This study explored the groundwater chemistry, groundwater suitability, and potential human health risks in the Jhenaidah district, Bangladesh. A total of 54 groundwater samples were collected from the study area, and a set of multivariate approaches were applied to achieve the study objectives. Study results show the concentration of HCO3, Ca2+, As, Fe, and Mn exceeded Bangladesh drinking quality guidelines in 100, 98, 44, 28, and 63% samples, respectively. The groundwater quality index shows only 15% of samples are suitable for drinking purposes, whereas various irrigation water indices like EC, TH, %Na, SAR, PI, and MH show that these sources of water are suitable for irrigation. In the study area, groundwater is mainly Ca2+–Mg2+–HCO3 types, and rock–water interactions are dominating the mineralization process. The sequential order of major cations and major anions are Ca2+ > Mg2+ > Na+ > K+, and Cl > HCO3 > SO42−, respectively. Multivariate analyses show that both geogenic and manmade sources regulate the groundwater quality. Arc-GIS inverse weighted method has been utilized to spatial interpolate the basic parameters. For the human health aspect, both adults and children have high carcinogenic and non-carcinogenic health risks.

  • Groundwater quality is not suitable for drinking purposes, while all of the samples were suitable for irrigation.

  • Groundwater is mainly Ca2+–Mg2+–HCO3 types, and rock–water interactions are dominating the mineralization process.

  • Multivariate analyses show that both geogenic and manmade sources regulate the groundwater quality.

  • Adults and children have high carcinogenic and non-carcinogenic health risks.

Safe drinking water is critical for life's existence, environmental stability, and economic growth (Sener et al. 2017). Groundwater is considered a superior alternative for drinking and household uses compared to surface water in many areas of the world due to its greater accessibility, availability, and lack of pathogens (Shaibur et al. 2019; Chakraborty et al. 2022). In Bangladesh, both rural (70%) and urban (95%) residents rely on groundwater for drinking and domestic use (WHO & UNICEF 2017), and with increasing water demand, groundwater withdrawals are rising (Rahman & Rahman 2018). The quality of groundwater is significantly regulated by natural (rock water association, weathering of bedrock, leaching from pollution sources), and manmade activities (unplanned industrial and urban development, agricultural works, improper waste management) (Shaibur et al. 2021; Chakraborty et al. 2023). Additionally, hydrogeological influences (pH, oxidation–reduction reaction, and ion exchanges) and seasonal deviation also regulate the groundwater quality and quantity (Chakraborty et al. 2016; Ghosh et al. 2020; Hossain et al. 2024). Generally, groundwater often contains a variety of ions, metals, and metalloids, all of which pose serious health risks since they are exposed to high concentrations for longer periods (Bodrud-Doza et al. 2019). Around the world, contaminated drinking water is the cause of roughly 80% of illnesses and one-third of mortalities in developing nations (WHO 2011). As, Fe, and Mn concentrations in the groundwater of Bangladesh were found to be greater than those of other trace metals reported by several studies (Islam et al. 2019; Ghosh et al. 2020; Chakraborty et al. 2022). Long-term exposure to elevated levels of As, Fe, and Mn in drinking water may result in a variety of health risks, including neurological disorders, cardiovascular disease, hematological disorders, renal problems, respiratory disorders, mental disorders, and neurological diseases (Islam et al. 2019; Ghosh et al. 2020). Drinking water pollution is directly linked to human health, where methodology-based risk appraisal methods help to classify and illustrate the quantitative (calculation and mapping) and qualitative (chronic, carcinogenic) risk levels (Şener et al. 2017). In Bangladesh, irrigation water quality is crucial for agricultural activities since, as an agro-economic nation, it not only causes significant financial losses by lowering crop productivity but also reduces soil fertility. Thus, high-quality irrigation water is a significant factor for agricultural output over the long run (Chakraborty et al. 2023). Hydro-chemical studies of groundwater provide complete information regarding the groundwater quality and also assist in predicting the groundwater quality governing factors (Islam et al. 2017). Therefore, sustainable utilization of groundwater for household, agricultural, industrial, and drinking purposes is highly needed, where periodically checking the water quality indicators is necessary for exploring the actual status of water quality (Şener et al. 2017; Bodrud-Doza et al. 2019; Ghosh et al. 2023). Even though various studies have been conducted in Bangladesh, no work has been done in the study region, where groundwater is primarily used for drinking, household, and agricultural reasons. Humans have a right to safe and affordable water to drink, hence this sort of research must investigate the current state of drinking water quality. Thus, the objectives of this study are to: (i) explore the hydro-chemical properties of groundwater; (ii) evaluate the suitability of groundwater for irrigation and drinking; and (iii) assess the possible health risks to humans associated with oral ingestion of As, Fe, and Mn.

