Spatial Variation of Water Quality in Nigeria

By
Thaddaeus Ayuba
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0
1952
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Abstract

Approximately 60 million Nigerians are living without access to basic drinking water living. Datasets from over 200 studies of water samples collected from 37 regions in the country were collected and analyzed. This study analyzed 12 ions: phosphate (PO43-), sulphate (SO4 2-), chloride (Cl–), nitrate (NO3-), potassium (K+), sodium (Na+), calcium (Ca2), magnesium (Mg2), zinc (Zn2), manganese (Mn3+), iron (Fe3-), and lead (Pb2). These ions were selected because they were the most tested. Analysis of the obtained data and ions whose values exceed W.H.O and USEPA guidelines was carried out, and the areas with the highest risk factor were identified using appropriate statistical descriptions. The Water Quality scale rating, Relative weight, and arithmetic water quality index for each sample was calculated. The results of this analysis revealed Pb2+, Mn3+, PO43-, Fe3- as the parameters with the highest concentration in analyzed samples. Delta (57%), Jigawa (60%), and Ondo (66%) had the highest percentage of samples that scored high on the WQI Index making them the most polluted states (as determined by this study).

Introduction

Sustainable Development Goal Target 6.1 calls for universal and equitable access to safe and affordable drinking water. This remains a challenge in Nigeria, with the majority of Nigerians lacking access to a safe drinking water source. It is estimated that approximately 70% of Nigerians have access to basic water services and more than half of these water sources are contaminated. The average Nigerian only has access to nine liters of water per day for general use which is three liters below the global average recommended by the World Health Organization (WHO). At the current rate, the country will miss the SDG targets for people’s access to water.

The health concerns associated with drinking water chemical constituents stem from their ability to cause adverse health effects after prolonged exposure. Aside from massive accidental contamination of a drinking water supply, some water chemical constituents can cause health problems with a single exposure. Due to the use of contaminated drinking water, the human population suffers from a variety of waterborne diseases such as cholera, Hepatitis, Shigellosis, and Typhoid Fever. Chemicals from pesticides and fertilizers that end up in water may increase the risk of cancer and reproductive problems, as well as impair eye, liver, kidney, and other body functions.

Due to increased human population, industrialization, use of fertilizers, and man-made activity, water is highly polluted with different harmful contaminants. Ground and surface waters are being polluted by indiscriminate disposal of sewage, industrial waste, and a plethora of human activities which affects their physicochemical characteristics1. These incidents make water unfit to drink due to an unacceptable taste, odor, and appearance.

The pollution of surface and groundwater is often caused by a variety of factors and stems from different sources. Pollutants encompass detergents, disinfection by-products like chloroform in chemically treated drinking water, food processing waste (oxygen-demanding substances, fats, grease), insecticides, herbicides, various organic halides, petroleum hydrocarbons (including fuels and lubricants from stormwater runoff), volatile organic compounds (e.g., industrial solvents from improper storage), chlorinated solvents (dense non-aqueous phase liquids), polychlorinated biphenyls (PCBs), perchlorate, chemicals from personal hygiene, cosmetic products, and pharmaceutical drug pollution (including drug residues and metabolites

Nigeria has the world’s highest number of deaths from water-borne diseases with an increase from 14.61 to 50.56% within three years2. 70% of water at the point of consumption is contaminated and 117,000 children alone die in Nigeria each year due to preventable water-related illnesses – the highest number of any nation.3.

Most studies carried out on water contamination only focus on specific regions and extensive studies of the general state of water have not been carried out yet. This study aims to give a proper analysis of the state of water in the country, and provide a framework that informs general and specific economic decisions regarding access to clean water. The results of this study identify the most affected areas and generally provides a robust assessment of individual ions that constitute most polluted water.

Methods

STUDY AREA

Fig 1: Spatial distribution of samples across the study area.

