)and

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Tharparkar(Brahman et al. 2013). Higher Asconcentrations about 50 µg/L have been recorded in

drinking water inMultan, Rahim YarKhan and Bahawalpur (Punjab),whereas in some areas of

Sindh, these concentrations have been increased by 4-folds compared to Punjab(Kahlown et al.

2002).

Numerous reports are available on As contamination in groundwater and its effects on human

healthbut limited data is available from Pakistan. High arsenic concentrations have been reported

from the surrounding areas of Sargana and Mailsi including Multan and Muzaffargarh (Nickson

et al 2005), Arsenic concentrations are spatially variable. So far, no research work has been done

on As contamination in the study area. Therefore, the current study was aimed to 1) identify the

status of arsenic in Tehsil Mailsi(2) source identification of As contamination using multivariate

analysis and other statistical tools (3) to conduct health risk assessment in the study area due to

As contamination.

2. Materials and methods

2.1. Study area

Tehsil Mailsiis located between 29°78'Latitude and 72°17' Longitude, with a size of 1639

km2 and a population of about 704,878 (Figure 1). It has hot and semi-arid climate with average

precipitation of 243 mm/year and a mean temperature of 26 °C. The major drinking water source

is groundwater, by means of hand, motor or rotor pumps, whereas canal water is also supplied

for drinking purpose only in those areas having brackish water (District census organization

report, 1998). Hydrology and aquifer sediments of the Punjab were first described in detail

(Greenman et al. 1967) comprising of alluvial plains where>340 m thick Holocene and

Pleistocene sediments are transported by the Sutlej river. Sediments comprised ofa high

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percentage of fine to very fine sand, silt, clay and low organic matter content. The study area is

towards the southwestern part of Bari Doab (area between the two rivers, Sutlej and Chenab)

containing relatively older alluvial depositsthat tend to coincide with zones of highly mineralized

groundwater (Greenman et al. 1967).

2.2. Sampling and pretreatment

Two villages (Mailsi city and Sargana) potentially exposed to severe agricultural and

anthropogenic activities were selected for water sampling (Fig. 1). Mailsi is situated in active

flood plain area, around 2 km away from Sutlej River. Sampling was conducted in August, 2013

following the standard procedures (Khan et al., 2012).

In total 44 ground water samples consisting of 22 from Mailsi and 22 from Sargana were

collected (Figure 1). All groundwater samples were from the shallow depths ranging from 80-

140 feet. Water samples were collected in pre-cleaned polyethylene bottles after pumping for

about 2-5 min to flush the pipe water. Duplicate water samples were collected and preserved as

either acidified samples or non-acidified samples. Acidified water samples were used for the

determination of cations and non-acidified samples were used for anion analysis. A field

duplicate was collected at every 10th site. The latitude and longitude were recorded via Global

Positioning System (GPS). During sampling, pH, Electric Conductivity (EC), Total Dissolved

Solids (TDS) and temperature of the samples were measured in situ using pH and EC meters

(470, Jenway), respectively. The dissolved oxygen (DO) was determined by using DO meter

(DO W2015) in all the drinking water samples during field . All the samples were kept in the

dark at 4oCtill further analysis. For the quality control duplicate samples and spiked samples

were analyzed.

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2.3. Physicochemical analysis of samples

Total hardness (TH) of the water samples was determined by computing calcium (Ca2+

) which

was analyzed by volumetric titration using 0.05 N Ethylene Diamine Tetra Acetic Acid (EDTA).

Concentrations of Mg2+

were calculated by subtracting the concentrations of calcium from total

concentration of calcium and magnesium determined in total hardness. Nitrates and sulphates

were determined using UV/Visible Spectrophotometer (Model UV 1601Shimadzu) at a

wavelength of 220 nm. Alkalinity (HCO3-) was determined by titration method (Standard

method, 1992). Chloride (Cl-) concentrations in water samples were measured by titration

method (ISO 9297, 1989). Arsenic and other cation concentration in the samples was determined

using atomic absorption spectrophotometer (Spectra AA 220 FS, Varian, New Jersey, USA).

