Arsenic contaminated groundwater and its potential health risk a case study in long an and tien giang provinces of the mekong delta, vietnam (nước ngầm bị ô nhiễm asen và nguy

Arsenic-contaminated groundwater and
its potential health risk: A case study in
Long An and Tien Giang provinces of the
Mekong Delta, Vietnam
Van-Truc Nguyen, Thi-Dieu-Hien
Vo, Thanh-Dai Tran, Thi-Nhu-Khanh
Nguyen, Thanh-Binh Nguyen, BaoTrong Dang & Xuan-Thanh Bui
Environmental Science and Pollution
Research
ISSN 0944-1344
Environ Sci Pollut Res
DOI 10.1007/s11356-020-10837-6

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Environmental Science and Pollution Research
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GREEN TECHNOLOGIES FOR SUSTAINABLE WATER

Arsenic-contaminated groundwater and its potential health risk:
A case study in Long An and Tien Giang provinces of the Mekong
Delta, Vietnam
Van-Truc Nguyen 1 & Thi-Dieu-Hien Vo 2 & Thanh-Dai Tran 3 & Thi-Nhu-Khanh Nguyen 4 & Thanh-Binh Nguyen 5 &
Bao-Trong Dang 6 & Xuan-Thanh Bui 4,7
Received: 1 April 2020 / Accepted: 13 September 2020
# Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract
The occurrence of arsenic (As) in groundwater (drilled well water) that were used for drinking, cooking, and personal hygiene
and its risks to human health in Long An and Tien Giang provinces (Mekong delta, Vietnam) were evaluated in this study. The
average As concentrations were 15.92 ± 11.4 μg/L (n = 24, Long An) and 4.95 ± 4.7 μg/L (n = 24, Tien Giang). The average
concentrations of As in Long An had not reached the WHO and QCVN 01: 2009/BYT healthy drinking water standard
(10 μg/L). When used as a source of water for drinking and daily activities, arsenic-contaminated groundwater may have a
direct impact on human health. The risk assessment from groundwater established by the US Environmental Protection Agency
(USEPA) was conducted. The risk assessment showed that the average cancer risk (CR) values were 8.68 × 10−4 (adults) and
2.39 × 10−3 (children) for Long An, and 2.70 × 10−4 (adults) and 7.43 × 10−4 (children) for Tien Giang. These results were
significantly higher than the CR (1 × 10−4) proposed by the USEPA. The adverse health effect was therefore specifically warned
by the use of arsenic-contaminated groundwater. This research offers valuable knowledge for efficient water management

approaches to guarantee local communities’ health protection.
Keywords Drinking water . Heavy metal contamination . Non-carcinogenic risk . Carcinogenic risk . Water management strategy

Responsible Editor: Philippe Garrigues
Electronic supplementary material The online version of this article
( contains supplementary
material, which is available to authorized users.
* Thi-Dieu-Hien Vo


3

Faculty of Applied Sciences–Health, Dong Nai Technology
University, Bien Hoa, Dong Nai, Vietnam

* Xuan-Thanh Bui


4

Faculty of Environment and Natural Resources, Ho Chi Minh City
University of Technology (HCMUT), Ho Chi Minh City 700000,
Vietnam

5

Department of Marine Environmental Engineering, National
Kaohsiung University of Science and Technology,
Kaohsiung, Taiwan

6

Ho Chi Minh City University of Technology – HUTECH, 475 A
Dien Bien Phu, Binh Thanh district, Ho Chi Minh City, Vietnam

7

Key Laboratory of Advanced Waste Treatment Technology,
Vietnam National University Ho Chi Minh (VNU-HCM), Linh
Trung ward, Thu Duc district, Ho Chi Minh City 700000, Vietnam

Van-Truc Nguyen

Thanh-Binh Nguyen

1

Institute of Research and Development, Duy Tan University, Da
Nang 550000, Vietnam

2

Faculty of Environmental and Food Engineering, Nguyen Tat Thanh
University, Ho Chi Minh City, Vietnam


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Introduction

Arsenic is the poisonous element that is odorless, colorless, and tasteless (Kuivenhoven and Mason 2019).
People do not realize they are absorbing invisible toxic.
Thus, it is called the “invisible killer.” The highest risk of
arsenic exposure is through the digestive route. Arsenic
and its compounds have been attributed to high carcinogens (group 1) for humans (WHO 2010). Arsenic is wellknown to cause various diseases including bladder, skin,
kidney, prostate, lung, and liver cancers (Fallahzadeh
et al. 2017). Too much exposure to excessive arsenic
can cause all sorts of health problems, namely immediate
sickness and even death.
Besides the As exposure associated with the consumption
of fish, vegetables, and rice, the As exposure was considered
using groundwater as the drinking water (Liang et al. 2016). In
developing countries, particularly in Southeast Asia, where
surface water has been polluted and sanitized, groundwater
is one of the critical fresh-water sources for drinking and living (Buschmann et al. 2007). Natural As concentration in
groundwater was at low levels (0.5–0.9 μg/L). However, the
occurrence of high-level As in groundwater might be due to
the release of arsenic from natural or anthropogenic sources
(Gao et al. 2019). Indeed, in some regions, drinking waterbased on groundwater extracted by pumping wells can be
polluted by natural inorganic arsenic with the concentrations
more than the permission limit (10 μg/L) of the WHO (WHO
2001). Some regions facing with serious arsenic contamination were West Bengal of India (Rahman et al. 2015), Taiwan
(Liang et al. 2016), Chile (Marshall et al. 2007), Mexico
(Pacheco et al. 2018), and Bangladesh (Wasserman et al.
2004), Cambodia (Buschmann et al. 2007), China (Li et al.
2018), Vietnam (Berg et al. 2001).
Many studies about arsenic pollution of groundwater
were conducted in Red River’s Delta, for example, the
average As concentration of 159 μg/L in Hanoi (Berg
et al. 2001) and 294.66 μg/L in Ha Nam province (Van

