RESEARCH ARTICLE


Comparative Bacteriological and Heavy Metal Toxicity Evaluation of Groundwater Wells Proximal to Pollution Receiving Streams in Ondo City, Nigeria



Olufemi J. Akinnifesi1, *, Joseph O. Akinneye1
1 Department of Biology, Federal University of Technology, Akure, Nigeria.


© 2019 Akinnifesi & Akinneye.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* * Address correspondence to this author at Department of Biology, Federal University of Technology, Akure, Nigeria; Tel: +234 8064385025;
E-mail: olufemiakinnifesi@yahoo.com


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.

Keywords: Groundwater, Correlation, Percolation, Coliform, Heavy metals, Lead.



1. INTRODUCTION

In Nigeria, as most developing nations, clean portable water continues to remain one of the significant requirements of Mankind. The importance of water and the increasing need to access it has made humans to seek every cheap and economical ways to obtain it [1]. Of the known sources of water, surface water (streams, ponds) and groundwater (hand dug wells, boreholes) remain the two major natural sources in which water is globally abstracted [2, 3]. And of these two major sources, groundwater is reportedly the most trustable source of water available to developing population. Groundwater also account for a global daily dependence from an approximated 1.5 billion human population with over 50 fifty percent of rural and urban population still seeking water from hand dug wells and boreholes, many of which has been reported unsafe [4-6]

A survey by Majuru et al. estimated that 65 million Nigerians had no access to safe water. Many disease outbreaks in rural Nigeria like Cholera, Salmonellosis, and Diarrhoea have been greatly linked to poor water quality.

Owing to the human population explosion and its resultant effect on water demands, the challenge of achieving acceptable water quality is still on the increase. The use of water for agricultural activities, indiscriminate pesticide and agro allied use; and unguarded disposal of industrial wastes can also impact the safety of groundwater available to developing populations. Additionally, due to the sanitation inadequacies; well sited around poor sewage systems, pit latrines and waste dumps have also been reported to affect the physical, chemical and microbial integrity of wells sited close to them [7]. According to the different safe drinking standards, drinking water must not contain feacal contaminants. But earlier studies have reported an approximately 1.8 billion people that are globally affected by feacally contaminated drinking water [8]. More so, 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.

Even though government agencies are saddle with responsibility of providing safe water for the populace and accordingly managing potential threats to water quality [9], the deficiency of this necessitates for effective monitoring of groundwater available to communities. Ondo city is the second largest community in the Ondo state, Southwestern Nigeria. The sole water source for people in this area is groundwater. Owing to the financial limitations, most residents make use of shallow dug wells. These wells are often deliberately sited close to streams and ponds in order to have access to water all year round. Just like its water, inadequacy of effective sanitation systems in this city still exists. This study intends to assess the physico-chemical, microbial and heavy metals contamination of some selected hand dug wells and closely associated streams and evaluate the possible interaction between them.

2. MATERIALS AND METHODS

2.1. Study Area

This study was carried out in Ondo city, which is the second largest community in Ondo State, Nigeria. The city lies between 7.088923o N and 4.7990935oE. It is located at about 300 km northeast of Lagos and 45 km west of Akure. 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. Ondo is continually growing in human population and has no effective municipal pipe borne water supply.

2.1.1. Sampling Point Selection

Thirty (30) water samples were collected from fifteen (15) wells and fifteen (15) stream points close to each sampled wells across Ondo city (Fig. 1) Samples were collected in two seasons; Dry season samples were collected in the month of February, 2017 while the rainy season samples were collected in the month of June, 2017. Water samples from the two sources (well and stream) and seasons were taken for comparative analysis.

The coordinates of wells at the different study sites and their associated streams were used in generating map of the area. The core sites that were mapped are Ojojo, Ebido, Iluyemi, Olorunsola, Gani Fawehinmi, Lisaluwa, Irewole, Ogbodu, Sabo, Yemoja, Losunla, Oke gbogi, Bethlehem, Odojomu and Oke Odunwo. The locations of the wells illustrated on the map (Fig. 2) show a random but well spanned distribution of the sampled wells across the city.