Reproducibility of the analytical data was within 5% and the analytical error was estimated at

<10%.

2.4. Human health risk assessment

A health risk assessment model derived from USEPA (2005) was applied to assess health risk in

individuals exposed to As. Average daily dose (ADD) of As in drinking water was calculated by

the following equation:

ADD C IR ED EF/ BW AT (1)

Where C, IR, ED, EF, BW, AT represents the concentration of As in water (mg/L), water intake

rate (2L/day), exposure duration (assumed 67 years), exposure frequency (365 days/year), body

weight (72 kg) and average lifetime (24,455 days), respectively.

Generally, HQ can be calculated by the following formula (USEPA 2005).

HQ ADD / RfD (2)

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Where HQ is hazard quotient, if above 1, is considered to be health risk whereas a reference dose

(RfD)of As (0.0003 mg/ kg/day) cause toxicity (USEPA 2005).

Cancer risk (CR) was calculated using the following formula:

CR ADD CSF (3)

Where CSF is the cancer slope factor for As which is 1.5 mg/kg/day (USEPA 2005).

2.5.Multivariate statistical analysis

Multi Variate Statistical Package (MVSP) and Statistical Package for the Social Sciences (SPSS)

statistic software version 17 were used for Principle Component Analysis (PCA), Correlation

Matrix (CM) and Hierarchical Cluster Analysis (HCA), respectively.Arc-GIS and Surfer

software version 10 were used to make distribution maps of As for the study area. Hydro-

chemical facies was determined by the Piper diagram (Piper 1953).

3. Resultsand discussions

3.1. Hydrochemistry

Physical and chemical properties were determined in order to check the drinking water quality.

Chemistry of groundwater showed large variation in samples of Sargana, although the two sites

did not show much variation in the concentration (Table 1). The Geology of the area is same due

to which large variation between two sites is not observed. The pH was slightly alkaline in the

range of 6.5 to 8.2 and 6.8 to 8.1 in Sargana and Mailsi areas, respectively. Mean of pH in

samples from two sites showed differences in the order of Mailsi>Sargana, however, pH values

were within the permissible limits for drinking water according to WHO described range (6.5-

8.5). Likewise, EC values in drinking water samples ranged from 0.69 to 2.81 and 0.66 to 2.43

mS/cm in Sargana and Mailsi areas, respectively and followed the same order as for pH. In

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contrast, 36% drinking water samples exceeded the WHO specified limits (1.5 mS/cm) of EC

while other samples were below the limits (Table 1). TDS in drinking water ranged from 469 to

1911 and 503 to 1652 mg/L in Sargana and Mailsi sites, respectively. DO in drinking water

samples ranged from 6.1 to 8.1 and 6.2 to 8.3 mg/L in Sargana and Mailsisites. Concentrations of

Na+

ranged from 261 to 453 and 177 to 637.5 mg/L, K+ ranged from 3.2 to 9.7 and 3.1 to 18.8

mg/LCa2+

ranged from 48.6 to 356.5 and 61.44 to 402.6 mg/LMg2+

from 31.2 to 86.9 and 31.6 to

85.5 mg/L, while,for Fe2+

and Mn2+

ranged from 0.002 to 0.031 and 0.002 to 0.049, 0.003 to 0.09

and 0.001 to 0.08 mg/L, respectively for Sargana and Mailsi (Table 1). For Na+

WHO

recommended value is 200 mg/L and all the samples exceeded permissible limit in Sargana while

97% samples of Mailsi area exceeded WHO limits. For Ca2+

WHO recommended value is 100

mg/L and 99 % samples in sargana area while in Mailsi 83 % samples exceeded WHO limits.