et al. 2009). Studies in Mekong River’s Delta reported the
As concentration in Dong Thap province (666 μg/L), An
Giang province (1351 μg/L), and Kien Giang (16 μg/L)
(Hoang et al. 2010); in Vinh Long province (16.9 μg/L)
and Tra Vinh province (1.0 μg/L) (Nguyen and Itoi
2009). The characteristics of wells as well as groundwater
quality parameters also significantly affected the concentration of As. Berg et al. (2008) evaluated the correlation
between As concentration and Fe, ammonium, DOC, redox potential in the well water of Vinh Phuc province.
The results showed that positive correlations of As/
NH4+-N (r2 = 0.41) and As/DOC (r2 = 0.6) were recorded.
Meanwhile, Fe and redox potential had weak correlations
with As concentration. Gong et al. (2014) also found a
negative correlation between As and the well depth in

some areas of Texas, USA. Machado et al. (2019) found
the correlation between As concentration and pH, Fe, Mn,
F − , SO 4 2− in the well water of Medical Geology in
Uruguay. The positive correlations were recorded such
as As/pH (r 2 = 0.44), As/F − (r 2 = 0.59), and As/SO 42−
(r2 = 0.30). The weak negative correlations were found
for As/Fe and As/Mn. Most recently, Machado et al.
(2020) also found the positive correlation of As/Cl −
(r2 = 0.39), As/F− (r2 = 0.52), As/Na (r2 = 0.55), and As/
V (r2 = 0.62). From the review data, the physicochemical
factors are also significantly correlated with the concentration of As.
There is still a severe shortage of drinking water in certain
areas of the developing world. In rural areas of Vietnam,
groundwater is considered the main source of water when
surface water is limited and polluted. Most of the households
use sand filters to remove iron and odors in groundwater before drinking (Huy et al. 2014). Thereby, health risk assessment attributed to arsenic-contaminated groundwater is critical for protecting human health. The health risks were evaluated based on the hazard quotient (HQ) and target risk (TR)

established by USEPA. Many studies have applied these risk
assessment methods in many different countries such as Chile
(Marshall et al. 2007), China (Li et al. 2018), Mexico
(Pacheco et al. 2018), Pakistan (Shah et al. 2020), Taiwan
(Vu et al. 2017), Thailand (Wongsasuluk et al. 2018),
Turkey (Kavcar et al. 2009), and Vietnam (Phan and
Nguyen 2018). Indeed, arsenic-contaminated groundwater
caused significant human health influences in many areas of
the world, e.g., bladder cancer in the USA (Steinmaus et al.
2003), neurobehavioral disorders in Taiwan (Tsai et al. 2003),
and miscarriages in Bangladesh (Rahman et al. 2009) (details
information was described in Van et al. (2009). In general, the
results of the evaluation were intended to enhance the awareness of the residents and provide insight into the water management strategy.
According to the simulated data of Erban et al. (2013), As
concentrations in Long An and Tien Giang provinces were up
to 100 μg/L. However, no studies have conducted surveys of
As concentration in groundwater, its correlation with physicochemical parameters, as well as an assessment of human
health risks in these two provinces. The research results contribute to a better understanding of the health risks assessment
of As in groundwater and fill the information gap about heavy
metal pollution in groundwater from Mekong delta, Vietnam,
where there is a lack of information on heavy metals in
groundwater. Thus, it is necessary to investigate arsenic contamination in Long An and Tien Giang provinces to (i) identify the status of arsenic and create arsenic contamination
maps; (ii) find correlation factors, equations, and types between arsenic and groundwater parameters comprising alkalinity, ammonia, manganese, well depth; and (iii) assess human health risk due to As concentration.


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Materials and methods
Study area

The Mekong Delta is located in the southern part of Vietnam
(Fig. 1) and is known as the largest rice warehouse in Vietnam
with the total land area of approximately 1.7 million hectares.
There are thirteen provinces such as An Giang, Bac Lieu, Ben
Tre, Ca Mau, Dong Thap, Hau Giang, Kien Giang, Long An,
Tien Giang, Vinh Long, the province-level municipality of
Can Tho, Soc Trang, and Tra Vinh. Long An is located between 106° 10′ E longitude and 10° 40′ N latitude. The area of
this province is 4495.5 km2 and has a population of 2,002,767
inhabitants. Tien Giang is located between 106° 10′ E longitude and 10° 25′ N latitude. It covers about 2510.5 km2 area
and has a population of 1,764,185. These areas are characterized by a dense and complex network of rivers, lakes, and
channels. The characteristics of delta sediments were similar
to the Ganges Delta (Hoang et al. 2010). The Mekong Delta
had about 60% of the low flooded lowland areas with highsulfate acid soil. The characteristic of the weather here is tropical monsoon with an average annual temperature of 27 °C
and precipitation of 1660 mm. There are two distinct seasons
including sunny (November–April) and rainy (May–October)
seasons (Pham et al. 2017).
Main water resources for residents in Long An and Tien
Giang provinces consist of surface water, rainfall, and groundwater. The groundwater wells in suburban areas of these provinces where a water supply system was not available were

randomly selected for this study. Most of these wells serve
as the main sources of drinking water, cooking, and hygiene
for residents. The well water is directly used and is only treated by a simple sand filtration unit before using it. Therefore,
the quality of groundwater must be controlled here because it
has the potential to adversely affect human health. As contamination sources are mainly from natural sources which are
caused by the washing of As-rich sediments from natural soils
(Jessen 2009). Furthermore, herbicides used in agriculture are
also a source of As emissions. However, these herbicides have
been banned in Vietnam since 1997 (VMARD 1997).
Another source is industrial activity but it is not significant.