Datasets from over 240 studies of water samples collected from all 37 regions in the country were collected and analyzed. The samples were broadly collected from surface water (Rivers, lakes, reservoirs etc.), and groundwater (water from aquifers through sources such as wells and boreholes). The water quality parameters selected for this analysis were; Phosphate (PO43-), Sulphate (SO42-), Chloride (Cl–), Nitrate (NO3–), Potassium (K+), Sodium (Na+), Calcium (Ca2+), Magnesium (Mg2+), Zinc (Zn2+), Manganese (Mn3+), Iron (Fe3-), and Lead (Pb2+). These ions were selected to ascertain the quality status of the ground and surface water unlike in some other works where few parameters were tested. The selected ions are only a general representation of the most tested isotopes. The datasets contained studies of various isotopes of several of these parameters. Analysis of the obtained data was carried out to identify samples that exceed W.H.O/USEPA recommended limits, and a plethora of statistical descriptions were used to identify areas with the highest risk factor. To better achieve an objective/standardized measurement, the Water Quality scale rating, Relative weight, and arithmetic water quality index for each sample were calculated.

Fig 2. Number of samples in each state

SELECTION CRITERIA/SAMPLE SIZE

Selection of parameters was based on the number of completed studies that have been conducted. Important parameters including fluoride and copper ions were left out of the study because enough studies have not been done to conduct a proper synthesis analysis for those ions. Over 250 studies conducted on relevant ions were analyzed. Most datasets collected from studies carried out in all the regions contained measurements for multiple parameters.

GEOLOGY

The geology of the study area is such that the savannah biome accounts for more than 86% of the region’s vegetation cover. The greater percentage of geologic features like mountains are mostly found towards the north. Nigeria has an estimated 215 billion m3 of surface water and 87 billion m3 of ground water, but these resources are not spread out evenly. Almost 80% of the country’s surface water comes from the southern part of the country, while the northern part mostly depends on groundwater.

DATA ANALYSIS

The statistical description of sampled parameters and their corresponding values are presented in table 2. The values marked in red are values for parameters that are above W.H.O/USEPA safe levels. A mean value test was conducted and gives the average value of each parameter. The maximum and minimum values indicate the highest and lowest possible values of each ion. The median gives a better measure of central tendency for ions whose samples contain disproportionate outliers, while the standard deviation values give an estimate of distribution and spread of data.

WEIGHTED ARITHMETHIC WATER QUALITY INDEX (WQI) CALCULATION

The WQI is an effective tool for communicating water quality to the general public, policymakers and stakeholders. It is an unambiguous tool that enables the integration of the water parameters which are deemed important to the quality of the water accordingly and reflects the combined impact of various water quality parameters on overall water quality (Brown et al., 1970). For this study, the WQI was calculated using the weighted arithmetic index method in assessing groundwater quality for each region. Once the WQI scores were determined, they were compared to a scale.

WATER QUALITY RATING BASED ON ARITHMETIC METHOD

Water Quality Index LevelRating of Water QualityGrade
0-25Excellent water qualityA
26-50Good water qualityB
51-75Poor water qualityC
76-100Very poor water qualityD
>100Unsuitable for drinkingE
TABLE 1. Water quality rating scale

The water quality rating scale, relative weight, and overall WQI were calculated by the following formulae:

q_{i} = \left(\frac{C_{i}}{S_{i}}\right) \times 100

where qi, Ci, and Si indicated the quality rating scale, the concentration of ith parameter, and the standard value of i parameter, respectively. The Relative weight was calculated by

w_i = \frac{1}{S_i}

where the standard value of the ith parameter is inversely proportional to the relative weight.

\text{WQI} = \sum_{n=1}^{i=n} q_i w_i

Finally, overall WQI was calculated according to the following expression:

\text{Overall WQI} = \frac{\sum_{n=1}^{i=n} q_i w_i}{\sum_{n=1}^{i=n} w_i}

RESULTS

The results of the synthesis analysis of the datasets are presented in figures 2-4 and tables 4-7. Table 4 gives the total number of collected samples and number of that exceed W.H.O limits. Figure 4 gives the percentage of samples that exceed W.H.O Safe levels for each ion.