For Fe2+

,WHO recommended value is 0.3 mg/L and all the samples were belowWHO

limits.Whereas K+ and Mn

2+ were below the permissible limits (Table 1).

Anion concentrations: SO4-2

, HCO3-, NO3

- and Cl

- in drinking water ranged from 205.8 to 1053.4

and 238.7 to 1185.2, 25.3 to 1268.8 and 390.4 to 1171.2, 8.9 to 53.2 and 10.1 to 58.5, 55.1 to

225.3 and 30 to 355.4 mg/L in Sargana and Mailsi areas respectively. 98% drinking water

samples exceeded the WHO permissible limits (10mg/L) of NO3-andlikewise NO3

-

concentrations were higher in Mailsi area (Table 1). Almost 95% of the drinking water samples

of both sites exceeded their WHO permissible limit for SO4-2

concentrations. Water quality

showed the dominance of HCO3- among anions, while Ca

2+ among cations. Further, it employed

Ca-Mg-HCO3- type of water chemistry with elevated sulphate and calcium and chloride

concentrations (Figure 2). Our results revealed that physiochemical parameters of drinking water

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were influenced due to altered ion chemistry. Increased TDS are mainly due to HCO3-, SO4-2

,

Ca2+

and NO3-. Increased TDS simultaneously increase EC as a result of ion exchange(Baiget al.

2009). Higher EC values of drinking water samples exhibited higher pH. Similar results have

been reported previously by (Halimet al. 2009). Alkaline pH of the water in the area was due to

the presence of HCO3-, which was the weathering product of carbonaceous rocks (Breit and

Wanty 1991; Lopez-Pazos et al. 2010). Concentrations of SO4-2

, Cl- and NO3

- were slightly

higher in samples of Mailsi than Sargana. It could be either due to anthropogenic activities

because Mailsiis more populated as compared to Sargana and is located at lower altitude where

water flows from North to South-West. Due to the lower altitude the contaminants have the

possibility of accumulation. Overload of SO4-2

imparts unacceptable taste and may be laxative

and corrosive, especially when combined with Na+ or Mg

2+ (Ashraf and Foolad 2007). High

levels of SO4-2

can be attributed to the sulfide mineralization (Shah 2000) or due to massive use

of soaps and detergents in the urban areas (Li et al. 2006). Drinking water samples had higher Cl-

concentrations because the area is under arid environment so high Cl- concentrations could be

due to high rate of evaporation in arid environments (Farooqi et al. 2007b). NO3- concentrations

in samples of the study area were higher than those reported by(Nickson et al. 2005) in

Multan,probably due to higher sewage discharges, animal excreta, and agricultural activities. In

the study area, urea, Di-ammonium Phosphate (DAP) and numerous other fertilizers are broadly

applied to various cash crops, including cotton, wheat, rice, maize and sugar-cane. In Pakistan

the fertilizer consumption has increased during the past 30 years and the Punjab Province

consumes the largest split due to its largest agricultural area (Nrmed 2004). The yearly

production of various fertilizers in Pakistan is: urea (4.3 million tonnes), DAP (450 thousand

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tones) and for Nitrogen, Phosphorus and Potassium (NPK) compounds is 100 thousand tones

(total 5.78 million tons),(Nrmed 2004) which are the principle source of groundwater

contamination with nitrates and phosphates in various regions of Punjab (Farooqi et al. 2007)

High concentrations of Ca2+

in groundwater may be due to the weathering of silicate minerals

whereas lower concentrations of K+

as compared to Na+

can be explained by the fact that K+

tends to be fixed on clay minerals and rate of disintegration of K+

is low as compared to Na+

minerals. The reason for low Fe2+

and Mn2+

concentrations in the area is because the groundwater

from certain rock types such as dark muddy lime stones, shale and sandstone areas contain low

Fe2+

and Mn2+

concentrations (Kelly and Moran 2002).