Description of the study area

The Sadar Upazila in Jhenaidah District is situated in the southwest of Bangladesh, between 23°26′ and 23°36′ north latitudes and between 88°57′ and 89°20′ east longitudes (Figure 1). The aquifer organization is categorized as an aquitard, which covers the uppermost layer and comprises mainly clay to fine sand materials. The aquifer is the main underground water source consisting of medium- to coarse-grained sandy sediments. The annual average temperature ranged from 11.2 to 37.1 °C and the annual rainfall is 1,467 mm (57.8 inches). However, the total area of the Upazila is 308.09 km2, with a population of 455,932 and the main water bodies are the Begabati and Nabaganga Rivers, while this Upazila consists of 17 unions. Agriculture (60.12%) is the main source of income in the study area. The sources of drinking water for this study area are tube wells (91.6%), tap water (6.1%), and others (2.3%).
Figure 1

Map of the study area, showing the sampling locations.

Figure 1

Map of the study area, showing the sampling locations.

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Sample collection, preparation, analysis, and quality assurance

In August 2022, a total of 54 groundwater well samples were randomly taken from the study region (Figure 1), and sampling points were selected based on the uses (domestic, drinking, and irrigation purposes) of groundwater, where 500 mL polystyrene bottles were used to collect groundwater samples, rinsed three times with distilled water and once with 1:1 HNO3. The tube wells were pumped for 15–20 minutes before sampling, and water samples were then taken and placed in a pre-cleaned sampling vial after being washed three times with sample water. These water samples were subjected to laboratory tests (, Cl, and hardness as CaCO3, As, Fe, Mn, Na+, K+, Mg2+, and Ca2+) as well as field measurements of pH, electrical conductivity (EC), and total dissolved solids (TDS). Portable devices that have been calibrated were used to measure the field analyses. pH of the water sample was measured by a pH Meter (Model: Hanna HI98107), and EC and TDS were measured using a Conductivity Meter (Hanna HI98303 and Hanna HI98303). Concentrated HNO3 (69%, Merck, Germany) was used for samples especially for trace elements (As, Fe, and Mn) and ions (Na+, K+, Mg2+, and Ca2+). After being labeled and placed in a cooler box, all of the water samples were sent to our laboratory and frozen at 4 °C until further chemical analysis could be completed. The methods used for sample collection and preservation are taken from Chakraborty et al. (2022). According to the acidimetric titrimetric technique (APHA 2012), , Cl, and hardness as CaCO3 were measured. The samples' concentrations of As, Fe, Mn, Na+, K+, Mg2+, and Ca2+ were measured using an air-acetylene flame Atomic-absorption-spectrophotometer system (Model: AA-7000, SHIMADZU, Japan) and a Hydride Generator. Lab-grade deionized (DI) water was used for the entire experimental work. All laboratory equipment and glassware were cleaned before use. For quality assertion, each sample was made to run identical analyses, including blank and validated. Based on the necessity, water samples were diluted several times, and the relative standard deviations of detected major ions and elements were within ± 5–7%. The concentration of all analyzed parameters was evaluated with WHO (2011) and BDWS (1997) drinking water guidelines.

Groundwater quality evaluation

Suitability of drinking water

Based on national and international regulations, groundwater quality was evaluated using the groundwater quality index (GWQI) adopted by Vasanthavigar et al. (2010). Equation (1) was used to calculate the relative weight (Wi):
(1)

In this instance, Wi stands for the relative weight, n for the overall number of parameters, and wi for each parameter's weight (Table 1).

