The rate at which freshwater sources are being contaminated by mining operations in the South-Western part of Ghana is alarming. However, no study has quantified the degree of contamination of the freshwater in such areas, leaving a gap in the literature that requires immediate attention. This study assessed the quality of the surface and groundwater in the Tarkwa Nsuaem Municipality. Even though the physical parameters such as pH and electrical conductivity were indicative of safe freshwater, other parameters such as turbidity, total suspended solids (TSS), dissolved oxygen (DO), and heavy metals in the water sources were high; thus, confirming possible leaching, runoff, and dissolution of the hazardous substances employed in the manganese mining operations. The water quality of 82% of the water sources along the Kawere Stream was low (Classes III and IV). Therefore, the local people are at risk of contracting water-related diseases, and health problems associated with the ingestion of Fe, As, and Mn. The findings in this study are important in establishing the rate at which mining operations are reducing the quality of freshwater in developing countries, and potentially affecting human health.

  • The local people around the Kawere Stream depend more on groundwater due to the non-potable state of the stream.

  • The public health of the local people may be a major issue in the nearest future if the contaminants present in the groundwater are life-threatening.

  • 82% of the water sources are of poor quality.

  • Fe, As, and Mn contribute immensely to water contamination.

  • Indigenes are at risk of water-related diseases.

The importance of water for human survival as well as the contamination of water resources due to rapid industrialization and globalization necessitated the documentation of certain declarations by the World Health Organization (WHO) and United Nations Organization (UNO) (Arthington et al. 2018; Herrera 2019; Adesakin et al. 2020; Okumah et al. 2020; Syafrudin et al. 2021). In 2002, the UNO declared that about 1.1 billion people do not have access to safe drinking water and about 5 million people die each year due to the contraction of water-related diseases (Osiemo et al. 2019; Price et al. 2019; Abanyie et al. 2020). The UNO added that about two-thirds of the world's population is more likely to reside in countries where water shortage is moderate or severe (UN 2002; Abanyie et al. 2020). The years 2005–2015 were declared as the global decade for substantial action on water in an attempt to save the majority of the world's population from fatal consequences due to water shortage (Kumar et al. 2018). This was followed by the WHO estimation that by 2030, many developing countries will import drinking water due to the fast rate at which their water resources are being depleted; and the UN-endorsed projection that by 2030 global demand for freshwater will exceed supply by 40% due to anthropogenic activities, increasing human population and climate change (Irfan et al. 2018; Zhang et al. 2019; Borrelli et al. 2020; Cui et al. 2020).

Various water treatment methods including bioremediation (Pacheco et al. 2020; Berillo et al. 2021), iron-based adsorption (Cheng et al. 2020; Marcelo et al. 2020; Huang et al. 2021; Anang et al. 2022), nanotechnology (Yang et al. 2018; Liu et al. 2019), membrane technology (Cooray et al. 2019; Asif & Zhang 2021), reverse osmosis (Albergamo et al. 2019; Couto et al. 2020), filtration (Fu & Zhang 2018; Beratto-Ramos et al. 2021), myco-remediation (Mooralitharan et al. 2021), and chemisorption (Sumaraj et al. 2020) have been developed to remove contaminants from surface water, in a bid to ensure human survival. An alternative method that involves tapping into groundwater reserves has also been proposed and widely considered (Devic et al. 2014; Mester et al. 2020). Pumping groundwater for communities riddled with water shortage due to mining activities is the main corporate social responsibility employed by mining companies in developing countries of which Ghana is no exception (Akurugu et al. 2020). Even though groundwater can be potentially contaminated in the event where hazardous substances from mine tailings' dams leach into the earth, the groundwater resource is protected from surficial contamination. This is due to the fact that the rock bed filters the hazardous content before it reaches the groundwater. The same action occurs when the groundwater is being pumped for use (Li et al. 2020; Belle et al. 2021).

The issue of water contamination has escalated in Ghana, particularly in the rural mining communities located in the south-western part of the country (Bawa et al. 2020). Ghana is famous for its large reserves of gold, diamond, and manganese (Bawa et al. 2020). The operations of the Ghana Manganese Mine (GMM) fall within the Nsuta, Akyim, and Banso communities in the Tarkwa Nsuaem Municipality. The Kawere Stream drains the concession area of the mine from Banso in the north to the Bonsa River through Akyim in the south. The indigenous people in these areas depend more on groundwater due to the non-potable state of the surface water in the communities. The main problem is that the level of contamination of both the groundwater and surface water is not fully established. It is therefore difficult to associate the life-threatening health conditions of the local people with the water they consume. The public health of the local people may be a major issue in the near future if the contaminants present in the groundwater are at life-threatening levels. Currently, there is no information on the quality of both surface and groundwater in the Tarkwa Nsuaem Municipality, which is a major mining area in Ghana. In addition to the scarce literature on the subject in the municipality, it is important to study the interconnection of the contamination of the two water sources and make known the main health problems associated with the ingestion of the contaminated water in the Tarkwa Nsuaem Municipality.

Considering the above, the current study (1) determined the levels of physicochemical and biological parameters in surface water and groundwater in the mining area; (2) determined water quality index (WQI) for the surface water and groundwater in the area; (3) investigated the interconnection of surface water and groundwater contamination through hierarchical cluster analysis; and (4) established the extent of surface water and groundwater contamination. The establishment of the WQI and the extent of water contamination would enable stakeholders in the mining sector to develop strategic plans and water treatment methods to safeguard water resources in Ghana.