STATISTICAL DESCRIPTION OF IONS

DESCRIPTION OF SAMPLED PARAMETERS. (<0.001 = BDL)
IONS (mg l-1)
PO43- NO3– SO42- Cl– Mg2+ Ca2+ Fe3+ Pb2+ Mn3+ Zn2+ Na+ K+
USEPA 0.1 50 — 200 50 200 0.1 0.05 0.05 5 — 30
WHO 0.1 — 250 250 50 200 0.3 0.01 0.05 5 100-200 30
MEAN 5.6 23.36 51.8 131.65 23.57 44.94 5.02 2.62 5.52 6.08 57.49 18.89
MINIMUM <0.001 <0.001 <0.001 <0.001 <0.001 0.005 0.0028 <0.001 0.001 0.004 0.005 0.01
MAXIMUM 146.67 329.4 968.1 8029 292.67 479 161 145.71 152 398 900 322
MEDIAN 0.77 3.91 9.35 29.55 8.5 21.07 0.4 0.08 0.18 0.3 8.54 5.53
ST. DEV 18.33 49.7 134.02 696.7 54.81 74.28 22.07 17.43 33.89 44.7 157.67 48.86

From table 2, the values that exceed WHO and USEPA safe levels are shown in red. Parameters whose minimum is given as <0.001 were below the detection limit. The WHO and USEPA limit for phosphate (PO43-) is 0.1 mg l-1. In this study, the phosphate (PO43-) levels ranged between 0.001 mg l-1 and 146.7 mg l-1. The estimated standard deviation for phosphate (PO43-) is 18.33 mg l-1, and the median is 0.77 mg l-1. The mean value is 5.6 mg l-1, and is above both WHO and USEPA limits. Nitrate (NO3–) concentrations in the samples ranged from <0.001 mg l-1 (below detection limit) to 329 mg l-1, with an average value of 23.36 mg l-1. The standard deviation for NO3– is 49.70 mg l-1, and the median is 3.91 mg l-1. The WHO maximum permissible limit of NO3– in drinking water is 10 mg l-1. Most values are within the permissible limit of WHO and USEPA standards. The WHO standard limit of sulfate in drinking water is 250 mg l-1. The concentration of sulfate (SO42-) in this study ranged from <0.001 mg l-1 to 968.1 mg l-1. Most values were within USEPA’s limit of 250 mg l-1. The mean and standard deviation were calculated to be 134.02 mg l-1 and 51.8 mg l-1 respectively. The median value is 9.35 mg l-1. Chloride (Cl–) concentrations in water samples range between <0.001 mg l-1 and 8029 mg l-1, with a standard deviation value of 696.70 mg l-1. Both the mean (131.65 mg l-1) and median (29.55 mg l-1) values in ground and surface water samples fall within W.H.O and USEPA limits of 200 mg l-1 and 250 mg l-1 for drinking water.

According to WHO and USEPA standards, the permissible limit of magnesium in drinking water should be 50 mg/l. Magnesium (Mg2+) concentration ranged from <0.001 mg l-1 to 292.67 mg l-1. The concentration of Mg2+ in all the water samples from the study area is generally low with mean and median values of 23.57 mg l-1 and 8.5 mg l-1. The estimated standard deviation of Mg2+ is 54.81 mg l-1. The WHO and USEPA guideline for calcium (Ca2+) ions in drinking water is 200 mg l-1. The results of the study show that the concentration of Ca2+ ranges from 0.005 mg l-1 to 479 mg l-1 with an average of 44.94 mg l-1. The estimated standard deviation is 74.28 mg l-1, and the median is 21.07 mg l-1. Iron (Fe3-) concentrations range between 0.0028 mg l-1 and 161 mg l-1 with a very high mean value of 5.02 mg l-1. Fe3- concentration in ground and surface water samples are mostly above the permissible WHO and USEPA limits for drinking water (68%) with Edo, Ogun, and Jigawa having the highest values. The median measured is 0.4 mg l-1 with a standard deviation of 22.07 mg l-1. The USEPA lead standard for drinking water quality is 0.05 mg l-1, while WHO recommends 0.01 mg l-1 as the maximum permitted amount. The mean (2.62 mg l-1) value for lead (Pb2+) is significantly above W.H.O limits and the standard deviation is 17.43 mg l-1. The minimum and maximum values reported are <0.001 mg l-1 and 145.71 mg l-1, while the median is 0.08 mg l-1.

