Distribution of highly arsenic and fluoride contaminated groundwater fromeast Punjab, Pakistan, and the controlling role of anthropogenic pollutants
in the natural hydrological cycle
ABIDA FAROOQI,1 HARUE MASUDA,1* MINORU KUSAKABE,2** MUHAMMAD NASEEM3 and NOUSHEEN FIRDOUS3
1Department of Geosciences, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan2Institute for the Study of the Earth’s Interior, Okayama University, Japan
3Geosciences Laboratory, Geological Survey of Pakistan, Chak Shehzad, Islamabad, Pakistan
(Received July 13, 2006; Accepted November 26, 2006)
This paper reports the extended study from a previously-described study on As and F contaminated groundwater froma small village, Kalalanwala, in east Punjab, Pakistan (Farooqi et al., 2007). Of the 147 groundwater samples investigated,91% exceeded the WHO standard (10 µg/L) for As and 75% exceeded the WHO standard (1.5 mg/L) for F–. The highlycontaminated As (max. 2400 µg/L) and F– (max. 22.8 mg/L) groundwaters were found from shallow depths down to 30 mfrom the surface. The contaminated groundwaters are characterized by high pH (max. 8.8), alkalinity (HCO3
– up to 1281mg/L), SO4
2– (max. 960 mg/L), Na+ (max. 1058 mg/L) and maximum electric conductivity >4.6 mS/cm.Fluoride concentrations showed positive correlations with those of Na+ and HCO3
– and negative ones with Ca2+
and Mg2+. The alkaline waters were saturated with calcite in spite of the low Ca2+ concentrations. Fluoride concentrationis governed by fluorite solubility. Speciation analysis showed As is mostly in the form of AsV. There was a positivecorrelation between As and pH, while there is no relationship between As vs. Fe and F–. Thus, the fluoride and As con-tamination occurred in the oxidizing and alkaline conditions of the groundwater. However, F– and As are derived from twoor more sources. Suspected contaminant sources in the study area contained considerable amounts of F– and As; fertilizers(DAP, n = 5) contained leachable F– ranging from 53–255 mg/kg, and As 5–10 mg/kg, and coals (n = 8) contained F–
ranging from 5–20 mg/kg.Sulfur isotopic ratios indicated that the high SO4
2– in groundwater (3.2–7.0‰, CDT) is mainly derived from coalcombusted atmospheric pollutants, fertilizers and household wastes. Nitrogen isotope data (8–30‰, Air) showed thatNO3
––N is attributed to animal waste distributed in the study area. The major chemical characteristics of the groundwatersare related with anthropogenic activities on the ground surface. The resultant major chemistry, especially highly alkalineand low Ca2+ and Mg2+ concentrations, must promote the high concentrations of F– and As in the studied groundwaters.
tion (WHO) guideline of As concentration in drinkingwater was reduced from 50 µg/L to 10 µg/L in 1993(WHO, 1993). According to the WHO recommendationmany developed countries changed the maximum admis-sible concentrations to 10 µg/L, however the developingcountries, where arsenicosis is more widespread, are stillusing the previous guideline value (50 µg/L) due to thelack of facilities to analyze smaller concentrations pre-cisely (Nickson et al., 2005).
High F– groundwater causes fluorosis in several re-gions of the world; East Africa (Nanyaro et al., 1984),India (Rao et al., 1993), and Inner Mongolia in China(Wang et al., 1999). The drinking water limit (DWL) forF– is 1.5 mg/L (WHO, 1994). Fluoride in drinking waterhas a narrow optimum concentration range in relation tohuman health. It prevents dental caries in the range of0.7–1.2 mg/L, but is responsible for dental and skeletal
INTRODUCTION
Natural and anthropogenic pollutants threaten the qual-ity of life through the environmental pollution. From thepoint of view of groundwater contamination, As and F–
have received the most attention due to their toxicity (e.g.,Smedley et al., 2002). The release of soluble As speciesinto groundwater is a serious problem in many areas ofthe world (e.g., Varsanyi et al., 1991; Lepkowski, 1998;Welch et al., 2000; Tian et al., 2001; Bhattacharya et al.,2004; Nickson et al., 2005). The World Health Organiza-
214 A. Farooqi et al.
fluorosis, if it is higher than 1.5 mg/L (CDCP, 1999).The Pakistan Council for Research and Water Re-
sources (PCRWR) and UNICEF have undertaken the as-sessment of drinking water quality since 1999 followingthe As crisis in Bangladesh and other neighboring coun-tries. Consequently, the presence of As contaminatedgroundwaters (10–200 µg/L) has been recognized in manyareas of Pakistan (www.pcrwr.gov.pk/Arsenic).
We reported As and F– contamination of groundwaterin a small village Kalalanwala, 30–35 km south of La-
hore, where >400 residents, mostly less than 15 years old,were diagnosed with bone deformity disease and moltedteeth (Farooqi et al., 2007). The maximum concentrationof As was 1,900 µg/L and that of F– 21.1 mg/L. In addi-tion to the high As and F–, the groundwater containedhigh concentrations sulfate and was highly alkaline. Al-though As and F– contaminated groundwater is distrib-uted throughout the whole country, the situation of ourreported area is more serious than in other areas wherethe maximum concentration of total As reported by
Fig. 1. Index map showing the Punjab, study area, and location of brick kilns. Flood plain is shaded. The abbreviations fordescription of villages are the same as those in Table 1. The hatched area with abbreviations is the residential area.
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 215
PCRWR was 200 µg/L, and that of F– was <2.0 mg/L(www.pcrwr.gov.pk/Arsenic), and As in groundwater fromMuzaffargarh area (south western edge of the Punjab) was960 µg/L (Nickson et al., 2005).
On the basis of the previous report (Farooqi et al.,2007), this study has been extended to 17 villages sur-rounding Kalalanwala, in order to reveal the extent anddegree of groundwater pollution and to estimate the prin-cipal controlling geochemical factors concerned with theAs and F– pollution. This is based on the water chemistryincluding H, O, S and N isotopic ratios.
GEOGRAPHY, GEOLOGY AND CLIMATE
OF THE STUDY AREA
The Punjab province, Pakistan, is located between 24–37°N and 62–75°E within an alluvial plain of the south-flowing Indus River and its five major tributaries. Thedistricts of Lahore and Kasur are located in the centralPakistan at the eastern edge of the Punjab Province occu-pying an area of 3,995 and 1,772 km2 and total popula-tion of 2.31 and 6.31 million, respectively. The presentstudy area covers 1/5th of the Kasur and 1/6th of the La-hore districts. The area is located along the eastern bankof River Ravi (Fig. 1) and includes 17 villages betweenChung, 15–20 km south from main Lahore and Zahirabadnear to the district Chunian (Fig. 1). For daily water use,including drinking water, most of the residents usegroundwater extracted from tube wells drilled up to 30 min depth from the ground surface within individual dwell-ings.
Hydrology, hydrogeology, and aquifer sediments ofthe Punjab were first described in detail by Greenman etal. (1967); the Punjab Province is in an alluvial plain com-prising >350 m thick Holocene and Pleistocene sedimentstransported by the Ravi and Satluj rivers. The sedimentsare mostly sand, containing high percentage of fine tovery fine sand and silt and low organic matter content.The area is mainly recharged by the Ravi and Satluj riv-ers during monsoon season; however, the recharge fromthe rivers has diminished since canal irrigation started inthe 17th century.
The Punjab province has a semiarid and subtropicalcontinental climate characterized by sultry summers andcold winters. The mean annual maximum temperaturerecorded from May to June is 41°C and the mean annualminimum temperature from December to January is 4°C(Ali et al., 1968).
Quaternary sediments, mainly of alluvial and deltaicorigin, occur over large parts of the Indus Plain of Paki-stan, predominantly in Punjab Province, (WAPDA-EUAD, 1989). The sediments there have some similari-ties to those of the As affected aquifers in Bangladeshand West Bengal, being Quaternary alluvial-deltaic
sediments derived from Himalayan source rocks. How-ever, the Indus basin is climatically arid, and comprisesolder Pleistocene deposits including eolian sediments andis dominated by aerobic conditions of unconfined ground-water aquifers (Mahmood et al., 1998; Tasneem, 1999;Cook, 1987).
SAMPLING AND ANALYSIS
The wells are installed into three different depths inthe ca. 800 km2 study area, and 147 groundwater sam-ples were collected from those different depths: thesecomprise 123 samples from the shallow hand tube wellsinstalled at 27–30 m in depth, 14 from 40–80 m in depthand 8 from deep wells 80–200 m in depth. In addition,two samples were collected from a canal drawn fromChenab River which originates from Indian Territory (Fig.1).
