DSpace at VNU: Arsenic and other trace elements contamination in groundwater and a risk assessment study for the residents in the Kandal Province of Cambodia

Environment International 35 (2009) 455–460

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Environment International
j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / e n v i n t

Arsenic and other trace elements contamination in groundwater and a risk
assessment study for the residents in the Kandal Province of Cambodia
Thi Thu Giang Luu a,b, Suthipong Sthiannopkao a,⁎, Kyoung-Woong Kim a
a
b

International Environmental Research Center, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea
Hanoi University of Science, 334 Nguyen Trai Street, Hanoi, Vietnam

a r t i c l e

i n f o

Available online 5 September 2008
Keywords:
Arsenic
Manganese
Lead
Barium
Groundwater
Kandal Province

a b s t r a c t
Concentrations of arsenic and other trace elements in groundwater were examined at three villages (PT, POT

and CHL) in the Kandal Province of Cambodia. Concentrations of arsenic in the groundwater ranged from 6.64
(in POT village) to 1543 μg/L (in PT village), with average and median concentrations of 552 and 353 μg/L,
respectively. About 86% out of fifteen samples contained arsenic concentrations exceeding the WHO drinking
water guidelines of 10 μg/L. Concentrations of arsenic (III) varied from 4 (in POT village) to 1334 μg/L (in PT
village), with an average concentration of 470 μg/L. In addition, about 67%, 80% and 86% of the groundwater
samples had higher concentrations for, respectively, barium, manganese and lead than the WHO drinking
water guidelines. These results reveal that groundwater in Kandal Province is not only considerably
contaminated with arsenic but also with barium, manganese and lead. A risk assessment study found that
one sample (PT25) had a cumulative arsenic concentration (6758 mg) slightly higher than the threshold level
(6750 mg) that could cause internal cancer in smelter workers with chronic exposure to arsenic from
groundwater. High cumulative arsenic ingestion poses a health threat to the residents of Kandal Province.
© 2008 Elsevier Ltd. All rights reserved.

1. Introduction
The occurrence of high concentrations of arsenic (As), one of the
most hazardous chemical elements in drinking water has been
recognized, over the past two or three decades, as a great public
health concern in several parts of the world (Mukherjee et al., 2006).
As exists in varying concentrations within the shallow zones of
groundwater in many countries, among them Argentina, Bangladesh,
India, Pakistan, Mexico, Mongolia, Germany, Thailand, China, Chile,
the USA, Canada, Hungary, Romania, Vietnam, Nepal, Myanmar and
Cambodia (Mondal et al., 2006; Stanger et al., 2005). In particular,
elevated As concentrations in groundwater have been identified and
reported for many regions in Cambodia, such as Kratie, Kandal, and
areas south and southeast of Phnom Penh (Berg et al., 2007;
Buschmann et al., 2007; Buschmann et al., 2006; Kubota et al.,
2003). The As in Cambodia may originate in a natural enrichment
process by geothermal activities in the upper Mekong basin (Kouras
et al., 2007; Mukherjee et al., 2006).

Although surface water is still used as drinking water in some
areas, groundwater from tube-wells, which is considered relatively
free of pathogens, is one of the main sources of drinking water in
Cambodia, especially in rural areas (Berg et al., 2007; Polya et al.,
2005; Buschmann et al., 2007). However, in the year 2000, one small-