Table 1

Relative weight of parameters

ParametersWHO guideline (2011)Weight (wi)Relative weight, Wi=
pH 8.5 0.0816 
TDS (mg/L) 500 0.1020 
EC (μS/cm) 750 0.0816 
Na+ (mg/L) 200 0.0816 
K+ (mg/L) 30 0.0408 
(mg/L) 200 0.1020 
Cl (mg/L) 200 0.1020 
(mg/L) 100 0.0204 
Ca2+ (mg/L) 50 0.0612 
Mg2+ (mg/L) 75 0.0612 
Fe (mg/L) 0.3 0.0816 
Mn (mg/L) 0.1 0.0816 
As (mg/L) 0.01 0.1020 
    
ParametersWHO guideline (2011)Weight (wi)Relative weight, Wi=
pH 8.5 0.0816 
TDS (mg/L) 500 0.1020 
EC (μS/cm) 750 0.0816 
Na+ (mg/L) 200 0.0816 
K+ (mg/L) 30 0.0408 
(mg/L) 200 0.1020 
Cl (mg/L) 200 0.1020 
(mg/L) 100 0.0204 
Ca2+ (mg/L) 50 0.0612 
Mg2+ (mg/L) 75 0.0612 
Fe (mg/L) 0.3 0.0816 
Mn (mg/L) 0.1 0.0816 
As (mg/L) 0.01 0.1020 
    

To generate a quality rating scale (qi), the concentration of each water sample was multiplied by the relevant standard for each parameter. So, the following equation is:
(2)
Finally, the GWQI was computed using computed qi and Wi, as shown in the following equation:
(3)
where qi is the rating point of groundwater quality, Si is the standard value (WHO 2011) and Ci is the concentration of each parameter. Then, SIi is the ith sub-index of parameters.

Irrigation water suitability evaluation indices

The sodium percentage (Na%) and sodium absorption ratio (SAR) were calculated to ascertain if groundwater in the research region is acceptable for irrigation (Chakraborty et al. 2023). These calculations determined the concentrations of groundwater expressed in meq/L. The investigation of irrigation water quality indices' parameter values has been conducted using the following equations. The total hardness is measured by the following equation:
(4)
Additionally, magnesium hazard (MH) is calculated by the following equation:
(5)
Kelley's ratio (KR) is provided by the following equation:
(6)
Electrical conductance is calculated by the following equation:
(7)
The SAR in the following equation:
(8)
The sodium percentage is calculated by the following equation:
(9)
The permeability indices (P1) are measured by the following equation:
(10)

Health risk assessment

The non-carcinogenic risk (NCR) and cancer risk (CR) were assessed using the US Environmental Protection Agency (USEPA) proposed protocols, where this study evaluates the health risks of children and adults who are associated with drinking water use.

CDI is the chronic daily intake (mg/kg/day) (USEPA 1989) and is calculated using the following equation:
(11)
where C is the concentration of heavy metals (mg/L), IR is the drinking water ingestion rate in L/day (3.53 L/day for adults, and 1.0 L/day for children (USEPA 1989)). ED is the exposure duration in years (70 years for adults and six years for children) and EF is the exposure frequency in days per year (365 days for adults and children) (USEPA 1989). BW is the average body weight in kilograms (50 kg for adults and 15 kg for children, according to USEPA 1989), and AT is the average time (AT = 365 × ED(day)).
The NCR comes from exposure to non-carcinogenic pollutants and is measured using the hazard quotient (HQ) (Islam et al. 2017; Chakraborty et al. 2023). Equation (12), which is used to determine HQ, is as follows:
(12)
where RfD (mg/kg/day) is the reference dose (0.7 mg/kg/day for Fe, 0.14 mg/kg/day for Mn, and 0.0003 mg/kg/day for As (USEPA 2001).
The NCR is evaluated by the hazard index (HI) presented in the following equation:
(13)
CR is estimated by multiplying the CDI and slope factor (SF) of cancer-created heavy metals, presented in the following equation:
(14)
where SF is the slope factor of contaminants (mg/kg/day) (1.5 mg/kg/day for As) (USEPA 1989).

The classification of NCR and CR detail is described in Bodrud-Doza et al. (2019).

Statistical and geostatistical analysis

SPSS (V.20) and Microsoft Excel 2010 were utilized to calculate the mean and standard deviations based on the analysis results. Principle component analysis (PCA) and Pearson correlation matrix (PCM) were also analyzed using SPSS (V.20). The inverse distance weighting (IDW) approach was utilized for spatial distribution using ArcGIS (V.10.5).