Water temperature, pH, ORP, electric conductivity(EC) and alkalinity (quoted as HCO3
–) were measured insitu. The ORP values were transformed to standard hy-drogen electrode (SHE) readings (Eh) because the Ag/AgCl reference electrode had a difference of +200 mVwith respect to SHE (Szogi et al., 2004). At each site,water samples were collected for the laboratory analysis.After filtering the sample water using a 0.45 µm mem-brane filter, the water was transferred to two polyethylenebottles; one was acidified to 0.06 N HCl for the quantita-tive analysis of cations (Na+, K+, Ca2+, and Mg2+), totalAs, and sulfur isotopes. The other aliquot was not acidi-fied and used for anion analysis (Br–, Cl–, F–, PO4
3–, andSO4
2–) and hydrogen and oxygen isotope analyses. ForAsIII and nitrogen isotope analysis 50 mL of water acidi-fied to be 0.09 N H2SO4 solution was tightly sealed in aglass bottle. Sodium and K+ were determined by atomicabsorption spectrometry (SAS 7500, Seiko). Calcium andMg2+ were analyzed by volumetric titration with ethyl-enediaminetetraacetic acid (EDTA 0.05N) with an ana-lytical error <±2%. Chloride, Br–, PO4
3–, SO42– and F–
were determined by Ion chromatograph (DX-120, Dionex)with a precision <±2%, estimated using duplicated stand-ard solutions. Silica and Fe were determined with ICP-AES.
Water soluble fluoride in fertilizers was extracted todetermine the concentration. Five grams of fertilizer sam-ple and 25 mL distilled water were placed in polyethylenebottles, shaken for 0.5 hour on a shaker, centrifuged andthe resultant water was used for the analysis by ion se-lective electrode (Orion) and ion meter (Metro Ohm).Total F– in coal samples was analyzed by ion chromatog-raphy after the coal was alkali fused and dissolved in water(Shimizu et al., 2006; Crossley, 1944). The reproducibil-ity of analytical data was <10% for the duplicated sam-ples. For total As in coal samples, acid digestion was used
216 A. Farooqi et al.
(Aruscavage, 1977). A 0.1 g sample was taken into 125mL Erlenmeyer flask; 20 mL HNO3 and 2 mL H2SO4 wereadded and left overnight. 3 mL of HClO4 was added intothe flask, which was then heated at 175°C with a refluxer.After heating for 30 min., the refluxer was removed andthe flask was heated continually till dense fumes cameout. Finally, the flask was cooled down and 25 mL 6NHCl was added. The obtained sample solution wasanalyzed by hydride generation atomic absorptionspectrometry (HGAAS, SAS 7500, Seiko Instruments).
For total As analysis, 2 mL of 12M HCl was added to15 mL of sample water together with 0.25 mL of a solu-tion containing 10% KI and 10% ascorbic acid. Hydridegeneration atomic absorption spectrometry (HGAAS,
SAS 7500, Seiko Instruments) was employed to measurethe total As produced as the gaseous form (AsH3) by re-duction using sodium borohydride as reductant. Repro-ducibility of the analytical data was within 5%, and theanalytical error estimated to be <10%, based on the ana-lytical results of standard stock solutions independentlyprepared from the commercially distributed standard so-lution using a standard calibration line. The lower limitof quantification of As was 1 ppb.
Arsenite (AsIII) concentrations were determined by theVoltammetry introduced by Holak (1980). TheVoltammetry applied for natural waters has an advantageto reduce interference by dissolved salts. The lower de-tection limit of arsenite was 5 ppb, and the relative stand-
Table 1. Concentration ranges of major anions, cations and isotopic ratios of groundwater in east Punjab, Pakistan
Locality Abbr. HCO3− [mg/L] Cl− [mg/L] SO4
2− [mg/L] NO3−−N [mg/L]
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 217
ard deviation was 8.5% for 20 ppb of the solution in thismethod. AsV is calculated from the concentration differ-ence between the total As and AsIII. The detection limitwas determined from the lowest concentration of thestandard solution giving the optical peak.
Sulfate was extracted as BaSO4 by adding 10% BaCl2solution in water samples for sulfur isotope analysis. Theprecipitated BaSO4 was collected on a 0.45 µm membranefilter paper, dried, and ground together with SiO2 andV2O5. The sample powder was reduced to produce SO2
gas by heating at 1120°C following the method byYanagisawa and Sakai (1983). To analyze the sulfur iso-topes of coal, the sample was processed according to theprocedure modified from Nakai and Jensen (1967), andOhizumi et al., (1997). Two grams of coal was accuratelyweighed and combusted at 900°C in a vacuum line. Theresulting gases were oxidized in 3% H2O2 solution to pro-duce sulfate ions. The obtained solution was passedthrough a 0.45 µm membrane filter and the dissolvedsulfates were recovered via BaSO4 precipitation using the
Table 1. (continued)
“bdl” means below detection limit.Detection limits for NO3
––N, and Fe are 0.05 and 0.01, respectively.
Locality Abbr. EC [mS/cm] Eh [mV] pH SiO2 [mg/L]
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
same procedure as that for groundwater. The sulfur iso-tope ratio was measured using a mass spectrometer VGSIRA 10. The obtained isotope ratios are expressed in thefamiliar delta notation δ34S, referring to the CDT (Can-yon Diablo Troilite) scale and defined by Eq. (1). Theanalytical precision for δ34S was <±0.2‰.
δ 3434 32
34 321 1000 1S
S S
S S
sample sample
standard standard
=( )
( ) −
× ( ).
Oxygen isotope ratios (18O/16O) were measured byH2O–CO2 equilibration method originally developed byEpstein and Mayeda (1953), using an online vacuum sys-tem attached to a mass spectrometer (VG-PRISM,Micromass). The analytical error was within 0.1‰. Hy-drogen isotope ratios (D/H) were determined by the onlineCr reduction method (Itai and Kusakabe, 2004) attachedwith a mass spectrometer (VG-SIRA10, Micromass). Theanalytical error was within 0.5‰.
The Devarda’s alloy/ammonia protocol, developed bySigma et al. (1997), was used for pretreatment of NO3
––N isotope analysis. Nitrogen isotope analysis was carriedout using an online elemental analyzer interfaced with anisotope ratio mass spectrometer (EA-IRMS). Based onthe multiple analyses of laboratory standards (KNO3,(NH4)2SO4, and DL-alanine), the precision of the ana-lytical data was <0.20‰.
To estimate the equilibrium condition of the mineralspossibly controlling the soluble chemical species, satu-ration indices were calculated using an internet-basedversion of the USGS program PHREEQ (Parkhurst, 1995).
RESULTS
Analytical results of all water samples are listed inAppendix. Groundwater samples were categorized intothree groups for convenience according to the well depth;shallow (20–27 m), middle (40–80 m) and deep (80–200m). Geochemical characteristics of the groundwater aredescribed in the following.
Major constituentsAnalytical results of major and stable isotope ratios
are summarized according to location in Table 1. Thechemistry is summarized according to well depth in Ta-ble 2. Chemistry of the groundwater showed large varia-tion in the concentration ranges, however, many of thosecontained high salinity. As described below, the rangesof each ion overlapped among the groundwaters from thedifferent depths; the highest concentration of major ani-ons and Na+ were almost twice as high in the shallowgroundwaters than in the middle and deep groundwaters.
The shallow groundwaters gave the widest range ofEC within 0.4 and 4.6 mS/cm, and most of those have EC>2.0 mS/cm. The alkalinity calculated as HCO3
–, was195–1280 mg/L and sulfate ranged from 38.0 to 960 mg/L, such that 35% of the analyzed groundwaters exceededthe WHO guideline value (250 mg/L). Sulfate and bicar-bonate were the most abundant anions. The Cl– rangedfrom 2.0 to 415 mg/L. Sodium, the most dominant cation,was up to 1,060 mg/L, while Ca2+ concentrations werelow, ranging from 2.0 to 140 mg/L with a mean value of32.0 mg/L.
Electric conductivity of the middle groundwaters was0.2–2.2 mS/cm, SO4
2– 24.0–480 mg/L, alkalinity (as
Unit Shallow (n = 123) Middle (n = 14) Deep (n = 8) Canal water (n = 2)
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Table 2. Ranges of analytical data of groundwaters classified by the well depth and canal water
“bdl” means below detection limit.Detection limits for Br–, NO3
––N and PO43– are 0.02, 0.05 and 0.025, respectively.