⁎ Corresponding author.
E-mail address: (S. Sthiannopkao).
0160-4120/$ – see front matter © 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.envint.2008.07.013

scale drinking water quality survey of hand-pumped tube-wells in
Cambodia identified As concentrations above 100 μg L− 1 for the first
time, much higher than the maximum contaminant level guidelines of
the World Health Organization (10 μg L− 1). The As levels were
particularly high in Kandal Province, with an average concentration of
233 μg L− 1 (Berg et al., 2007; Buschmann et al., 2007; Kris, 2007; WHO,
2006). Recently in this province, about 1 million people have stopped
using surface water or water from shallowly dug wells due to bacterial
diseases. Instead, it has become popular to pump groundwater using
individual, private tube-wells (Buschmann et al., 2007). For this
reason, it is necessary to evaluate current As contamination levels in
consumed groundwater in Kandal Province.
As can enter the human body in several ways, including through
air, food and water; of these water is generally the most common
medium of entry. In water, As can be present in various oxidation
states (+5, +3, 0, −3) (California Public Health Goal, 2004; Zhang et al.,
2002). From contaminated water, As can be converted into insoluble
compounds and can be co-precipitated with the hydroxides of Fe and
Mn in an aqueous medium under certain conditions (Smedley and

Kinniburgh, 2002). Different forms of As have significant impacts on
the toxicity and treatment efficiency of water purifying systems. If the
less common compounds of As are excluded from our consideration,
the most toxic As compound likely to be encountered is arsine (AsH3),
which is more toxic than arsenite (AsO33−); the compound arsenate
(AsO43−) is less toxic than arsenite (Mondal et al., 2006; http://www.
soton.ac.uk/~agh/arsenic.htm). Therefore, the determination of total
As in a sample is in itself insufficient to assess its actual environmental


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T.T.G. Luu et al. / Environment International 35 (2009) 455–460

risk (Zhang et al., 2002); distinguishing between arsenite and arsenate
also assumes importance.
In addition to its chemical forms, As toxicity depends on the
exposure route and dosage to the human recipient. Long-term As
exposure can cause skin diseases, including hyperkeratosis, blackfoot
disease, and epithelioma, as well as myocardial ischemia, liver dysfunction, and several cancers ( />Divisions/AWM/SIRB/…/New/rms05038.pdf). In general, in order to
assess exposure, it is needed to determine how long people are
exposed to a chemical; how much of the chemical they are exposed to;
whether the exposure is continuous or intermittent; and how people
are exposed—through eating, drinking, breathing or skin contact
(California Environmental Protection Agency, 2001).
The presence of trace elements in groundwater is also an important issue because it affects possible uses of water (Kouras et al.,
2007). The accumulation of trace elements in environmental samples
(soil, sediment, water, biota, etc.) can cause a potential risk to human
health due to the transfer of these elements in aquatic media, their
uptake by plants and subsequent introduction into the food chain

(Al Rmalli et al., 2005). In recent times, some studies have pointed out
the high concentrations of such trace elements as Mn, Pb, Ba, Ni, Co, Sr,
Fe, Se, Zn, Cu and Cr in groundwater, which constitute a threat to
humans, plants and animals in contact with them (Agusa et al., 2006;
Buschmann et al., 2007; Farías et al., 2003; Frisbie et al., 2002). Hence,
it is necessary to conduct research on the contaminated situation of
groundwater by trace elements.
The objectives of this study are: (1) to study the magnitude of As
and other trace element contamination in groundwater in Kandal
Province, Cambodia, (2) to reveal the As species present in the As
contaminated groundwater and (3) to assess the risk of cumulative
exposure to As in Kandal Province, by application of a formula.
2. Materials and methods
2.1. Water samples collection
Fifteen tube-well water samples were taken in February, 2007 (a dry season) from
Kandal Province (Prek Thom village: Kbal Kaoh commune (PT), Phoum Thom village:
Phoum Thom commune (POT), and Chounlork village: Korkifrom commune (CHL)).
Samples were collected from tube-wells following this sequence: (1) pumping the
tube-well for several minutes; (2) washing out a clean polyethylene bottle with the well
water; (3) taking water without filtering, for total As (including total soluble As and
particulate As); (4) filtering the water through a 0.45 μm filter, for total soluble As, other
trace elements and dissolved organic carbon (DOC); (5) filtering the water through both
a 0.45 μm filter and an As speciation cartridge packed with 2.5 g of selective
aluminosilicate adsorbent for separating arsenate and arsenite in groundwater
samples; (6) immediately storing the samples taken in an ice box. During sample
collections, a series of in-situ measurements was conducted: pH, electrical conductivity,
total dissolved solids (TDS), temperature, redox potential, turbidity, alkalinity, hardness,