Sampling, pretreatment, and analysis
A total of 48 groundwater samples were collected from 24
wells in rural areas or urban fringe of Long An and 24 wells
in those of Tien Giang province (detailed information of the
sampling locations shown in Table S1). All wells in this study
were operated by high-pressure water pumps. Wells were categorized into two types including shallow wells with less than
60 m depth and deep wells with more than 60 m depth. The
surveyed wells of Long An were deep wells. In Tien Giang,
18 deep wells and 6 shallow wells were sampled. In this study,
the sampling time was during March and April (dry season,
less influence of rainwater). The sampling process followed
the TCVN6663-11 (2011). A record was made for every sample collected and a tag or label was used to identify the information of groundwater samples. Information to provide

Fig. 1 Location map of the studied area and sampling sites in Long An and Tien Giang


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accurate sample identification, including the specific sample
identification number, the sample collector name, sampling
time (hour, day, month, and year), and the exact location
was determined using global positioning systems (GPS), and
other data such as weather conditions, water level, and water
temperature was also performed. Before sample collection,
groundwater was left to flow for about 5 min. Sampling bottles were washed with DI water and 5% HNO3 solution to
ensure their purity. After passing through a 0.45-μm
Whatman filter, samples were added with 3 mL of 69%
HNO3, then stored at 4 °C, and transported directly to the
laboratory. Groundwater samples were analyzed within

2 weeks. Field measurements included pH, TDS, and turbidity. Alkalinity, ammonia, phosphate, and sulfate were tested in
the laboratory. The pH value was determined with a pH meter
(Mi 150, Milwaukee, Rumania). TDS was measured by
Greisinger G1410 conductivity tester TDS, conductivity, salinity (G1410, Greisinger, Germany), and turbidity was measured onsite using a HI-93703 portable turbidity meter (HI93703, Hanna, Rumania). Total alkalinity was determined by
titration using methyl orange and bromocresol green indicators in the laboratory. The DR/2010 spectrophotometer (DR/
2010, Hach, USA) was used for the ammonia, phosphorus,
and sulfate. All laboratory analyses were carried according to
standard methods (APHA 1998). Heavy metals were determined by an inductively coupled plasma mass spectrometryICPMS (ICP-MS, model 7700x, Agilent, USA) using an ICPMS-grade standard in Gwangju Institute of Science and
Technology, South of Korea. The metals were measured in
triplicate for each sample and a reagent blank was analyzed for
every 10 samples. Reagent blanks were prepared and analyzed
for metals using the same procedure, and the results showed
that all concentrations of metals were lower than the detection
limits (MDL of As (0.01 μg/L); Ba (0.008 μg/L); Fe
(0.081 μg/L); Mn (0.27 μg/L)). To ensure analytical accuracy,
certified reference standards were used (SRM-1648a). The
recoveries were 90–120% for all metals.

Risk assessment
In this study, the risk assessment for human health of As is
according to USEPA (2005). The average daily dose (ADD)
of As was determined as follows:
ADD ¼ ðC  IR  E F  EDÞ=ðAT  BW Þ

ð1Þ

where ADD is average daily dose from ingestion (mg/kg day),
C is arsenic concentration in water (mg/L), IR is water ingestion rate (L/day), EF is exposure frequency (day/year), ED is
exposure duration (year), AT is averaging time (day), and BW
is body weight (kg). In this study, IR is 2 L/day for adults and

1 L/day for children (Phan and Nguyen 2018). ED is 70 years
for adults and 10 years for children (Radfard et al. 2019). EF is

365 days/year for both adults and children (Muhammad et al.
2010). AT is 25,550 days for adults and 3650 days for children (Rasool et al. 2016; Radfard et al. 2019). BW is 55 kg for
adults and 10 kg for children (Van et al. 2009; Phan and
Nguyen 2018).
The hazard quotient (HQ) was determined as follows:
HQ ẳ ADD=R f D

2ị

Where HQ is hazard quotient (cases with HQ > 1 are attributed to human health risks), RfD is a reference dose
(mg/kg day). In this study, the RfD of As is
0.0003 mg/kg day (USEPA 2005; Radfard et al. 2019).
The carcinogenic risk (CR) was determined as follows:
CR ẳ CS F  ADD

3ị

where CSF is the cancer slope factor for As. In this study, CSF
is 1.5 (mg/kg day)−1 (Rasool et al. 2016; Radfard et al. 2019).
The total carcinogenic risk less than and equal to 1 × 10−4 was
proposed as the maximum acceptable risk level (USEPA
2005; Alidadi et al. 2019).

Statistical analysis
Descriptive statistics including average and standard deviation
were performed. Pearson’s correlation was employed to reveal
the relationship between the As concentration and physicochemical parameters. Statistical Package for Social Sciences

software (SPSS) version 16.0 was used for all statistical
analyses.