3.2. Spatial distribution of As in study area related to active flood plain

As concentrations in water samples of Sargana and Mailsi sites are shown in Table 2. Sargana

samples contained As in the range of 14 to 787µg/L, whereas Mailsi samples had 11 to 828 µg/L

of As. Relatively higher concentrations of As were found in Mailsi as compared to Sargana.

Comparative analysis of our samples with WHO permissible limits (10 µg/L) revealed 100%

contamination of samples, whereas 60% when compared with PakEPA (50 µg/L). Spatial

distribution of As concentration in groundwater is shown in Figure 3a. Maximum As was found

in Mailsi area, according to the contour map in west to east. 3-D imaging and dome shape

(Figure 3b) revealed variation in As concentrations in both Mailsi and Sargana areas.

Slightlypositive correlations was found between As and HCO3- (r

2= 0.444) (Table 3 and

Figure4b). Significant negative correlationwas found between As and Mn2+

(r2= -0.051), As and

Fe2+

(r2= -0.062) as shown in Figure 4c and 4d.

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The results of the current study showed that the As concentration was higher in the regions

located near to the Sutlej River as compared to the areas located far from it (Figure 3a and b).

This similar pattern was also observed in the previous study of district Muzaffargarh and Multan

(Nickson et al. 2005).It have been reported that As concentration is generally higher in the

regions near rivers or in floodplain areas. Some of the most As affected flood plain areas of the

world include Bengal delta of Bangladesh (Berg et al. 2001), Ganga-Mehgna Brahmaputra plain

of India (Chakraborti 2004), Red River Delta and Mekong basin of Vietnam and Cambodia

(Berg et al. 2007) and Western Snake River Plain of Idaho, USA (Busbee et al. 2009). Recently

Pakistan Council for Research in Water Resources (PCRWR) has declared 6 cities of Punjab as

the most affected areas in terms of As levels, which include Multan, Bahawalpur, Sheikhopura,

Gujranwalan, Kasur and Lahore. All of these areas are located near the river and thus fall under

the category of flood plain areas (kahlown 2005). Water from shallow aquifers with recent

alluvial sediments contain distinctly higher As than the water from deeper aquifers with

presumed Pre-Holocene sediments: only 1% of the wells in the depth range of 150-200 m have

aqueous As above 50 µg/L according to British Geological Survey (Kinniburgh and Smedley

2001).

3.3. Oxidative dissolution and evaporative enrichment: probable mechanism of As release

Four basic geo-chemical mechanisms are responsible for the release of As in water. These

mechanisms include oxidative and reductive dissolution (McArthur et al. 2001; Nickson et al.

1998), desorption (Smedley 2005) and concentration by evaporative enrichment (Welch et al.

2000). Natural enrichment of drinking water by As can arise in numerous ways such as;

hydrothermal volcanism, oxidation of arsenical sulphide minerals (Schreiber et al. 2000),

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reduction of FeOOH and the release of its sorbed load in groundwater (Ravenscroft et al. 2001),

desorption of As from mineral sorption sites in response to increase of pH (Robertson 1989), and

evaporative concentration (Nicolli et al. 1989). Oxidative dissolution is characterized by high

concentrations of HCO3- (>500ppm) and SO4

-2 (> 250ppm) and pH (>7.5)(Smedley and

Kinniburgh 2002). The findings of the current study can be supported by oxidative dissolution

and in some extent evaporative enrichment. In arid environments, evaporative concentration of

dissolved species can produce elevated As concentrations in groundwater (Bhattacharya et al.