Fe2+, NH4+, NO2−, NO3−, PO43−, Si, SO42−, and dissolved oxygen (DO). The on-site
measurements of both cations and anions were conducted by using a portable

spectrophotometer. All of the samples except the DOC analysis were on-site acidified
with 1 ml concentrated HNO3 (70%). As measured by Meng and Wang, (1998), the
average recovery of As (III) in the filtrates by using a cartridge was 98%. The cartridge
can be used for As speciation in a pH range of 4–9. Another four samples used as
controls (PNP) were from the Phnom Penh water supply, taken from water taps in the
city using the same sampling procedure sequence as for groundwater.
2.2. Water samples analysis
As concentrations in the groundwater and water supply samples were determined
by Graphite Furnace-Atomic Absorption Spectrometry (GF-AAS; Perkin Elmer 5100 PC,
USA). Arsenic standard solutions prepared in 0.2% HNO3 were used to determine the
calibration curve. The blank solution was the Milli-Q water acidified with HNO3.
Interference with the measurement method was prevented by using recommended
matrix modifiers for Pd and Mg. Standard Reference Material, SRM1640 (NIST) 26.67 ±
0.41 µg/kg of As concentration, was used to check the quality control of the analytical
procedures. Concentrations of 20 elements (Ag, Al, B, Ba, Cd, Co, Cr, Cu, total iron, Ga,
Mn, Mo, Ni, Pb, Rb, Se, Sr, Tl, U and Zn) were determined by inductively coupled plasma
mass spectrometry (ICP-MS; Agilent 7500ce, USA). DOC was analyzed using a total
organic carbon analyzer Sievers 820.
3. Results and discussion
3.1. General characteristics of groundwater
The results of total 17 parameters measured on-site are shown in Table 1. In general,
most of the groundwater samples were in a reductive condition with the low redox
potential, high ammonium, DOC, PO43− and ferrous concentrations and low nitrate
concentrations. Most of the parameters which are indicated in the table below
measured in the water supply were within the allowed limits for drinking water set by
the WHO.
3.2. Arsenic contamination in groundwater
3.2.1. Total arsenic concentrations in groundwater
Fig. 1(a) shows that very high total As concentrations are present in the
groundwater in Kandal Province. Concentrations of As in the groundwater ranged

from 6.64 (in POT village) to 1543 μg/L (in PT village), with average and median
concentrations of 552 and 353 μg/L, respectively. The total As concentrations in the
water supply (PNP) taken from Phnom Penh City ranged from 0.8–2.5 μg/L. About 86% of
the groundwater samples contained As concentrations exceeding the WHO drinking
water guidelines of 10 μg/L. In particular, elevated As concentrations were observed in
PT village, with four out of five samples having As concentrations higher than 1000 μg/L,
while in CHL and POT villages, the average As concentrations were 376 and 213 μg/L,
respectively. These high concentrations of As may occur because the groundwater has
its source in the Upper Mekong Floodplain, an area where As accumulates in the
sediments (Mukherjee et al., 2006, Buschmann et al., 2007). These sediments are
abundant in hydrated ferric oxides, on whose surface arsenic is sorbed. Under reductive
conditions, the sorbed arsenic may dissolve because of the activity of micro-organisms.
Our results are in accordance with the research conducted by Buschmann et al. (2007),
who reported that elevated arsenic is extremely limited to the Mekong River bank and
the alluvium braided by this river. PT, POT and CHL villages in our study are located near
the Mekong River banks, with average distances from these villages to the Mekong
River bank of 2330 m, 2130 m and 4510 m, respectively (Fig. 1b). Therefore, a huge