Characterization and drinking water suitability of groundwater

The analyzed physicochemical parameters are compared with the WHO (2011) and BDWS (1997) drinking water quality guidelines to assess the suitability of groundwater for drinking purposes. Slightly alkaline types of groundwater were indicated by the pH values, ranging from 7.2 to 7.8, with a mean value of 7.45 ± 0.14 (Table 2). The quantity of dissolved solids and ionic conductivity of the source water were measured by EC, which is a crucial parameter for determining the quality of drinking water (Ahmed et al. 2019). An average of 773.78 ± 184.45 μS/cm was found for the EC concentration in the drinking water sample, while TDS in water samples from the studied area ranged from 230 to 659 mg/L, with an average of 384.20 ± 85.50 mg/L (Table 2). Most groundwater samples were classified as freshwater based on the EC and TDS levels. Ca2+, Mg2+, Na+, and K+ concentrations varied from 25.06 to 112.22, 15.09 to 68.01, 8.94 to 64.91, and 1.11 to 6.06 mg/L with average concentrations of 63.32 ± 17.91, 38.30 ± 10.87, 21.20 ± 11.22, and 2.95 ± 0.95 mg/L, respectively.

Table 2

Descriptive statistics of groundwater in the study area

ParametersMinMaxMean ± SDBDWS (1997) WHO (2011) Sample exceeding (%) BDWS
pH 7.2 7.8 7.8 ± 0.14 6.5–8.5 6.5–8.5 — 
EC (μS/cm) 346 1,330 773.78 ± 184.45 2,000 750 — 
TDS (mg/L) 230 659 384.20 ± 85.30 1,000 500 — 
(mg/L) 140 278 214.38 ± 38.64 100 100 100 
Cl (mg/L) 17.5 124.25 54.71 ± 31.42 600 200 — 
(mg/L) 0.526 0.711 0.59 ± 0.04 400 200 — 
Na+ (mg/L) 8.94 64.61 21.20 ± 11.22 200 200 — 
K+ (mg/L) 1.11 6.06 2.58 ± 0.95 12 30 — 
Ca2+ (mg/L) 25.06 112.22 63.32 ± 17.91 35 50 98 
Mg2+ (mg/L) 15.09 68.01 38.30 ± 10.87 75 75 — 
As (mg/L) 0.001 0.264 0.05 ± 0.06 0.05 0.01 44 
Fe (mg/L) 0.02 8.54 1.06 ± 1.73 0.3–1.0 0.3 28 
Mn (mg/L) 0.01 2.21 0.65 ± 0.52 0.4 0.1 63 
TH (mg/L) 124.67 560.07 315.69 ± 89.48    
SAR (meq/L) 1.05 8.05 3.04 ± 1.49    
KR 0.06 0.54 0.22 ± 0.11    
Na% 0.06 0.38 0.19 ± 0.07    
PI 12.90 59.46 30.25 ± 9.01    
MH 37.54 38 37.68 ± 0.07    
Na+/ Ca2+ 0.09 0.86 0.36 ± 0.18    
Mg2+/Ca2+ 0.60 0.61 0.60 ± 0.01    
Cl/∑ All anions   0.20    
ParametersMinMaxMean ± SDBDWS (1997) WHO (2011) Sample exceeding (%) BDWS
pH 7.2 7.8 7.8 ± 0.14 6.5–8.5 6.5–8.5 — 
EC (μS/cm) 346 1,330 773.78 ± 184.45 2,000 750 — 
TDS (mg/L) 230 659 384.20 ± 85.30 1,000 500 — 
(mg/L) 140 278 214.38 ± 38.64 100 100 100 
Cl (mg/L) 17.5 124.25 54.71 ± 31.42 600 200 — 
(mg/L) 0.526 0.711 0.59 ± 0.04 400 200 — 
Na+ (mg/L) 8.94 64.61 21.20 ± 11.22 200 200 — 
K+ (mg/L) 1.11 6.06 2.58 ± 0.95 12 30 — 
Ca2+ (mg/L) 25.06 112.22 63.32 ± 17.91 35 50 98 
Mg2+ (mg/L) 15.09 68.01 38.30 ± 10.87 75 75 — 
As (mg/L) 0.001 0.264 0.05 ± 0.06 0.05 0.01 44 
Fe (mg/L) 0.02 8.54 1.06 ± 1.73 0.3–1.0 0.3 28 
Mn (mg/L) 0.01 2.21 0.65 ± 0.52 0.4 0.1 63 
TH (mg/L) 124.67 560.07 315.69 ± 89.48    
SAR (meq/L) 1.05 8.05 3.04 ± 1.49    
KR 0.06 0.54 0.22 ± 0.11    
Na% 0.06 0.38 0.19 ± 0.07    
PI 12.90 59.46 30.25 ± 9.01    
MH 37.54 38 37.68 ± 0.07    
Na+/ Ca2+ 0.09 0.86 0.36 ± 0.18    
Mg2+/Ca2+ 0.60 0.61 0.60 ± 0.01    
Cl/∑ All anions   0.20    

