A comprehensive assessment of groundwater quality for drinking purpose in a Nigerian rural Niger delta community

Journal Pre-proof A comprehensive assessment of groundwater quality for drinking purpose in a Nigerian rural Niger delta community H.I. Owamah PII:

S2352-801X(18)30304-7

DOI:

https://doi.org/10.1016/j.gsd.2019.100286

Reference:

GSD 100286

To appear in:

Groundwater for Sustainable Development

Received Date: 26 December 2018 Revised Date:

13 July 2019

Accepted Date: 6 October 2019

Please cite this article as: Owamah, H.I., A comprehensive assessment of groundwater quality for drinking purpose in a Nigerian rural Niger delta community, Groundwater for Sustainable Development (2019), doi: https://doi.org/10.1016/j.gsd.2019.100286. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.

A comprehensive assessment of groundwater quality for drinking purpose in a Nigerian rural Niger Delta community a*

H. I. a*Owamah Department of Civil Engineering, Faculty of Engineering, Delta State University, PMB1, Abraka, Oleh Campus, Delta State, Nigeria *Email: [email protected]; [email protected] *Tel: +2348035705814

Abstract This study gives a first time comprehensive report on the quality of groundwater in Emevor community in the Niger Delta region of Nigeria, for dry and wet season monitoring. Water samples were collected from ten (10) bore-holes (BHs) and 10 hand-dug wells (HDWs), on monthly basis, for eight (8) consecutive months spanning from May to August, 2016 (wet season) and October 2016 to January 2017 (dry season). Following standard procedures, thirtythree (33) water quality parameters were analyzed. But for pH being less and Ba higher than the prescribed values of the WHO and SON, all other physicochemical parameters were within the WHO and SON standards. While the low pH value was linked to mineral dissolution, the high Ba value was attributed to oil exploration activities in the area. The main mineral classes in the aquifer (Calcium-Iron, Sodium-Magnesium and Zinc-Potassium) were found to be the determinants of the groundwater chemical composition and ionic exchanges. ANOVA showed a significant difference in the concentration of parameters that exceeded regulatory limits for BHs and HDWs. Microorganisms isolated from the water samples obtained from BHs and HDWs are Enterobacter aerogenes and E. coli. The higher organic pollution recorded for the HDWs corroborated the higher values of E. coli obtained. By implication, this study shows that BHs were safer drinking water sources in the community. Regular monitoring of groundwater in Emevor and neighboring communities is recommended given the increase in anthropogenic activities in the area of study. Keywords: Groundwater, quality parameters, public health, pollution, Niger-Delta

1

A comprehensive assessment of groundwater quality for drinking purpose in a Nigerian

2

rural Niger Delta community

3 4

Abstract

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

This study gives a first time comprehensive report on the quality of groundwater in Emevor community in the Niger Delta region of Nigeria, for dry and wet season monitoring. Water samples were collected from ten (10) bore-holes (BHs) and 10 hand-dug wells (HDWs), on monthly basis, for eight (8) consecutive months spanning from May to August, 2016 (wet season) and October 2016 to January 2017 (dry season). Following standard procedures, thirty-three (33) water quality parameters were analyzed. But for pH being less and Ba higher than the prescribed values of the WHO and SON, all other physicochemical parameters were within the WHO and SON standards. While the low pH value was linked to mineral dissolution, the high Ba value was attributed to oil exploration activities in the area. The main mineral classes in the aquifer (Calcium-Iron, Sodium-Magnesium and Zinc-Potassium) were found to be the determinants of the groundwater chemical composition and ionic exchanges. ANOVA showed a significant difference in the concentration of parameters that exceeded regulatory limits for BHs and HDWs. Microorganisms isolated from the water samples obtained from BHs and HDWs are Enterobacter aerogenes and E. coli. The higher organic pollution recorded for the HDWs corroborated the higher values of E. coli obtained. By implication, this study shows that BHs were safer drinking water sources in the community. Regular monitoring of groundwater in Emevor and neighboring communities is recommended given the increase in anthropogenic activities in the area of study.

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Keywords: Groundwater, quality parameters, public health, pollution, Niger-Delta

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Introduction

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One of the essential requirements for the sustenance of life and good health is water (Abubakar,

26

2018a). Within the last two decades, the world has recorded some achievements in the area of

27

improvement of access to improved drinking water (IDW) and hygiene in line with the Sustainable

28

Development Goals (SDGs) (WHO/UNICEF JMP Report, 2015; Abubakar, 2016, Kulinkina et al.,

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2017). IDW source could be described as a source well protected from external contamination, in

30

particular, faecal matter (Abubakar, 2018b). Report has shown that globally, more than 2.6 billion

31

people gained access to IDW sources since the 1990s (Mkwate et al., 2017). This achievement

32

notwithstanding, access to IDW is still a problem as about 663 million people in the world are yet

33

to have access to IDW sources (Mkwate et al., 2017). This has made many people depend heavily

34

on untreated water from private boreholes, unprotected shallow wells, streams, rivers etc.

35

(WHO/UNICEF JMP, 2015).

1

36

While with a population of 319 million people, as at 2015, only 24% of the people in Sub-Saharan

37

Africa had access to improved drinking water (IDW). Latin America and Caribbean, West Asia

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and North Africa, East Asia and South-east Asia had theirs as 65%, 90% and 94% respectively

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(UNICEF/WHO, 2017, p. 3; Abubakar, 2018). It is also worthy to note that 70% of the global

40

population that depends on surface water for drinking reside in sub-Saharan bet (UNICEF/WHO,

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2015 p. 11). While 723 million new users of piped water were recorded in the Eastern part of Asia

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between 1990 and 2015, a decline from 43% to 33% was obtained in the sub-Saharan African

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(UNICEF/WHO, 2015, p. 9). In Nigeria, 67% of the population were reported in 2015 to have had

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access to improved drinking water sources. This was however still short of meeting with the 77%

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MDG goal and much less than the global mean of 91% (UNICEF/WHO, 2015, p. 9). The Nigeria

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Demographic and Health Surveys of 2013 showed that 50.8% (rural) and 14.4% (urban) of

47

Nigerian households used unimproved drinking water sources (Abubakar, 2019).

48 49

Drinking of contaminated water alongside inadequate hygiene and poor sanitation has been

50

indicted of being directly or indirectly, the cause of over a million annual global deaths (WHO,

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2012). It has also been reported that not less than eighty percent (80%) of all water-borne diseases

52

in developing nations are traceable to drinking of contaminated water, poor hygiene, and open

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defecation (Abubakar, 2018). About 50% and one fifth of these people without access to improved

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drinking water sources in the world reside in Sub-Saharan Africa (SSA) and Southern Asia

55

respectively (Mkwate et al., 2017). Recently, countries in SSA were reported to have recorded

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some achievements, as forty-three percent of their population now have access to potable water.

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This is however, through private boreholes that are mostly not tested for quality (WHO/UNICEF

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JMP, 2015). Nigeria, with it a 2017 estimated population of more than 190 million people, is a

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notable nation in the Sub-Saharan Africa (NPC, 2017). She however, still

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challenges in the in the area of provision of IDW, given the near absence of treated public water

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supply scheme, especially in the rural areas and small towns. This has thus, made a lot of people

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resident in Nigerian depend on groundwater for drinking (Dahunsi et al., 2014). Though some

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groundwater drinking water quality studies have been carried out on mostly, urban cities of

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Nigeria, with findings showing that many of the wells were contaminated with faecal bacteria and

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in some cases, other pollutants (Owamah et al., 2013; Dahunsi et al., 2014; Sojobi, 2016), such

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extensive drinking water quality studies cannot be said of rural communities that are even more 2

has enormous

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prone to anthropogenic activities that create water contaminants such as open defecation, careless

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disposal of waste materials on the soil, open dumps, unsanitary systems of sewage disposal, siting

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of water wells near pit latrines and septic tanks etc. (Sojobi, 2016).