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 219
mg/L, Ca2+ 6.0–86 mg/L, and Cl– up to 160 mg/L. Thehigh EC and high concentration of the above dissolvedspecies in shallow groundwater show that the shallowgroundwater could be easily affected by the human ac-tivities.
More than half of the samples had Na+–HCO3– domi-
nant type chemistry (Fig. 2). The classification based onmajor ions does not depend on the well depth. However,Ca2+ and Mg2+ tend to be slightly higher in the middleand deep groundwaters than in the shallow groundwater.Despite this, the groundwaters containing high amountsof dissolved species appear mostly from the shallow wells.The trilinear diagram showing anion composition in Fig.2 gives the linear relationship for the anion compositionbetween HCO3
– and Cl– + SO42–, suggesting that the lat-
ter two have common origins as major contaminants, e.g.,household waste and fertilizers. The waters were in neu-tral to alkaline pH of 7.1–8.7.
The two canal water samples had EC 0.5–0.7 mS/cm,pH 7.3, and SO4
2– 36.0–72.0 mg/L, alkalinity 427 mg/L,Na+ 12.0–19.0 mg/L, Ca2+ 60.0–66.0 mg/L and Cl– 10.0–15.0 mg/L. The concentrations of the soluble componentswere much lower than the average values of the studiedgroundwaters with the exception of Ca2+.
High NO3––N concentrations were observed in shal-
low groundwaters, which can easily be affected by land
Fig. 2. Piper diagram showing the chemical compositions ofgroundwater samples. Solid triangles are symbols for shallow,diamond for middle, and square for deep groundwaters.
0 100 200 300 400 5000
5
10
15
20
25
(e)(d)
0 100 200 300 400 5000
200
400
600
800
1000
0 100 200 300 400 5000
500
1000
1500
2000
2500
0 100 200 300 400 5000
200
400
600
800
1000
1200
(b)
0 100 200 300 400 500
Cl–(mg/L)
0
200
400
600
800
1000
(a)
0 100 200 300 400 500
0
10
20
30
40
50
0 100 200 300 400 5000
4
8
12
16
20
(f)
0 100 200 300 400 5000
400
800
1200
1600
(c)
Cl–(mg/L) Cl–(mg/L)
Cl–(mg/L)Cl–(mg/L)Cl–(mg/L)
Cl–(mg/L)
Cl–(mg/L)
SO42–
(m
g/L
)
Na
(mg/
L)
HC
O32–
NO
3–N
(m
g/L
)
F (m
g/L
)
As
(µg/
L)
As
(µg/
L)
NO
3–N
(m
g/L
)
Fig. 3. Relationships of Cl– vs. SO4 (a), Na+ (b), HCO3 (c), As (d), F– (e) and NO3–N (f). Circles are symbols for canal water andthe rest of the symbols are the same as those in Fig. 2.
HCO3–) 153–732 mg/L, Na+ up to 322 mg/L, Ca2+ 19–73
mg/L with a mean value of 45 mg/L, and Cl– up to 250mg/L. Groundwater from the deep aquifers showed nar-row ranges of analytical data compared with those of shal-low and middle groundwaters; EC 0.5–1.9 mS/cm, SO4
2–
32.0–341 mg/L, alkalinity 146–671 mg/L, Na+ up to 306
220 A. Farooqi et al.
Loc
alit
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s(II
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µ g/L
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mg/
L]
Min
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Tabl
e 3.
Su
mm
ary
stat
isti
cal
data
for
flu
orid
e an
d ar
seni
c in
stu
dy a
r ea
“nd
” m
eans
not
det
ect e
d.D
etec
t ion
li m
i t f
or A
s(II
I) i
s 5
ppb.
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 221
Fi g
. 4.
D
i st r
i but
i on
map
of
As
and
F– i
n t h
e st
udy
area
wi t
h t h
eir
mi n
i mum
, m
axi m
um a
nd m
ean
conc
ent r
ati o
ns.
222 A. Farooqi et al.
use. Six of them contained NO3––N in excess of the WHO
standard (10 mg/L) for drinking water. The highest con-centration of NO3
––N was 46 mg/L. Middle and deepwaters had NO3
––N of <10 mg/L (WHO standard), withthe exception of two samples from the middle depth. Theabsence of NO3
––N in the deep waters would not be re-lated to NO3
– reduction as the groundwaters showed Ehvalues, up to 775 mV (Table 1). It is more likely due tothe lack of nitrogen pollution at depths >30 m.
Fe concentration was low in the studied groundwatersin accordance with the highly positive Eh, indicating theoxidizing conditions prohibit high Fe dissolution. Mostof the studied groundwater showed Fe concentrationsbelow the detection limit, 0.01 mg/L. Only twelve sam-ples had higher Fe, i.e., more than the WHO standard of0.3 mg/L, and the maximum concentration was 2.8 mg/Lat depth of 20–27 m.
The relationships between Cl– vs. SO42–, Na+, NO3
––N, and HCO3
–, are given in Figs. 3a to 3f. Sulfate, Na+,HCO3
– and NO3––N concentrations show positive corre-
lations with Cl– (Figs. 3a, 3b, 3c, and 3f). Thus, amongthese elements the pollutant source(s) are either identicalor the courses are similar.
ArsenicArsenic concentrations in the groundwater samples
widely range from 1 to 2400 µg/L. The concentration ofthis element in the two canal water samples was 1 µg/L.Of 123 shallow groundwaters, 11 (ARK-1, 2, MM-4, 5,8, 9, DN-1, 3, SKB-12, JK-2, and CNG-1, Appendix)contained <10 µg/L of As. One common feature amongthese groundwater samples was that they contain highNO3
––N, e.g., MM-5 was amongst the highest containingNO3
––N. In the middle groundwaters, As ranged from 22to 91 µg/L (n = 14) with one exception, ARK-8, whichcontains 881 µg/L As and has an exceptionally low SO4
2–
concentration (29 mg/L). The deep groundwaters (n = 8)had a 8–80 µg/L range of As cnocentration with the ex-ception of two samples, KLW-2 and MM-13, having Asconcentrations 242 and 611 µg/L respectively.
Enormously high concentrations of As were foundfrom shallow-well waters in four villages from the west-ern and eastern part of the study area; 2400 µg/L inKalalanwala and Kot Asad Ullah (KLW and KAD havedifferent names but share residential areas), 883 µg/L inShamkey Bhatian (SKB), 672 µg/L in Manga Mandi(MM), and 681 µg/L in Waran Piran Wala (WP) (Table 3and Fig. 4a). These four villages are located near the areawhere brick kilns are concentrated. The maximum Asconcentrations of groundwaters in the villages distributedtoward west to southwest from the kiln area are between50 and 112 µg/L except in Kot Ashraf (KA) where themaximum concentration is 625 µg/L. At Chung (CNG),15 km away from the main Lahore City, the groundwaters
had As concentrations up to 67 µg/L, while those inSundar (SUN) had 90 µg/L As. Such a distribution of Asconcentrated groundwaters can support the previouslyproposed hypothesis that wet and dry deposition of Asderived from combusted coals in the brick kilns is one ofthe contributing factors to high As and F– in the studyarea (Farooqi et al., 2007). On the other hand, canal wa-ters (Cantt Colony, CCO) had As values <1 µg/L, imply-ing that the surface running water is not seriously con-taminated by As.
Voltammetry demonstrated that 97.3% of the 147 sam-ples did not contain detectable amounts of AsIII. Only theremaining 4 groundwaters contained detectable AsIII.Those were found in the groundwater from the villageARK (Arain Da Khu), where the maximum concentra-tion of AsIII was 23 µg/L in 56 µg/L total As. Two of thefour samples were from the shallow wells (ARK-1, 3),while the other two were from the middle (ARK-6) anddeep (ARK-9) wells. The chemical compositions of thesewaters were mostly similar to those of the other waterscollected from this village, where the EC value is 0.2–1.0 mS/cm and pH is neutral to alkaline. This village isthe only one located in the flood plain among the studiedvillages, thus, its geographical location is probably re-lated to the appearance of AsIII.
Water soluble As in fertilizers (DAP) is estimated to
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 223
be 5–10 mg/kg with an average value of 7.4 mg/kg. Thecoal samples contain this element ranging from 4 to 12mg/kg with an average value of 8 mg/kg (Table 5). Sucha high concentration of As in fertilizers would be a po-tentially large pollutant source of surface soil and under-lying groundwater associated with cultivation in the studyarea. The major anthropogenic introduction of As into theenvironment occurs by the use of pesticides in the formof calcium arsenate, arsenic acid, lead arsenate and so-dium arsenate (Alloway, 1970; Woolson et al., 1971). Wehave not analyzed pesticides in this study; however theuse of pesticides must be responsible for the high As con-centrations in the local groundwater.