The concentration of dissolved anions such as , Cl, and varied from 140 to 278, 17.5 to 124.25, and 0.526 to 0.711 mg/L with the mean concentrations of 214.38 ± 38.64, 54.71 ± 31.42, and 0.59 ± 0.04 mg/L, respectively (Table 2). The WHO and BDWS drinking water quality requirements are met by all other dissolved cations and anions. The sequential order of major cations and major anions are Ca2+ > Mg2+ > Na+ > K+, and Cl > > , respectively. The descending order of metals and metalloids in the groundwater samples were in the following order Fe > Mn > As, respectively (Table 2). The concentrations of As ranged from 0.001 to 0.264 mg/L with an average value of 0.053 ± 0.057 mg/L (Table 2). The study found that almost 44% of the groundwater samples surpassed the BDWS (0.05 mg/L), while the average As concentration was 1.06 and 5.3 times greater than BDWS (0.05 mg/L) and WHO (0.01 mg/L), respectively. The Fe concentrations in the groundwater ranged from 0.02 to 8.54 mg/L, with an average content of 1.06 ± 1.73 mg/L (Table 2). About 28% of the groundwater samples surpassed the BDWS permitted levels. The average iron concentration in the studied area groundwater was approximately 1.06 and 3.53 times above the BDWS (0.3–1.0 mg/L) and WHO (0.3 mg/L) limits, respectively. The concentration of Mn in groundwater samples ranged from 0.01 to 2.21 mg/L with a mean value of 0.65 ± 0.52 mg/L (Table 2). This study shows that about 63% of groundwater samples surpassed the BDWS (0.1 mg/L). The average concentration of Mn was 6.5 times greater than the BDWS (0.1 mg/L) and 1.63 times above the former health guideline by WHO (0.4 mg/L). Elevated concentrations of As, Fe, and Mn were reported by Ghosh et al. (2020, 2023).

Hydro-geochemical facies and water type

Hydro-chemical facies evaluate the hydrochemistry of groundwater. The Piper diagram is a widely used and effective method for this purpose, where cation and anion concentrations are applied to illustrate groundwater hydrochemistry. Figure 2(a) reveals that Ca2+, Mg2+, and play a significant role in illustrating the groundwater quality in the study area. According to the results of the analyzed sample, the groundwater of this area is Ca2+–Mg2+ type, which denotes that the Ca2+, Mg2+, and are more abundant than Na+, K+, Cl, and . The Ca2+–Mg2+ water type is linked to the area where the alkaline rock–groundwater inter-relation is the main dominating factor for the alteration in the groundwater chemical properties from the hydrologic basins (Yidana 2010).
Figure 2

Piper plots (a) and Gibbs plot (b) for groundwater samples of the study.

Figure 2

Piper plots (a) and Gibbs plot (b) for groundwater samples of the study.

Close modal

However, the Ca2+–Mg2+ facies result from the dissolution of calcite that exists on the limestone of the Eocene age in the aquifer (Tanvir Rahman et al. 2017). A Gibbs plot is used to evaluate the main procedures that control the hydro-geochemistry. Figure 2(b) shows that the groundwater samples fall in the rock dominance region, which is regulated by the development of carbonate mineral dissolution within the aquifer. The rock governance in the groundwater chemistry is also determined by the calculation of Hounslow ratios: when Cl/∑ all anion value is 0.20 (Table 2), below 0.8 indicates mostly weathering of rock, especially, carbonate rock (Tanvir Rahman et al. 2017). The results are in correspondence with the findings for the southwestern part of Bangladesh's groundwater resources (Shaibur et al. 2019, 2021; Chakraborty et al. 2022).

Suitability of groundwater for drinking water and irrigation purposes

The GWQI is applied to assess the overall quality of drinking water. In this study, the GWQI is calculated using all of the analyzed physicochemical data at each sampling site. The values of GWQI ranged from 66.75 to 360.46 with an average of 171.33 ± 73.59 (Table 3). The results suggest that just 15% of the sampling area is in the good water class, while 54% is in the poor water class due to elevated levels of As, Fe, and Mn in the water samples, which makes the groundwater in these areas unfit for drinking without treatment.