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Furthermore, Nigeria in the last 20 years, has witnessed an unprecedented growth in the number of

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individual boreholes but drinking water from these, especially the ones in rural communities, are

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rarely checked for quality compliance (Owamah et al., 2013). Detailed scientific information on

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the quality of groundwater used as source of drinking water is crucial for the formulation of

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policies relating to water supply and public health. It is however noteworthy to state that only little

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or none of such about Emevor community in the Niger-Delta region of Nigeria is available in

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scientific literature. This research was therefore carried out to critically assess the quality status of

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groundwater in the study area to serve as baseline water quality data for the community and other

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Isoko neighboring communities with similar geological formation and anthropogenic activities.

79

2. Materials and methods

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2.1.Study Area

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Emevor is one of the popular communities in the Isoko North Local Government Area

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(INLGA), Delta State, Nigeria. The siting of the National Open University of Nigeria study

83

center in Emevor has increased both her population and pressure on resources such as water.

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Fig. 1a shows that the INLGA lies between 50 − 20′ and 50 − 37′ north latitudes and 6 0 − 12′

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and 6 0 − 13′ east longitudes. The map of Nigeria showing Delta State is also shown in Fig. 1b.

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The INLGA is made up of eight clans and a total of 43 communities with two unique climatic

87

seasons. The wet season (WS) runs from March through August while the dry season (DS)

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begins from September to end in February (Agbogidi et al. 2007). The INLGA with

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predominantly rainforest vegetation, has a mean annual precipitation of 2800 mm, monthly

90

temperature of 310C and relative humidity range of 76- 90%

91

INLGA with a population of about 140,000 persons as at 2006 is well known as a major crude

92

oil producing LGA in Nigeria (Owamah et al., 2013).

93 94

2.2. Sampling and analysis

3

(Owamah et al., 2013). The

95

Following standard methods, water samples were obtained in triplicate from randomly selected

96

sites (APHA, 2012). Because Emevor community has ten (10) small distinct villages, water

97

samples were collected from ten (10) bore-holes [BHs] (wells with electric pump) and 10

98

hand-dug wells[HDWs] (artificial pumpless wells), on monthly basis, for eight (8) consecutive

99

months spanning from May to August, 2016 (wet season) and October 2016 to January 2017

100

(dry season) as shown in Fig. 1a. (Sojobi, 2016). Collection of samples was done in a manner

101

that ensured that each of the ten small villages that make up the community had two wells (BH

102

and HDW) sampled. New polyethylene bottles, washed three times on site with the same water

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to be sampled, were used for samples collection. Preservation of samples was done in line with

104

standard protocol (APHA, 2012).

105

Samples for physico-chemical and microbial investigations were placed in an ice-containing

106

box before being transported to Dukoria Laboratories, Nigeria for water quality analyses.

107

Concentrated HNO3 was used for the preservation of water samples meant for metal analysis.

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Thirty BH and HDW water samples were respectively obtained monthly to give 240 samples

109

each of BHs and HDWs (120 per climatic season). Samples were stored at 40C, using a

110

refrigerator, to ensure that contents remained intact prior to laboratory analyses.

111

2.3.

Analytical procedures

112

Adopting standard protocol, samples were analyzed for numerous physicochemical parameters

113

(Emenike et al., 2018). Turbidity was measured in-situ with a movable 2100P turbidimeter

114

(HACH). pH, total dissolved solids (TDS) and electrical conductivity (EC) were determined

115

with a movable multimeter (Hanna Instruments, Model HI 9812). The concentrations of the

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other physicochemical parameters (Na, Ca, Mg, K, NO3-, Cl-, NO3-, HCO3-, SO42-, Fe, Ba, Cu,

117

Pb, Ca etc.) were determined in the laboratory. Following APHA (2012) and Owamah (2013),

118

anions were measured with an ultraviolet (UV) spectrophotometer (DR 2800, HACH, USA)

119

through the (UV) spectrophotometer screening method.

120

The analysis of the concentration of metals was done using an atomic absorption

121

spectrophotometer (AAS) (Sens AA 3000, GBC, Australia) in accordance with procedures

122

outlined in APHA (2012). The estimation of the faecal coliforms (FC) bacteria was through the

123

use of the membrane filtration technique (APHA, 2012). Standard plate count method was

124

adopted to count the bacterial colonies that are visible in “colony forming units” (CFU) /100

125

mL. The other physiochemical parameters were measured in accordance with standard 4

126

methods outlined in APHA (2012) and Khan et al. (2013). The mean of data gotten for the

127

various physicochemical and biological parameters were compared with the drinking water

128

standard of the WHO and SON. The correlational relationships among the parameters tested

129

were also investigated. For reproducibility sake, blank, pre-analyzed and standard samples

130

were analyzed after every ten (10) samples (Owamah et al., 2013).

131

2.4. Statistical analysis

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In-situ and laboratory data obtained were analyzed with Microsoft Excel (2010 version) to

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compute mean, standard deviation (SD) and correlation coefficient (CC) (Sojobi, 2016). The

134

mean groups of variables were compared using the Analysis of Variance (ANOVA) at 95%

135

confidence level. Patterns among the result variables were shown in graphs and tables

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(Emenike et al., 2018).

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3. Results and Discussion

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3.1.

Physicochemical and microbiological parameters

139

The statistics of the experimental data obtained from this study are displayed in Tables 1 and 2

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for wet and dry seasons respectively. pH values ranged from 4.92 to 6.28 and 6.50 to 4.82 for

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the wet and dry seasons respectively. Average values were 5.63 (wet) and 5.55(dry) to give a

142

seasonal mean variation of 0.08. Greater values were recorded in the peak of the WS. This

143

could be attributed to dilution effect as water level rose, thereby making the pH move from

144

slightly acidic toward neutral. In both seasons, while the BH water samples were generally

145

more acidic than those of the HDWs, the most acidic values were obtained from BH samples of

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DS (Fig. 2a.). The highest pH value (6.50) was obtained in a sample collected from a HDW in

147

November. These pH values corroborate information in literature on the groundwater quality of

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communities in the Niger Delta region of Nigeria (Owamah et al., 2013).

149

Since the stipulated pH range of the WHO and SON goes from 6.50 – 8.50 (Table 3), it shows

150

that groundwater in the community is generally acidic and needs to be given some chemical

151

treatment to bring it to normal. pH of less than 6.5 could cause gastrointestinal irritation in

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humans and would therefore require alkaline treatment for improvement to the required range

153

of 6.5–8.5 (Sojobi, 2016). The acidic nature of groundwater in the area of study could be

154

linked to the geological formation of the area (Owamah et al., 2013; Egboh and Emeshie,

5

155

2008). Sojobi (2016), and Akinyemi and Souley (2014) had earlier reported acidic pH values

156

(<6.5) for the groundwater of Omu-Aran, Kwara State and Ogun State of Nigeria, respectively.

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The TDS of the study area groundwater showed average values of 41.93 mg/L (WS) and 40.65

158

mg/L (DS). Seasonal mean variation value of 1.28 mg/L (wet-dry) was also obtained. Actual

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values ranged from (33.00-53.70) mg/L in the WS and (32.80-49.00) mg/L in the dry season.

160

The highest WS and DS values were respectively recorded in October and December. BH

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water samples, generally, had higher TDS values than those of HDWs; showing that it is more

162

of natural than anthropogenic cause.