FluorideFluoride concentrations were high in the shallow-well
waters that showed the high EC values >2.0 mS/cm. The75% of water samples exceeded the WHO standard (1.5mg/L), the maximum F– content was 22.8 mg/L found inKLW. Twenty seven groundwater samples contained <1.5mg/L F– and nine of them were from MM, and six fromARK (Appendix), both of which are close to the kiln con-centrated area. One of the F– source(s) was suggested tobe from air pollutants since the local rainwater containeda certain amount of F– (Farooqi et al., 2007). Howeverless contaminated groundwaters in MM (Manga Mandi)imply that other larger source(s) of F– must be present inthis area.
Of the middle groundwaters, 63% had F– content <1.5and 37% have >1.5 mg/L. The maximum concentrationwas up to 4.2 mg/L found in KAD. The groundwater sam-ples from the deep wells were <1.5 mg/L with the onlyexception of one sample KLW-2 that contained F– 3.1 mg/L. The canal waters had F– content 1.7–2.3 mg/L. Suchan occurrence implies that the F– is derived from the sur-face, and this ion decreases with increasing well depth.
Figures 4a and 4b, show that the highly As contami-nated areas were also contaminated by high F–, e.g., inKLW, KAD, SKB and WP, but not the same well waters.
Figure 5 shows that F– and As had a negative correlation.These facts suggest that not only one but rather more thantwo mechanisms and/or pollutant sources are responsiblefor the formation of the highly As and F– contaminatedgroundwaters in the study area.
From Figs. 5b, 5c, 5d and 5e, weakly positive corre-lations are observed between F– vs. HCO3
2– and Na+ (Figs.5b and 5c), while negative correlations exist between F–
vs. Ca2+ and Mg2+ (Figs. 5d and 5e). Such negative cor-relations suggest that the low Ca2+ and Mg2+ concentra-tions lead to occurrence of highly F– containinggroundwaters. Low Ca2+ and high Na+ concentrationscould be explained by the cation exchange reaction inwhich Ca2+ originally in the water has been exchangedby Na+, or removed due to precipitation of carbonate min-erals under high alkalinity (e.g., Nickson et al., 2005).Fluoride did not show good relationship with pH (Fig.5f).
Air pollutants from coal combustion and phosphatefertilizers are common sources of F– in the environment(Pickering, 1985). The fertilizers contained soluble F–
ranging from 60 to 255 mg/kg with an average value of175 mg/kg, while, coal samples contained total F– rang-ing 5.12 to 20.1 mg/kg with an average value of 10.2 mg/kg (Table 5).
Stable isotopic compositionsOxygen and hydrogen isotopes The ranges of stable iso-topic ratios of hydrogen and oxygen of the groundwatersamples are summarized in Table 1. The relationship be-tween δ18O and δD of groundwaters is plotted in Fig. 6,along with those values of local rainwaters.
Oxygen isotopic ratios of the groundwater rangedwithin –9.6 and –7.0‰, while δD within –61.9 to –42.5‰.The compositions did not show any distinctive relation-ship to well locations or depth. The δ18O of canal watersranged from –9.6 to –9.3‰ and δD from –59.8 to –52.4‰.The δ18O and δD of all studied groundwater samples fellbetween those of the rain and canal waters, indicating
Table 5. Fluoride and As concentrations in coals and fertilzers
All values are in mg/kg.
224 A. Farooqi et al.
mixing between local meteoric water and the water fromthe river, which is mainly recharged at higher altitudes inIndian territory. The waters plot on a slope parallel to thatof global meteoric water line (GMWL, δD = 8 × δ18O +10, Fig. 6), indicating that evaporation was not signifi-cant in the local groundwaters.Sulfur isotopes Sulfur isotopic composition is an effi-cient tool for tracing and identifying the SO4
2– pollutantsources. The δ34S values of the studied groundwatersrange from +3.7 to +7.0‰, and three groups can be iden-tified from the data (Fig. 7a); groundwaters having con-stant δ34S values (5.5–5.7‰) irrespective to the SO4
2–
concentration (A), those with high δ34S values (6.3–7.0‰)and low SO4
2– (B), those with low δ34S values (3.7–4.8‰)and high SO4
2– (C). The δ34S values of rainwater (n = 3)range from 5.0 to 7.0‰. The δ34S values of coal collectedfrom the study area (n = 8) range within 3.5–10‰ withan average value of 6.0‰. The δ34S values of fertilizer(DAP, n = 5) ranged within 3.4–7.6‰ with the mean valueof 5.7‰.
In group A, all samples had δ34S values around 5.5–5.7‰ with widely varying SO4
2– concentrations. One ofthe SO4
2– sources must be atmospheric pollution, sincerainwater and coal samples also showed average δ34Svalue around 6.0‰ and SO4
2– concentration in the rainwas 14 mg/L. The range is also concordant with the aver-
age δ34S value of the fertilizers. In conjunction with thefact that considerable evaporation-condensation does notoccur following recharge, high SO4
2– concentration in thegroundwaters of this group must be caused by the ferti-lizers distributed in the study area, although the recharg-ing water was already contaminated by airborne sulfur.
Group B is characterized by the δ34S values >6‰ withlow SO4
2– concentrations <250 mg/L. The maximum δ34Svalue is +7.0‰, which is close to that of household de-tergents (+8.5 to +13.6‰; Laura et al., 2004).
Group C groundwaters had low δ34S and high SO42–
concentrations. All waters of this group were obtainedfrom the villages RPNA, JK and ZAB, located at south-west of the study area in Fig. 7b, away from the brickkiln area. The effect of atmospheric pollution and ferti-lizers would be smaller in this area compared to otherlocations in the study.
The sulfur source cannot be elucidated, since δ34Svalues of fertilizers and air pollutants overlap. However,the SO4
2– in the groundwaters of the study area appearsgenerally to have originated from fertilizers, air pollut-ants and household waste water including detergent usedin the area.Nitrogen isotopes Nitrate δ15N was analyzed for 21groundwaters to identify the sources of nitrogen contami-nants (Table 4). Most of the groundwater samples give
10 15 20 250
40
80
120
160
Ca2
+(m
g/L
)
(d)
10 15 20 25F– (mg/L)
0
200
400
600
800
1000
As
(µg/
L)
(a)
10 15 20 25
F– (mg/L)
0250500750
1000125015001750200022502500
As
(µg/
L)
10 15 20 25F– (mg/L)
0
400
800
1200
1600
HC
O3 2–
(m
g/L
)
(b)
10 15 20 25F– (mg/L)
0
400
800
1200
Na+
(m
g/L
)
(c)
7.2 7.4 7.6 7.8 8.4 8.6 8.8pH
0
5
10
15
20
25
F– (m
g/L
)
(f)
0
20
40
60
80M
g+2
(mg/
L)
(e)
0 5
0 5
0 5 0 5
F– (mg/L)
0 5
F– (mg/L)10 15 20 250 5 8 8.2
Fig. 5. Relationships of F– with As (a), HCO3 (b), Na+ (c), Ca2+ (d), Mg2+ (e), and pH (f). Symbols are identical to those inFig. 3.
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 225
δ15NNO3 >5‰, with the maximum value 30‰ and themean one 10‰. The δ15NNO3 of the groundwater samplesare in the same range of those of animal waste: for exam-ple, nitrate originating from animal excrement displaysδ15NNO3 values typically in the range within +10 to 20‰(Heaton, 1986; Widory et al., 2004), and +8 to 25‰ (Fogget al., 1998). Volatilization and denitrification by micro-bial activities fractionate N isotopes such that 15N be-comes enriched in soil, although those two processes can-not increase δ15N by more than 10‰ (Gormly andSpalding, 1979). Thus, the δ15NNO3 indicates human andanimal waste distributed inside the villages as the majornitrate source.
The groundwaters from Zahir Abad (ZAB), the south-westernmost village among the studied villages, showeda narrow range of δ15N from 3.5–5.7‰. The δ15N of fer-tilizer samples (urea, n = 3) were also analyzed, and thosevalues were <2‰, close to that of air. The range of δ15N
of ZAB groundwaters is in concordant with that of soilorganic nitrogen (e.g., Chapella 2001) and chemical fer-tilizers used in China (Li et al., 2007) but slightly largerthan those used in this area. Since the concentration ofNO3
––N is not very low in the analyzed waters, the soilorganic nitrogen would not be the only source for thiscomponent. Denitrification of urea in the fertilizers wouldpromote to enrich in 15N in those waters.