Manganese (Mn3+) concentrations measured in water varied from <0.001 mg l-1 to 152 mg l-1. A high average concentration value of 5.52 mg l-1 was obtained. Similar to iron, > 60% of the samples evaluated for Mn3+ concentration is above the limits recommended by the two standards considered in this study. The estimated standard deviation is 33.89 mg l-1 with a median value of 0.18 mg l-1. The concentration of zinc (Zn2+) in the samples ranged between 0.004 mg l-1 and 398 mg l-1. Statistical analysis revealed 6.08 mg l-1 and 0.3 mg l-1as the mean and median values. The standard deviation of Zn2+ was 44.70 mg l-1. According to WHO standards, the recommended concentration of sodium in drinking water should fall within 100-200 mg l-1. The range of Na+ ions in the water samples varied from 0.005 mg l-1 to 900 mg l-1. The mean and median values obtained are 57.49 mg l-1 and 8.54 mg l-1. Most samples were within the WHO and USEPA standards. The concentration of potassium K+ in water samples ranged from 0.01 mg l-1 to 322 mg l-1 with an average value of 5.7 mg l-1. The median and standard deviation values obtained are 5.53 mg l-1 and 48.86 mg l-1. Most samples are within the standards recommended by W.H.O and USEPA.

SAMPLE FREQUENCY

Type of waterTotal number of SamplesNumber of Polluted SamplesPercentage of total samples that are polluted
Surface water1252721.6%
Groundwater1291813.9%
Table 3. Surface and Groundwater composition

From table 3, the total number of samples obtained from all the regions is 249. Out of the total number of samples, 125 samples were from surface water (including lakes, dams, reservoirs, and running water like rivers and streams), and 129 from ground water (aquifers, wells, and boreholes). Out of 125 samples obtained for surface water, 27 of them had values that were above WHO limit and that accounted for 21.6% of the total surface water samples. Out of 129 samples obtained for ground water, 18 of them had values that were above WHO limit and that accounted for 13.9% of the total surface water samples. While more than 92% of the datasets contained at least a parameter whose value was above WHO and USEPA limits, the percentages of polluted samples presented in table 3 is calculated from the cumulative values obtained from each dataset.

S/NCompoundNumber of samplesNumber of samples that exceed WHO limitsPercentage of samples that exceed WHO limits (%)Region with the highest average value
1Phosphate815871.6Enugu
2Nitrate1482214.7Niger
3Sulphate12275.7FCT
4Chloride138139.4Ondo
5Magnesium1191210.1Rivers
6Calcium12254.1Kebbi
7Iron1329672.7Ogun
8Lead694260.7Ondo
9Manganese765065.8Kano
10Zinc7922.5Osun
11Sodium5946.8Zamfara
12Potassium55610.9Ogun
Table 4.  Number of samples above W.H.O limits.
Fig 4.  For each ion, the percentage of samples that exceed the W.H.O. recommended limits is given.