Study area

The study was carried out in three main surrounding towns of the Ghana Manganese Company (GMC) Limited located in Nsuta Wassa – Tarkwa Nsuaem Municipality (latitude 5° 16″ N and longitude 1° 59″ W). The area is about 80 km North-West of the Takoradi port and 6.5 km South of Tarkwa. The three main surrounding towns include Akyim, Banso, and Nsuta. The locations as depicted in Figure 1 were chosen based on the identification of the GMC, and where the indigenes actively obtain water from the Kawere Stream.
Figure 1

Map of the study area depicting the Ghana Manganese Company (GMC) and sampling locations.

Figure 1

Map of the study area depicting the Ghana Manganese Company (GMC) and sampling locations.

Close modal

Sampling

The samples (500 mL each) were taken from 17 sampling sites comprising 9 groundwater samples and 8 surface water samples (Table 1). The groundwater samples (AG1, AG2, AG3, BG1, BG2, BG3, NG1, NG2, and NG3) were taken from borehole reservoirs drilled by the mining company to supply potable water for the inhabitants within the concession while the surface water samples were taken from the Kawere Stream at about 100 m apart. The Kawere Stream drains through Akyim and Banso, which are two villages in the mine's concession. Here, AS1, BS1, and BS2 were collected. In the Nsuta open-pit surface mine excavations which are about 30 m deep and capable of reaching the water table in the area, NS1, NS2, NS3, NS4, and NS5 were collected. The locations of the sample sites were picked strategically in order to avoid obstructions from trees, mountains and entangled vegetation. The locations were then recorded by a hand-held Global Position System (GPS) receiver. A total of 85 samples (45 – groundwater; 40 – surface water) were taken from the sample sites over a period of 5 months (April to August). The samples were coded with a station identity depending on the source as shown in Table 1. The protocol for the sampling followed the acceptable standard (APHA 2012). The physical parameters of the sampled water including pH and total dissolved solids (TDS) were determined in situ using the Extech Oyster Series Multimeter 341350A.

Table 1

Sampling points and their corresponding GPS locations

GPS locations
CodeWater typeNorthernEastern
Ground water 
AG1 Akyim groundwater 1 580394.4775 613074.9528 
AG2 Akyim groundwater 2 580498.3184 613024.2456 
AG3 Akyim groundwater 3 580631.2388 613111.0294 
BG1 Banso groundwater 1 584393.8196 615241.3168 
BG2 Banso groundwater 2 584117.9471 615355.1507 
BG3 Banso groundwater 3 584362.9697 615502.9114 
NG1 Nsuta groundwater 1 583754.8435 612795.5047 
NG2 Nsuta groundwater 2 583609.5030 612956.3259 
NG3 Nsuta groundwater 3 583902.1533 613027.3278 
Surface water 
AS1 Akyim surface water 1 580663.6028 612889.5413 
BS1 Banso surface water 1 584113.5867 615193.7987 
BS2 Banso surface water 2 584856.0732 614319.7206 
NS1 Nsuta surface water 1 584081.7876 613485.6193 
NS2 Nsuta surface water 2 583451.7188 613281.8529 
NS3 Nsuta surface water 3 584354.5605 613233.9351 
NS4 Nsuta surface water 4 582774.3753 613238.8555 
NS5 Nsuta surface water 5 582633.7581 613178.3536 
GPS locations
CodeWater typeNorthernEastern
Ground water 
AG1 Akyim groundwater 1 580394.4775 613074.9528 
AG2 Akyim groundwater 2 580498.3184 613024.2456 
AG3 Akyim groundwater 3 580631.2388 613111.0294 
BG1 Banso groundwater 1 584393.8196 615241.3168 
BG2 Banso groundwater 2 584117.9471 615355.1507 
BG3 Banso groundwater 3 584362.9697 615502.9114 
NG1 Nsuta groundwater 1 583754.8435 612795.5047 
NG2 Nsuta groundwater 2 583609.5030 612956.3259 
NG3 Nsuta groundwater 3 583902.1533 613027.3278 
Surface water 
AS1 Akyim surface water 1 580663.6028 612889.5413 
BS1 Banso surface water 1 584113.5867 615193.7987 
BS2 Banso surface water 2 584856.0732 614319.7206 
NS1 Nsuta surface water 1 584081.7876 613485.6193 
NS2 Nsuta surface water 2 583451.7188 613281.8529 
NS3 Nsuta surface water 3 584354.5605 613233.9351 
NS4 Nsuta surface water 4 582774.3753 613238.8555 
NS5 Nsuta surface water 5 582633.7581 613178.3536 