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The WHO and SON prescribed maximum TDS value of 250 mg/L (Table 3) is well above the

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values obtained in the study. Since the mean TDS values for the BH and HDW water samples

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for both seasons are less than 1gL−1, it shows that groundwater in Emevor is freshwater

166

(Sojobi, 2016; Emenike et al., 2018). Though the SON and WHO stipulated limit is 5.00 NTU,

167

turbidity was not detected in any of the samples. This could be very deceptive, if used by the

168

residents to consider their groundwater water clean and safe (Akhtar et al., 2014). Electrical

169

conductivity (EC) being a function of dissolved mineral matter, has a direct relationship with

170

TDS. For the wet and dry seasons, the average EC values obtained were 77.21µS/cm and 78.92

171

µS/cm respectively and had -1.71µS/cm as the seasonal mean variation. As shown in Fig. 2c,

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the highest conductivity value of 98.55 µS/cm was found in a BH water sample of DS in the

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month of December. This value is within the WHO prescribed limit of 1,000 µS/cm. The

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mean EC values of 77.21µS/cm and 78.92µS/cm further show that the groundwater is

175

freshwater since both mean values are less than 1500 µS/cm (Mondal et al., 2008; Sojobi,

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2016). Conductivity is a function of the total ionic composition of water and thus shows its

177

level of chemical richness. It is usually boosted by sodium, magnesium, calcium, other

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minerals and the geology of the soil. The electrical conductivity of natural waters is mainly due

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to dissolved mineral matter (Ademoroti, 1996). Tables 1 and 2 show that Emevor groundwater

180

is not saline as salinity was not detected in all of the samples for both wet and dry seasons. The

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maximum acceptable limit is however 200‰ (Table 3).

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While the mean value of TSS in the WS is 0.38 mg/L, it was not detected in the DS for all

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samples. Only few samples showed results for TSS and this corroborates the finding in this

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study that turbidity was not detected in all of the water samples. The presence of suspended

185

solids in water affects the clarity of the water and makes it unaesthetic. Though there is no 6

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guideline limit stipulated for TSS by the WHO and SON, previous studies showed that TSS of

187

1000mg/L is acceptable (Sojobi, 2016). The alkalinity values of the groundwater were found to

188

be on the average of 8.50 mg/L and 6.73mg/L in the WS and DS respectively to give a mean

189

seasonal variation of 1.77 mg/L. Similar values were earlier obtained by Egboh and Emeshie

190

(2008) for groundwater in the neighbouring Ndokwa East Local Government Area. Alkalinity

191

was only not detected in samples with low pH values, there was no distinct pattern of seasonal

192

variation as the presence of alkalinity depends on pH of solution. However, the overall values

193

were relatively higher in the HDW samples of the WS as shown in Tables 1 and 2. Although

194

there are no regulatory guideline values for alkalinity by the WHO and SON, values obtained

195

in this study lie within the safe limits in literature (Dahunsi et al., 2014). Chemical oxygen

196

demand (COD) is a measure of the required oxygen for complete oxidation of carbon (IV)

197

oxide and organic matter present in a sample of water. Tables 1 and 2 show that COD was only

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slightly detected. The seasonal mean values were 1.62mg/L (WS) and 2.28mg/L (DS). This

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resulted in a negative seasonal mean variation of -0.66 mg/L, indicative of higher COD values

200

in the dry season. These mean values are less than the maximum desired value of 5 mg/L by

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the WHO and hence, in order.

202

For the case of ammonia-nitrogen, though no value was detected in the wet season, some

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samples in the DS had variable values. The seasonal mean value calculated for the DS was

204

2.41mg/L. The major sources of ammonia in groundwater could be excessive availability of

205

nitrogen in the soil following indiscriminate disposal of nitrogen reach organic substances on

206

the soil. The desired level of NH3-N in drinking water is 0.5mg/L (SON, 2007). Water with

207

higher values need to be treated chemically to acceptable limit. The measurement of colour and

208

appearance are important indices in ascertaining the aesthetic acceptability of potable water.

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Pure water is usually colourless and insipid. Colour was not detected in all the samples. While

210

total organic carbon (TOC) was not detected in many of the WS water samples, values

211

obtained in the DS ranged from 0.01 to 0.80%. The DS mean value is 0.28%. In the same vein,

212

total hydrocarbon was not detected in most of the samples for both seasons. The DS however

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had a mean value of 0.01mg/L.

214

Odour, calculated as threshold odour intensity number (TON) was not detected in any of the

215

samples analyzed. Ideally, drinking water should not have any detectable odour. Odour in

216

drinking water usually shows that pollution had occurred in the water source. Total hardness, 7

217

defined in terms of the total concentration of calcium and magnesium ions expressed as

218

calcium carbonate showed seasonal mean values of 15.63mg/L (wet) and 10.75mg/L (dry) with

219

a variation of 4.88 mg/L. The peak and least values of 25.00 mg/L and 8.00 mg/L were

220

obtained from HDWs in the months of August and February, respectively.

221

obtained are far lower than the WHO and SON guideline values (Table 3). Furthermore, since

222

the mean values are less than 50.00 mg/L, the groundwater is classified as soft water (Owamah

223

et al., 2013; Abd El Salam and Abu-Zuid, 2015). Ejoh et al. (2018) also found water from

224

Egini and Ubogo rivers, in the Niger Delta region of Nigeria to be soft. Water hardness poses

225

no real health threat but may result in soap wastage.

The values

226 227

There were no values of total phosphorous in the WS unlike the DS that had considerably low

228

values from few samples collected from the HDWs. The DS mean value calculated is

229

0.02mg/L. Phosphorous compounds occur in natural water, effluent and sludge almost entirely

230

in phosphate forms (Ademoroti, 1996). Phosphate in drinking water of ≤75mg/L has been

231

reported to pose no health risk in drinking water (Owamah et al., 2013). The obtained values in

232

this study therefore show that phosphorous has no health-related impact on the groundwater of

233

the study area. The detection of phosphorous at an insignificant level unlike the nitrogen

234

related contaminants shows that wastewater effluent and other solid waste from the community

235

could be mainly nitrogenous. Sojobi et al. (2016) obtained mean phosphate values of 14.27

236

mg/L and 15.6 mg/L respectively for BHs and HDWs of Omu-Aran, Kwara State, Nigeria.

237

Values of 27.5 ± 0.9 mg/L and 6.8–18.8 mg/L were obtained for boreholes in different cities of

238

Northeastern Nigeria and were linked to domestic effluent, fertilizer and open defecation

239

(Ishaku et al., 2011). HCO3- was not detected in many samples of the wet season. The seasonal

240

mean values are 10.37mg/L (wet) and 3.30mg/L (dry) with a seasonal mean variation of 7.07

241

mg/L. The values of the SD show that the variation pattern for rainy and dry seasons were

242

random and suggestive of being caused by anthropogenic activities (Sojobi, 2016). The

243

seasonal mean values obtained for chloride are 5.50mg/L and 13.63mg/L for dry and wet

244

seasons respectively. The highest was obtained in the WS, from a HDW water sample, in the

245

month of October.

246

Egboh and Emeshie (2008) also found greater levels of chloride in the WS for communities in

247

the neighbouring Ndokwa East Local Government Area of Delta State. Similar values were 8

248

also reported for several neighbouring communities by Owamah et al. (2013). The presence of

249

large concentration of chloride in water could be as a result of natural processes like the

250

passage of water through salty hydrogeological formations or pollution from sea water

251

intrusion. The values obtained as shown in Tables 1 and 2 are below the maximum guideline

252

value of 200.00 mg/L stipulated by the SON. The mean nitrate (NO3-) values obtained in this

253

study are 2.88 mg/L and 3.03 mg/L for BH and HDW water samples, respectively. A higher

254

nitrate (0.02–42.45 mg/L) was obtained by Devic et al. (2014) and they attributed it to the

255

activities of the residents. Ingestion of NO3- above permissible limits could cause

256

methemoglobinemia in kids (Emenike et al., 2018) and in some cases cancer (Sojobi, 2016).