2006). In these systems, evaporation increases the concentrations of all ions in the residual

waters, a process documented to occur in closed evaporative basins or locations where the water

table is sufficiently near-surface to be affected by evaporation (Nickson et al. 2005). Human

activities that can potentially promote evaporative enrichment include increasing evaporation

rates by decreasing the water table to the near-surface or by groundwater pumping for irrigation

(Nickson et al. 2005). Natural evaporation over long periods can cause solute concentrations in

shallow groundwater to increase (Welch 2000) and effects of evaporative concentration under

oxic conditions will be sorption of As to soils (Jones et al. 2009) and aquifer sediments (Nimick

et al. 1998). In the present study, high Cl-

and Na+concentrations are indication of high

evaporation in the area. This is also supported by the dendrogram (Figure 5). Na+, Cl

- and As fall

in the same group. So in the area arsenic seems to be released by oxidative dissolution under the

influence of high alkaline water and high pH (Figure 6) and to some extent high arsenic

concentrations are related with the high evaporation in the area.

Moreover, in the present study high DO values and the presence of high NO3, high SO4 and

alkaline pH indicate the oxidative nature of water, which in turn indicates that As is present in

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the form of AsV in this study. As

V is most effectively adsorbed on the Fe-oxyhydroxide/oxide at

weakly acid to neutral pH conditions, and it releases into the solution with increasing pH at

alkaline condition (Smedley and Kinniburgh 2002). On the other hand, the persistent intake of

high AsV drinking water would potentially cause health hazards in future over an extended

period, since this element is reduced into arsenite, which is accumulated in the human body, and

arsenite is more difficult to remove from drinking water supplies than arsenate (Gupta and Chen

1978; Schneiter and Middlebrooks 1983).

3.4. High health risk area due to high arsenic in groundwater

The results showed that residents of the area had a toxic risk index in order of Mailsi>Sargana

(Table 2). ADD ranged from 5×10-4

to 2.2×10-2

and 5×10-4

to 2.3×10-2

mg/kg/day in drinking

water samples of Sargana and Mailsi. The highest value of ADD was found in sample 17 of

Mailsi area. HQ of drinking water ranged from 1.3 to 73.3 and 1 to 76.6 in Sargana and Mailsi

areas, respectively (Table 2). Highest HQ (76.6) was found in sample 17 of Mailsi site, whereas

HQ=73.3 was observed in sample 8 of Sargana area. In drinking water of both Sargana and

Mailsi, the potential CR values ranged from 0.0006 to 0.033 and 0.0009 to 0.0345, respectively

(Table 2).

In the study area, local people were interviewed for information such as age, sex, health,

economic status, nutritional habits, body weight, profession, qualification and drinking water

sources. It has been observed that local people in Mailsi and Sargana used both groundwater and

surface water for drinking and domestic purposes. The results suggest that ADD values have

been increased and comparable with the results reported in Bangladesh (5.00×10−2

– 5.00×10−1

mg/kg/day), Vietnam (1.1×10−3

–4.3× 10−3

), and Turkey (2.3×10−5

–5.21× 10−3

) (Karim 2000,

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Nguyen et al. 2009; Caylak 2012) and is much higher than other studies done in different areas

of Pakistan (0.00–5.56×10−7

mg/kg/day (Muhammad and Khan 2010). The ADD range is larger

in Mailsi area as compared to Sargana area. The calculated HQ through consumption of As

contamination in drinking water was found highest (76.6) in Mailsi area as compared to the

Sargana area. About 85% people in Mailsi area were using the water for drinking and household

purpose and therefore considered at high risk, when compared with USEPA approach (1999).

CR values greater than one in a million was generally considered significant by (Boobis et al.

2006). The calculatedCR index values show that the order of As cancer risk was Mailsi

area>Sargana area. The results indicate that CR values (3.5×10-2

mg/kg/day) in drinking water of

the study area Mailsi were higher than Sargana except for the 15% people of Mailsiarea that

showed medium risk, when compared with USEPA approach (1999). The results warn study area

to be at high risk. This is an alarming situation within the area and needs urgent remediation to

save health of people at risk.

3.5. Identification of pollution sources by statistical techniques

Multivariate analysis was performed in order to discriminate distinct groups of physic-chemical

parameters and Asas tracer of natural or anthropogenic sources. Principal Component Analysis

(PCA) is an effective tool for source identification of physicochemical parameters (Mico et al.