Table 1
Average, median and range parameters for the groundwater in the villages of PT, POT, CHL in the Kandal Province and of the water supply (PNP) in Phnom Penh
PT village
Parameter
pH
Conductivity
TDS
Redox
Turbidity
Alkalinity
Hardness
Ferrous

NH4+
NO2−
NO3−
PO43−
Si
SO42−
DO
DOC

POT village

CHL village

PNP

Unit

Average

Median

Range

Average

Median

Range

Average

Median

Range

Average

Median

Range

mS/cm
g/L
mV
NTU
mg/L as CaCO3
mg/L as CaCO3
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L

7.2
0.666
0.325

−140.1
13.011
273.6
319.4
0.07
8.945
0.0115
2.16
3.561
30.07
175.9
3.17
4.998

7.2
0.5
0.24
−77.5
7.52
297
232
0.06
10.55
0.008
1.65
3.105
20.85
10.5
2.7
4.86

6.8–7.5
0.48–1.29
0.23–0.64
−449–18
1.355–32.75
182–313
191–662
b 0.02–0.115
b0.025–15.55
0.005–0.026
1–4.45
2.36–5.19
6.15–83.3
1–850
2.1–6.1
4.25–5.76

7.37
0.824
0.406
37.9
11.23
402.8
242.8
0.182
12.31
0.01
1.91
1.302

273
19.9
2.48
5.71

7.25
0.79
0.39
62
6.575
371
188
0.06
12.55
0.0105
1.7
0.75
34.05
6.5
2.3
5.91

7.2–7.6
0.65–1.21
0.32–0.6
− 73–122
1.225–32.8
225–580
123–405
b 0.02–0.475

4.85–23.75
0.004–0.0155
0.25–3.15
b 0.75–2.89
3.35–1260
0.5–71.5
1.1–4.05
3.75–7.96

7.22
0.704
0.345
45.42
10.151
399.4
353.4
0.762
14.82
0.0085
2.79
3.475
53.03
13.4
2.45
5.348

7.2
0.74
0.36
38

4.005
428
358
0.61
16
0.0065
2.6
3.565
70.6
12
2
5.88

7.05–7.4
0.57–0.835
0.28–0.41
25–89
1.745–27.5
301–497
273–445
0.35–1.43
9–20.6
0.0045–0.018
2.25–3.9
2.95–3.845
7.8–77.75
5.5–22
1.75–4.05
3.54–6.52

7.62
0.176
0.084
312
1.5
55.2
55.8
0.035
0.031
0.0164
0.89
0.138
60.31
16.4
8.28
2.722

7.6
0.2
0.1
325.5
2.035
65
63
0.04
0.025
0.008
0.8
0.125
60.6

16.5
8.75
1.81

7.45–7.75
0.12–0.21
0.06–0.1
203–391
0.26–2.645
32–74
35–72
b 0.02–0.06
b 0.025–0.05
0.0065–0.044
0.7–1.3
Under range
22.1–93.8
14.5–17.5
7–9.1
1.59–4.58


T.T.G. Luu et al. / Environment International 35 (2009) 455–460

457

Fig. 1. Total As concentrations (a) in the groundwater (PT, POT, CHL) and in the water supply (PNP) and (b) the sampling locations of groundwater (PT, POT, CHL).

amount of As may be loaded into the groundwater from this river basin, especially
under the reductive condition demonstrated by low redox potential, and high