DISCUSSIONS
Pollutant sourcesAlthough As and F– rich groundwaters are well known
to occur naturally in many parts of world, anthropogenic
contamination cannot be excluded in the studied area.Arsenic in ambient air in the Lahore district is 230–
2230 ng/m3 (JICA and Pakistan EPA, 2000), which ismuch higher than those reported in the other areas in theworld; e.g., 91–512 ng/m3 in Calcutta, India (Chakrabortiet al., 1992), 25 ng/m3 in Wuhan City, China (Waldmanet al., 1991), and 1.2–44 ng/m3 in Los Angles, USA(Rabano et al., 1989). The SO2 in the ambient air was133–212 µg/m3/hr in Lahore (Punjab EPD, 1998–99),which is lower than the WHO guideline value for SO2 inair, i.e., 350 µg/m3/hr. We also reported high concentra-
–11 –10 –9 –8 –7 –6 –5δ18O (permil)
–75
–70
–65
–60
–55
–50
–45
–40
–35
δD (
perm
il)
Fig. 6. Oxygen versus Hydrogen isotope ratios. Symbols areidentical to those in Fig. 3.
0 200 400 600 800 1000SO4
2– (mg/L)
3.5
4
4.5
5
5.5
6
6.5
7
7.5
δ34S
(per
mil)
Group B
Group A
Group C
Rai
n w
ater
(a)
Group A
Group B
Group C
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
δ34S
(per
mil)
Localities
(b)
Fert
ilize
r
Coa
l
Rai
n
KL
W
SUN
CC
O
KA
NK
DN
AR
K BP
WP
SKB
MM
MPU
KA
D
CN
G
RPN
A JK
ZA
B
Fig. 7. The relationship between sulfur isotope ratios andsulfate concentrations (a), and the sulfur isotope ratios ofgroundwater samples corresponding to the sampling villages,coal, fertilizers and rainwater samples (b). In (a), solid trian-gles are symbols for shallow, diamond for middle and squarefor deep groundwaters and stars are for rainwaters.
226 A. Farooqi et al.
tion of As (<10–90 µg/L), with SO42– (5–14 mg/L) in the
local rain (Farooqi et al., 2007). Although the concentra-tion of SO2 in ambient air is lower than the WHO stand-ard, the presence of As in the air and rainwater supportthat those elements in the studied groundwater are partlyderived via ambient air.
Fluoride can be released in the environment from phos-phate fertilizers, which include fluorine as an impurity(Pickering, 1985; Skjelkvale, 1994). Phosphate fertiliz-ers commonly contain from 1.3 to 3.0% fluorine(McLaughlin et al., 1996), much higher than thoseanalyzed here. The annual consumption of fertilizers in1999 was 2,824 thousand metric tonnes with 129 kg/hacropland in Pakistan and mostly in Punjab (http://earthtrends.wri.org). The presence of leachable F– and Asin fertilizer and coal samples also shows anthropogenic
contribution of fertilizers being used in the study areaand combusted coal in the brick factories. Local rainwa-ter contained 0.16–0.23 mg/L F–, and we presumed thatthe F– was partly derived from combusted coal in the stud-ied area (Farooqi et al., 2007). The presence of F– and Asin coal samples (though not so high) substantiates ourhypothesis of the contribution of combusted coal; how-ever, fertilizers (DAP) consumed in the surroundingswould be more important as an anthropogenic source ofF– in the study area.
Controlling role of major chemistry on As and F– behaviorHigh concentrations of As were found in groundwaters
from shallow depths. The highly As contaminated waterswere characterized by high EC values >2 mS/cm, Na–HCO3
– dominant major chemistry and have pH > 8. As
0 20 40 60 80 100 120 140
Ca2+ (mg/L)
–4
–3
–2
–1
0
1
2
Satu
ratio
n in
dex
of f
luor
ite (
SIf)
(d)
0 5 10 15 20 25
F– (mg/L)
–4
–3
–2
–1
0
1
2
Satu
ratio
n in
dex
of f
luor
ite (
SIf)
(c)
0 20 40 60 80
Mg2+ (mg/L)
–1
0
1
2
3
4
Satu
ratio
n in
dex
of d
olom
ite (
SIdo
)
(b)
0 40 80 120 160
Ca2+ (mg/L)
–0.5
0
0.5
1
1.5
2Sa
tura
tion
inde
x of
cal
cite
(SI
c)(a)
Fig. 8. Relationships between calcite saturation index (SIc) and Ca2+ (a), dolomite saturation index and Mg2+ (b), fluoritesaturation index (SIf) and F– (c), fluorite saturation index (SIf) and Ca2+ (d). Symbols are the same as those in Fig. 2.
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 227
0 200 400 600 800 10000
0.5
1
1.5
2
2.5
3
Fe (
mg/
L)
(a)
As (µg/L)
7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8pH
0
200
400
600
800
1000
As
(µg/
L)
(b)
7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8pH
0
500
1000
1500
2000
2500
As
(µg/
L)
Fig. 9. Relationship between As and Fe (a) and pH (b). Sym-bols are the same as those in Fig. 2.
noted before, the As concentration increases with increas-ing pH (Fig. 9b) and AsV is the dominant As species inthe studied groundwaters. Naturally As contaminatedgroundwater is mainly caused by two different processes:oxidation of arsenic-bearing sulfide minerals (Schreiberet al., 2000) and desorption from and/or following re-duction of FeOOH adsorbing As (Matisoff et al., 1982;Robertson, 1989; Nimick, 1998; Nickson et al., 1998,2005; McArthur et al., 2001) in response to the increaseof pH and decrease of redox potential of the groundwater.
Based on laboratory experiments of As adsorption onthe metal oxides, such as Fe, Mn and Al oxyhydroxide/oxides (Anderson et al., 1976; Pierce and Moore, 1982;Dzombak and Morel, 1990; Gustafsson and Jacks, 1995;
Lindberg et al., 1997) and clay fractions (Jacobs et al.,1970; Manning and Goldberg, 1997), AsV is most effec-tively adsorbed on Fe-oxyhydroxide/oxide at weaklyacidic to neutral pH conditions, and it is released intosolution with increasing pH to alkaline conditions. Re-gardless of whether the As originates from anthropogenicsource(s) or from natural substances, we can say that al-kaline conditions promote the dissolution of As into thestudied groundwaters.
Figure 9a shows that As and Fe have a negative corre-lation, and the groundwater containing <0.2 mg/L Fe,contains >400 µg/L As. Thus, FeOOH, if it controls theAs concentration in the studied groundwater, would fixthe As to prohibit the dissolution of this element into thegroundwater. As shown in Fig. 9b a positive correlationis observed between As and pH which has a dominantrole on the As mobilization. Arsenate is desorbed fromFe oxides at alkaline pH (Dzombak, and Morel, 1990).Many researchers have pointed out that desorption of Asfrom mineral oxides is responsible for the highly As-containing groundwater in Quaternary sedimentary aqui-fers, e.g., As release into the groundwater can occur with-out apparent reduction in the arid basins of Argentina(Smedley et al., 2002).
Fluoride concentration in groundwater in arid andsemiarid regions is promoted by evaporation andevapotranspiration (Jacks et al., 2005). However, wepointed out that this mechanism cannot explain the caseof our studied area, since F– concentrations did not havethe linear relationship with Cl– (Fig. 3e), which is themost conservative component in the hydrosphere. Also,as shown in Fig. 6, plots of δD and δ18O were parallel tothe global meteoric water line (GMWL, Fig. 6), confirm-ing that the studied waters were not affected by evapora-tion and condensation. Thus, the high concentrations ofCl–, F– and also SO4
2– would be explained by one or moresources distributed on the land surface or intruded directlyinto the aquifer. Directly supplied pollutants and wet anddry deposition must be condensed on the land surface.
High F– concentrations were found in alkaline water,although the F– and pH did not show a clear correlation(Fig. 5b). As described above, F– concentration increasedwith decreasing Ca2+ and Mg2+ and increasing Na+ con-centrations under alkaline conditions. Calcium and Mg2+
concentrations were low and controlled mainly by thesolubilites of calcite and dolomite due to high HCO3
–
concentrations. As shown in Figs. 8a and 8b, most of thestudied groundwaters were saturated with those miner-als. The saturation index of fluorite (SIf) increased withincreasing F– concentration (Fig. 8c), while Ca2+ did notshow a clear relationship with SIf (Fig. 8d). Therefore,the low concentrations of Ca2+ (and probably Mg+) mustpromote high concentrations of F– in the studied ground-water, and that the upper limit of F– concentrations is
228 A. Farooqi et al.
controlled by fluorite solubility as seen in Fig. 8c. LowCa2+ would also result from the intense cation exchangereaction between Ca2+ and Na+ (Sarma and Rao, 1997).In the study area, the source water not only introduces Asand F–, but also determine the chemistry of the ground-water. It controls the dissolution rates of the toxic sub-stances and must play an important role in the formationof polluted groundwater.