2006). The results of cluster analysis (CA) agreed well with PCA. An explorative hierarchical

analysis causes toxicity through increase in salinity, change in ironic composition of water. CA

grouped the sampling sites into clusters (called Zones in this study) on the basis of similarities

within a zone and dissimilarities between different zones. The results of CA helped in

interpreting the data and indicating patterns of similar objects. In drinking water samples three

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groups of elements were identified. In cluster analysis, similar objects fall into the same class

and dissimilar group fall into another group (Danielsson et al. 1999) levels of similarity at which

observations merge are used to construct a dendogram (Chen et al. 2007).

The first group includes pH, K+, EC, NO3

- and Mg

2+parameters as shown in Figure 5, suggesting

all these parameters are from the same source, mainly anthropogenic activities, (industrial and

natural activities). The electrical conductivity (EC) can be used as an indirect measurement of

dissolved solids in the water (Bityukova and Petersell 2010). The major cause of nitrate in the

water is industrial, domestic effluents, fertilizers, decayed animals and plant material, farm

leachates and atmospheric washout (Kahlown 2006), Excess of nitrate may cause infantile

methaemoglobinaemia (USEPA 1977) and gastric cancer (Xu 1981). Mg2+

contributes in

hardness of water together with calcium (Corkill et al. 1981).The high concentration of

magnesium can cause muscle slackening, nerve problems, depressions and personality changes,

vomiting and diarrhea (Sarma and Rao, 1997).

The second group includes Na+, As, Cl

- and Ca

2+ as shown in Figure 5. It is possible that all of

the ions of second group may beoriginated from the parent rock material. Elevated Ca2+

, Na+, Cl

-

and As concentrations were caused by the interaction of drinking water with aquifer sediments

rich in carbonate (Ahmed et al. 2004). Cl- find its way to groundwater from underground salt

deposits of NaCl, KCl and MgCl, mostly intrusion of sea water and other saline water, and also

from the intrusion of municipal sewages (Kahlown 2006). Calcium being the important minerals

that are considered as essential for carrying out numerous functions in the human body like

blood clotting and transmission of nerve impulse and the regulation of the heart rhythm (WHO

1996). The main sources of calcium are calcite rock mineral weathering, fertilizers and

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agrochemical wastes. The third group includes TDS, TH, SO4-2

and HCO3- as shown in Figure 5.

Similar to group 2, the elements of this group may be originated from anthropogenic, natural and

parent rock materials. High SO4-2

concentrations may be derived from leaching of chemical

fertilizer, household waste and animal manure (Kahlown 2006). Sulfate is the common anion of

water, which enters the water from its naturally occurring minerals in some soil and rock

formation that contains groundwater (Shakirullah et al. 2005). Increasing sulfate causes health

concern may be laxative, cathartic and corrosive, especially when combine with Na+, result in the

decline of water quality (Shakirullah et al. 2005).

PCA was employed to compare the compositional patterns between the drinking water systems

and identification of the factors that influence each one. Five components of PCA analysis

showed 76% of the variance on the data of ground water samples (Table 4).The five factors were

obtained by drinking water sample data using a Varimax normalized Algorithm that gives an

easier interpretation of the principle component loadings and maximized of the variance

explained by the extracted factors. VF1 explained 30.4% of the total variance and has high factor

loadings for Ca2+

, Mg2+

, SO4-2

and TH which are associated with common natural origin (Harvey

et al. 2002). The sources of these parameters could be the weathering of Calc-silicate rocks

suggesting that Varimax Factor 1 (VF1) has geogenic sources. VF2 accounted for 18.2% of the

total variance and reflected significant loadings for EC, pH, TDS, HCO3- and As having geogenic

sources (Stuben et al. 2003; Hasan et al. 2007). VF3 explains 10.3% of the total variance and

significant factor loadings for Cl- origin from anthropogenic activities, (Mico et al. 2006). VF4

accounted for 8.9% of the total variance and revealed the significant loading for NO3- and K

+

originated from weathering of minerals and agricutural activity (Khan et al. 2004; Zan et al.