2.1.2. Collection of Samples

For well samples, sterile 50ml bottles (attached with a clean bob) were carefully lowered with a string inside the wells for water collection. To collect streams samples, sterile bottles were gently submerged in each of the streams to collect water. Samples were collected in triplicate, properly screw capped and transported to the laboratory in ice box, in order to maintain the microbial population and were processed for microbial presence within 24 hours according to the International guideline [10]

2.2. Physico-chemical Analysis

Physicochemical parameters like Temperature, pH, Turbidity, Total Dissolved solids and Electrical Conductivity were measured following appropriate water measuring apparatus.

2.2.1. Heavy Metal Analysis

The heavy metals screened were Aluminium (Al), Cadmium (Cd), Lead (Pb) and Chromium (Cr). The analysis was carried out using a furnace Atomic Absorption Spectrophotometer.

2.3. Microbial Analysis

2.3.1. Test for Total coliform

0.1ml of water was plated in a petri dish containing MacConkey agar as the growth medium. It was then incubated at 37°C for 24hrs after which the observed colonies were counted and result expressed as cfu/ml. This experiment was carried out in three replicates for each well water sample. Same was carried out for the stream water sample. The appearance of a pink to dark red colonies indicated the presence of coliforms [11]

2.3.2. Test for Faecal coliform

0.1ml of well water was inoculated into plates containing Eosin-Methylene Blue (EMB) agar and was then incubated for 24 hours at 44°C; this was replicated three times for each well water sample. Same experiment was carried out for the stream water samples. Bacterial colonies were counted to obtain the viable cell count. Differential colour range, from green metallic sheen to pinkish and creamy colouration was used in identifying specific faecal coliform growth [11].

Fig. (1). Section of some sampled wells with accompanying streams.

Fig. (2). Map of the study area showing the location of sampled wells and associated stream points in Ondo city.

2.4. Statistical Analyses of Data

T-test was used to compare physicochemical parameters and coliform counts for rainy and dry season. A correlation analysis was carried out to establish the degree of relationship between all parameters measured in the streams and wells. All analyses were carried out using Statistical Package for Social Sciences (SPSS) version 21.0.

3. RESULTS

Results recorded from the study show (Tables 1) that all hand dug wells tested had coliform contaminations higher that the WHO permissible limits. Also, most of the physico-chemical parameters and heavy metal measured were higher than the permissible limits.

3.1. Difference in Well Water Parameters Between Dry and Rainy Seasons

The differences in parameter concentrations across well water showed only temperature and faecal coliform counts to have significant differences between the wet and dry season. The concentration of Cd, Pb, Cr and pH were not significantly different (p>0.05) amongst well waters during dry and rainy season (Table 2).

3.2. Difference in Stream Water Parameters Between Dry and Rainy Seasons

From Table 3, the differences in Temp, EC, TDS, Al, Pb and Cr concentrations were significantly different (P ≤ 0.05) during both season while pH, turbidity, Total coliform, Faecal coliform, Cd were not significantly different from one another amongst well waters during dry and rainy season.

3.3. Difference in Water Parameters Between Stream and Wells in Dry Season

The differences recorded in the concentrations between streams and wells in the rainy seasons are shown. In all, the pH, Faecal coliform, Cd, Pb, Cr concentrations were significantly different (P ≤ 0.05) while Temperature, Turbidity, EC, TDS, Total coliform and Al contents were not of significant different between streams and wells in dry season (Table 4).