Topographic constraintsHighly As and F– polluted groundwaters were con-
centrated in eastern and western part of the study area,e.g., KLW, KAD, SKB, and MM. The altitude of thesevillages is slightly lower than the other villages of thestudy area. Villages where the groundwater contains lessamounts of As, are located in the surrounding area ofKLW, KAD, SKB, and MM: CNG and SUN at northeast,BP at south and JK, ZAB, and RPNA at southwest. Thesevillages are located at slightly higher altitudes (>220 m)than the higher polluted villages (KLW, KAD, SKB, andMM), which are situated at about 200 m. If the surfacetopography was concordant with the structure of the aq-uifer, groundwater would flow toward topographic low.The highly As and F– polluted groundwaters are very al-kaline and of Na––HCO3
– dominant type, indicating typi-cal characteristics of groundwater chemistry in stagnantaquifers (e.g., Hinkle, 1997). Thus, it is probable that theAs and F– are coincidently dissolved into the stagnantgroundwater. Although we must wait evaluation of therelationship between aquifer structure and pollutedgroundwater formation to obtain geological profiles, thegroundwater flow system, including flowing rate and di-rection, would deeply affect the groundwater chemistryand formation of the studied highly polluted groundwater.
CONCLUSIONS
This study demonstrates that As and F– contamina-tion of groundwater is not limited to a small area com-prising two adjacent villages, KLW and KAD, but widelyextends to the surrounding areas. In the studied 17 vil-lages, a population of more than 2.0 million are directlyexposed to As and F– through air, surface soils and ground-water. In particular, the levels of As and F– in the ground-water are much higher than the WHO standards. The stud-ied groundwaters are not only polluted by high concen-trations of As and F– but also by SO4
2–, NO3–, alkalinity
and other anthropogenic pollutants. Ca2+ and Mg2+ aregenerally low due to the precipitation of carbonate min-erals and cation exchange reactions with Na+. Low Ca2+
concentration promotes the dissolution of F–, with F– con-centration being controlled by the solubility of fluorite.Speciation analysis shows that As is in the form of AsV.Given low Fe2+ concentration under positive Eh values,
As is dissolved into groundwater mainly under alkalinepH, at which As cannot be effectively adsorbed onto Feand other metal oxyhydroxide/oxides and/or clay miner-als.
Our present results indicate that the main anthropo-genic source of As is air pollutants derived from kiln fac-tories, with fertilizers being a possible secondary source.Minor amounts of F– and SO4
2– are also derived from airpollutants; however, major sources of these componentsmust be fertilizers. Household waste water also contrib-utes to the high SO4
2–, although waste water lacks F– andAs. These pollutants can remain under alkaline conditionsin our studied groundwaters, where major chemical com-position would be controlled by the stagnant condition ofthe aquifer. Groundwater pollution is most serious in shal-low sections of the aquifer between 20 and 30 m depth;however, highly polluted groundwater, especially by Asoccasionally occurs in the deep aquifers >40 m. Thus,whilst the groundwaters are grouped into three depths byconvenience, are in reality probably connected, and thepollutants could migrate into the deeper part of the sameaquifer. To evaluate this possibility, we should clarify thestructure of the aquifers in this area, and we should planto protect the groundwater quality in at least the deeperparts of the aquifer in this area.
Acknowledgments—We are thankful to Mr. M. Sakhawat, Di-rector of Geoscience Laboratory, Geological Survey of Paki-stan, Islamabad, for his cooperation and providing all neces-sary facilities for field and laboratory works. Technical sup-port from Ms. K. Okazaki, Osaka City University, is appreci-ated. We also thank to Dr. X. D. Li, Osaka City University, Dr.K. Koba, Tokyo Institute of Technology, for assistance in theanalysis of nitrogen isotopes, which were analyzed using thefacilities at Centre for Ecological Research, Kyoto University.We thank to Dr. H. Chiba, Okayama University, for guidingfluoride analysis using an ion meter. The authors are indebtedto Mr. M. Rehan-ul-Haq Siddiqui for his help during the fieldwork and Ms. N. Haider, Geoscience Laboratory, GeologicalSurvey of Pakistan, for laboratory assistance. Thanks are ex-tended to Dr. M. Imran Al-Haq, University of Tokyo, for lin-guistic suggestions. This work was financially supported byJSPS (Scientific aid: No. 12440145) and Sumitomo Founda-tion.
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APPENDIX
(see p. 231–234).
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 231
App
endi
x.
Che
mis
try
and
stab
le i
soto
pe d
ata
of g
r oun
dwat
ers
in e
ast
Pun
jab,
Pak
ista
n
Sam
ple
IDD
epth
Tem
.E
CpH
Eh
F−C
l−B
r−N
O3−
NP
O43−
SO
42−H
CO
3−T
anN
a+K
+C
a2+
Mg2+
Tca
As(
V)
As(
III)
FeSi
O2
δ18O
*δ D
*δ15
Nδ34
S
m°C
mS/
cmm
Vm
g/L
meq
/Lm
g/L
meq
/Lµ g
/Lm
g/L
CN
G-1
20−2
727
2.00
7.3
257
4.94
131
0.33
7.00
bdl
192
976
24.7
946
09.
0048
1323
.65
6nd
0.17
18.8
1−8
.00
−50.
32na
5.4
CN
G-2
20−2
727
1.36
8.1
297
2.67
780.
23bd
lbd
l12
054
914
.06
230
4.76
3918
13.5
8271
nd0.
0527
.00
−7.5
0−4
6.89
nana
CN
G-4
20−2
726
1.70
7.7
301
8.36
960.
30bd
lbd
l16
567
117
.88
322
5.07
3415
17.0
923
nd0.
0519
.50
−8.2
0−5
2.66
na5.
1
CN
G-5
20−2
727
1.25
7.3
320
6.08
510.
14bd
lbd
l11
661
014
.33
299
3.90
4214
14.9
014
nd<
0.00
12.0
0−8
.37
−53.
82na
na
SUN
120
−27
291.
308.
127
310
.13
21bd
lbd
l0.
4012
088
418
.13
380
4.68
84
17.3
292
nd0.
1022
.50
−8.5
0−5
3.25
na5.
7
SUN
220
−27
291.
618.
028
98.
3660
0.16
0.98
bdl
192
732
18.3
736
83.
1220
818
.12
57nd
0.10
21.3
0−8
.00
−52.
34na
5.7
SUN
320
−27
272.
568.
036
34.
7517
80.
364.
20bd
l43
285
428
.91
575
7.80
3118
28.2
885
nd<
0.00
24.8
0−7
.65
−48.
61na
5.7
SUN
420
−27
272.
267.
433
34.
1814
20.
341.
680.
7033
691
526
.69
483
8.58
5124
26.2
219
nd<
0.00
23.2
4−7
.30
−46.
59na
na
SUN
520
−27
282.
607.
233
71.
5217
70.
454.
48bd
l43
210
4031
.85
575
11.7
3735
30.8
01
nd0.
0122
.44
−7.3
0−4
5.91
nana
SKB
-220
−27
301.
238.
328
93.
8028
bdl
bdl
bdl
106
671
14.2
029
93.
906
313
.62
91nd
0.06
17.0
1−8
.74
−59.
11na
na
SKB
-320
−27
281.
258.
427
91.
1441
0.16
bdl
bdl
105
610
13.5
720
75.
4640
2313
.08
70nd
0.24
27.6
6−8
.28
−51.
40na
5.9
SKB
-420
−27
281.
498.
531
05.
7019
bdl
bdl
bdl
9685
416
.84
345
5.07
127
16.3
392
nd0.
0124
.00
−8.2
0−5
1.42
nana
SKB
-520
−27
291.
138.
531
210
.14
100.
040.
420.
6050
732
13.9
327
63.
903
1313
.38
443
nd0.
0423
.98
−8.8
9−5
7.02
na5.
7
SKB
-620
−27
281.
228.
432
43.
0410
bdl
4.20
2.90
3873
213
.57
288
1.95
36
13.1
928
3nd
0.05
16.1
1−9
.03
−56.
4310
.0na
SKB
-820
−27
281.
218.
631
45.
709
bdl
2.24
0.80
3563
611
.87
276
3.90
23
12.4
619
5nd
0.12
15.0
0−9
.03
−59.
83na
5.6
SKB
-920
−27
271.
068.