Table 4 gives the number of studies conducted for each parameter, the region with the highest average value, and the percentage amount that exceeds WHO limits. Out of 81 samples, 58 exceeded the WHO limit for phosphate (PO43-) with a peak value from Enugu. Out of 148 nitrate (NO3–) samples, 22 exceeded the WHO limit, with the highest value recorded from Niger. For Sulphate (SO42-) and chloride (Cl–), a small fraction of 7, and 13 samples out of a total of 122, and 138 samples were above the WHO limit. The highest average values were from FCT and Ondo. Magnesium (Mg2+) recorded 12 polluted samples out of 122 with a peak value from Rivers. Calcium (Ca2+) recorded the lowest rate of polluted samples per total number of samples among all the parameters with 5 polluted samples out of 122 with the highest value from Kebbi. In contrast, iron (Fe3-) recorded a high number of 96 polluted samples out of a possible 132. High iron levels were mostly found in Ogun. Lead (Pb2+) had a high number of 42 polluted samples out of 69 with a peak value from Ondo. Manganese (Mn3+) also had high values with 50 polluted samples out of 92. Kano recorded the highest values. Zinc (Zn2+) had only 2 polluted samples out of 79 with all of those values coming from Osun. Sodium (Na+) had 4 polluted samples out of 59- with peak values in Zamfara- and potassium (K+) also recorded a similar number with 6 polluted samples out of 59(with the highest values coming from Ogun).

Fig 4 gives the measure of pollution of each ion as a percentage. 71.6% of phosphate samples exceeded the limits, while 14.9% of nitrate samples exceeded the WHO limits. 5.7% of sulphate samples exceeded the limits, and 10.2% of chloride samples was above WHO standards. Magnesium and calcium recorded 10.1% and 4.1% of samples above the limits. 72.7% of iron samples were above WHO limits, while 60.9% of lead samples exceeded the limits. Manganese and zinc recorded 65.8% and 2.5% of samples that exceeded the limits, while 6.8% and 10.9% of sodium and potassium samples were found to be above the standard.

WQI INDEX

FIG 3. Water Quality Index

Calculation of the arithmetic water index shows that 75% of the water scored between 0-25. Approximately 7 percent of the water scored between 26-50. Just under 2% of samples scored between 51-100. and over 17% of water scored above 100. While these values give a general picture of water quality, most samples have high concentrations of certain ions that the indexing does not account for. Water quality is more unsuitable than is shown because of high concentration of these specific ions.

Discussion

The WHO and USEPA limit for phosphate is 0.1 mg l-1. Phosphate (PO43-) is one of the parameters with a very high mean and standard deviation of 5.60±18.33 mg l-1. PO43- values contain outliers and this highly influences the mean. Because the data is skewed, the median gives a more useful midpoint with a value of 0.77 mg l-1 for PO43-. High PO43- levels is very toxic and causes calcification of body organs. Samples with high PO43- (?50 mg l-1)- the highest being 146.7 mg l-1– mostly came from the north. This is because of the high livestock production and agricultural runoff due to intense agricultural activities. While nitrate (NO3–) concentrations in some of the samples reached unprecedented levels i.e. 100?x?329 mg l-1, most samples were within the limits, with a central trend of 23.36±49.70 mg l-1, a value below half the WHO limit of 50 mg l-1. The high values obtained were mostly from tests conducted on surface water found near areas with high industrialization. This indicates significant anthropogenic pollution, and emerges mostly from industrial waste.

The concentration of sulfate (SO42-) in this study ranges from <0.001 mg l-1 (BDL) to a high maximum of 968.1 mg l-1, but the mean and standard deviation were calculated to be 134.02±51.8 mg l-1. This means most values were within USEPA’s limit of 250 mg l-1. SO42- is abundantly found in almost all water bodies. It is mainly derived from the dissolution of salts of sulfuric acid. SO42- concentration in natural water ranges from a few to a several hundred mg per liter but no major negative impact of SO42- on human health is reported. High concentration of SO42- may be due to oxidation of pyrite and mine drainage etc. (Mohsin et al., 2013).