257

Values of nitrate concentration recorded for the study area are below the SON permissible

258

limit of 50 mg/L and WHO limit of 10 mg/L for both seasons and water wells and therefore

259

portends no health risk to residents of the community. Sulphate (SO42-) obtained in the

260

groundwater samples ranged from 1.50 mg/L to 5.00 mg/L in the WS and 2.00 mg/L to 12.00

261

mg/L in the DS. The seasonal mean values are 3.24 mg/L (WS) and 6.63mg/L (DS) with a

262

variation of -3.39 mg/L. Higher values were obtained in the DS from BH water samples.

263

Sulphate is one of the least toxic ions but cathartic problems could be experienced by people

264

when ingested at concentration of 600.00 mg/L and above. Taking in of excess sulphate has

265

also been reported to have caused dehydration (WHO, 1996). The values of SO42- obtained in

266

this study are below the maximum permissible values of 500 and 100.00 mg/L stipulated by

267

WHO and SON respectively. For DO, seasonal mean values obtained are 10.38mg/L (wet) and

268

10.00mg/L (dry) with a mean seasonal variation of 0.38 mg/L. Actual values obtained ranged

269

from 8.00 – 12.00mg/L in both seasons. Borehole and HDW water samples had mean DO

270

values of 9.8 mg/L and DO (9.1 mg/L) respectively. These are all above the minimum SON

271

and WHO recommendations of 7.5 mg/L and 4 mg/L, respectively, and hence in order.

272

The BOD5 values ranged from 4.00 – 6.80 mg/L in the WS and 3.00 – 6.00 mg/L in the DS.

273

Seasonal average values are 4.83mg/L (WS) and 4.78 mg/L (DS) with a seasonal mean

274

variation of 0.05 mg/L. According to Owamah et al. (2013), the highest allowable BOD5 value

275

is 6.00 mg/L. Greater values indicate organic pollution. The HDW water samples were found

276

to have higher mean BOD5 of 5.22 mg/L in comparison with mean value of 4.60 mg/L from

277

BH water samples. This indicates the occurrence of higher organic pollution in HDWs than

278

BHs. The observed higher organic pollution of the HDW water samples could be attributed to 9

279

nearness to septic tanks, and poor design and construction of the HDWs (unsealed wells and

280

wells without caps etc.) in the community. The later could contaminate groundwater as it

281

enables polluted surface water to reach the groundwater without filtration by the soil.

282 283 284

3.2. Microbial contamination

285

The higher organic pollution obtained from the HDW water samples as noticed by its higher

286

BOD5 values corroborates the values of E. coli obtained from water samples of the boreholes

287

and HDWs. Samples from the HDWs had higher mean E. coli value of 228.44 cfu/ml than

288

BHs’ with mean value of 180.56 cfu/ml. HDW water samples also had a mean total coliform

289

count of 2.65 cfu/ml, which is again, greater than the mean value of 0.94 cfu/ml obtained from

290

BH water samples. The values recorded for total coliform count/100ml sample revealed

291

seasonal mean values of 0.38 cfu/ml (WS) and 3.30 cfu/ml (DS). The actual values ranged

292

from 0.00 cfu/ml to 1.80 cfu/ml in the WS and 1.00 cfu/ml to 5.76 cfu/ml in the DS. While

293

greater values were gotten from the HDW samples of dry season, the BH water samples had

294

the least count. The highest value of 5.76 cfu/ml was found in a HDW water sample in the DS

295

of January. The WHO standard is zero count per 100ml and therefore implies that groundwater

296

of the study area is slightly contaminated with fecal matter and need to be treated chemically or

297

by simple boiling. Microorganisms isolated from the water samples obtained from BHs and

298

HDWs are Enterobacter aerogenes and E. coli.

299

The presence of these microorganisms in the water samples, whether pathogenic or non-

300

pathogenic, provides a warning signal that the water should be treated before being used

301

(Abubakar, 2018; Ugochukwu and Ojike (2019). These organisms are typically found in the

302

intestinal tract of animals and humans, grains, plant surfaces and feces (Thakur et al., 2012;

303

Sojobi, 2016). The detection of these organisms in the sampled BH and HDW water samples

304

shows that the groundwater would have had contact with the feces of man and or animals

305

(Mackie, et al. 2006). Agbabiaka and Sule (2010) found E. aerogenes in the borehole water

306

samples of Ilorin metropolis, Kwara State and attributed it to unsanitary surroundings of the

307

water wells, animal litter and fowl droppings. Sojobi (2016) recorded similar finding in his

308

study of groundwater in Omu-Aran, Kwara State. The study attributed the bacterial

309

contamination to droppings from sheep and goat litter in the community, and the closeness of

10

310

septic tanks to water wells. This is also the situation in Emevor community where goat and

311

poultry litters is easily seen. Poorly constructed water wells are in some cases sited close to

312

poorly constructed septic tanks. Majority of the BHs are also shallow. Okiki and Ivbijaro

313

(2013) and Thakur et al. (2012) had earlier reported the presence of E. aerogenes in the water

314

samples of HDWs and boreholes in Imota, Lagos, Nigeria and Sloan, Pradesh. Jacinta and

315

Adebayo (2015) found E. coli and E. aerogenes in the boreholes and HDWs of Gwagwalada

316

area of Abuja, Nigeria.

317

Though Mackie et al. (2006) reported that E. aerogenes do not cause diseases in healthy

318

persons, Sojobi (2016) revealed that they are of considerable health risks to man given their

319

resistance to common antibiotics. Furthermore, Olufemi and Oluwole (2012) had noted that E.

320

coli and E. aerogenes caused the last cholera outbreak in Ibadan, Nigeria. While there was no

321

detection of fungi in all the water samples of HDWs and BHs, spore-forming yeasts were

322

detected. Yeast contamination of groundwater resource had been reported in Umudike, Benin

323

City, Calabar, and Jos (Sojobi, 2016).

324

It is advisable for residents of Emevor community to treat their groundwater before

325

consumption in order to prevent the outbreak of water-borne diseases in the community as the

326

presence of these microorganisms in the water samples is a warning signal Uzochukwu and

327

Chibike (2018).

328

Though ANOVA test revealed no significant difference (P<0.05) between the physico-

329

chemical parameters of BH and HDW water samples, it indicated that there was a significant

330

difference between the microbial parameters. There was also, no significant difference

331

(P<0.05) in the seasonal variation of the physical and chemical factors obtained. It can

332

therefore be said that though the geological formation in the community is similar, the aquifers

333

through different anthropogenic activities now have different microbiological properties. This

334

is evidenced by the fact that the BH and HDWs were found to have different levels of bacterial

335

contamination even when some were located close to each other.

336 337

3.3.Metals

338

The major cations studied in this research are sodium (Na), potassium (K), magnesium (Mg)

339

and calcium (Ca). Results obtained show that the most abundant of the cations is sodium with

340

the highest concentration value of 18.99 mg/L followed by calcium with the value of 18.00 11

341

mg/L, magnesium (7.80 mg/L) and potassium (13.01mg/L) as found in the water samples

342

collected from BHs in the wet season. The seasonal mean values of the cations (wet – dry) are

343

14.49mg/L –13.92mg/L, 6.89mg/L–6.52mg/L, 10.50mg/L–5.76mg/L and 11.62mg/L–

344

5.30mg/L for sodium, potassium, magnesium and calcium respectively. This showed that the

345

distribution of cations concentration decreased from WS to DS. The observed values are within

346

acceptable WHO/SON limits except for potassium which exceeded the threshold limit value of

347

2 mg/L. K is usually not a serious health related parameter in drinking water quality studies.

348

The other metals studied in this research include Lead (Pb), Cadmium (Cd), Zinc (Zn), Copper

349

(Cu), Iron (Fe) and Barium (Ba).