632
55.
3211
bdl
0.70
1.4
4854
910
.65
230
3.90
42
10.4
223
1nd
0.05
16.1
0−9
.20
−61.
17na
na
SKB
-10
20−2
730
0.66
7.2
334
4.56
6bd
lbd
lbd
l43
366
7.31
115
4.30
1613
6.97
223
nd0.
0422
.03
−9.0
6−5
9.32
nana
SKB
-12
20−2
730
0.84
8.0
218
0.95
13bd
l2.
38bd
l44
550
10.4
969
9.75
7146
10.3
83
nd<
0.00
16.5
6−8
.26
−51.
03na
na
SKB
-13
20−2
727
0.93
8.0
306
3.42
210.
060.
84bd
l58
490
10.1
118
46.
2423
1210
.32
56nd
0.05
25.2
5−8
.98
−55.
25na
na
SKB
-14
20−2
727
1.44
7.2
309
3.04
500.
153.
50bd
l11
073
216
.27
322
6.80
2511
16.1
715
nd0.
0425
.53
−8.2
7−5
2.75
12.5
5.7
SKB
-15
20−2
728
1.14
7.8
271
4.56
140.
060.
56bd
l91
732
14.6
429
94.
7011
413
.96
43nd
0.05
21.1
0−8
.67
−52.
43na
5.6
SKB
-16
20−2
727
0.85
7.2
349
1.90
7bd
l1.
54bd
l48
427
8.39
138
6.24
2714
8.72
12nd
0.07
26.3
6−8
.64
−55.
95na
7.0
SKB
-17
20−2
726
0.83
7.8
338
5.32
8bd
l0.
14bd
l44
457
8.94
161
4.00
1510
8.68
41nd
0.08
20.7
6−9
.20
−56.
13na
6.2
SKB
-18
20−2
726
1.67
8.2
343
17.1
490.
160.
84bd
l11
085
418
.836
87.
808
316
.88
63nd
0.23
24.3
8−8
.30
−53.
88na
5.8
SKB
-19
20−2
727
1.13
8.2
293
8.55
290.
13bd
lbd
l86
427
10.2
207
4.70
146
10.3
279
nd0.
1321
.84
−8.4
4−5
5.09
na5.
7
SKB
-20
20−2
726
1.04
7.8
300
5.70
130.
05bd
lbd
l72
550
11.2
220
75.
8522
1111
.13
30nd
0.11
22.7
3−8
.52
−54.
17na
na
SKB
-21
20−2
726
1.31
7.3
316
7.03
240.
09bd
lbd
l87
702
14.4
427
67.
8018
1314
.14
155
nd0.
1216
.70
−8.7
1−5
6.03
na5.
6
SKB
-22
20−2
727
1.13
7.4
352
2.09
140.
063.
08bd
l88
671
13.5
920
78.
2042
2413
.25
27nd
0.02
17.0
0−7
.79
−48.
8111
.9na
SKB
-23
20−2
727
0.86
7.6
279
4.94
5bd
l1.
12bd
l43
490
9.38
161
5.10
2214
9.39
33nd
0.20
25.2
5−8
.50
−54.
11na
5.7
SKB
-24
20−2
727
0.70
7.7
290
3.04
5bd
l4.
200.
2048
550
10.6
123
03.
909
511
.00
38nd
0.10
18.4
3−9
.30
−61.
91na
na
MM
-220
−27
281.
377.
535
11.
1410
60.
308.
68bd
l21
744
515
.80
170
11.7
093
5016
.48
36nd
<0.
0034
.00
−7.5
2−4
6.78
30.0
na
MM
-320
−27
281.
447.
331
41.
3380
0.21
7.42
bdl
165
457
14.0
116
115
.60
8436
14.6
210
nd0.
3130
.00
−7.5
0−4
6.39
14.0
na
MM
-420
−27
291.
017.
226
50.
8668
0.20
5.60
bdl
149
323
10.9
712
48.
8068
2611
.23
4nd
0.00
26.0
0−7
.70
−47.
6613
.05.
0
MM
-520
−27
281.
437.
336
42.
2826
20.
7646
.00
bdl
499
550
30.9
746
039
.00
8455
29.8
08
nd<
0.00
32.0
0−7
.20
−42.
5425
.0na
MM
-620
−27
291.
828.
331
63.
0412
40.
40bd
l2.
0048
042
721
.08
414
13.0
027
1520
.91
46nd
0.01
30.0
0−7
.40
−44.
98na
5.6
MM
-720
−27
281.
168.
031
31.
3350
0.20
0.84
bdl
259
610
17.1
325
319
.50
7333
17.8
023
nd0.
0615
.10
−7.7
0−4
6.53
nana
MM
-820
−27
271.
407.
734
71.
1467
0.23
6.72
bdl
113
490
13.0
323
08.
1944
1113
.35
4nd
<0.
0026
.30
−7.5
0−4
4.29
12.5
na
MM
-920
−27
271.
577.
435
01.
9011
00.
307.
56bd
l20
746
015
.87
253
9.40
5126
15.9
85
nd0.
0330
.00
−7.5
2−4
6.20
na5.
7
MM
-11
20−2
727
1.17
8.3
333
0.76
620.
23bd
lbd
l18
737
011
.92
138
9.36
6825
11.6
868
nd0.
0428
.33
−8.0
9−4
9.42
na5.
3
MM
-12
20−2
728
0.55
8.3
362
0.46
280.
101.
26bd
l82
213
6.22
465.
8556
196.
5342
nd0.
0724
.60
−8.1
2−5
1.66
nana
MM
-14
20−2
727
0.58
8.6
328
0.57
230.
06bd
lbd
l75
201
5.62
465.
4636
185.
4613
4nd
0.04
21.7
2−8
.47
−53.
79na
na
MM
-15
20−2
726
1.90
8.5
332
0.57
990.
63bd
lbd
l33
655
019
.47
368
9.00
2912
18.6
770
nd0.
3723
.51
−8.3
2−5
2.02
nana
MM
-16
20−2
727
1.83
8.7
324
0.60
117
0.37
bdl
bdl
355
506
19.4
129
97.
8038
6120
.28
75nd
0.56
27.7
5−7
.80
−48.
62na
na
MM
-17
20−2
726
1.18
8.4
303
4.18
11bd
l0.
840.
6065
610
11.9
427
62.
735
212
.45
424
nd0.
0118
.43
−8.7
0−5
6.35
na5.
6
232 A. Farooqi et al.
App
endi
x.
(con
tinu
ed)
Sam
ple
IDD
epth
Tem
.E
CpH
Eh
F−C
l−B
r−N
O3−
NP
O43−
SO
42−H
CO
3−T
anN
a+K
+C
a2+
Mg2+
Tca
As(
V)
As(
III)
FeSi
O2
δ18O
*δD
*δ15
Nδ34
S
m°C
mS/
cmm
Vm
g/L
meq
/Lm
g/L
meq
/Lµg
/Lm
g/L
WP
-120
−27
290.
828.
329
16.
0813
bdl
bdl
bdl
7252
010
.69
220
3.90
137
10.8
233
nd0.
1616
.44
−8.3
0−5
1.77
na5.
1
WP
-320
−27
261.
908.
532
05.
7011
30.
225.
88bd
l24
161
019
.17
391
7.80
3016
19.9
816
6nd
0.13
17.3
3−7
.84
−46.
48na
4.9
WP
-420
−27
271.
308.
230
83.
8042
bdl
2.52
bdl
9852
012
.10
276
3.90
52
12.5
224
2nd
0.00
12.1
8−8
.13
−52.
02na
5.1
WP
-520
−27
292.
027.
829
86.
6512
90.
662.
38bd
l24
061
619
.93
437
5.10
157
20.4
515
3nd
<0.
020
.00
−8.2
4−5
1.55
na5.
6
WP
-720
−27
271.
868.
032
47.
0396
0.26
bdl
bdl
288
550
18.3
639
15.
4616
1018
.80
69nd
0.02
24.5
0−7
.44
−45.
97na
5.7
WP
-820
−27
281.
908.
030
77.
9810
30.
24bd
lbd
l25
452
017
.36
368
5.46
2610
18.2
686
nd0.
0221
.35
−7.6
6−4
7.45
nana
WP
-920
−27
271.
778.
133
38.
3666
0.17
bdl
0.52
221
610
17.0
836
84.
7014
717
.42
46nd
<0.
0020
.00
−7.7
6−4
8.47
na5.
8
WP
-10
20−2
728
1.80
8.6
315
11.0
271
0.18
bdl
bdl
206
610
17.0
636
35.