Table 1. Seasonal variation of quality parameters of well water and comparison with WHO standards
PARAMETER DRY SEASON
Min Max Mean±SE
RAINY SEASON
Min Max Mean±SE
HD MP
Temperature (oC) 27.1 31.0 29.1±0.32 23.9 27.4 29.5±0.36 - -
pH 5.5* 7.6 6.8±0.13 6.00 8.10* 7.6±0.18 7.0-8.9 6.5-9.5
Turbidity (NTU) 0.61 508* 111.47±45.94 5.10* 512* 68.77±20.91 < 1 5
Electrical Conductivity(µs/cm) 601 1110* 822.31±35.65 498 1342* 816.79±37.87 900 1200
Total Dissolved Solid(mg/l) 383* 823* 474.6±18.50 279* 751* 364.2±18.85 0 500
Total coliform (x104 cfu/ml) 1.08* 1.12* 0.69±0.69 1.0* 1.13* 0.79±0.47 0 0
Faecal coliform (x104cfu/ml) 0.23* 0.84* 0.51±0.27 0.48* 1.21* 0.80±0.37 0 0
Aluminium 0.046* 0.210* 0.102±0.013 0.009* 1.632* 0.146±0.028 0 0.05
Cadmium 0.000 0.031* 0.010±0.003 0.000 0.820* 0.063±0.018 0 0.003
Lead 0.002* 0.046* 0.016±0.003 0.000 0.079* 0.067±0.020 0 0.01
Chromium 0.000 0.048* 0.027±0.006 0.000 0.079* 0.081±0.021 0 0.05
Table 2. Independent sample T-test for difference in concentration of well water parameters between dry and rainy seasons.
PARAMETER PAIR MEAN±SE N SD df TCalc Sig(2-tailed) RMKS
Temperature (oC) Dry season
Rainy season
29.1±0.32
25.4±0.30
15
15
1.23
1.15
14
14
8.294 0.000 S
pH Dry season
Rainy season
6.8±0.13
6.9±0.15
15
15
0.51
0.59
14
14
-0.89 0.381 NS
Turbidity (NTU) Dry season
Rainy season
111.5±45.94
120.9±45.79
15
15
177.91
177.35
14
14
-0.146 0.885 NS
EC (µs/cm) Dry season
Rainy season
822.31±35.65
792.20±55.22
15
15
138.06
213.89
14
14
0.458 0.650 NS
TDS (mg/l) Dry season
Rainy season
474.6±18.50
444.9±30.50
15
15
71.65
118.13
14
14
0.833 0.412 NS
Total coliform(x104 cfu/ml) Dry season
Rainy season
5.8±0.79
6.9±0.69
15
15
3.05
2.67
14
14
-1.115 0.274 NS
Faecal coliform(x104 cfu/ml) Dry season
Rainy season
5.1±0.148
7.9±0.59
15
15
1.87
2.28
14
14
-3.769 0.001 S
Aluminium (mg/l) Dry season
Rainy season
0.102±0.013
0.153±0.027
15
15
0.05
0.11
14
14
-1.709 0.099 NS
Cadmium (mg/l) Dry season
Rainy season
0.001±0.003
0.014±0.005
15
15
0.12
0.02
14
14
-0.616 0.543 NS
Lead (mg/l) Dry season
Rainy season
0.016±0.003
0.016±0.005
15
15
0.11
0.02
14
14
0.055 0.956 NS
Chromium (mg/l) Dry season
Rainy season
0.021±0.005
0.029±0.006
15
15
0.02
0.02
14
14
-1.045 0.305 NS
Table 3. Independent sample T-test for difference in concentration of stream water parameters between dry and rainy seasons
PARAMETER PAIR MEAN±SE N SD df TCalc Sig(2-tailed) RMKS
Temperature (oC) Dry season
Rainy season
29.5±0.36
26.7±0.24
15
15
1.39
0.92
14
14
6.536 0.000 S
pH Dry season
Rainy season
7.6±0.18
7.4±0.16
15
15
0.69
0.64
14
14
1.015 0.319 NS
Turbidity (NTU) Dry season
Rainy season
68.77±20.91
111.35±33.86
15
15
81.01
131.14
14
14
-1.070 0.294 NS
EC (µs/cm) Dry season
Rainy season
816.79±37.87
651.40±33.70
15
15
146.65
130.52
14
14
3.263 0.003 S
TDS (mg/l) Dry season
Rainy season
477.1±24.39
364.2±18.85
15
15
94.46
73.02
14
14
3.662 0.001 S
Total coliform(x104 cfu/ml) Dry season
Rainy season
8.6±1.54
7.9±0.47
15
15
5.97
1.84
14
14
0.430 0.673 NS
Faecal coliform(x104 cfu/ml) Dry season