Table 3

Evaluation of groundwater quality in the study area

Evaluation categoriesMinMaxMeanSD
GWQI 66.75 360.46 171.33 73.59 
Index scoreWater classNumber of samples% of samples
GWQI <50 Excellent water 
 50–100 Good water 15 
 100–200 Poor water 29 54 
 200–300 Very poor water 11 20 
 >300 Unfit for drinking purposes 11 
Evaluation categoriesMinMaxMeanSD
GWQI 66.75 360.46 171.33 73.59 
Index scoreWater classNumber of samples% of samples
GWQI <50 Excellent water 
 50–100 Good water 15 
 100–200 Poor water 29 54 
 200–300 Very poor water 11 20 
 >300 Unfit for drinking purposes 11 

EC is essential for categorizing irrigation water; in the meantime, it measures the TDS and the salinity of groundwater. According to EC guidelines for the quality of irrigation water (Table 4), the majority of the sample's (65%) EC values are in the range of 750–2,000 μS/cm, telling permissible irrigation quality. Approximately 52% of the samples fall into the category of very hard quality, according to the calculated TH (Table 4). The concept of SAR is useful to evaluate the potential sodium hazard due to the soil adsorption capacity of sodium from irrigated water.

Table 4

Irrigation quality indices values and classes of water samples of the study area

Index methodCategoryWater classNumber of samples% of samples
EC value (μS/cm) <250 Excellent 
250–750 Good 19 35 
750–2,000 Permissible 35 65 
2,000–3,000 Doubtful 
>3,000 Unsuitable 
TH (mg/L) <75 Soft 
75–150 Moderately hard 
150–300 Hard 25 46 
>300 Very hard 28 52 
SAR 0–6 Good 52 96 
6–9 Doubtful 
>9 Unsuitable 
KR <1 Suitable 54 100 
>1 Unsuitable 
Na% <20 Excellent 54 100 
20–40 Good 
40–60 Permissible 
60–80 Doubtful 
>80 Unsuitable 
MH <50 Excellent 54 100 
 >50 Unsuitable 
PI >75 Good 
25–75 Suitable 39 72 
<25 Unsuitable 15 28 
Index methodCategoryWater classNumber of samples% of samples
EC value (μS/cm) <250 Excellent 
250–750 Good 19 35 
750–2,000 Permissible 35 65 
2,000–3,000 Doubtful 
>3,000 Unsuitable 
TH (mg/L) <75 Soft 
75–150 Moderately hard 
150–300 Hard 25 46 
>300 Very hard 28 52 
SAR 0–6 Good 52 96 
6–9 Doubtful 
>9 Unsuitable 
KR <1 Suitable 54 100 
>1 Unsuitable 
Na% <20 Excellent 54 100 
20–40 Good 
40–60 Permissible 
60–80 Doubtful 
>80 Unsuitable 
MH <50 Excellent 54 100 
 >50 Unsuitable 
PI >75 Good 
25–75 Suitable 39 72 
<25 Unsuitable 15 28 

Elevated values of SAR hamper the structure of the soil by interfering with the cations exchange process in the soil. The SAR value indicates that about 96% of water samples are suitable for irrigation water for this study area (Table 2; Table 4). KR displays the association amongst Na+, Ca2+, and Mg2+ ions in groundwater samples, where KR > 1 denotes that the water is not appropriate for irrigation due to an excess of Na+, whereas KR < 1, denotes that the water is good for irrigation. The obtained KR values (Table 2) indicate that all sample sites are in the ‘suitable’ category (Table 4). The percentage of sodium in irrigation water was shown as Na%. The advanced sodium level in irrigation water hindered the growth rate of plants. Approximately 100% of the water sample falls into the ‘excellent’ category (Table 4). PI helps in managing the soil quality, which may be influenced by long-term irrigation. PI is classified into three classes: Class 1 (PI > 75%), Class 2 (25% < PI < 75%), and Class 3 (PI < 25%). About 72% of the samples fall in the Class 2 category, meaning that the research area is appropriate for long-term irrigation (Table 4). MH varied from 37.54 to 38 with average values of 37.68 ± 0.07, representing no negative impacts on the soil for irrigation. The results of Mg2+/Ca2+ and Na+/Ca+ ratios are 0.60, and 0.36, respectively, representing no danger of soil infiltration from groundwater in the research area. In Wilcox's diagram, Na percentage values derived from 0.07 to 0.38 with a mean value of 0.19, indicating good quality (Figure 3).
Figure 3

Wilcox diagrams showing the rating of groundwater samples for irrigation purposes.