Chloride (Cl–) concentrations in water samples range between <0.001 mg l-1 and 8029 mg l-1, with a standard deviation value of 696.70 mg l-1. This high Standard deviation value is as a result of the variable spread of chloride in samples. Industries and sectors differ in their contribution to chloride contamination with many regions having high, average and low chloride content.  The maximum value of 8029 mg l-1 represents the greatest outlier in this study. In contrast, both the mean (131.65 mg l-1) and median (29.55 mg l-1) values in ground and surface water samples fall within W.H.O and USEPA limits of 200 mg l-1 and 250 mg l-1 for drinking water. High concentration of Cl– gives a salty taste to water and beverages. Taste thresholds for the chloride anion depend on the associated cation and are in the range of 200-300mg l-1. Some concentrations in excess of 250mg l-1 are increasingly likely to be detected by taste, but consumers may become accustomed to low levels of Cl– -induced taste (WHO, 2006). The Cl– content investigated is lesser than the tolerable limits.

The WHO and USEPA permissible limit of magnesium in drinking water is 50 mg/l. Magnesium (Mg2+) concentration values range from <0.001 mg l-1 to 292.67 mg l-1. The concentration of Mg2+ in all the water samples from the study area gave mean and median values of 23.57±54.81 mg l-1 and 8.5 mg l-1. The concentration of Mg2+ in all the water samples from the study area is generally low. The development of Mg2+ in drinking water is mostly attributed to the dissolution of minerals in the various basement rocks underlain the studied areas.

The WHO and USEPA limit for calcium (Ca2+) ions in drinking water is 200 mg l-1. The high level of Ca2+ is an indication of water hardness. The results of the study show that the concentration of Ca2+ ranges from 0.005 mg l-1 to 479 mg l-1 with an average of 44.94 mg l-1±74.28 mg l-1. Ca2+ may dissolve readily from carbonate rocks and lime stones or be leached from soils. Other sources include industrial and municipal discharges. Ca2+ is an essential nutritional element for human being and aids in maintaining the structure of plant cells and soils. Its deficiency may lead to protein energy malnutrition. The high deficiency of Ca2+ in humans may cause rickets, poor blood clotting, bones fracture etc. and the exceeding limit of calcium produced cardiovascular diseases4.

 Iron (Fe3-) concentrations range from 0.0028 mg l-1 to 161 mg l-1 with a very high mean value of 5.02±22.07 mg l-1 These high values show significant Fe3- concentration in ground and water samples. Fe3- concentrations in ground and water samples are mostly above permissible WHO and USEPA limits for drinking water. The implication of a high amount of Fe3- on human health is iron overload which can cause diabetes, hemochromatosis, stomach problems, and nausea. A high concentration of iron in ingested water can cause significant damage to the liver, pancreas, and the heart.

 USEPA lists 0.05 mg l-1 as maximum permitted Pb2+ level in drinking water, while WHO recommends 0.01 mg l-1 in drinking water. The health implication of Pb2+ presence in excess of 0.05 in drinking water is cancer, interference with vitamin D, metabolism, slowing down of mental development in infants and toxicity to the central and peripheral nervous systems. The mean (2.62±17.43 mg l-1) value for Pb2+ is significantly above W.H.O limits and is extremely harmful to health. Such high levels indicate great contamination. Unsafe mining and ore processing are the biggest contributors to high lead levels in water. Proper control of these activities will cushion lead contamination. Manganese falls above the W.H.O permissible standard for drinking water. Mn3+ concentrations measured in water varied from <0.001 mg l-1 to 152 mg l-1. A high average concentration value of 5.52±33.89 mg l-1 and a median value of 0.18 mg l-1 was obtained. Anaerobic groundwater often contains elevated levels of dissolved manganese. High concentrations of Mn3+ can cause mental diseases such as Alzheimer’s which affect the intellectual functions of children below 10.

Similar to Fe3-, Pb2+, and Mn3+, studies of the samples evaluated for zinc concentration mostly obtained values above W.H.O and USEPA guidelines. The concentration of Zn2+ in the samples ranged between 0.004 mg l-1 and 398 mg l-1. Statistical analysis revealed 6.08±44.70 mg l-1 as the average value. The mean is also significantly higher than the limit. Very high levels of Zn2+ can cause nausea and vomiting.