Analytical procedure

Physical parameters including total suspended solids (TSS), colour (apparent and true), turbidity, and dissolved oxygen (DO) which could not be determined in situ were analyzed in the laboratory. The samples were transported on ice. A LaMotte SMART 3 Colorimeter (USA) was used to determine the turbidity and true and apparent colour of the samples, while the Wagtech HydroTest HT1000 (WSL50 Pro, Aquasafe, UK) was used to determine the TSS in the samples. The Wagtech HydroTest HT1000 (WSL50 Pro, Aquasafe, UK) uses a photo-spectrometric technique to analyze the constituents of water. It has a light source that flashes through the sample; a 10-mL cuvette that holds the sample and liquid crystal display (LCD) screen for viewing the results; and a power source. In determining the TSS of the water samples, 10 mL of double distilled water was poured into the cuvette as a blank sample. The blank sample was then discarded, and 10 mL of the water sample was poured into the cuvette and scanned to obtain its TSS. The same procedure was employed to obtain the turbidity and apparent colour of the water samples (using the LaMotte SMART 3 Colorimeter). The true colour of the water samples was determined by filtering the water samples with 0.45 μm filter paper before pouring into the cuvette to obtain results. To ensure quality control, two cuvettes were used in the determination of the physical parameters. One cuvette functioned as the blank (containing 10 mL deionized water) for equipment calibration while the other cuvette was used to determine the concentration of the physical parameters. The DO concentration was determined with the HANNA HI 9146 DO meter. During this process, the meter was air-calibrated before immersing into the water sample to determine its DO concentration. The result on the LCD screen was allowed to stabilize before being recorded.

Analysis of the heavy metal ions, cations, and anions (Fe, As, Mn, Mg2+, Na2+, Ca2+, K+, , , ) in the water samples was carried out in the Minerals Laboratory in the University of Mines and Technology, Ghana. Prior to the heavy metal and cation analyses, the samples were filtered with Whatman 0.45 μm paper and reacted with 10% HNO3. The reaction with HNO3 was done to de-activate the activities of microbes and preserve the ions in solution (Egbi et al. 2018). The total and faecal coliforms were analyzed with Wagtech Aquasafe WSL50 Pro Dual Microbiological Incubator (UK). 100 mL of each of the samples were filtered through 0.45 μm filter papers and placed on M-Endo Broth and M-FC prepared media.

Data analyses

The concentrations of the heavy metal ions and cations in solution were analyzed with the Flame Atomic Absorption Spectrometer (SHIMADZU AA7000 Series, Japan). The concentrations of the anions were determined with Ion Chromatograph (Dionex ICS 3000, USA). The concentrations of the chemical parameters are presented in mg/L. For the analysis of the total coliforms, the prepared samples immersed in the broth were incubated at 37 °C for 24 h. Similarly, the prepared samples for faecal coliform determination were incubated at 44.5 °C for 24 h. Counting of the coliforms was performed immediately. The samples were removed from the incubator, with the aid of a colony counter (count/100 mL). Colonies that were too many to count were recorded as >100/100 mL. The piper tri-linear diagram was plotted with the AqQA software version 1.1.1 in order to determine whether the surface water mixes with the groundwater (Omo-Irabor et al. 2008) (Figure 2). The findings were confirmed with the hierarchical cluster analysis (SPSS version 21). The samples in the top quadrant in Figure 2 are calcium sulphate waters which are typical of mine drainage and gypsum groundwater. Those in the left quadrant are calcium bicarbonate waters which are indicative of shallow fresh groundwater, while the right quadrant denotes sodium chloride water. The sodium chloride waters are typical of marine and deep ancient groundwater. The bottom quadrant depicts sodium bicarbonate waters which also represent deep groundwater (Omo-Irabor et al. 2008).
Figure 2

The three-component piper plot.

Figure 2

The three-component piper plot.

Close modal

Determination of the WQI comprised the following three steps. First, each of the chemical parameters was assigned a weight (wi) based on their perceived effects on primary health. The highest weight of five was assigned to parameters which have the major effects on water quality (Yidana et al. 2007). For instance, , , TDS,  and Cl were assigned the highest weight because of their importance in water quality assessment (Table 2).

Table 2

Acceptable level of parameters in drinking water (Galindo et al. 2007) and their assigned weights

ParameterWHO guideline valueWeight assigned (wi)
pH 6.5–8.5 2.0 
Electrical conductivity (μS/cm) 1,500 – 
Arsenic (mg/L) 0.01 4.0 
Potassium (mg/L) 30 2.0 
Sodium (mg/L) 200 4.0 
Iron as Fe (mg/L) 0.3 3.0 
Manganese (mg/L) 0.1 3.0 
Total coliform and E. coli (No./100 mL) Absent (0) – 
Total dissolved solids (mg/L) 1,000 5.0 
Total suspended solids (mg/L) 10 – 
Turbidity (NTU) – 
Calcium (mg/L) 150 3.0 
Chloride (mg/L) 250 5.0 
Magnesium (mg/L) 100 3.0 
Sulphate (mg/L) 250 5.0 
(mg/L) 1.0 
  wi = 41.0 
ParameterWHO guideline valueWeight assigned (wi)
pH 6.5–8.5 2.0 
Electrical conductivity (μS/cm) 1,500 – 
Arsenic (mg/L) 0.01 4.0 
Potassium (mg/L) 30 2.0 
Sodium (mg/L) 200 4.0 
Iron as Fe (mg/L) 0.3 3.0 
Manganese (mg/L) 0.1 3.0 
Total coliform and E. coli (No./100 mL) Absent (0) – 
Total dissolved solids (mg/L) 1,000 5.0 
Total suspended solids (mg/L) 10 – 
Turbidity (NTU) – 
Calcium (mg/L) 150 3.0 
Chloride (mg/L) 250 5.0 
Magnesium (mg/L) 100 3.0 
Sulphate (mg/L) 250 5.0 
(mg/L) 1.0 
  wi = 41.0 