350

Tables 1 and 2 contain the mean, standard deviation and range of the metals concentrations.

351

The BHs in the WS had a relative abundance for cations (Na>Ca>Mg>K> Ba>Zn>Cu>Fe) and

352

anions (Cl->SO42->NO3-> HCO3-). The HDWs however, had a relative abundance of

353

Na>Ca>Mg>K>Ba>Zn>Cu>Fe for cations and HCO3->Cl->SO42->NO3- for anions. For the dry

354

season, the boreholes had a relative abundance of Na>K>Mg>Ca>Zn>Ba>Cu>Fe for cations

355

and

356

Na>Ca>Mg>K>Ba>Cu>Fe>Zn and Cl-> HCO3-> SO42-> NO3- for cations and anions,

357

respectively. This finding is unlike the relative cations and anions abundance obtained by

358

Devic et al. (2014) which were Ca>Mg>Na>K and HCO3−, SO42− >Cl−> NO3−, respectively.

359

Sojobi (2016) also obtained different cations and anions relative abundance of Na > k > Ca

360

>Mg> Zn > Pb and Cl− >PO42− > SO42− > NO3– respectively, in the BHs, and cations

361

(Ca>Na>K>Mg>Pb) and anions (NO3−> PO42− > SO4

362

Aran groundwater, Kwara State, Nigeria.

363

Mean Na concentration of 12.67 mg/L (boreholes) and 13.82 mg/L (HDWs) obtained, are less

364

tha the SON and WHO stipulated maximum value of 200 mg/L. Todd (1980) reported that

365

sodium could cause corrosion and formation of scale in boilers. High sodium concentration in

366

water can be suggestive of strong water-aquifer interaction due to exchange of cations and or

367

anthropogenic activities like wastewater disposal (Sojobi, 2016). For Mg, the mean

368

concentration values are 10.25mg/L for BHs and 5.12 mg/L for HDWs. Though these mean

369

values exceeded the SON prescribed maximum value of 0.2 mg/L, they are below the WHO

370

maximum limit of 200 mg/L. The relative high Mg value can be associated with the presence

371

of basalts, kaolinite, and hematite in the geological formation of the study area (Owamah et al.,

Cl->SO42->NO3->

HCO3-

for

anions.

12

The

2−

HDWs

however,

had

it

as

> Cl−) in the shallow wells of Omu-

372

2013; Trostle et al., 2014). Values obtained in this study corroborate the finding of

373

Nwankwoala et al. (2014) of mean Mg value of 0.89 mg/L for boreholes in Yenagoa, in the

374

same Niger-Delta Region of Nigeria like the study area. Nwankwoala et al. (2014) linked the

375

presence of the high Mg to dissolution of minerals like feldspar and mica. Anthony et al.

376

(2008) had reported of extreme high concentrations of 68–173 mg/L for groundwater in

377

Manali, India. High magnesium concentration in the groundwater of Serbia was attributed to

378

domestic effluents, chemical fertilizers and minerals (Devic et al., 2014).

379

Though mean Ca values of 8.65 mg/L (BHs) and 12.82 mg/L (HDWs) were less than the 49.3

380

mg/L of Viswanath et al. (2015), they are higher than the 2.97 mg/L for neighboring Yenagoa,

381

Bayesa State, Nigeria as obtained by Nwankwoala et al. (2014) . This suggests that coastal

382

areas may be prone to having lower calcium values in their groundwater, possibly due to the

383

effects of dilution.

384

Since the WHO permissible limit is 200 mg/L, the mean Ca concentration values obtained in

385

this study for both BHs and HDWs are compliant. The presence of Ca in the groundwater of

386

communities in the Niger-Delta Region of Nigeria had been attributed by Nwankwoala et al.

387

(2014) to feldspars and micas dissolution in the groundwater. Kim et al. (2015) however,

388

reported that Ca in groundwater could be as a result of the release of carbonate minerals in the

389

course of the dissolution of silicate compounds. The mean K values in the HDW and borehole

390

water samples are 6.82 mg/L and 5.52 mg/L, respectively, and are above the mean values of

391

4.9 mg/L and 0.91 mg/L recorded respectively by Ishaku et al. (2011) and Trostle et al. (2014).

392

For the other metals studied, as displayed in Tables 1 and 2, the highest concentration of 1.90

393

mg/L was recorded for barium in the month of October in a sample collected from a HDW.

394

Lead and cadmium had the least concentration. Pb was only slightly detected with a value of

395

0.01mg/L in just one sample of the wet season. It was neither detected in the BH or HDW

396

water samples of the dry season, nor had measurable overall seasonal mean values for wet and

397

dry seasons. Lead is therefore not of health concern in the groundwater of the community. Oni

398

and Hassan (2013) found elevated Pb concentration in groundwater samples of wells close to a

399

landfill and reported that Pb in groundwater could be linked to improper disposal of Pb-

400

containing domestic waste substances within the surrounding of water wells especially when

401

there is absence of industrial activities. Pb can lead to subencelophalopathic disorders (Sojobi,

402

2016). Cadmium was not detected in the WS and DS for the BH and HDW samples. Zinc 13

403

concentrations ranged from 0.01 to 1.00mg/L in the WS and from <0.001 to 0.12mg/L in the

404

DS. The overall seasonal mean values are 0.16mg/L in the WS and 0.04mg/L in the DS. For

405

copper, the concentrations ranged from <0.001 to 0.09mg/L in the WS and from <0.001 to

406

0.20mg/L in the DS with seasonal mean values of 0.14mg/L and 0.05mg/L respectively. Iron

407

concentration values ranged from <0.001 to 0.06mg/L in the WS and from <0.001 to 0.05mg/L

408

in the DS with seasonal mean values of 0.03mg/L and 0.03mg/L for wet and dry seasons

409

respectively. Lastly, Barium had values ranging from 0.88 to 1.90mg/L in the WS and from

410

<0.001 to 1.88mg/L in the DS. The overall seasonal mean values for barium are 1.16mg/L for

411

the WS and 0.58mg/L for the DS. Apart from barium, the other metals tested had seasonal

412

mean values that complied with the WHO/SON limit for potable water (Table 3). As shown in

413

Fig. 2b, Ba was higher in the WS for both BHs and HDWs. This could be attributable to

414

greater dissolution of barium containing minerals during the rains.

415

4. Correlation analysis of the physicochemical parameters studied

416

In accordance with the work of Sojobi (2016), the correlation classes adopted for the study are:

417

perfect (R2 = 1), very strong (±0.9 ≤ R2 <1), strong (±0.7 ≤ R2 < ±0.9), moderate (±0.5 ≤ R2 < ±0.7),

418

and weak (R2 < ±0.5). From Table 4, by correlation coefficients (CC), the main cations influencing

419

the presence and concentration of TDS in the groundwater were identified as Ca (0.99), Mg (0.99),

420

Ba (0.99), Fe (-0.98), Na (0.95), and K (0.85). TDS was also, very strongly correlated with BOD5

421

(0.89), NO3- (-0.84), TSS (0.86) and perfectly with dissolved oxygen (DO) (0.97). These results are

422

in accordance with the findings of Emenike et al. (2018); Sojobi (2016) and Viswanath et al. (2015)

423

in which Ca was reported to be an influential factor for the estimation of TDS in groundwater. Table

424

4 also shows that the notable mineral classes influencing the TDS and EC in the study area

425

groundwater are Mg-Ca (0.98), Ca-Fe class (-0.98), Na-K (0.97) and Na-Mg class (0.96). NO3- was

426

associated with Mg-Ca group with CC (-0.91- (0.85) respectively. Mg and Ca were found to have no

427

correlation with Cl-. Following the finding of Skrzypek et al. (2013), the presence of Mg2+ and Ca2+

428

in the groundwater may be associated with other anions. The strong CC of (0.98) between

429

Magnesium and Calcium reflects huge mutual dependence and same anthropogenic sources (Devic

430

et al., 2014; Emenike et al., 2018). NO3- has perfect CC with Cd (0.98) and Mg (-0.91) and very

431

strong CC with Ba (-0.84) showing that it could have come from anthropogenic activities such as the

432

release of domestic wastewater on the environment.