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2011). VF5 was loaded by Na+ with variance of 8.2 percent and dominanting solutes in

seawateand anthropogenic activities (Villalobos et al. 2001).

4. Conclusions

The current study demonstrates that groundwater of Mailsi and Sargana areas of Punjab province

are heavily contaminated with SO4-2

, HCO3- and As. Maximum concentration of As (828 µg/L)

was recorded in the urban area of Mailsi. Additionally, calcium and magnesium concentrations

crossed the permissible limits in the presence of As. The type of water that predominates in the

study area is Na+-HCO3

--SO4

-2. The Desorption under alkaline and high pH seems to be the

dominating mechanism along with the evaporative enrichment. CR index of As indicates that

85% people of the urban area of Mailsi are under threat. It is further suggested that groundwater

of Tehsil Mailsi and Sargana is not fit for drinking purpose and immediate measures are required

to save the health of population residing in the area.

Acknowledgments

We are indebted to Geological Survey of Pakistan, Advanced Geosciences Research laboratories

for the arsenic analysis and Dr. Riffat Naseem Malik for providing lab facilities.

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Table 1: Ranges of Physio-Chemical drinking water quality parameters collected from the study

area

Parameters Sargana Mailsi

Drinking water

Drinking water

n=22

n=22

Range Mean Range Mean

pH 6.5-8.2 7.58 6.8-8.1 7.5

EC (mS/cm) 0.69-2.81 1.39 0.66-2.43 1.4

TDS (mg/L) 469-1911 947.72 503-1652 940.73

DO (mg/L) 6.1-8.1 7.19 6.2-8.3 7.2

TH (mg/L) 368-1244 707.05 284-1330 665.91

Cl- (mg/L) 55.1-225.3 105.59 30-355.4 130.38

HCO3- (mg/L) 25.3-1268.8 816.01 390.4-1171.2 728.89

NO3- (mg/L) 8.9-53-2 28.19 10.1-58.5 25.06

SO4-2

(mg/L) 205.8-1053.4 596.67 238.7-1185.2 642.33

Na+ (mg/L) 261-453 375.34 177-637.5 400.57

K+ (mg/L) 3.2-9.7 5.15 3.1-18.8 5.23

Ca2+

(mg/L) 48.6-356.5 187.29 61.44-402.6 178.09

Mg2+

(mg/L) 31.2-86.9 55.42 31.6-85.5 53.86

Mn2+

(mg/L) 0.003-0.09 0.024 0.001-0.08 0.09

Fe2+

(mg/L) 0.002-0.031 0.012 0.002-0.049 0.017

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Table 2: Ranges of As, ADD, HQ and CR in drinking water samples of Sargana and

Mailsi,Pakistan

Parameters Sargana Mailsi

Drinking water

n=22

Drinking water

n=22

Range Mean Range Mean

As (μg/L) 14 - 787 165.82 11 - 828 145.6

ADD (mg kg-1 day-1) 0.0005-0.022 0.0046 0.0005-0.023 0.004

HQ 1.3-73.3 15.3 1-76.6 13.4

CR 0.0006-0.033 0.0069 0.0009-0.0345 0.006

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Table 3: Correlation coefficient among drinking water quality parameter. Significant values are