concentrations of ammonium, DOC, PO43− and ferrous. In addition, the pH ≥ 7 found
in most groundwater samples might possibly enhance the mobilization of arsenic at
some locations.
3.2.2. Arsenic speciation in groundwater
Fig. 2 shows that the most striking feature of the data was the predominance of As
(III) in all of the groundwater samples, with the concentrations of As (III) about 3 to 115
times higher than the concentrations of As (V) (Table 2). The concentrations of As (III) in
groundwater varied from 4 (in POT village) to 1334 μg/L (in PT village) with an average
concentration of 470 μg/L. The predominance of As (III) in groundwater has both
geochemical and toxicological implications. As geochemical implications, the reasons
for very high As (III) may be related to factors including the very low redox potential,
the neutral to alkaline pH, high amounts of ammonium, DOC, PO43− and ferrous and low
nitrate concentrations. These reducing conditions can favor As release by microbial
reductive dissolution of metal oxides (Berg et al., 2007, Buschmann et al., 2007). As (III)
is more toxic than As (V) in some effects, with respect to chromosome breakage, or to
toxicological carcinogenesis. In addition, As (III) is more difficult to remove from a
drinking water supply than is As (V) (Stephen and Danial, 1999), and this could pose an
additional health threat to people living in this area. The range of As (III) in the water
supply was 0.125–0.2 μg/L and the dominant forms were As (V) and particulate As.
These results may be related to the high value of redox potential, with the range of 203–
391 mV, associated with an alkaline pH.

3.3. Trace elements contamination in groundwater
A series of various trace elements including Ag, Al, B, Ba, Cd, Se, Co, Cr, Cu, Fe, Ga,
Mn, Mo, Ni, Pb, Rb, Sr, Tl, U and Zn were also measured in the groundwater and in the
water supply. Among these, concentrations over the WHO drinking water guidelines
(here given) were found for Ba (700 μg/L), Mn (400 μg/L), Pb (10 μg/L) (WHO, 2006) in
most groundwater samples from three villages in Kandal Province. The concentrations
in water supply samples taken from Phnom Penh were lower than those in the
groundwater for most of the elements.

Our study reveals that 67% of the groundwater samples have Ba concentrations
higher than the WHO drinking water guidelines (700 μg/L). The average and median
concentrations of Ba in the groundwater were 1271 and 1281 μg/L, respectively (Fig. 3a).
Ba exerts toxic effects associated with hypokalemia and electrocardiographic changes
(Agusa et al., 2006). In contrast, Ba concentrations in the water supply samples were
very low, ranging from 22–28 μg/L.
Our study also indicates that Mn concentrations in 80% of the groundwater samples
were higher than the WHO drinking water guidelines (400 μg/L). The highest Mn
concentration (10,930 μg/L ) in the groundwater was found in PT22. The median and
average concentrations were 908.3 and 1788 μg/L, respectively, (Fig. 3b). The
concentrations of Mn in the water supply samples ranged from 1 to 11 μg/L. Although
Mn is known as an essential element for human survival, high doses of Mn may cause
lung embolisms, bronchitis, impotency, hallucinations, forgetfulness and nerve damage,
even to the point of parkinsonism (Buschmann et al., 2006; www.lenntech.com/
Periodic-chart-elements/Mn-en.htm).


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T.T.G. Luu et al. / Environment International 35 (2009) 455–460

Fig. 2. As speciation (As (III), As (V) and particulate As) of the groundwater in the villages of PT (a), POT (b), CHL (c) in the Kandal Province and of the water supply (PNP) in Phnom
Penh (d).
Concentrations of lead (Pb) in the groundwater ranged from 7.1 to 58.4 μg/L
with a median Pb concentration of 18.7 μg/L (Fig. 3c). About 86% of these samples
contained lead concentrations exceeding WHO drinking water guidelines of 10 μg/L.
Conversely, the concentrations of Pb in the water supply samples were very low, in
the range of 0.1 to 0.3 μg/L. There is still no evidence for an essential function of Pb in
the human body; it seems it can merely do harm after uptake from water and food,
such as disruption of or damage to organ systems (www.lenntech.com/Periodic-chartelements/Pb-en.htm).