14

433

Table 4 reveals that affinity reactions and ionic exchanges were occurring in the hydrogeological

434

formation of the area of study (Sojobi, 2016; Emenike 2018). While Cl- and SO42- had strong

435

preferential affinity for the anions and cations, NO3- was perfectly correlated with Mg (-0.91) and Cd

436

(0.98).

437

notwithstanding, majority of the anions that make up the aquifer minerals may not prefer the

438

dissolved Mg and hence may be the cause of the high mg concentration in the BH and HDW

439

samples (Sojobi, 2016). Emenike et al. (2018) reported that groundwater chemistry is mainly

440

affected by the dissolution of minerals and the activities of man. pH and EC were respectively found

441

to be, perfectly (0.96) and very strongly (-0.90) correlated with SO42-. Electrical conductivity

442

correlated weakly with DO, Iron, NO3−, Ca and BOD5 showing that the mentioned physicochemical

443

factors may not be appropriate for the estimation of EC in the study area groundwater. This is

444

however, different from the report of Sojobi (2016) for Omu-Aran groundwater, in Kwara State

445

Nigeria.

When an aquifer is rich in magnesium, it will allow its dissolution into it. This

446 447

Table 5 gives a brief of the different groundwater contaminants and their related health effects. It

448

also shows that ground water pollutants vary from location to location as a result of differences in

449

geological formations and anthropogenic activities. Table 6 however compares the results obtained

450

from different previous authors about groundwater quality in different locations of the world with

451

the findings of this study. It can be seen from Table 6, that quality of groundwater in the study area

452

is relatively safer and cleaner than lots of other groundwater studied in the past. However, in line

453

with the SDG 6.1 goal of achieving universal and equitable access to safe and affordable drinking

454

water for all by 2030, the study area needs urgent attention as bacterial and barium contamination

455

found, could have adverse health effects on the community dwellers especially on children and the

456

aged.

457 458

5. Conclusion

459

A detailed evaluation of the quality of groundwater in Emevor community of the Niger-Delta

460

region of Nigeria was carried out. The groundwater was found to be mainly contaminated with

461

coliform bacteria and slightly with Ba. Entero bacteriaceae and Escherichia coli species were

462

also found in the water samples, most especially, the HDWs. The presence of coliform bacteria

463

in the groundwater samples was linked to the nearness of HDWs and BHs to pit-latrines,

15

464

poorly constructed septic tanks and presence of many open dumps in the community. The Ba

465

contamination was linked to oil explorations and processing activities in the region, geological

466

formation and careless disposal of electronic wastes.

467

The study recommends the development of modern sanitary systems in the community and

468

public awareness by the supervising ministry and relevant non-governmental organizations.

469

Though huge priorities should be given to the provision of improved water to the people by

470

government; in the interim, improvement of water quality at household level, through

471

chlorination, addition of alum, filtration, solar disinfection and boiling is advised. This study

472

has been able to generate a broad water quality database for the study area, which could help

473

engineer future water project development in the region.

474 475

Acknowledgement

476

The financial support of the Academic Research and Entrepreneurship Development Initiative, Asaba,

477

Nigeria and the technical support of its Vice-President (consultant Chemist), Mr Samuel Ilabor are

478

highly appreciated.

479 480 481 482 483 484 485 486 487

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Gerlach, R. F., Cury, J. A., Krug, F. J.,& Kine, S. R. (2002). Effect of lead on dental enamel formation. Toxicology, 175, 27–34. Ishaku, J. M., Kaigama, U., & Onyeka, N. R. (2011). Assessment of groundwater quality using factor analysis in Mararaba-mubi area, Northeastern Nigeria. Journal of Earth Sciences and GeotechnicalEngineering, 1(1), 9–33. Jacinta, A. N., & Adebayo, I. A. (2015). Determination of coliforms in different sources of drinking water in Gwagwalada Abuja. Report and Opinion, 7(1), 1–6. Khan, S., Shahnaz, M., Jehai, N., Rehman, S., Shah, M. T.,& Din, S. (2013). Drinking water quality and human health risk in Charsadda district, Pakistan. Journal of Cleaner Production, 60, 93–101. Kulinkina A. V., Plummer, J. D., Chuic, K.H.K., Kosinski, C.K., Adomako-Adjei, T., Egorov, A.I., Nwankwoala, H. O., Amadi, A. N., Oborie, E., & Ushie, F. A. (2014). Hydrochemical factors and correlation analysis in groundwater quality in Yenagoa, Bayelsa State, Nigeria. Applied Ecology and Environmental Sciences, 2(4), 100–105. Machdar, E., N.P. van der Steen, L. Rashid- Sally and P.N.L. Lens, 2013. Application of quantitative microbial risk assessment to analyze the public health risk from poor drinking water quality in a low income area in Accra, Ghana. Science of the Total Environment 449: 134-142. 17

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Vasanthaviger, M., Srinivasamoorthy, K., & Prasanna, M. V. (2013). Identification of groundwater contamination zones and its sources by using multivariate statistical approach in hirumanimuthar sub-basin, Tamil Nadu, India. Environmental Earth Science, 68, 1783– 1795. Verd, V. S., Domingues S. J., Gonzales, Q. M., Vidal, M. M., Mariano, S. A. C., de Roque, C. C., & Sevilla, M. J. M. (1992). Association between calcium content of drinking water and fractures in children (in Spanish). Anales Españoles de Pediatría, 37, 461–465. Viswanath, N. C., Kumar, P. G. D., & Ammad, K. K. (2015). Statistical analysis of quality of water in various water shed for Kozhikode City, Kerala, India. Aquatic Procedia, 4, 1078–1085. Wanke, H., Nwakfila, A., Hamutoko, J. T., Lohe, C., Nembo, F., Petrus, I., David, A., Beukes, H., Masule, N., & Quinger, M. (2015). Hand dug wells in Namibia: an underestimated water source or a threat to human health? Journal of Physical Chemistry. doi:10.1016/j.pce.2015.01.004. WHO 2003. “Emerging issues in water and infectious disease”. Geneva: World Health Organization. WHO, 2011. World Health Organization (WHO). Guidelines for Drinking-water Quality, fourth ed. WHO Press, Geneva, Switzerland. ISBN 978 92 4 154815 1. WHO, 2012. World Health Organization (WHO). Global Burden of Disease. WHO Press, Geneva, Switzerland. WHO/UNICEF, 2015. World Health Organization (WHO) and United Nations Children's Fund (UNECEF), Progress on Sanitation and Drinking Water e 2015 Update and MDG Assessment, WHO, Switzerland, 2015. Available. http://www. unicef.org/publications/index_82419.html. Yang, C. Y., & Chiu, H. F. (1999). Calcium and magnesium in drinking water and risk of death from rectal hypertension. American Journal of Hypertension, 12, 894–899. Yang, C. Y., Chiu, H. F., Chang, C., Wu, T. N., & Sung, F. C. (2002). Association of very low birth weight with calcium levels in drinking water. Environmental Research Section A, 89, 189–194. List of Tables

634

Table 1: Summary statistics of groundwater quality for wet (rainy) season

635

Table 2: Summary statistics of groundwater quality for dry season 19

636

Table 3. Drinking water quality guidelines

637

Table 4: Correlation Analysis

638

Table 5: Review of water-related diseases and causative contaminants

639

Table 6: Comparison of groundwater monitoring results of previous studies and this study