The second step involved computing the relative weight (wi) of each parameter using Equation (1).
formula
(1)
where ∑wi refers to the sum of the weights of all the parameters.
In the third step, the quality rating scale (qi) was computed for each parameter using Equation (2).
formula
(2)
where Ci refers to the mean concentration (mg/L); Si refers to the WHO standard for each parameter (mg/L).
The water quality sub-index (SIi) was then calculated for each parameter using Equation (3).
formula
(3)

WHO Standards and the relative weights (wi) were assigned for water quality parameters based on their relative importance in water quality for drinking purposes (Table 3) (Yidana et al. 2007). The water quality classification based on the WQI values is shown in Table 3. Analysis of Variance (ANOVA) was performed for the parameters to determine whether any significant difference exists in the water chemistry of the study area (p < 0.05).

Table 3

Ranges for water quality classification based on WQI values

WQIDescriptionClass
<50 Excellent water 
50–100 Good water II 
100–200 Poor water III 
200–300 Very poor water IV 
>300 Water unsuitable for drinking 
WQIDescriptionClass
<50 Excellent water 
50–100 Good water II 
100–200 Poor water III 
200–300 Very poor water IV 
>300 Water unsuitable for drinking 

Levels of physical and chemical (heavy metal ions) parameters in surface water and groundwater sources

The mean levels of the physical and heavy metal ion parameters of groundwater and surface water are shown in Tables 4 and 5, respectively. It is observed that the mean pH of both water types in the selected areas was well within the WHO standard (6.50–8.50) (Table 2). The individual pH shows that the water types were either neutral or close to neutral. No significant variation existed in the pH of the groundwater (p > 0.05) and surface water (p > 0.05). The surface water in the Nsuta area (524 ± 52.45) and the groundwater in the Akyim area (510 ± 0.60) recorded high levels of electrical conductivity as compared to the other sample sites. However, the electrical conductivity levels recorded fell below the 1,500 μS/cm limit outlined by the WHO, thus showing that the electrolytes in the water samples are relatively low. The TDS levels were below the 1,000 mg/L WHO limit for TDS in freshwater. High TDS levels prove that the mineral content of the water can cause significant hazards to people's health. The TSS levels for Nsuta surface water (41 ± 24.54 mg/L) and groundwater (35 ± 1.80 mg/L), and Banso surface water (26 ± 24.54 mg/L) were more than the 10 mg/L WHO limit as presented in Table 2. The TSS level of the Akyim surface water fell on the threshold whereas those of the Akyim groundwater (3 ± 0.99) and Banso groundwater (7 ± 1.90) were low. The variations in the TSS mean levels were not significant (p > 0.05).

Table 4

Mean levels of physical and chemical (heavy metal ions) parameters of groundwater

ParameterAKYIMNSUTABANSOp-value
MeanMeanMean
pH 6.85 ± 0.04 6.68 ± 0.16 6.67 ± 0.25 0.337 
Electrical conductivity (μS/cm) 510 ± 0.60 463 ± 47.67 440 ± 106 0.337 
Total dissolved solids (mg/L) 345 ± 0.81 309 ± 32.07 297 ± 71.78 0.448 
Total suspended solids (mg/L) 3 ± 0.99 35 ± 1.80 7 ± 1.90 0.427 
Apparent colour (FAU) 48 ± 8.21 92 ± 89.16 246 ± 12.38 – 
True colour (FAU) 26 ± 6.47 43 ± 25.38 62 ± 5.48 – 
Dissolved oxygen (mg/L) 5.15 ± 0.56 4.85 ± 0.31 5 ± 0.55 – 
Total hardness (mg/L) 82 ± 7.74 72 ± 18.40 89 ± 7.18 – 
Turbidity (NTU) 4 ± 1.24 8 ± 6.15 7 ± 2.63 0.570 
Manganese (mg/L) 0.36 ± 0.18 0.59 ± 0.04 0.61 ± 0.17 0.414 
Iron (mg/L) 0.28 ± 0.10 2.31 ± 1.23 0.50 ± 0.17 0.203 
Arsenic (mg/L) 0.08 ± 0.01 0.07 ± 0.04 0.11 ± 0.07 0.540 
ParameterAKYIMNSUTABANSOp-value
MeanMeanMean
pH 6.85 ± 0.04 6.68 ± 0.16 6.67 ± 0.25 0.337 
Electrical conductivity (μS/cm) 510 ± 0.60 463 ± 47.67 440 ± 106 0.337 
Total dissolved solids (mg/L) 345 ± 0.81 309 ± 32.07 297 ± 71.78 0.448 
Total suspended solids (mg/L) 3 ± 0.99 35 ± 1.80 7 ± 1.90 0.427 
Apparent colour (FAU) 48 ± 8.21 92 ± 89.16 246 ± 12.38 – 
True colour (FAU) 26 ± 6.47 43 ± 25.38 62 ± 5.48 – 
Dissolved oxygen (mg/L) 5.15 ± 0.56 4.85 ± 0.31 5 ± 0.55 – 
Total hardness (mg/L) 82 ± 7.74 72 ± 18.40 89 ± 7.18 – 
Turbidity (NTU) 4 ± 1.24 8 ± 6.15 7 ± 2.63 0.570 
Manganese (mg/L) 0.36 ± 0.18 0.59 ± 0.04 0.61 ± 0.17 0.414 
Iron (mg/L) 0.28 ± 0.10 2.31 ± 1.23 0.50 ± 0.17 0.203 
Arsenic (mg/L) 0.08 ± 0.01 0.07 ± 0.04 0.11 ± 0.07 0.540 
Table 5