Rainy season
7.8±0.70
9.3±0.47
15
15
2.69
1.82
14
14
-1.787 0.085 NS
Aluminium (mg/l) Dry season
Rainy season
0.146±0.028
0.535±0.129
15
15
0.11
0.50
14
14
-2.951 -2.951 S
Cadmium (mg/l) Dry season
Rainy season
0.063±0.018
0.252±0.100
15
15
0.07
0.39
14
14
-1.853 0.084 NS
Lead (mg/l) Dry season
Rainy season
0.067±0.020
0.518±0.167
15
15
0.08
0.52
14
14
-2.680 0.018 S
Chromium (mg/l) Dry season
Rainy season
0.081±0.021
0.372±0.121
15
15
0.08
0.37
14
14
-2.378 0.031 S
Table 4. Paired sample T-test for difference in concentration of water parameters between streams and wells in dry season.
PARAMETER PAIR MEAN±SE N SD df TCalc Sig(2-tailed) RMKS
Temperature (oC) Well water
Stream water
29.1±0.32
29.5±0.36
15
15
1.23
1.39
14
14
-1.049 0.312 NS
pH Well water
Stream water
6.8±0.13
7.6±0.18
15
15
0.51
0.69
14
14
-5.655 0.000 S
Turbidity (NTU) Well water
Stream water
111.47±45.94
68.77±20.91
15
15
177.91
81.01
14
14
1.518 0.151 NS
EC (µs/cm) Well water
Stream water
822.31±35.65
816.79±37.87
15
15
138.06
146.65
14
14
0.137 0.893 NS
TDS (mg/l) Well water
Stream water
474.6±18.50
477.1±24.39
15
15
71.65
94.46
14
14
-0.110 0.914 NS
Total coliform(x104 cfu/ml) Well water
Stream water
5.8±0.44
6.1±0.59
15
15
2.98
3.97
14
14
-0.560 0.578 NS
Faecal coliform(x104 cfu/ml) Well water
Stream water
5.1±0.27
8.0±0.37
15
15
1.83
2.46
14
14
-8.359 0.000 S
Aluminium (mg/l) Well water
Stream water
0.102±0.013
0.146±0.028
15
15
0.05
0.11
14
14
-1.615 0.129 NS
Cadmium (mg/l) Well water
Stream water
0.010±0.003
0.063±0.018
15
15
0.01
0.07
14
14
-3.009 0.009 S
Lead (mg/l) Well water
Stream water
0.016±0.003
0.067±0.020
15
15
0.01
0.08
14
14
-2.582 0.022 S
Chromium (mg/l) Well water
Stream water
0.021±0.005
0.081±0.021
15
15
0.02
0.08
14
14
-3.255 0.006 S
Table 5. Paired sample T-test for difference in concentration of water parameters between streams and wells in rainy season.
PARAMETER PAIR MEAN±SE N SD df TCalc Sig(2-tailed) RMKS
Temperature (oC) Well water
Stream water
25.5±0.30
26.7±0.24
15
15
1.14
0.92
14
14
-3.885 0.002 S
pH Well water
Stream water
6.9±0.15
7.4±0.16
15
15
0.59
0.64
14
14
-2.563 0.023 S
Turbidity (NTU) Well water
Stream water
111.35±33.86
68.77±20.91
15
15
131.14
81.01
14
14
1.765 0.099 NS
EC (µs/cm) Well water
Stream water
792.2±55.22
651.40±33.70
15
15
213.89
130.52
14
14
3.902 0.002 S
TDS (mg/l) Well water
Stream water
444.9±30.50
364.2±18.85
15
15
118.13
73.02
14
14
4.010 0.001 S
Total coliform(x104 cfu/ml) Well water
Stream water
6.9±0.69
7.9±0.47
15
15
2.67
1.84
14
14
-2.356 0.034 S
Faecal coliform(x104 cfu/ml) Well water
Stream water
7.9±0.59
9.3±0.47
15
15
2.29
1.82
14
14
-3.029 0.009 S
Aluminium (mg/l) Well water
Stream water
0.153±0.028
0.535±0.129
15
15
0.11
0.50
14
14
-2.930 0.011 S
Cadmium (mg/l) Well water
Stream water
0.014±0.005
0.252±0.100
15
15
0.02
0.39
14
14
-2.454 0.028 S
Lead (mg/l) Well water
Stream water
0.016±0.005
0.518±0.167
15
15
0.02
0.65
14
14
-3.043 0.009 S
Chromium (mg/l) Well water
Stream water
0.027±0.006
0.372±0.121
15
15
0.02
0.47
14
14
-2.899 0.012 S