Results and discussion
Arsenic concentration in groundwater
Arsenic forms in aqueous media consist of arsenious acid
(H3AsO30, H2AsO3−, As (III)) and arsenic acid (H2AsO4−,
HAsO42−, As (V)). The toxicity of As (III) is stronger than
that of As (V) (Corsini et al. 2018). Average As concentration
of both provinces were shown in Fig. 2a (detailed information
on the sampling locations shown in Table S2). As concentration in Long An was significantly higher than in Tien Giang.
The occurrence of As in groundwater was attributed to the
geological origin. Soils in Long An have a sulfuric horizon
that can adsorb As (Husson et al. 2000). Nevertheless, sulfuric
acid may be extracted from soils under reduced conditions,
resulting in the release of arsenic (Nguyen and Itoi 2009).
These might explain why As concentrations in Long An were
higher than in Tien Giang. As shown in Fig. 2a, two outliers
(L7 and L8 with high As concentrations) were also observed
in Long An. According to the survey during the sampling
process, the current potential sources of As emissions were


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Fig. 2 Boxplot of arsenic contamination (a), the concentration of arsenic in groundwater (b), and the map of arsenic contamination level (c) in Long An
and Tien Giang

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virtually absent in these sites. This high As pollution may,
therefore, be attributable to the natural geological characteristics as well as the anthropogenic activities that have taken
place in the past, as described above in the definition of the
study area.
Figure 2b shows the As concentration of all samples in the
Long An and Tien Giang provinces. As concentration ranged
from 0.03 to 46.88 μg/L and 0.05 to 13.33 μg/L in Long An
and Tien Giang, respectively. The highest (46.88 μg/L) in
sampling point L7 and the lowest As concentration
(0.03 μg/L) in sampling point L23 was detected in Long An.
The average As concentrations were 15.92 ± 11.4 μg/L (Long
An) and 4.95 ± 4.7 μg/L (Tien Giang). Figure 2c presented
that was 18 sampling points (75% of samples) in Long An,
and 6 sampling points (25% of samples) in Tien Giang
exceeded the safe limit of WHO as well as QCVN 01: 2009/
BYT (10 μg/L). Therefore, these results provided useful information that gives warnings to the residents to get the most
appropriate treatment and usage plan.
Table 1 shows that As concentration in northern Vietnam is
much higher than in southern Vietnam. The mean As concentration observed in this work was significantly lower than the
one found in the samples collected in the northern part of
Vietnam (Berg et al. 2001; Van et al. 2009) and Dong Thap
and An Giang (Van et al. 2009; Hoang et al. 2010), but higher
than in the southern part of Vietnam such as Vinh Long, Tra
Vinh and Kien Giang (Nguyen and Itoi 2009; Hoang et al.
2010). This study also showed the As concentration was much
lower than the one detected in Pakistan (Shakoor et al. 2015;
Rasool et al. 2016), Cambodia (Buschmann et al. 2007),

Bangladesh (Wasserman et al. 2004), India (Rahman et al.
2015; Chakraborti et al. 2016), Taiwan (Liang et al. 2016),
and China (Li et al. 2018). In general, the presence of arsenic
in groundwater fluctuated significantly. This might be related
to the geochemical characteristics of the sampling area. The
soluble products of weathering and decomposition of rock
also greatly affect the mineral concentration in groundwater
samples (Chenini et al. 2010). The accumulation of ions in
groundwater might vary according to the geological frame of
the geographic location. In this case, an important factor might
be the different types of aquifers encountered in the different
study areas.

Physicochemical characteristics of groundwater
The pH was slightly acidic in the range of 5.50–7.08 in Long
An and alkaline in the range of 6–8.59 in Tien Giang. The
average pH in groundwater samples of both provinces was
6.59 and 7.85, respectively. pH is one of the most important
indicators of water quality because it affects the dissolution of
minerals, resulting in to change in As concentration (Sracek
et al. 2004). Indeed, the pH in Long An was lower than in Tien
Giang. It might be the cause of significantly higher As

concentration in Long An than that of Tien Giang. At low
pH (less than pH 6.9), under oxidizing condition, H2AsO4−
is dominant, whilst at higher pH, HAsO42− becomes dominant. Under reducing condition at pH less than about
pH 9.2, the most abundant were the uncharged arsenic species
H3AsO30, which was more toxic than other forms of As
(Corsini et al. 2018). Besides, pH affected some of the water
quality parameters such as ionic solubility and pathogen survival, which will impact human health eventually. Too high

pH made the water tastes bitter, whereas too low pH caused
the sour taste (Muhammad et al. 2010). The pH value in the
aquifer in this study was within the recommended range (6.5–
8.5) recommended by WHO, except that in Long An.
Alkalinity in groundwater fluctuated from 27 to 230 mg/L
and 60 to 644 mg/L in Long An and Tien Giang, respectively.
The alkalinity of water in the study area may be due to the
presence of HCO3− that was formed from the weathering of
carbonate rock (Langman et al. 2019). The average concentrations of phosphate in both provinces were low, ranging
from 0.028 ± 0.03 to 0.29 ± 0.75 mg/L. The highest concentration of phosphate was 3.8 mg/L for groundwater of Tien
Giang and the lowest concentration (0.003 mg/L) was found
in Long An. Similarly, low phosphate was also found in the
well water in Turkey (Ağca et al. 2014). The occurrence of
phosphate in groundwater might be caused by leakage from
runoff and/or soil. However, phosphorus is highly immobile
in the soil since most of the total phosphorus in the soil consists of calcium phosphate and magnesium phosphate. Some
phosphorus had been contained in the soil by clay. When
anthropogenic deposits were therefore overlooked, the phosphate leakage into groundwater was very small (Ağca et al.
2014). This might explain for relatively low phosphate levels
that were found in some aquifers. The average concentration
of ammonium in groundwater range from 0.734 ± 1.12 to
4.72 ± 2.01 mg/L. The lowest ammonium nitrogen concentration in Long An was 0.19 mg/L and 51.27 times lower than
the concentration detected in Tien Giang. Ammonium nitrogen in groundwater was also primarily derived from anthropogenic activities. The ammonium nitrogen concentration in
this study was significantly lower than that (0.11–63.72 mg/L)
found by Ağca et al. (2014).
The average TDS in groundwater samples from Long An
and Tien Giang was 282 mg/L and 349 mg/L, respectively.
The lowest observed value for TDS was 140 mg/L for Long
An and the highest TDS (1150 mg/L) was found in the Tien
Giang sampling sites. In groundwater samples, most solutes,