Figure 3

Wilcox diagrams showing the rating of groundwater samples for irrigation purposes.

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Spatial analysis

Using the IDW interpolation approach, the geographical distribution maps are presented in Figure 4.
Figure 4

Spatial distribution of the GWQI values of groundwater samples in the study area.

Figure 4

Spatial distribution of the GWQI values of groundwater samples in the study area.

Close modal
In the study region, the GWQI geographical distribution maps indicated excellent and good water quality values (Figure 4). According to the EC spatial map, the groundwater values in the northern and central parts were significantly greater than in the southern part (Figure 5(a)). The central and northwestern parts had the highest SAR values; also, the lowest and medium values of SAR exist in all aspects. The bulk of the groundwater samples are fit for irrigation, according to the SAR geographical map (Figure 5(b)).
Figure 5

Spatial analysis of groundwater samples in the study area: (a) distribution of EC values, (b) distribution of SAR values, (c) distribution of KR values, and (d) distribution of TH values.

Figure 5

Spatial analysis of groundwater samples in the study area: (a) distribution of EC values, (b) distribution of SAR values, (c) distribution of KR values, and (d) distribution of TH values.

Close modal

The middle region contains the highest KR values. The bulk of the groundwater samples, according to the KR geographical map, are suitable for irrigation (Figure 5(c)). The northern half had greater TH values, whereas the western and southern regions had lower TH values (Figure 5(d)). High TH levels might be the result of substantial ionic exchange developing within an aquifer system.

Human health risks assessment

High concentrations of toxicants (e.g. As, Fe, and Mn) in drinking water might generate diverse health hazards to exposure groups. The non-carcinogenic and carcinogenic risks of toxicants (e.g. As, Fe, and Mn) consumption via drinking water for both children and adults are assessed in this study. Table 5 shows the evaluation results for children and adults. While the HQ values of As and Fe in water samples for adults and children are above the recommended level (HQ > 1), indicating that As may be carcinogenic to human health, the HQ values of Mn in water samples for children and adults are less than the recommended level (HQ < 1), indicating that Mn does not significantly pose a health risk.

Table 5

Results of human health risk assessment for children and adults ingesting drinking water

Adult
Children
MaxMinMean ± SDMaxMinMean ± SD
HQAs 27.65 0.12 5.57 ± 6.02 58.66 0.22 11.84 ± 12.78 
HQFe 38.34 0.09 4.80 ± 7.78 81.33 0.19 10.18 ± 16.50 
HQMn 0.49 0.01 0.14 ± 0.11 1.05 0.01 0.30 ± 0.24 
HI 46.354 0.718 10.527 ± 9.69 98.32 1.52 22.33 ± 20.57 
CRAs 1.24×10−2 4.71×10−5 2.51×10−3 ± 2.71×10−3 2.64×10−2 1.00×10−4 5.33×10−3 ± 5.75×10−3 
Adult
Children
MaxMinMean ± SDMaxMinMean ± SD
HQAs 27.65 0.12 5.57 ± 6.02 58.66 0.22 11.84 ± 12.78 
HQFe 38.34 0.09 4.80 ± 7.78 81.33 0.19 10.18 ± 16.50 
HQMn 0.49 0.01 0.14 ± 0.11 1.05 0.01 0.30 ± 0.24 
HI 46.354 0.718 10.527 ± 9.69 98.32 1.52 22.33 ± 20.57 
CRAs 1.24×10−2 4.71×10−5 2.51×10−3 ± 2.71×10−3 2.64×10−2 1.00×10−4 5.33×10−3 ± 5.75×10−3 

Note. HI value for non-carcinogenic.