3.4. Difference in water parameters between streams and wells in rainy season

Differences in concentrations between stream and wells in rainy seasons showed that aside turbidity, all water parameters were significantly different (p<0.05) between well and streams during the rainy season (Table 5).

3.5. Correlation of water parameters between streams and wells in dry season

Water parameters between streams and wells in dry season (Table 6) showed that pH, Turbidity Cr conc. and faecal coliform counts of streams in dry season positively and significantly correlated with wells at P<0.05. The Temperature, EC, TDS, Total coliform, Al, Cd and Pb levels of stream also positively correlated with wells, though not significant at P>0.05 (Table 6)

3.6. Correlation of water parameters between streams and wells in rainy season

In the rainy season, the Turbidity, EC, TDS, and Cd, of streams positively and significantly correlated with well water at P<0.05. Temperature, pH, Al, Pb, were also positive but not significant. Conversely, the Total coliform and faecal coliform counts were negatively correlated between stream and wells respectively p>0.05 (Table 7).

Table 6. Correlation of water parameters between streams and wells in dry season.
PARAMETER PAIR MEAN±SE N SD df PEARSON CORRE
LATION
Sig(2-tailed) RMKS
Temperature (oC) Well water
Stream water
29.1±0.32
29.5±0.36
15
15
1.23
1.39
14
14
0.236 0.398 NS
pH Well water
Stream water
6.8±0.13
7.6±0.18
15
15
0.51
0.69
14
14
0.544 0.036 S
Turbidity (NTU) Well water
Stream water
111.47±45.94
68.77±20.91
15
15
177.91
81.01
14
14
0.914 0.000 S
EC (µs/cm) Well water
Stream water
822.31±35.65
816.79±37.87
15
15
138.06
146.65
14
14
0.398 0.141 NS
TDS (mg/l) Well water
Stream water
474.6±18.50
477.1±24.39
15
15
71.65
94.46
14
14
0.446 0.095 NS
Total coliform(x104 cfu/ml) Well water
Stream water
5.8±0.44
6.1±0.59
15
15
2.98
3.97
14
14
0.217 0.153 NS
Faecal coliform(x104 cfu/ml) Well water
Stream water
5.1±0.27
8.0±0.37
15
15
1.83
2.46
14
14
0.414 0.005 S
Aluminium (mg/l) Well water
Stream water
0.102±0.013
0.146±0.028
15
15
0.05
0.11
14
14
0.243 0.383 NS
Cadmium (mg/l) Well water
Stream water
0.010±0.003
0.063±0.018
15
15
0.01
0.07
14
14
0.361 0.187 NS
Lead (mg/l) Well water
Stream water
0.016±0.003
0.067±0.020
15
15
0.01
0.08
14
14
0.221 0.429 NS
Chromium (mg/l) Well water
Stream water
0.021±0.005
0.081±0.021
15
15
0.02
0.08
14
14
0.597 0.019 S
Table 7. Correlation of water parameters between streams and wells in rainy season.
PARAMETER PAIR MEAN±SE N SD df PEARSON CORRELATION Sig(2-tailed) RMKS
Temperature (oC) Well water
Stream water
25.5±0.30
26.7±0.24
15
15
1.14
0.92
14
14
0.299 0.279 NS
pH Well water
Stream water
6.9±0.15
7.4±0.16
15
15
0.59
0.64
14
14
0.398 0.142 NS
Turbidity (NTU) Well water
Stream water
111.35±33.86
68.77±20.91
15
15
131.14
81.01
14
14
0.708 0.003 S
EC (µs/cm) Well water
Stream water
792.2±55.22
651.40±33.70
15
15
213.89
130.52
14
14
0.775 0.001 S
TDS (mg/l) Well water
Stream water
444.9±30.50
364.2±18.85
15
15
118.13
73.02
14
14
0.766 0.001 S
Total coliform(x104 cfu/ml) Well water
Stream water
6.9±0.69
7.9±0.47
15
15
2.67
1.84
14
14
-0.821 0.000 S
Faecal coliform(x104 cfu/ml) Well water
Stream water
7.9±0.59
9.3±0.47
15
15
2.29
1.82
14
14
-0.680 0.005 S
Aluminium (mg/l) Well water
Stream water
0.153±0.028
0.535±0.129
15
15
0.11
0.50
14
14
0.047 0.868 NS
Cadmium (mg/l) Well water
Stream water
0.014±0.005
0.252±0.100
15
15
0.02
0.39
14
14
0.655 0.008 S
Lead (mg/l) Well water
Stream water
0.016±0.005
0.518±0.167
15
15
0.02
0.65
14
14
0.434 0.106 NS
Chromium (mg/l) Well water
Stream water
0.027±0.006
0.372±0.121
15
15
0.02
0.47
14
14
-0.408 0.131 NS