including inorganic salts, small amounts of organic matter,
and dissolved gases will contribute to TDS (Prakash and
Somashekar 2006). High levels of TDS in groundwater might
mainly due to the presence of iron, sulfate, and occasionally
arsenic. The high TDS concentration at Cho Moi station, An
Giang province (Mekong Delta) was 4516 ± 2768 mg/L in
groundwater recorded by (Phan and Nguyen 2018).


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Table 1

Concentration of As (μg/L) in groundwater from this study and other sites reported in the literature

Site

Country

Mean As conc.(μg/L)

References

Long An (Southern of Vietnam)
Tien Giang (Southern of Vietnam)
Dong Anh (Northern of Vietnam)

Vietnam
Vietnam
Vietnam

15.9
4.95
220

This study
This study
Berg et al. (2001)

Tu Liem (Northern of Vietnam)

Vietnam

230

Berg et al. (2001)

Gia Lam (Northern of Vietnam)

Vietnam

3050

Berg et al. (2001)

Thanh Tri (Northern of Vietnam)

Vietnam

3010

Berg et al. (2001)

Ha Nam (Northern of Vietnam)

Vietnam

348

Van et al. (2009)

Dong Thap (Southern of Vietnam)

Vietnam

666

Van et al. (2009)

An Giang (Southern of Vietnam)

Vietnam

1351

Hoang et al. (2010)

Kien Giang (Southern of Vietnam)

Vietnam

16.0

Hoang et al. (2010)

Vinh Long (Southern of Vietnam)
Tra Vinh (Southern of Vietnam)
Mashhad

Vietnam
Vietnam
Iran

16.9
1.00
0.18

Nguyen and Itoi (2009)
Nguyen and Itoi (2009)
Alidadi et al. (2019)

Jinghui irrigation

China

0.54

Zhang et al. (2019)

Jinghuiqu

China

1.89

Zhang et al. (2019)

Ubon Ratchathani

Thailand

1.06

Wongsasuluk et al. (2014)

Ubon Ratchathani

Thailand

2.19

Wongsasuluk et al. (2018)

Sungai Petani, Kedah

Malaysia

2.51

Ahmad et al. (2015)

Brisbane River estuary

Australia

3.90

Duodu et al. (2017)

Sumatra

Indonesia

5.18

Winkel et al. (2008)

I’Zmir

Turkey

6.47

Kavcar et al. (2009)

Mexico

Mexico

> 10.0

Pacheco et al. (2018)

Uruguay

Uruguay

15.7

Machado et al. (2019)

Rahim Yar Khan of Punjab

Pakistan

31.0

Shakoor et al. (2015)

Kandal, Takeo, and Prey Vêng

Cambodia

81.7

Buschmann et al. (2007)

Araihazar

Bangladesh

118

Wasserman et al. (2004)

Mailsi, Pụnab

Pakistan

156

Rasool et al. (2016)

West Bengal

India

255

Rahman et al. (2015)

Pingtung Plain

Taiwan

348

Liang et al. (2016)

Jianghan Plain

China

1081

Li et al. (2018)

Patna

India

1466

Chakraborti et al. (2016)

Rainwater runoff, agricultural runoff, leakage from industrial
activities, and solid waste deposit could contribute greatly to
turbidity in groundwater. It is essential to encapsulate pathogenic organisms in particles that cause turbidity resulting in
health hazards (Prakash and Somashekar 2006). In this study,
turbidity varied from 0.5 to 280 NTU and 1 to 68 NTU in
Long An and Tien Giang, respectively. These results were
noticeably lower than those (0–316 NTU) in the study of
Prakash and Somashekar (2006).
Sulfate was present in almost all samples. The highest
(26.73 mg/L) and lowest (1.06 mg/L) sulfate (SO42−) concentrations were detected in Tien Giang. The average concentration of sulfate in groundwater samples from two
sites Long An and Tien Giang was 12.81 ± 7.18 mg/L

and 5.09 ± 5.54 mg/L, respectively. High sulfate concentration may be due to both pyrite oxidation and gypsum
dissolution (Nguyen and Itoi 2009). Samples with high
concentrations of sulfate were found in wells near the

rivers and seas. Therefore, the interaction between
groundwater and marine deposits or disturbance between
freshwater and seawater has led to high sulfate levels.
Similar results were found in the study of Nguyen and
Itoi (2009). The sulfate concentrations in this study were
significantly lower than the sulfate concentrations (average 53 mg/L, max. 773 mg/L) found in other areas along
the Mekong River (Nguyen and Itoi 2009).
Total Fe in groundwater fluctuated from 0.27 to
9.45 mg/L and 0.03 to 9.02 mg/L in Long An and Tien