640 641

List of Figures

642

Fig. 1a: Map of Isoko North showing Study Area

643

Fig. 1b. Map of Nigeria showing Delta State

644

Fig 2a. Average value of pH in boreholes and HDWs for wet and dry seasons

645

Fig 2b. Average concentrations of barium in boreholes and HDWs for wet and dry seasons

646

Fig 2c. Average concentrations of electrical conductivities in boreholes and HDWs for wet and dry

647

seasons

648 649 650 651 652 653 654 655

20

Table 1: Summary statistics of groundwater quality for wet (rainy) season Parameters

Borehole

No. of Data

Handdug Well

Temp.0C pH EC( µS/cm) Salinity (‰)

120 120 120 120

Max. Value 27.00 5.49 88.70 ND

Min. Value

Mean

STD

No. of Data

Max. Value

Min. Value

Mean

SD

25.40 4.92 80.55 ND

26.20 5.14 84.51 ND

0.75 0.24 2.91 ND

120 120 120 120

28.90 6.28 76.00 ND

25.90 5.94 63.00 ND

27.05 6.12 69.91 ND

1.17 0.16 5.17 ND

TDS (mg/L) TSS (mg/L) Turbidity(NTU) Alkalinity (mg/L) DO (mg/L) BOD5 (mg/L) COD (mg/L) NH3-N (mg/L) Colour (pt-co) NO3-N (mg/L) TOC (%) THC (mg/L) Odour (TON) Total Hardness (mg/L) Total Phosphorous (mg/L) HCO3 (mg/L) Cl (mg/L) SO4 (mg/L) TCC (Count/100ml) Na (mg/L) K (mg/L) Mg (mg/L) Ca (mg/L) Pb (mg/L) Cd (mg/L) Zn (mg/L) Cu (mg/L) Fe (mg/L) Ba (mg/L)

120 120 120 120 120 120 120 120 120 120 120 120 120 120

53.70 1.00 ND ND 12.00 5.00 2.70 ND ND 0.05 0.01 0.01 ND 15.00

38.40 ND ND ND 8.00 4.00 ND ND ND ND ND ND ND 1ND

44.53 0.25 ND ND 9.75 4.25 1.33 ND ND 0.01 ND ND ND 11.50

5.68 0.43 ND ND 1.48 0.43 1.33 ND ND 0.02 ND ND ND 2.06

120 120 120 120 120 120 120 120 120 120 120 120 120 120

51.70 2.00 ND 23.00 12.00 6.80 2.00 ND ND ND ND 0.01 ND 25.00

33.00 ND ND 1ND 1ND 4.00 1.80 ND ND ND ND ND ND 15.00

39.33 0.50 ND 17.00 11.00 5.40 1.90 ND ND ND ND ND ND 19.75

7.37 0.87 ND 6.04 1.00 1.08 0.07 ND ND ND ND ND ND 3.96

120

ND

ND

ND

ND

120

ND

ND

ND

ND

120 120 120 120

ND 3.00 2.80 1.20

ND ND 1.50 ND

ND 3.00 1.98 0.30

ND ND 0.51 0.52

120 120 120 120

28.06 1ND 5.00 1.80

12.20 6.00 4.00 ND

20.74 8.00 4.50 0.45

7.37 1.41 1.00 0.80

120 120 120 120 120 120 120 120 120 120

18.99 13.01 17.80 18.00 0.01 ND 0.07 0.07 0.06 1.22

3.03 1.52 1.30 8.00 ND ND 0.02 0.01 ND 1.04

14.32 6.86 10.75 11.23 ND ND 0.04 0.03 0.02 1.10

6.55 4.08 6.91 6.48 ND ND 0.02 0.02 0.03 0.61

120 120 120 120 120 120 120 120 120 120

15.76 9.45 15.00 15.32 ND ND 1.00 0.09 0.05 1.90

13.70 5.34 5.00 8.00 ND ND 0.01 ND ND 0.88

14.65 6.92 10.25 12.00 ND ND 0.27 0.25 0.03 1.22

0.74 1.67 3.70 2.83 ND ND 0.42 0.14 0.03 0.50

Note: ND=Not detected

Table 2: Summary statistics of groundwater quality for dry season

Parameters

Boreholes

Hand-dug Wells

No. of Data

Max. Value

Mean

STD

27.90 4.95 98.55 ND

Min. Value 25.30 4.82 87.10 ND

Max. Value 26.50 6.50 71.30 ND

Min. Value

Mean

SD

1.00 0.06 4.23 -

No. of Data 120 120 120 120

Temp.0C pH EC( µS/cm) Salinity (‰).

120 120 120 120

26.53 4.90 92.74 -

26.00 5.99 6ND ND

26.30 6.20 65.10 ND

0.19 0.26 4.10 ND

TSS (mg/L) Turbidity(NTU) Alkalinity (mg/L) DO (mg/L) BOD5 (mg/L) COD (mg/L) NH3-N (mg/L) Colour (pt-co) NO3-N (mg/L) TOC (%) THC (mg/L) ODOUR (TON) Total Hardness (mg/L) Total Phosphorous (mg/L) HCO3 (mg/L) Cl (mg/L) SO4 (mg/L) TCC (Count/100ml) Na (mg/L) K (mg/L) Mg (mg/L) Ca (mg/L) Pb (mg/L) Cd (mg/L) Zn (mg/L) Cu (mg/L) Fe (mg/L)

120 120 120 120 120 120 120 120 120 120 120 120 120

ND ND ND 12.00 6.00 3.00 4.00 ND 5.00 0.80 ND ND 13.00

ND ND ND ND 3.00 ND 2.70 ND ND 0.01 ND ND 9.00

ND ND ND 1ND 4.80 1.73 2.63 ND 2.38 0.40 ND ND 11.25

ND ND ND 2.00 1.30 1.31 1.59 ND 1.85 0.32 ND ND 1.48

120 120 120 120 120 120 120 120 120 120 120 120 120

ND ND 22.70 1ND 5.00 4.00 3.40 ND 5.00 0.30 0.02 ND 15.00

ND ND 8.00 ND 4.00 0.40 ND ND ND 0.02 ND ND 8.00

ND ND 13.45 1ND 4.75 2.83 2.18 ND 3.03 0.16 0.01 ND 10.25

ND ND 5.82 ND 0.43 1.47 1.31 ND 1.84 0.11 0.01 ND 2.77

120

0.01

ND

0.01

ND

120

0.02

ND

0.02

ND

120 120 120 120

ND 2ND 12.00 3.60

ND 13.00 2.00 1.00

ND 18.25 8.50 2.35

ND 3.03 4.09 0.92

120 120 120 120

26.40 9.00 5.00 5.76

ND ND 4.00 1.80

6.60 9.00 4.75 4.24

10.44 ND 0.43 1.48

120 120 120 120 120 120 120 120 120

18.52 11.00 8.00 8.00 ND ND 0.12 0.09 0.03

12.00 7.30 4.00 2.00 ND ND ND ND <0.001

15.94 8.26 6.25 4.79 ND ND 0.06 0.04 0.02

2.59 1.04 1.48 2.17 ND ND 0.14 0.03 0.01

120 120 120 120 120 120 120 120 120

15.00 5.50 6.70 9.00 ND ND 0.05 0.20 0.05

9.68 3.00 2.20 2.00 ND ND <0.001 <0.001 0.02

11.90 4.77 5.27 5.81 ND ND 0.02 0.05 0.04

2.01 1.03 1.79 2.57 ND ND 0.03 0.09 0.01

Ba (mg/L)