Average concentrations of physical and chemical (heavy metal ions) parameters of surface water

ParameterAKYIMNSUTABANSOp-value
MeanMeanMean
pH 7.01 ± 0.00 6.99 ± 0.07 6.80 ± 0.28 0.533 
Conductivity (μS/cm) 507 ± 0.00 524 ± 52.45 225 ± 5.37 0.001 
Total dissolved solids (mg/L) 341 ± 0.00 353 ± 33.92 148 ± 3.90 0.001 
Total suspended solids (mg/L) 10 ± 0.00 41 ± 24.54 26 ± 8.45 0.443 
Turbidity (FAU) 11 ± 0.00 38 ± 20.83 24 ± 1.54 0.422 
Apparent colour (FAU) 130 ± 0.00 343 ± 22.88 411 ± 14.81 – 
True colour (FAU) 36 ± 0.00 101 ± 26.29 140 ± 67.38 – 
Dissolved oxygen (mg/L) 4.27 ± 0.00 4.40 ± 0.78 4.16 ± 0.46 – 
Total hardness (mg/L) 69 ± 0.00 85 ± 7.64 57 ± 23.28 – 
Manganese (mg/L) 0.78 ± 0.00 1.67 ± 0.41 1.32 ± 1.21 0.483 
Iron (Fe) 0.30 ± 0.00 1.37 ± 0.14 0.80 ± 0.13 0.640 
Arsenic (mg/L) 0.08 ± 0.00 0.08 ± 0.04 0.03 ± 0.01 0.374 
ParameterAKYIMNSUTABANSOp-value
MeanMeanMean
pH 7.01 ± 0.00 6.99 ± 0.07 6.80 ± 0.28 0.533 
Conductivity (μS/cm) 507 ± 0.00 524 ± 52.45 225 ± 5.37 0.001 
Total dissolved solids (mg/L) 341 ± 0.00 353 ± 33.92 148 ± 3.90 0.001 
Total suspended solids (mg/L) 10 ± 0.00 41 ± 24.54 26 ± 8.45 0.443 
Turbidity (FAU) 11 ± 0.00 38 ± 20.83 24 ± 1.54 0.422 
Apparent colour (FAU) 130 ± 0.00 343 ± 22.88 411 ± 14.81 – 
True colour (FAU) 36 ± 0.00 101 ± 26.29 140 ± 67.38 – 
Dissolved oxygen (mg/L) 4.27 ± 0.00 4.40 ± 0.78 4.16 ± 0.46 – 
Total hardness (mg/L) 69 ± 0.00 85 ± 7.64 57 ± 23.28 – 
Manganese (mg/L) 0.78 ± 0.00 1.67 ± 0.41 1.32 ± 1.21 0.483 
Iron (Fe) 0.30 ± 0.00 1.37 ± 0.14 0.80 ± 0.13 0.640 
Arsenic (mg/L) 0.08 ± 0.00 0.08 ± 0.04 0.03 ± 0.01 0.374 

The turbidity levels of the water types were higher than the acceptable limit of 5 NTU, thus implying that both surface and groundwater in the areas are cloudy/murky (Khan et al. 2018). In effect, the cost of treating such water for drinking and food processing purposes can be high. The high turbidity, particularly in the surface water, can be attributed to the relatively high TSS levels. The DO levels were low (between 4.0 and 6.0 mg/L), thus indicating that the groundwater and surface water do not have sufficient oxygen content to support aquatic life. Such low levels of DO could be attributed to the high turbidity, high TSS and the presence of hazardous substances in the water. The hazardous substances transform into their oxidized forms upon reaction with the DO in the water. Similarly, the microbes in the water use the DO to break down the TSS present, thus reducing the DO content (Ashwaniy et al. 2020; Edori & Edori 2021).

The Mn and As levels in the groundwater and surface water were more than their acceptable limits (0.1 and 0.01 mg/L, respectively). The Fe levels of the water types were also more than the 0.3 mg/L limit except that of Akyim surface water (0.28 ± 0.10 mg/L). The relatively high Mn, As, and Fe levels in both groundwater and surface water could be due to leaching and dissolution processes of the manganese-bearing rock formations in the study area. High concentration of Mn, As, and Fe followed by calcium clearly suggests that the rock-water interaction process is the main source for degrading the water quality in the study area. The geological formation of the study area has been established to comprise Mn-carbonate and calcium-rich manganese oxide by Dzigbodi-Adjimah and Sogbor (Baig et al. 2009). Further work carried out by Yeh et al. (1995) states that the Nsuta ore mined by GMC mainly consists of outcrops of rhodochrosite (manganese carbonate) and Ca-Rhodochrosite. It is obvious that the local people in Akyim, Nsuta, and Banso are at significant risk of certain health problems (skin cancer, cardiovascular disorders, diabetes, neurological disorders, immunological disorders, severe stomach crumps, bloody diarrhoea, and vomiting) associated with the ingestion of these heavy metals.

