Abstract
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.
HIGHLIGHTS
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.
INTRODUCTION
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.
METHODS
Study area
Map of the study area depicting the Ghana Manganese Company (GMC) and sampling locations.
Map of the study area depicting the Ghana Manganese Company (GMC) and sampling locations.
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.
Sampling points and their corresponding GPS locations
. | . | GPS locations . | |
---|---|---|---|
Code . | Water type . | Northern . | Eastern . |
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 . | |
---|---|---|---|
Code . | Water type . | Northern . | Eastern . |
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
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).
Acceptable level of parameters in drinking water (Galindo et al. 2007) and their assigned weights
Parameter . | WHO guideline value . | Weight 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) | 5 | – |
Calcium (mg/L) | 150 | 3.0 |
Chloride (mg/L) | 250 | 5.0 |
Magnesium (mg/L) | 100 | 3.0 |
Sulphate (mg/L) | 250 | 5.0 |
![]() | 1 | 1.0 |
∑wi = 41.0 |
Parameter . | WHO guideline value . | Weight 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) | 5 | – |
Calcium (mg/L) | 150 | 3.0 |
Chloride (mg/L) | 250 | 5.0 |
Magnesium (mg/L) | 100 | 3.0 |
Sulphate (mg/L) | 250 | 5.0 |
![]() | 1 | 1.0 |
∑wi = 41.0 |
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).
Ranges for water quality classification based on WQI values
WQI . | Description . | Class . |
---|---|---|
<50 | Excellent water | I |
50–100 | Good water | II |
100–200 | Poor water | III |
200–300 | Very poor water | IV |
>300 | Water unsuitable for drinking | V |
WQI . | Description . | Class . |
---|---|---|
<50 | Excellent water | I |
50–100 | Good water | II |
100–200 | Poor water | III |
200–300 | Very poor water | IV |
>300 | Water unsuitable for drinking | V |
RESULTS AND DISCUSSION
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).
Mean levels of physical and chemical (heavy metal ions) parameters of groundwater
Parameter . | AKYIM . | NSUTA . | BANSO . | p-value . |
---|---|---|---|---|
Mean . | Mean . | Mean . | ||
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 |
Parameter . | AKYIM . | NSUTA . | BANSO . | p-value . |
---|---|---|---|---|
Mean . | Mean . | Mean . | ||
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 |
Average concentrations of physical and chemical (heavy metal ions) parameters of surface water
Parameter . | AKYIM . | NSUTA . | BANSO . | p-value . |
---|---|---|---|---|
Mean . | Mean . | Mean . | ||
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 |
Parameter . | AKYIM . | NSUTA . | BANSO . | p-value . |
---|---|---|---|---|
Mean . | Mean . | Mean . | ||
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.
Average concentrations of anions and cations in groundwater
S/N . | Cl̄ (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/N . | Cl̄ (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 |
Average concentrations of anions and cations in surface water
S/N . | Cl̄ (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/N . | Cl̄ (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



Dendogram for the samples grouping with respect to their physico-geochemical parameters.
Dendogram for the samples grouping with respect to their physico-geochemical parameters.
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.
Faecal and total coliforms in groundwater and surface water
S/N . | Faecal coliforms (count/100 mL) . | Total coliforms (count/100 mL) . |
---|---|---|
AG1 | 1 | 4 |
AG2 | 0 | 0 |
AG3 | 0 | 0 |
BG1 | 0 | 1 |
BG2 | 0 | 1 |
BG3 | 0 | 1 |
NG1 | 0 | 1 |
NG2 | 0 | 0 |
NG3 | 0 | 0 |
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/N . | Faecal coliforms (count/100 mL) . | Total coliforms (count/100 mL) . |
---|---|---|
AG1 | 1 | 4 |
AG2 | 0 | 0 |
AG3 | 0 | 0 |
BG1 | 0 | 1 |
BG2 | 0 | 1 |
BG3 | 0 | 1 |
NG1 | 0 | 1 |
NG2 | 0 | 0 |
NG3 | 0 | 0 |
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.
WQI classification
S/N . | Water Quality Index . | Description . | Class . |
---|---|---|---|
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/N . | Water Quality Index . | Description . | Class . |
---|---|---|---|
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 |
CONCLUSION
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.
ACKNOWLEDGEMENTS
We acknowledge the support of Prof Ndur and Mrs Ivy Arthur.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conflict.