highlighted in bold where, p<0.05

Paramet

ers PH Ec TDS TH

Ca2

+

Mg2

+

HC

O3- Cl

-

SO4-

2 NO3

- Na

+ K

+

A

s

pH 1

EC

0.10

9 1

TDS

0.10

9 0.99

6 1

TH 0.09 0.25

9

0.24

2 1

Ca2+

0.08

3

0.24

8

0.23

1

0.99

8 1

Mg2+

0.11

3 0.29

1

0.27

4 0.97

0.95

1 1

HCO3-

0.27

6

0.39

8

0.40

7

0.17

8

0.17

6

0.17

8 1

Cl-

-

0.22

6 0.1

0.10

3

0.23

9

0.25

3 0.18

-

0.07

9 1

SO4-2

0.07

8 0.11 0.09

0.69

9

0.69

6

0.68

7

0.05

6

0.06

6 1

NO3-

-

0.05

-

0.24

6

-

0.24 0.21

0.22

6

0.14

5

-

0.06

6

0.05

5

0.11

7 1

Na+

-

0.07

5

-

0.08

1

-

0.08

9

0.02

1

0.02

5

0.00

4

0.14

1

0.05

2

0.02

2

0.04

7 1

K+ 0.01

-

0.05

2

-

0.04

5

0.06

6

0.06

9

0.04

9

0.13

5 0.23

1

0.08

7

0.09

7

-

0.0

4 1

As

0.08

1

0.28

3

0.27

6

0.04

9

0.02

4

0.13

2

0.44

4

-

0.06

-

0.03

8

-

0.09

9

-

0.0

7

-

0.10

4 1

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Table 4: Factor loading of drinking water quality parameters

Parameters VF1 VF2 VF3 VF4 VF5

pH 0.166 0.238 -0.626 0.114 -0.362

Ec 0.522 0.735 0.284 -0.127 -0.002

TDS 0.507 0.742 0.289 -0.115 -0.012

TH 0.94 -0.282 -0.041 -0.061 0.029

Ca2+

0.932 -0.298 -0.03 -0.052 0.029

Mg2+

0.934 -0.212 -0.079 -0.093 0.027

HCO3- 0.364 0.544 -0.263 0.543 0.08

Cl- 0.248 -0.184 0.735 0.222 -0.016

SO4-2

0.716 -0.337 -0.143 -0.125 -0.022

NO3- 0.118 -0.5 -0.143 0.276 0.004

Na+ 0.005 -0.113 -0.02 0.435 0.782

K+ 0.096 -0.158 0.267 0.666 -0.544

As 0.2 0.527 -0.214 0.181 0.131

Eigenvalues 3.952 2.371 1.333 1.159 1.065

Variability (%) 30.397 18.238 10.252 8.916 8.192

Cumulative (% 30.397 48.635 58.888 67.804 75.996

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Figure 1: Location maps showing the sampling points of drinking water samples of Sargana and

Mailsi

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Figure 2: Water chemistry in the area (DW stands for drinking water)

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Figure (3a): spatial distribution of arsenic in drinking water of Sargana and Mailsi

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Figure (3b): Maximum arsenic is from Mailsi as indicated by the dome

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(4a) (4b)

(4c) (4d)

Figure 4: (a, b, c and d) Showing the correlations of As with SO4, HCO3, Mn and Fe

200

400

600

800

1000

1200

1400

10 510 1010

SO4

(mg/

L)

As(µg/L)

350

550

750

950

1150

1350

0 500 1000

HC

O31

- (m

g/L)

As(µg/L)

0

0.02

0.04

0.06

0.08

0.1

0.12

0 500 1000

Mn

(m

g/L)

As(µg/L)

0

0.5

1

1.5

2

2.5

3

3.5

10 510 1010

Fe (

mg/

L)

As(µg/L)

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Figure (5): Dendrogram of selected physicochemical parameters in drinking water samples

using average linkage (within group) method

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Figure (6) Scores for distribution of As species and water quality parameters in Tehsil Mailsi.

pH

EcTDS

THCa+2Mg+2

HCO3-

Cl

SO4

NO3

NaK

As

-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

-1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1

F2 (1

8.24

%)

F1 (30.40 %)

Variables (axes F1 and F2: 48.64 %)

Dow

nloa

ded

by [

Inst

itute

of

Geo

chem

istr

y] a

t 23:

37 3

0 Ju

ne 2

015