Abstract
Background: Groundwater is the main and easily accessible source of water supply. Aside its over-exploitation problems, groundwater has undergone quality challenges-owing to its proximity to pollution sources. Methods and Materials: This study assessed the quality of hand-dug wells situated close to the pollution receiving streams in the Ondo City. Thirty water samples; from fifteen hand-dug wells and fifteen closely associated streams across the city were collected for the study. Physico-chemical, microbial and heavy metals parameters were comparatively analyzed in stream and groundwater samples to assess percolation impact on groundwater quality. Studies were carried out in wet and dry seasons. Results: The results obtained from the wells water show that beside temperature and PH, the mean values of other physicochemical parameters like turbidity (111.47 NTU & 68.77 NTU/), total dissolved solid (474.6 mg/l & 68.77mg/l), and electrical conductivity (822.31 µS/cm & 816.79 µS/cm) in both season respectively were above the World Health Organisation (WHO) highest desirable limits. The highest total coliform (T.col) recorded at 11,200 (cfu/100ml) and 11,300 (cfu/100ml) and Faecal coliform at 8,400 (cfu/100ml) and 12,100 (cfu/100ml) for dry and rainy seasons respectively. Highest level of aluminium, cadmium, lead, and chromium concentrations in well water at 1.632mg/l, 0.820mg/l, 0.079mg/l and 0.079mg/l recorded in the rainy season exceeded WHO’s recommendations. Pearson Correlation analysis between well and stream in the dry season shows positive correlation for all water parameters, with strong significance in PH, turbidity, faecal coliform and chromium concentration (0.544, 0.914, 0.414 &0.597) respectively. Similarly, in the rainy season, both well and stream had positive correlations for most parameter tested with significances in turbidity, electrical conductivity, total dissolved solid and cadmium concentration (0.708, 0.775, 0.766&0.655) respectively. Conclusion: The major outcome of this research revealed most water samples (well and stream) failed quality assessments. The positive correlations between wells and polluted stream parameters suggested that distance contributed significantly to well contaminations.
Highlights
In Nigeria, as most developing nations, clean portable water continues to remain one of the significant requirements of Mankind
Ondo city falls within the humid tropical region with two distinct seasons, the rainy season, which usually runs from March to October, and dry season, from November to March
Results recorded from the study show (Tables 1) that all hand dug wells tested had coliform contaminations higher that the WHO permissible limits
Summary
In Nigeria, as most developing nations, clean portable water continues to remain one of the significant requirements of Mankind. The use of water for agricultural activities, indiscriminate pesticide and agro allied use; and unguarded disposal of industrial wastes can impact the safety of groundwater available to developing populations. Earlier studies have reported an approximately 1.8 billion people that are globally affected by feacally contaminated drinking water [8]. There is a rising trend of groundwater contamination with heavy metals, especially in rapidly industrialized communities, with poor environmental monitoring systems. Underground water in such areas can be highly prone to metal leachates, with many of these metals being reported to predispose varying diseases and health disorders. Aside its over-exploitation problems, groundwater has undergone quality challenges-owing to its proximity to pollution sources
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