The WHO sodium limit in drinking water should is ideally within 100-200 mg l-1. The range of Na+ ions in the water was 0.005?x? 900 mg l-1. The mean and median values obtained were 57.49±157.67 mg l-1 and 8.54 mg l-1 respectively. Most samples were within the WHO and USEPA standards. Higher concentration of Na+ ion in drinking water may cause heart problems. Excessive amount of Na+ ion in water normally affects the palatability of the water. Proper quantity of sodium in human body prevents many fatal diseases like kidney damages, hypertension, headache etc.5. Most samples were within the permissible limit of WHO and USEPA standard. Concentration of potassium in water samples from our study ranges from 0.01?x? 322 mg l-1 with an average value of 5.7±48.86 mg l-1. Most samples are within the standards recommended by W.H.O and USEPA.

Groundwater accounted for nearly one-third of water samples that scored high on the WQI index, while surface water accounted for only about 37% of high scoring samples. Similarly, surface water accounted for 60% of polluted samples compared to groundwater’s 40%. (Table 3). Based on this result, surface water is more polluted. From figure 2, five regions had 9 samples each (FCT, Gombe, Kaduna, Kogi, and Plateau). Two regions had up to ten samples obtained (Adamawa and Bayelsa), while Kebbi state had more than 10 samples, making it the most polluted state (as determined by this study). Osun and Ekiti emerged as the states with the lowest pollution with three samples each, all of which scored well on the WQI index (Figure 1).

Tables 4 and figure 4 give the number of studies conducted for each parameter, the amount that exceeds WHO limits, and their relative percentages. Phosphate, iron, and manganese had >50% of samples that exceed WHO levels. Generally, calcium and zinc posed little risk with less than 5% of samples above WHO. Based on these results, phosphate, iron, and manganese posed the highest risk to health because of their high concentrations in water.

The regions with the highest average recorded values for each ion are given in table 4. Ogun had the highest values for the K+ and Fe3- ions. This is most likely because of the high mining operations carried out in the region and heavy use of potassium-rich fertilizers which ultimately affect water bodies. Ondo recorded the highest average values for Cl– and Pb2+ ions because of heavy industrialization in the region. Most regions with highest ion values are found in the southwestern and northwestern regions of the country, which happens to be the most industrially active regions.

Conclusion

The results show that majority of the samples contain large quantities of ions that are harmful to health. The samples that contain high levels of heavy metal will pose the greatest risk. More analyses must be carried out continuously to obtain relevant information of the state of the art of ground and surface water across all regions in the country.

The primary limitation to the generalization of these results is the omission of important ions like copper and fluoride due to insufficient studies. This affects the overall assessment of water quality. This can be addressed in future research by conducting more studies that involve ions of fluorine, copper, and other important heavy metals, then including them in overall quality assessments. This will give a more accurate picture of water quality.

Another limitation of this study is the absence of temporal assessment. An analysis of these ions and their values over time will give a better understanding of their trend and inform better decisions.

References

  1. M. Koshy and T. Nayar, 2000, 19, 665–668. [↩]
  2. L. L. Nwidu, B. Oveh, T. Okoriye and N. A. Vaikosen, African Journal of Biotechnology, 2008, 7, year. [↩]
  3. UNICEF, Nearly one third of Nigerian children do not have enough water to meet their daily needs – UNICEF, 2021,
    https://www.unicef.org/nigeria/press-releases/nearly-one-third-nigerian-children-do-not-have-enough-water-meet-their-daily-needs. [↩]
  4. A. Sharma and C. Rout, International Journal of Environmental Science, 2011, 2, 933–945. [↩]
  5. A. A. Dusa, T. Nachana’a, S. T. Magili and S. Tukur, author, 2017. [↩]

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