4. DISCUSSION

Generally, the study revealed that the water from wells in Ondo city contained high coliform bacteria. These coliform counts were higher than the WHO standard which stated that coliforms or faecal coliform must not be detectable in any 100ml of drinking water [12]. Similar studies also recorded high values for Total coliform counts in various groundwater wells [13, 14]. The mean faecal coliform count of the wells in this study was generally higher in the rainy season (12.10 x 104 cfu/ml) than in the dry season (8.40 x 104cfu/ml). attributed to excess rainwater that infiltrates and percolates the soil which could facilitate microbes transport.[15]. In another reported work of [16], the impacts of leaking sewers on urban groundwater produce a potential risk for soil and groundwater contamination. Beside the proximity of understudied wells to polluted streams, various other factors such as well depth, prevailing weather condition, orientation of wells to sewage pit, well properties and nature of well-site could have facilitated the migration and entrance of faecal contaminants from streams into well water.

The Pearson correlation matrix of well water and associated streams for most of the parameter tested were positive during the dry and rainy season. The total and faecal coliform counts correlation of well to streams during the dry season were also positive but not significant. This result conforms to the observations [17, 19] that reported a positive correlation between well distance and bacterial counts of well water samples; thus, suggesting the closeness of polluted stream as a factor for well contamination.

Contrarily, the rainy season correlation of the faecal coliform count to the distances between wells and streams was negative, which is in agreement with another work [20] which did not find any association between the bacteriological quality of dug-well and distance to the nearest pollution source probably due to the season of the year in which the study was conducted. However, the low significant negative correlation recorded in the rainy season with respect to total and faecal coliform contamination may be a result of increasingly high water activity which might have led to constant disengagement of bacterial adhesion and proliferation as against the dry season’s lesser water activity and warmer temperature that aid bacterial growth. Some other factors such as underlying rocks and seepage propensity, or other edaphic factors could also contribute to well water contamination [19].

Additionally, most of the wells recorded a mean value of metal presence that is higher than both desirable and permissible limits. This high metal contamination may be attributed largely to the disposal of batteries, lead-based paints and other industries based wastes into the streams which could have seeped into wells. The positive correlations of heavy metal contaminants recorded between stream water and well water also corroborates the findings of other studies [21] and [22].

CONCLUSION

Findings from this research revealed that most wells studied in Ondo city failed quality standards measured. Positive correlations of well and streams parameters also suggest reasonable levels of influence, which associated polluted streams exerted on the groundwater tested. The primary treatment of water by boiling, filtering before use for drinking, cooking and washing should also be encouraged. In addition to this, there should be restrictions on the disposal of domestic solid wastes on water bodies and stream whether close or far from hand dug wells.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

Not applicable.

HUMAN AND ANIMAL RIGHTS

No animals/humans were used for studies that are the basis of this research.

CONSENT FOR PUBLICATION

Not applicable.

AVAILABILITY OF DATA AND MATERIALS

The authors confirm that the data supporting the findings of this study are available within the article.

FUNDING

None.

CONFLICT OF INTEREST

The authors declare no conflict of interest, financial or otherwise.

ACKNOWLEDGEMENTS

Declared none.

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