Concentrations of anions and cations in groundwater and surface water sources

Table 6 shows the mean concentrations of the cations and anions in groundwater while Table 7 shows those in surface water. The concentration of the ions in both the groundwater and surface water sources were very low (<9.5 mg/L). The content was also lower than the WHO standard (<10.5 mg/L). However, the concentrations were either higher than or close to 1.0 mg/L. The groundwater and surface water sources (AG2, AG3, BG1, BG2, BG3, NG3, BS1, BS2, NS3, NS4) with high indicate possible leaching and runoff from un-engineered dumpsites and agrochemicals from nearby farms (Azizullah et al. 2011; Abanyie et al. 2020). The high amount of could cause eutrophication on the water surface, thus reiterating the low amount of DO in the Kawere Stream. The concentration of the ions was high, thus improving the potential of the water to neutralize acids (Akhurst et al. 2006; Báez et al. 2007). The concentration of Mg2+ in the water sources was lower than the WHO acceptable limit (100 mg/L). Similarly, the concentrations of the Na+, Ca2+, and K+ were lower than their acceptable limits. This confirms the low electrical conductivity reported in Tables 4 and 5.

Table 6

Average concentrations of anions and cations in groundwater

S/NCl̄ (mg/L) (mg/L) (mg/L) (mg/L)Mg2+ (mg/L)K+ (mg/L)Na+ (mg/L)Ca2+ (mg/L)
AG1 7.26 ± 3.02 6.83 ± 0.57 0.93 ± 1.13 34.80 ± 5.27 5.80 ± 1.21 2.23 ± 1.47 24.21 ± 2.14 30.99 ± 0.67 
AG2 5.48 ± 2.13 8.44 ± 2.23 1.07 ± 0.05 41.20 ± 3.11 5.49 ± 0.22 2.70 ± 1.11 24.55 ± 3.93 28.84 ± 5.17 
AG3 6.22 ± 2.18 8.25 ± 1.22 1.22 ± 0.01 37.60 ± 7.21 5.53 ± 0.28 2.66 ± 1.02 23.98 ± 4.08 28.50 ± 4.91 
BG1 6.58 ± 1.07 9.80 ± 2.19 1.03 ± 0.12 44.80 ± 3.37 5.38 ± 0.98 1.36 ± 0.12 24.76 ± 2.67 39.63 ± 3.31 
BG2 7.36 ± 2.14 9.41 ± 2.12 1.09 ± 0.44 22.40 ± 5.13 4.00 ± 0.37 0.66 ± 0.08 10.45 ± 2.45 21.80 ± 1.82 
BG3 5.66 ± 1.14 6.59 ± 1.93 1.15 ± 0.25 34.00 ± 0.07 4.28 ± 0.57 0.78 ± 0.27 15.16 ± 1.83 29.55 ± 3.11 
NG1 3.15 ± 1.18 4.63 ± 0.91 0.42 ± 0.31 42.40 ± 3.28 4.59 ± 0.13 0.49 ± 0.06 22.82 ± 4.08 25.45 ± 2.47 
NG2 5.05 ± 1.27 5.21 ± 1.32 0.83 ± 0.16 52.80 ± 6.23 4.53 ± 1.92 0.74 ± 0.11 31.62 ± 2.15 22.44 ± 3.81 
NG3 8.80 ± 1.17 9.04 ± 1.32 1.01 ± 0.03 45.20 ± 5.92 4.10 ± 1.67 0.65 ± 0.21 33.75 ± 6.18 30.03 ± 4.22 
S/NCl̄ (mg/L) (mg/L) (mg/L) (mg/L)Mg2+ (mg/L)K+ (mg/L)Na+ (mg/L)Ca2+ (mg/L)
AG1 7.26 ± 3.02 6.83 ± 0.57 0.93 ± 1.13 34.80 ± 5.27 5.80 ± 1.21 2.23 ± 1.47 24.21 ± 2.14 30.99 ± 0.67 
AG2 5.48 ± 2.13 8.44 ± 2.23 1.07 ± 0.05 41.20 ± 3.11 5.49 ± 0.22 2.70 ± 1.11 24.55 ± 3.93 28.84 ± 5.17 
AG3 6.22 ± 2.18 8.25 ± 1.22 1.22 ± 0.01 37.60 ± 7.21 5.53 ± 0.28 2.66 ± 1.02 23.98 ± 4.08 28.50 ± 4.91 
BG1 6.58 ± 1.07 9.80 ± 2.19 1.03 ± 0.12 44.80 ± 3.37 5.38 ± 0.98 1.36 ± 0.12 24.76 ± 2.67 39.63 ± 3.31 
BG2 7.36 ± 2.14 9.41 ± 2.12 1.09 ± 0.44 22.40 ± 5.13 4.00 ± 0.37 0.66 ± 0.08 10.45 ± 2.45 21.80 ± 1.82 
BG3 5.66 ± 1.14 6.59 ± 1.93 1.15 ± 0.25 34.00 ± 0.07 4.28 ± 0.57 0.78 ± 0.27 15.16 ± 1.83 29.55 ± 3.11 
NG1 3.15 ± 1.18 4.63 ± 0.91 0.42 ± 0.31 42.40 ± 3.28 4.59 ± 0.13 0.49 ± 0.06 22.82 ± 4.08 25.45 ± 2.47 
NG2 5.05 ± 1.27 5.21 ± 1.32 0.83 ± 0.16 52.80 ± 6.23 4.53 ± 1.92 0.74 ± 0.11 31.62 ± 2.15 22.44 ± 3.81 
NG3 8.80 ± 1.17 9.04 ± 1.32 1.01 ± 0.03 45.20 ± 5.92 4.10 ± 1.67 0.65 ± 0.21 33.75 ± 6.18 30.03 ± 4.22 
Table 7