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Giang, respectively. The highest observed values for total
Fe was 9.45 mg/L in Long An and the lowest total Fe
(0.03 mg/L) was found in Tien Giang. The average of
total Fe values in groundwater samples from two sites
Long An and Tien Giang was 3.78 ± 2.99 mg/L and
1.23 ± 2.62 mg/L, respectively. Compared with the study
of Machado et al. (2019) in Uruguay (2.0 to 242.7 μg/L),
the concentration of Fe in the aquifer in this study was
much higher. As concentration in Uruguay was slightly
lower than in Long An but much higher than in Tien
Giang. Iron had little effect on health, but caused unpleasant odors and affected the quality of food cooked or laundered. The presence of iron in groundwater was related to
the rock formation. The high concentration of Fe in
groundwater may be due to the casing pipe corrosion,
not using the well for a long time, permeating iron pollutants, solid waste disposal, industrial activities, etc.
(Prakash and Somashekar 2006).
The Ba concentration in groundwater ranged from

67.55 to 420 μg/L and 2.25 to 728.3 μg/L in Long An
and Tien Giang, respectively. The highest (728.3 μg/L)
and the lowest Ba concentration (2.25 μg/L) was observed in Tien Giang. The average Ba concentrations in
Long An and Tien Giang were 202.35 ± 94.72 μg/L and
143.51 ± 154.79 μg/L, respectively. It can be seen that Ba
concentration increases with an increase in As concentration. A similar trend was found by Hoang et al. (2010)
when studying in An Giang and Dong Thap, Vietnam.
Concentrations of Ba as well as As in this study were also
significantly lower than in An Giang and Dong Thap. The
Mn concentration in groundwater ranged from 1 to
489.1 μg/L and 0.02 to 3745 μg/L in Long An and Tien
Giang, respectively. The highest (3745 μg/L) and the lowest Mn concentrations (0.02 μg/L) were measured in Tien
Giang. The average Mn concentrations in Long An and
Tien Giang were 115.02 μg/L and 561.03 μg/L, respectively. Compared with the study of Hoang et al. (2010),
Mn concentration in this study was 5–14 times lower for
Long An and 1.9–3 times for Tien Giang.
In general, the pH, sulfate, and Ba values in all samples
were within the safety limits (5.5–8.5 for pH, 250 mg/L
for sulfate, 0.7 mg/L for Ba). The ammonium, total Fe,
and turbidity in both provinces exceeded the safety limits
for drinking water of the QCVN 01: 2009/BYT (VMOH
2009). Approximately 8% of samples in Long An and
79% samples of Tien Giang exceeded the allowed limit
for ammonium (3 mg/L). The TDS and Mn concentration
in the sample from Long An was within the safety limits
of the QCVN 01: 2009/BYT (1000 mg/L for TDS,
300 μg/L for Mn), except in Tien Giang. Compared to
USEPA standards (USEPA 2001), about 50% and 91%
of samples in Long An and 37% and 23% of samples in

Tien Giang exceeded the allowed limit for Mn (50 μg/L)
and Fe (0.3 mg/L).

Correlation of arsenic and other parameters
Pearson’s correlation coefficient is set to quantify the relationship between two quantitative variables. In this
study, the correlation analysis at p < 0.01 was conducted
between arsenic and other parameters (Table 2). As mentioned in the discussion of arsenic concentration results in
groundwater, the distribution of As concentration depends
on various factors such as physicochemical properties of
groundwater, geological characteristics, and anthropogenic activities. Therefore, the correlations between the parameters for each province were assessed in this study.
The result shows that strong correlations were found between the elemental pairs of As/alkalinity (r2 = 0.606),
As/ammonium (r2 = − 0.611) and As/Ba (r2 = 0.560) for
Long An; while strong correlation was noted by As/TDS
(r2 = −0.513) and As/Mn (r2 = − 0.509) for Tien Giang.
Similar to the research results of Bundschuh et al.
(2004) and Machado et al. (2019), a positive correlation
recorded for As/sulfate in Long An. As and pH had a
positive correlation for all samples in the studied areas.
As negatively correlated to Fe and Mn. This might be
because hydroxyl ions competed for adsorption sites on
Fe and Mn oxides and clay minerals at higher pH,
resulting in the release of As into groundwater. These
findings were in line with the previous studies
(Bundschuh et al. 2004; Machado et al. 2019). Based on
Table 2, positive correlations were obtained for As and
the depth of the well for both provinces, particularly a
strong correlation (r 2 = 0.583) that occurred in Tien
Giang. This was similar to the predicted results for Long
An and Tien Giang by Erban et al. (2013).
For linear or non-linear regression analysis, arsenic

correlated with manganese as compound, growth, exponential curves (medium correlation factor, confidence interval 99%) in Long An and Tien Giang provinces. Thus,
it is concluded that correlation curves of arsenic with
manganese were compound, growth, exponential forms.
Arsenic correlated with ammonia as a cubic curve in
Long An and Tien Giang provinces. However, this relationship was S curve in Long An. With high regression
coefficients (above 0.8) and 99% confidence intervals,
alkalinity and ammonia were the two parameters used to
predict the concentration of arsenic in groundwater
(Table 3). The correlation equations are as follows:
As ẳ e4:316 246:294=Alkalinityị

4ị

As ẳ 1:142  Ammonium 1:924Þ

ð5Þ


Author's personal copy
Environ Sci Pollut Res
Table 2

Correlation analysis between arsenic and other physicochemical parameters for Long An and Tien Giang
As pH

Long An and Tien
Giang (n = 48)
Long An (n = 24)
Tien Giang (n = 24)