The HI value represents the combined influence of several contaminants. In the present study, the values of HI ranged from 1.52 to 98.32 with an average of 22.33 ± 20.57 and 0.71 to 46.34 with an average of 10.527 ± 9.69 for children and adults, respectively. This suggests that there are significant non-carcinogenic health risks for both groups, including vomiting, diarrhea, abdominal pain, skin, gastrointestinal, and respiratory tract injuries, liver damage, cardiovascular, hematopoietic, and nervous system disorders, diabetes, hair loss, reproductive, and neurological issues. The average values of CR for children and adults are 5.33×10−3, and 2.51×10–3, indicating that for every 10,000 persons in the study area, 5.33, and 2.51 persons would have CR (Table 5). It has been noted that adults > children was the declining order of CR among the two categories. Both the adult and child CR values are above the USEPA (2001) recommended safe ranges (1×10−6 to 1×10−4), indicating a potential for carcinogenicity. However, the study did not identify any specific forms of arsenic-associated cancer disease in the study area. Many scholars have said that skin, kidney, and bladder cancers are the most common kinds of cancer caused by long-term exposure to arsenic-contaminated drinking water (Sadeghi et al. 2018). Smith et al. (2000) discovered that arsenic intake in water was about 500 g/L and that by the age of 60, more than one in 10 had been diagnosed with skin cancer. Approximately 51% of assessed tube well water in the Jashore region contained higher than 50 g/L arsenic (Smith et al. 2000).

Source of ions and factors controlling groundwater quality

The multivariate analyses (PCA and PCM) are applied to know the source, distribution, and geochemical interaction of groundwater quality parameters (Supplementary material, Tables S1 and S2, respectively). To identify the likely sources of the groundwater quality indicators, this study applied PCA and PCM. In PCA, groundwater datasets that exhibit 75.175% of the total variance are extracted into five components with eigenvalues larger than one. In the present study, PC1, PC2, PC3, PC4, and PC5, highlight more than 27.48, 17.93, 12.39, 9.60, and 7.86%, of the total variance, respectively (Tables S1 and S2). The PC1 is loading with EC, TDS, and Na+, and represents a strong positive correlation among them [r2 (EC-TDS = 0.984) and (EC-Na+ = 0.733); Table S2], According to Drever (1997), the greatest value of EC verifies the geogenic process – rather than human activities – those results in the storage of salts in soils. Reinforcement water seeps into the ground, carrying these salts with it. PC2 consists of Ca2+ and Mg with positive loading [r2 (Ca2+–Mg2+ = 1.00) Table S2], The dissociation of dolomite and limestone rock is one of the probable sources of Mg2+ in groundwater (Lasaga 1984). PC3 is associated with Fe and Mn with a negative correlation [r2 (Fe–Mn = −0.354); most likely the result of organic matter breakdown and rock–water interaction (Bodrud-Doza et al. 2019). PC4 is positively loaded with As and . This load may be the result of rock–water interaction, such as weathering of arsenopyrite, ferruginous quartzite, and pyrites, and leaching of secondary salt through rainfall. Groundwater in Bangladesh is highly decreasing, which results in arsenic in groundwater discharge from Holocene alluvial/deltaic sediments (Chakraborty et al. 2023). The PC5 alone K+ loading is altered by anthropogenic inputs such as agrochemicals. Despite certain discrepancies, the multivariate approach indicates a fair agreement for identifying groundwater quality metrics sources. Ultimately, the findings of the principal component analysis demonstrated that the major governing factors for the groundwater quality of the research area were human activities (agrochemicals and household sewage) and geogenic sources (rock weathering and ion exchange). Furthermore, the PCA results are confirmed by PCM analyses, which correspond to earlier research by Chakraborty et al. (2023).

This study stated the groundwater suitability and human health risk in the southwest part of Bangladesh. Groundwater in shallow aquifers is slightly alkaline. The hydro-geochemical facies of groundwater is dominantly –Ca2+–Mg2+ type. Multivariate analysis (PCA and PCM) shows that both geogenic and anthropogenic activities are responsible for the variation of studied parameters in the study area. Several irrigation quality indices show that the groundwater under study is safe for long-term irrigation, while about 85% of the sampling area groundwater is not suitable for drinking. Due to drinking water contaminated with metals and metalloids (As, Fe, and Mn), the risk of both carcinogenic and non-carcinogenic health effects in the study area's population (adults and children) increases. Arsenic requires special attention due to its high HQ, which renders groundwater unfit for direct intake without further treatment. This study suggested several actions to improve the situation, including installing deep tube wells, sealing unsafe tube wells, and putting in place affordable water treatment facilities (like community-based or household-level) for contaminated tube well water. This study also recommends further research on prevention and control measures for groundwater pollution and the development of new water quality assessment methods.

The authors want to acknowledge the Jashore University of Science and Technology for Laboratory facilities.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

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Supplementary data