1019
1217
.78
70nd
0.12
21.6
0−8
.07
−49.
74na
na
WP
-11
20−2
727
1.02
8.4
360
2.09
16bd
lbd
l2.
0072
490
10.0
723
02.
734
210
.41
677
nd0.
0226
.11
−8.2
7−5
1.32
na5.
7
KA
D-1
20−2
727
2.82
8.2
290
7.60
241
0.60
bdl
bdl
624
550
29.8
162
17.
8017
928
.96
42nd
0.04
15.0
2−7
.55
−47.
39na
5.5
KA
D-2
20−2
726
0.81
8.1
311
7.80
216
0.55
1.96
bdl
624
550
29.2
162
17.
8013
828
.52
142
nd0.
0419
.27
−7.8
5−4
9.90
na5.
5
KA
D-6
20−2
727
2.74
7.8
222
11.0
250
0.57
bdl
bdl
576
550
29.1
960
06.
6322
1228
.25
42nd
0.02
19.6
4−7
.45
−45.
32na
5.4
KA
D-7
20−2
727
3.18
7.3
232
12.2
214
0.50
bdl
bdl
672
540
29.9
962
17.
8017
1028
.90
158
nd0.
0619
.60
−7.2
5−4
3.68
na5.
3
KA
D-8
20−2
727
2.04
8.0
258
9.50
213
0.53
bdl
bdl
528
671
29.0
462
17.
8014
928
.64
10nd
0.00
19.2
7−7
.41
−45.
79na
5.6
KA
D-1
020
−27
262.
557.
726
719
.018
40.
50bd
lbd
l52
879
330
.71
621
6.24
269
29.1
862
nd2.
4211
.14
−7.6
0−4
7.50
na5.
5
KA
D-1
120
−27
263.
77.
631
613
.323
8bd
lbd
lbd
l62
410
4037
.40
782
9.00
3016
37.0
934
nd2.
407.
35−7
.70
−48.
45na
5.3
KA
D-1
220
−27
272.
508.
328
19.
5017
70.
50bd
lbd
l48
091
531
.01
621
7.80
2514
29.5
817
1nd
0.01
24.4
0−8
.17
−52.
92na
5.6
KL
W1
20−2
727
3.38
8.0
246
3.23
430.
17bd
lbd
l19
280
518
.76
345
7.80
3513
18.2
638
nd0.
3123
.36
−8.4
5−5
4.35
na5.
5
KL
W3
20−2
728
1.60
8.5
301
9.50
32bd
lbd
l0.
5017
885
419
.12
414
4.30
83
18.9
161
5nd
0.00
17.0
6−8
.23
−52.
68na
na
KL
W4
20−2
727
1.70
8.0
298
2.70
42bd
lbd
lbd
l19
279
318
.34
345
4.70
2215
17.6
490
nd0.
1824
.72
−8.4
0−5
3.41
na5.
7
KL
W5
20−2
727
1.63
8.2
299
7.60
36bd
l0.
84bd
l14
479
317
.46
345
7.80
166
16.7
082
nd0.
0623
.5−8
.16
−51.
41na
5.6
KL
W6
20−2
728
2.21
8.4
295
19.0
500.
15bd
lbd
l26
485
422
.05
460
5.85
212
21.4
113
1nd
0.22
27.1
1−8
.53
−56.
82na
5.5
KL
W7
20−2
728
1.60
8.4
257
11.4
34bd
l0.
70bd
l16
867
116
.11
334
5.85
166
15.9
315
9nd
0.07
26.0
0−8
.30
−53.
94na
5.7
KL
W8
20−2
728
3.25
8.5
302
17.9
200
0.50
2.52
bdl
576
915
33.7
671
37.
8026
1133
.50
217
nd0.
0326
.70
−7.6
9−4
6.98
na5.
3
KL
W9
20−2
726
2.61
8.5
329
19.0
163
0.35
bdl
bdl
432
701
26.4
555
211
.70
192
25.4
221
3nd
0.09
24.1
0−8
.40
−54.
76na
5.6
KL
W10
20−2
728
1.86
8.6
295
17.7
62bd
lbd
lbd
l19
297
622
.68
460
3.90
1216
22.0
023
4nd
0.03
21.4
4−8
.70
−58.
86na
5.5
KL
W11
20−2
727
2.66
8.4
276
19.0
167
0.40
0.14
bdl
408
841
28.4
257
55.
8521
1427
.11
157
nd0.
2519
.20
−8.4
9−5
2.00
na5.
6
KL
W12
20−2
726
3.01
8.2
326
17.7
217
0.45
bdl
1.20
576
915
34.5
773
65.
8523
1233
.75
103
nd0.
0523
.68
−8.4
8−5
3.40
nana
KL
W13
20−2
726
4.38
8.3
280
16.0
344
0.83
1.12
bdl
912
1280
51.4
610
6012
.10
2730
49.4
711
1nd
<0.
0023
.92
−8.3
0−5
3.48
na5.
4
KL
W14
20−2
729
3.17
8.0
255
14.1
220
0.45
bdl
bdl
624
945
35.9
073
67.
8030
1734
.42
79nd
0.25
22.2
7−7
.65
−47.
73na
5.7
KL
W15
20−2
728
4.60
8.3
247
10.1
328
0.71
3.92
bdl
864
1280
49.7
610
1211
.70
3222
48.3
018
5nd
<0.
0023
.66
−7.8
0−4
9.91
na5.
6
KL
W16
20−2
727
2.22
8.4
296
3.99
160
0.43
10.6
4bd
l38
454
922
.91
483
5.46
139
22.5
025
0nd
<0.
0020
.42
−7.9
0−4
9.32
15.0
5.7
KL
W17
20−2
729
3.27
8.2
261
7.98
249
0.53
2.38
bdl
672
1100
39.6
080
58.
5827
2238
.02
137
nd<
0.00
22.3
3−8
.00
−51.
96na
5.5
KL
W18
20−2
728
1.22
8.8
287
3.99
18bd
lbd
l1.
2048
732
13.7
230
03.
905
313
.64
2400
nd0.
1018
.45
−8.2
1−5
0.53
na5.
6
KL
W19
20−2
729
2.26
8.3
273
8.93
107
0.27
2.24
0.80
336
1040
27.9
157
56.
6314
1026
.85
460
nd0.
2221
.63
−8.0
1−5
1.22
na5.
7
KL
W20
20−2
728
1.72
8.5
264
14.1
351
bdl
2.80
bdl
192
915
21.3
846
04.
685
320
.60
634
nd0.
1818
.53
−8.1
0−5
3.25
na5.
8
KL
W21
20−2
729
1.13
7.8
313
6.46
34bd
lbd
lbd
l96
702
14.8
031
13.
907
614
.52
23nd
0.06
16.1
1−8
.40
−54.
72na
5.5
KL
W22
20−2
729
1.28
8.5
296
21.1
017
bdl
0.42
bdl
9667
114
.62
300
4.68
129
14.0
012
0nd
0.51
22.8
0−8
.60
−52.
40na
na
KL
W23
20−2
728
1.58
8.0
250
10.3
139
0.12
bdl
bdl
187
793
18.6
639
15.
1016
718
.75
30nd
0.03
21.7
6−8
.20
−51.
46na
5.6
KL
W24
20−2
729
1.25
8.6
267
6.08
210.
07bd
lbd
l96
671
13.9
928
05.
4624
814
.02
639
nd0.
0724
.66
−8.7
0−6
0.68
na5.
2
KL
W26
20−2
728
1.06
8.0
225
8.36
16bd
lbd
lbd
l82
610
12.5
925
33.
9013
512
.18
52nd
0.07
22.4
0−8
.50
−56.
68na
5.4
KL
W27
20−2
729
1.51
8.5
284
22.8
18bd
lbd
l0.
5012
679
317
.33
370
3.90
62
16.5
812
4nd
0.21
18.6
0−8
.55
−54.
26na
5.5
MPU
-120
−27
273.
128.
032
40.
1221
30.
63bd
lbd
l60
591
533
.64
670
7.80
5011
32.7
064
nd0.
1423
.28
−8.1
0−5
0.47
na5.
7
MPU
-220
−27
271.
347.
931
70.
5762
0.20
bdl
bdl
211
610
16.3
830
06.
2434
1416
.02
59nd
0.16
26.0
0−8
.05
−50.
35na
na
MPU
-320
−27
264.
107.
931
50.
1920
00.
70bd
lbd
l96
011
6039
.72
805
11.7
057
2340
.08
52nd
0.25
18.5
0−7
.90
−50.
98na
5.6
High arsenic and fluoride contaminated groundwater from East Punjab, Pakistan 233