Average concentrations of anions and cations in surface water

S/NCl̄ (mg/L) (mg/L) (mg/L) (mg/L)Mg2+ (mg/L)K+ (mg/L)Na+ (mg/L)Ca2+ (mg/L)
AS1 6.54 ± 1.45 8.72 ± 1.31 0.82 ± 0.01 38.80 ± 5.30 6.20 ± 3.02 11.35 ± 2.14 22.39 ± 1.22 29.77 ± 6.00 
BS1 3.41 ± 1.20 5.94 ± 1.41 1.16 ± 0.03 37.60 ± 4.04 3.82 ± 1.17 4.25 ± 1.14 8.43 ± 1.89 19.75 ± 3.05 
BS2 3.65 ± 1.08 3.04 ± 0.57 1.14 ± 0.02 45.60 ± 5.14 3.89 ± 1.21 1.02 ± 0.08 5.96 ± 1.27 14.94 ± 3.19 
NS1 5.28 ± 1.06 6.89 ± 1.04 0.77 ± 0.05 39.60 ± 2.11 3.95 ± 1.44 13.30 ± 2.16 27.79 ± 2.15 37.13 ± 4.03 
NS2 6.47 ± 1.17 7.67 ± 1.25 0.59 ± 0.12 39.20 ± 3.14 5.61 ± 1.63 17.47 ± 0.31 25.50 ± 4.66 30.29 ± 2.22 
NS3 5.83 ± 1.24 5.54 ± 1.32 2.30 ± 0.24 10.40 ± 1.89 3.56 ± 0.51 14.00 ± 1.67 29.18 ± 4.18 21.32 ± 3.91 
NS4 4.80 ± 1.63 4.55 ± 1.06 1.32 ± 0.31 29.20 ± 4.32 6.50 ± 0.43 14.39 ± 3.02 23.20 ± 2.47 30.87 ± 4.61 
NS5 5.91 ± 1.27 5.53 ± 1.91 0.35 ± 0.02 13.20 ± 1.51 6.48 ± 1.25 14.60 ± 2.18 22.44 ± 3.071 29.89 ± 6.10 
S/NCl̄ (mg/L) (mg/L) (mg/L) (mg/L)Mg2+ (mg/L)K+ (mg/L)Na+ (mg/L)Ca2+ (mg/L)
AS1 6.54 ± 1.45 8.72 ± 1.31 0.82 ± 0.01 38.80 ± 5.30 6.20 ± 3.02 11.35 ± 2.14 22.39 ± 1.22 29.77 ± 6.00 
BS1 3.41 ± 1.20 5.94 ± 1.41 1.16 ± 0.03 37.60 ± 4.04 3.82 ± 1.17 4.25 ± 1.14 8.43 ± 1.89 19.75 ± 3.05 
BS2 3.65 ± 1.08 3.04 ± 0.57 1.14 ± 0.02 45.60 ± 5.14 3.89 ± 1.21 1.02 ± 0.08 5.96 ± 1.27 14.94 ± 3.19 
NS1 5.28 ± 1.06 6.89 ± 1.04 0.77 ± 0.05 39.60 ± 2.11 3.95 ± 1.44 13.30 ± 2.16 27.79 ± 2.15 37.13 ± 4.03 
NS2 6.47 ± 1.17 7.67 ± 1.25 0.59 ± 0.12 39.20 ± 3.14 5.61 ± 1.63 17.47 ± 0.31 25.50 ± 4.66 30.29 ± 2.22 
NS3 5.83 ± 1.24 5.54 ± 1.32 2.30 ± 0.24 10.40 ± 1.89 3.56 ± 0.51 14.00 ± 1.67 29.18 ± 4.18 21.32 ± 3.91 
NS4 4.80 ± 1.63 4.55 ± 1.06 1.32 ± 0.31 29.20 ± 4.32 6.50 ± 0.43 14.39 ± 3.02 23.20 ± 2.47 30.87 ± 4.61 
NS5 5.91 ± 1.27 5.53 ± 1.91 0.35 ± 0.02 13.20 ± 1.51 6.48 ± 1.25 14.60 ± 2.18 22.44 ± 3.071 29.89 ± 6.10 

Piper tri-linear plot and hierarchical cluster analysis

The piper tri-linear plot was used to investigate the hydrogeochemical nature of the surface water and groundwater sources (Figure 3). The quadrilateral represents the surface water sources while the triangles are indicative of groundwater. 76.5% of the samples were plotted in the left quadrant of the quadrilateral, whereas the remaining were in upper and bottom quadrants. Hence, the majority of the samples in the study area are calcium bicarbonate waters which are indicative of typical shallow fresh groundwater. The dominant water types in the surface water are and (). The bottom quadrant depicts sodium bicarbonate waters which are typical of deep ground water affected by ion exchange. The kinds of surface water and groundwater are indicative of salt formations which are in line with the neutral pH levels determined in Tables 4 and 5. The clustering of the surface and groundwater as shown in Figure 4 suggests an interaction between the surface water and groundwater. Therefore, when the groundwater is contaminated, the surface water in the area also becomes contaminated.
Figure 3

Piper tri-linear plot of the mean concentrations of the samples.