These findings indicate that people in Kandal Province may be overexposed not
only to As but also to Ba, Mn and Pb from groundwater. Adverse health effects that may
manifest in coming years are a serious concern for the local population.

increase in cumulative As in the human body via the pathway of drinking water. The
cumulative As ingestion of Kandal Province residents ranged from 5 to 6758 mg (Fig. 4).
In order to determine the danger to the residents of Kandal Province exposed to As
contaminated groundwater, our calculated results were compared with the threshold
level for internal cancer caused by chronic As exposure to groundwater for smelter
workers, a figure of 6750 mg (Agusa et al., 2006). In this case, there was one sample
(PT25) with a cumulative As ingestion of 6758 mg, that is, slightly higher than the
threshold level linked to internal cancer. There were as well some samples (PT21:
4400 mg, PT23: 5461 mg, PT24: 5554 mg, POT29: 6173 mg) with a cumulative As
ingestion close to this threshold for internal cancer by As exposure. This poses a
potentially serious threat to those living in this area.

3.4. Risk assessment of cumulative exposure to arsenic

4. Conclusions

Four parameters were used to calculate cumulative As exposure: As level in the
groundwater; age of the tube-well (where groundwater was sampled, the period of
using groundwater of each household was used for the calculation); annual ingestion
rate of groundwater; and daily water consumption. These are related by the equation:
Cumulative As intake ðmgÞ ¼ ½As level in groundwater ðμg=Lފ  ½Age of well ðyearsފ
½Ingestion rate of groundwater ð365days=yearފ
½Water consumption ð2L=dayފ (Agusa et al., 2006).

According to the formula, there is a direct proportion between the As level in the
groundwater and cumulative As. An increase in the As level in groundwater leads to an

The present study revealed groundwater contamination by As, Ba,
Mn and Pb in Kandal Province, Cambodia. About 86% of groundwater
samples contained As concentrations above the WHO drinking water
guidelines. In addition, As (III) was found as a dominant species.
Furthermore, 67%, 80% and 86% of the groundwater samples exceeded
the WHO drinking water guidelines for Ba, Mn and Pb, respectively.
One sample (PT25) had a calculated cumulative As ingestion
(6758 mg) slightly higher than the threshold level (6750 mg) for
internal cancer caused by chronic As exposure from groundwater for

Table 2
Ratios of As (III) and As (V) concentrations in the groundwater of the villages of PT, POT, CHL in the Kandal Province and of the water supply (PNP) in Phnom Penh
Sample

As (III) concentration (μg/L)

As (V) concentration (μg/L)

As (III) concentration/ As (V) concentration

PT21
PT22
PT23
PT24
PT25
POT26
POT27
POT28
POT29

POT30
CHL31
CHL32
CHL33
CHL34
CHL35
PNP2
PNP3
PNP4
PNP5

928.84
4.61
1216.94
991.02
1334.13
61.02
54.19
3.92
719.37
64.64
319.57
192.32
303.88
317.87
533.62
0.13
0.20
0.13
0.13

136.57
1.50
130.20
42.14
41.55
2.61
1.40
0.63
69.85
13.56
2.77
18.09
34.74
21.19
6.19
0.49
0.17
1.25
0.53

6.80
3.06
9.35
23.52
32.11
23.35
38.63
6.27
10.30

4.77
115.38
10.63
8.75
15.00
86.26
0.26
1.19
0.10
0.24


T.T.G. Luu et al. / Environment International 35 (2009) 455–460

459

Fig. 3. Barium (a), manganese (b) and lead (c) concentrations in the groundwater (PT, POT, CHL) and in the water supply (PNP).

smelter workers. Therefore, further overall studies are needed to
evaluate the potential effects on health from As present in groundwater. Furthermore, research on the toxicity of As, Ba, Mn and Pb, as
well as their mixture toxicity, should be conducted to examine the
health risks to the residents of the Kandal Province of Cambodia.

Acknowledgements
This work was supported by the Korea Science and Engineering
Foundation (KOSEF) through the National Research Laboratory
Program funded by the Ministry of Science and Technology (No.
M10300000298-06J0000-29810) and by the research project from the
Ministry of Science and Technology through the International
Environmental Research Center (UNU and GIST Joint Program).

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