TDS

Turbidity Alkalinity Ammonium Sulfate Phosphate Fe

As 1

− 0.291* − 0.316* − 0.198

0.024

− 0.601**

0.278

As 1
As 1

0.165
0.397

0.606**
0.264

− 0.611**
− 0.196

0.101 − 0.452*
− 0.348 − 0.114

− 0.242 − 0.338

− 0.513* − 0.332

− 0.180

0.023

Ba

Mn

Well’s
depth

0.304*

− 0.351* 0.149

− 0.279 0.560** − 0.489* 0.011
− 0.290 − 0.155 − 0.509* 0.583**

**Correlation is significant at the 0.01 level (2-tailed)
*Correlation is significant at the 0.05 level (2-tailed)
The values of Pearson analysis in the range of 0.0–0.29 for poor, 0.3–0.49 for moderate, and 0.5–1.0 for strong correlation (Bundschuh et al. 2004; SS
2020)

Human health risk assessment
The average daily dose (ADD), hazard quotient (HQ), and
carcinogenic risk (CR) can be used for risk assessment
(Rasool et al. 2016; Radfard et al. 2019). The results indicate that the average CR for adults and children in Long An
province was 8.68 × 10 −4 and 2.39 × 10−3 , respectively

while the average CR for adults and children in Tien
Giang was 2.70 × 10−4 and 7.43 × 10−4, respectively. The
average CR was higher than the CR value of 1 × 10−4 which
provided by the USEPA (2005) and Zhang et al. (2019).
Figure 3 indicated that in Long An province, 83% CR for
adults and 83% CR for children were (avg. 8–24 times)
higher than CR of 1 × 10−4 while in Tien Giang province,
58% CR for adults children and 75% CR for children were
Table 3

higher (avg. 3–7 times) than CR of USEPA. High CR
values were observed at L7 and L8. Table 4 reveals that
the mean CR for children was higher than that for adults.
The results show that for every 10,000 people, 24 children
and 9 adults for Long An and 8 children and 3 adults for
Tien Giang would be at risk of cancer. The WHO standard
limit was 10 μg/L for As. This level could lead to 6 adults
and 15 children who are likely to face cancer risk in ten
thousand people. Risk levels in the present study were more
serious than those mentioned by Huy et al. (2014). Namely,
the average risk of CR for adults in Chuyen Ngoai
Commune, Hanam Province, Vietnam, was estimated at
2.53 × 10−4. The results show that for every 10,000 adults
in Chuyen Ngoai commune, about 3 people will have cancer due to the consumption of filtered groundwater. Phan
and Nguyen (2018) evaluated health risk for the residents
who were using groundwater contaminating As in An

Correlation analysis between arsenic and parameters in groundwater in Long An and Tien Giang provinces

Long An and

Tien Giang
n = 48
Long An
n = 24

Tien Giang
n = 24

Pearson factor

Linear and non-linear regression

Value (r2) Remarks

Curve type

R2

Equations

As vs.
ammonium

− 0.601** Strong
Cubic
negative

0.514 As = 21.783–11.509
× ammonium + 2.298 × ammonium2 – 0.138 × ammonium3

As vs.
ammonium
As vs.
manganese
(Mn)
As vs.
alkalinity
As vs.
manganese
(Mn)
As vs. Well’s
depth (WD)

− 0.611** Strong
Power
negative
− 0.489* Moderate Compound,
negative
growth,
exponential
0.606** Strong
S
positive
− 0.509* Strong
Compound,
negative
growth,
exponential
0.583** Strong
Cubic

positive

0.844 As = 1.142 × ammonium (−1.924)
0.685 Compound: As = 27.781 × 0.988Mn
Growth: As = e(3.324–0.012 × Mn)
Exponential: As = 27.781 × e(−0.012 × Mn)
0.845 As = e(4.316–246.294/alkalinity)
0.513 Compound: As = 3.835 × 0.999Mn
Growth: As = e(1.344–0.001 × Mn)
Exponential: As = 3.835 × e(−0.001 × Mn)
0.529 As = 21.783–11.509 × WD + 2.298 × WD2–0.138 × WD3

**Correlation is significant at the 0.01 level (2-tailed)
*Correlation is significant at the 0.05 level (2-tailed)
The values of Pearson analysis in the range of 0.0–0.29 for poor, 0.3–0.49 for moderate, and 0.5–1.0 for strong correlation (Bundschuh et al. 2004; SS
2020)


Author's personal copy
4.01 × 10−6–7.03 × 10−3
2.39 × 10−3
1.71 × 10−3
8.15 × 10−6–2 × 10−3
7.43 × 10−4
7.03 × 10−4
1.48 × 10−6–2.56 × 10−3
8.68 × 10−4
6.22 × 10−4
2.96 × 10−6–7.27 × 10−4
2.70 × 10−4

2.56 × 10−4
0.01–15.63
5.31
3.8
0.02–4.44
1.65
1.57

ADD, average daily dose; HQ, hazard quotient; CR, cancer risk

2.72 × 10−6–4.69 × 10−3
1.59 × 10−3
1.14 × 10−3
5.43 × 10−6–1.33 × 10−3
4.95 × 10−4
4.1693 × 10−4
Long An (n = 24)

Range
Mean
Std
Tien Giang (n = 24) Range
Mean
Std

0.03–46.88
15.92
11.40
0.05–13.33
4.95

4.7

9.87 × 10−7–1.7 × 10−3
5.79 × 10−4
4.15 × 10−4
1.97 × 10−6–4.84 × 10−4
1.80 × 10−4
1.71 × 10−4