Figure 3

Piper tri-linear plot of the mean concentrations of the samples.

Close modal
Figure 4

Dendogram for the samples grouping with respect to their physico-geochemical parameters.

Figure 4

Dendogram for the samples grouping with respect to their physico-geochemical parameters.

Close modal

Levels of microbial parameters in surface water and groundwater

The levels of faecal and total coliforms in the groundwater and surface water sources are shown in Table 8. The majority of the groundwater sources had no faecal coliforms except AG1 (1 count/100 mL). In the groundwater samples, total coliforms were found in AG1, BG1, BG2, BG3, and NG1. The surface water sources had more faecal and total coliforms than the groundwater sources. It could be inferred that the microbial content in the groundwater sources was much lower than in the surface water sources.

Table 8

Faecal and total coliforms in groundwater and surface water

S/NFaecal coliforms (count/100 mL)Total coliforms (count/100 mL)
AG1 
AG2 
AG3 
BG1 
BG2 
BG3 
NG1 
NG2 
NG3 
AS1 23 74 
BS1 20 61 
BS2 23 67 
NS1 >100 >100 
NS2 15 54 
NS3 >100 >100 
NS4 13 40 
NS5 22 83 
S/NFaecal coliforms (count/100 mL)Total coliforms (count/100 mL)
AG1 
AG2 
AG3 
BG1 
BG2 
BG3 
NG1 
NG2 
NG3 
AS1 23 74 
BS1 20 61 
BS2 23 67 
NS1 >100 >100 
NS2 15 54 
NS3 >100 >100 
NS4 13 40 
NS5 22 83 

Water quality index

The WQI of the surface water and groundwater sources are shown in Table 9. The WQI was calculated to establish the extent to which the water sources can impact human health when ingested (Ustaoglu et al. 2021). The values for the qi and SIi are shown in Supplementary material, Tables S1–S4. Water from the AG1, BG2, and BS1 locations was found to be good (Class II). The water from AG2, AG3, BG1, NG1, NG3, and AS1 was considered to be poor (Class III), whereas the remaining was classified as very poor (Class IV). The majority of the surface water sources were considered to be very poor; hence, the Kawere Stream is in no condition to be consumed by the local people.

Table 9

WQI classification

S/NWater Quality IndexDescriptionClass
AG1 88 Good water II 
AG2 132 Poor water III 
AG3 124 Poor water III 
BG1 173 Poor water III 
BG2 65 Good water II 
BG3 263 Very poor water IV 
NG1 115 Poor water III 
NG2 257 Very poor water IV 
NG3 115 Poor water III 
AS1 146 Poor water III 
BS1 81 Good water II 
BS2 205 Very poor water IV 
NS1 202 Very poor water IV 
NS2 243 Very poor water IV 
NS3 295 Very poor water IV 
NS4 208 Very poor water IV 
NS5 206 Very poor water IV 
S/NWater Quality IndexDescriptionClass
AG1 88 Good water II 
AG2 132 Poor water III 
AG3 124 Poor water III 
BG1 173 Poor water III 
BG2 65 Good water II 
BG3 263 Very poor water IV 
NG1 115 Poor water III 
NG2 257 Very poor water IV 
NG3 115 Poor water III 
AS1 146 Poor water III 
BS1 81 Good water II 
BS2 205 Very poor water IV 
NS1 202 Very poor water IV 
NS2 243 Very poor water IV 
NS3 295 Very poor water IV 
NS4 208 Very poor water IV 
NS5 206 Very poor water IV 

The quality of surface water and groundwater along the Kawere Stream in three selected communities in the Tarkwa Nsuaem Municipality was assessed in this study. The assessment was done by determining the levels of the different physical, chemical (heavy metals, cations and anions) and microbiological parameters in the water sources, which were further employed in the determination of the degree of water quality. The levels of the physical parameters were indicative of freshwater. However, the high turbidity and TSS levels showed that the freshwater sources were murky, thus denoting low DO content. The high concentrations of Mn, As and Fe were indicative of the adverse consequences of the Manganese mining operations in the GMC. The groundwater source was more of water type. There was more microbial content in the surface water than in the groundwater. The WQI of the majority of the surface water and groundwater sources except AG1, BG2, and BS1 were poor water, hence, unsafe for human consumption. However, considering the phenomenon of hydrological cycle, findings in the hierarchical clustering analysis, and the fact that about 80% of the surface water and groundwater sources in this study are not consumable, the Kawere Stream can be declared contaminated and unsafe for human consumption due to the Manganese mining operations in the GMC. Therefore, policy-makers and stakeholders in charge of managing natural water resources and mining wastewater discharge are asked to adopt efficient pretreatment techniques such as activated carbon adsorption, ion exchange or membrane filtration to minimize the concentration of toxic substances in discharged mine wastewater. It is recommended that further work should be done on the existence of heavy metals in the blood samples of inhabitants in the area. This will enable stakeholders of the company to improve the quality of potable water provided for the people within their concession.

We acknowledge the support of Prof Ndur and Mrs Ivy Arthur.

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