0.003–5.68
1.93
1.38
0.01–1.63
0.6
0.57

Children
Adults
Children
Adults
Children
Adults

Statistics Arsenic concentration (μg/L) Average daily dose from ingestion (ADD)
Province

Table 4

Risk assessment summary for Long An and Tien Giang provinces

Hazard quotient of As (HQ)

Carcinogenic risk of As (CR)

Environ Sci Pollut Res

Giang province. The results show that higher CR ranged
from 8.66 × 10−4 to 8.26 × 10−2 for both children and adults.
In 1999, from the epidemiology studies, the National
Research Council (NRC, USA) shows that there was enough
evidence to conclude that the ingestion of As in drinking water
leads to lung cancer. A high concentration of As in drinking
water would increase the risk of lung cancer (Celik et al.
2008). In Bangladesh, As concentration (above 100 μg/L) in
groundwater was associated with lung cancer (lung squamous
cell carcinoma) in males. CR of lung cancer was 159 males
and 23 females per 100,000 population (Mostafa et al. 2008).
In Northern Chile, Marshall et al. (2007) presented lung cancer mortality in region II where As concentration in groundwater was above 90 μg/L, compared with region V, which
was otherwise similar to region II but not exposed to arsenic
in groundwater. The results showed that lung cancer mortality
rates of 153 per 100,000 men and 50 per 100,000 women in
region II were higher than that in region V with 54 per
100,000 men and 19 per 100,000 women. Otherwise,
Baastrup et al. (2008) revealed no significant association between exposure to drinking water containing low arsenic concentration (0.05–25.3 μg/L) and lung cancer mortality in
Denmark.
The risk assessment summary for Long An and Tien Giang
is presented in Table 4. The average HQ of adults and children
in Long An province was 1.93 and 5.31, respectively while
the average HQ of adults and children in Tien Giang was 0.6
and 1.65, respectively. The highest HQ for adults (5.68) and

children (15.63) was found in the groundwater samples collected in sampling point L7 of Long An. The result shows that
in Long An, 75% cases for adults and 83% of cases for children had HQ > 1. In Tien Giang, 29% of cases for adults and
54% of cases for children had HQ > 1. These results reveal
that As concentration in groundwater samples of Long An and
Tien Giang posed an adverse health risk to residents through
using of As-contaminated groundwater (USEPA 2005;
Wongsasuluk et al. 2014).

Conclusions and future perspectives
In this study, As concentration in groundwater samples was
determined. The results show that As levels were ranging
from 0.03 to 46.88 μg/L and 0.05 to 13.33 μg/L in Long An
and Tien Giang, respectively. As concentration could be
found highly significant with alkalinity, ammonium nitrogen,
manganese concentration, and well’s depth. Erban et al.
(2013) indicated that contamination of As was not only influenced by the vertical movements of As due to pumping or the
intrusion of dissolved organic matter from surface water
sources but also the long-term pumping process that promoted
soil compaction resulting in the release of As-containing solutes from deep clay. Therefore, in order to have more insight,


Author's personal copy
Environ Sci Pollut Res

Fig. 3 Risk assessment summary for Long An and Tien Giang provinces. a Carcinogenic risk. b Hazard quotient

it is recommended to investigate the impact of nearby surface
water sources, the operating time of the wells, and the effect of
the geological conditions of the sites in future studies. The
health risk assessment of arsenic showed that the maximum

carcinogenic risk (CR) for adults and children in Long An
(2.56 × 10−3 and 7.03 × 10−3, respectively) was higher than
those in Tien Giang (0.73 × 10−3 and 2 × 10−3, respectively).
The average CRs for children were potentially higher than
those for adults. Exposure to arsenic through drinking water
is a public health concern; therefore, preventing arsenic exposure will reduce the incidence of cancer. In the study area,
awareness-raising activities on water use should be conducted
for the residents. Thus, pretreatment technologies for arsenic
removal from groundwater should be applied before use for

drinking purposes. Also, a long-term groundwater quality
monitoring program should be considered. Furthermore,
researching and developing appropriate groundwater treatment technologies is essential for the residents.
Acknowledgments The authors would like to thank for laboratory support and sampling of Ms. Thi-Kim-Yen Nguyen, Dr. Sunbeak Bang, and
Ms. Quy-Hao Nguyen. Thanks for the English elaboration of Dr. Mary
Ellen Chavez Camarillo (University of San Carlos). This study has been
conducted under the framework of CARE-RESCIF initiative.
Author contributions Investigation, software, writing—original draft,
writing—review and editing: Van-Truc Nguyen; Investigation, software,
writing—original draft: Thi-Nhu-Khanh Nguyen; Data curation, conceptualization, methodology: Thanh-Dai Tran and Thanh-Binh Nguyen;


Author's personal copy
Environ Sci Pollut Res
Investigation, software, writing— original draft: Bao-Trong Dang;
Funding acquisition, supervision, conceived, designed the methodology,
writing—review and editing: Thi-Dieu-Hien Vo and Xuan-Thanh Bui.
Funding This research is funded by Nguyen Tat Thanh University, Ho
Chi Minh City, Vietnam (No. 2020.01.064).
Data availability The data that support the findings of this study are

openly available at DOI.

Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
Ethical approval The authors confirm that the manuscript has been read
and approved by all authors. The authors declare that this manuscript has
not been published and not under consideration for publication elsewhere.
Consent to participate The authors have been personally and actively
involved in substantive work leading to the manuscript and will hold
themselves jointly and individually responsible for its content.
Consent to publish The authors consent to publish this research.

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