120

1.08

<0.001

0.50

0.50

120

1.88

<0.001

Note: ND=Not detected

Table 3. Drinking water quality guidelines S/N 1 2 3 4 5 6 7 8 9 10 111 12

Parameter Ph Cadmium (Cd) Chloride (Cl-) Chromium (Cr) Copper (Cu) Iron ( Fe) Lead (Pb) Zinc (Zn) Nickel (Ni) Barium (Ba) Nitrate (NO3-) Nitrite (NO2)

13

Sulphate (SO42-) Total coliform (TC) E. coli count Electrical Conductivity (EC) (µS/cm ) Total Suspended Solid (TSS) Total Solid (TS) Total Dissolved Solid (TDS) Salinity (%) Turbidity Magnesium (Mg) Calcium (Ca) Sodium (Na) Potassium (K) Dissolved Oxygen (DO) BOD5 Total Alkalinity (mg/L CaCO3) Hardness ((mg/L CaCO3) Colour apparent (Hz)

14 15 16 17 18 19 20 22 22 23 24 25 26 27 28 29 30

WHO (2006) 6.5–8.5 0.003 0.050 2.00 0.30 ND1 0.020

SON (2007) 6.5-8.5 0.003 250 0.050 1.00 0.30 0.01 3.00 0.02

10 1.0

50.0 0.2

500

100

0x102 0x102 1000

10 1000

500 1 200 200 200 30 4 500 15 -apparent (Hz)

500 5 0.2 200 7.5 6 150 15 (TCU)

Note: Beside pH, EC, Salinity and Colour apparent; other parameters were reported in mg/L. Sources: Adapted from Kulinkina et al. (2017) and Sojobi (2016) following minor updating

0.66

0.77

Table 4: Correlation Analysis

EC( µS/cm)

pH pH

TDS (mg/l)

TSS (mg/L)

ALKAL. (mg/l)

DO (mg/l)

BOD5 (mg/l)

NO3N (mg/l)

TH (mg/l)

HCO3 (mg/l)

Cl (mg/l)

SO4 (mg/l)

Na (ppm)

K (ppm)

Mg (ppm)

Ca (ppm)

EC( µS/cm)

-0.99

1

0.02

-0.04

1

TSS (mg/L)

0.32

-0.27

0.86

1

ALKAL,(mg/l)

0.59

-0.45

-0.21

0.32

1

DO (mg/l)

0.16

-0.14

0.97

0.96

0.03

1

BOD5 (mg/l)

0.46

-0.45

0.89

0.95

0.18

0.95

1

NO3-N (mg/l)

-0.48

0.53

-0.84

-0.76

0.11

-0.83

-0.92

1

TH(mg/l)

0.28

-0.24

0.90

0.99

0.23

0.98

-0.79

1

HCO3 (mg/l)

0.21

-0.05

-0.28

0.21

0.91

-0.05

0.96 0.032

0.38

0.13

1

-0.02

0.17

-0.31

0.12

0.80

-0.12

-0.16

0.52

0.04

0.98

1

0.96

-0.90

-0.10

0.33

0.80

0.10

0.38

-0,30

0.26

0.48

0.28

1

Na (ppm)

-0.15

0.17

0.95

0.87

-0.09

0.95

0.80

-0.65

0.90

-0.05

-0.04

-0.18

1

K (ppm)

-0.34

0.38

0.85

0.78

-0.08

0.85

0.64

-0.44

0.81

0.07

0.12

-0.31

0.97

1

0.99

0.86

-0.19

0.97

0.92

-0.91

0.90

-0.311

-0.38

0.00

0.90

0.77

1

0.99

0.93

-0.85

0.95

-0.16

-0.21

0.013

0.96

0.85

0.98

1

SO4 (mg/l)

Zn (ppm)

Cu (ppm)

Fe (ppm)

Ba (ppm)

1

TDS (mg/l)

Cl (mg/l)

Cd (ppm)

Mg (ppm)

0.14

-0.17

Ca (ppm)

0.10

-0.10

0.99

0.92

-0.08

Cd (ppm)

-0.60

0.66

-0.72

-0.66

0.09

-0.71

-0.86

0.98

-0.68

0.42

0.58

-0.39

-0.49

-0.26

-0.81

-0.73

1

Zn (ppm)

0.57

-0.46

0.49

0.87

0.75

0.68

0.76

-0.49

0.81

0.62

0.48

0.67

0.55

0.49

0.50

0.60

-0.43

0.550

0.48

0.52

0.61

-0.47

0.99

1

-0.98

0.58

-0.53

-0.54

1

0.99

-0.73

0.62

0.63

-0.98

Cu (ppm)

0.59

-0.49

0.50

0.87

0.74

0.70

0.789

-0.53

0.82

0.59

0.45

0.68

Fe (ppm)

0.10

-0.11

-0.98

-0.88

0.13

-0.97

-0.84

0.73

-0.91

0.13

0.15

-0.99

-0.94

-0.94

Ba (ppm)

0.11

-0.11

0.99

0.93

-0.05

0.99

0.94

-0.84

0.96

-0.1

0.14 0.189

0.03

0.95

0.85

0.98

1

1

Table 5: Water Quality Parameters Ph Sulphate Nitrite and Nitrate

Review of water-related diseases and causative contaminants Causes Related Health Condition(s)

Author(s)

Nature of geological formation and minerals Fertilizer contamination Excessive application of fertilizer, sewage disposal, manure application, wastewater, leakage, landfill leachate, municipal runoff

Gastrointestinal irritation Laxative action Methemoglobinemia in infants

Emenike et al. (2018), Kulinkina et al. (2017), WHO (2003), Khan et al. (2013) Mkwate (2017); Khan et al. (2013), Owamah et al. (2013) Saeedi et al. (2012)

Subencephalopathic, neurological, and effects

WHO (2003)

Acute toxicity

Tiredness, abdominal discomfort, irritability and anemia

Gerlach et al. (2002)

High levels of Pb in children

Khan et al. (2013); Dahunsi et al.(2014)

Moderate levels of Pb

Convulsion, neurological damage, organ failure, coma, and death Hearing loss, inhibit growth, learning disabilities

Khan et al. (2013)

Accumulative toxicity

Lead poisoning

Mkwate (2017), Shu et al. (2011)

Cadmium

High toxicity

Kidney disease, anaemia, albuminuria, and osteomalacia

Dahunsi et al. (2014), Shu et al. (2011)

Mercury

Accumulative toxicity

nervous system breakdown, heart, kidney, stomach troubles Harm liver, cardiovascular diseases

Shu et al. (2011)

Lead

Copper Mangnese Zinc Chromium Arsenic

High concentration

Calcium Magnesium

Deficiency Deficiency

Water low in Mg

Arthroncus, soft bone, Manganese-poisoning and pneumosclerosis Retard intelligence development and cardiosvascular, sickness, vomiting Contact dermatitis and respiratory cancer Stomach ache, diarrhea, bowel disease, edema, hernolytic anemia, jaundice, death Osteoporosis and hypertension Cardiovascular diseases atherosclerotic vascular disease, acute myocardial infarction, preeclampsia in pregnant women, diabetes, osteoporosis, Increase in morbidity and mortality, cardiovascular problems, pregnancy disorders, neurodegenerative disease, cancer

Source: Sojobi (2016) after slight updates

Table 6: Comparison of groundwater monitoring results of previous studies and this study

Owamah et al. (2013), Shu et al. (2011) Shu et al. (2011) Shu et al. (2011) Shu et al. (2011) Mkwate (2017), Shu et al. (2011) Khan et al. (2013), Yang and Chiu (1999) Melles and Kiss (1992); Yang et al. (2002); Sojobi (2016)

Sojobi (2016), Verd et al. (1992)

Author(s)

Contaminants present

Ugochukwu and Ojike (2019) Emenike et al. (2018)

Area covered in the Study/Country Enugu Metropolis, Enugu State/Nigeria Abeokuta South/Nigeria

Pb, Coliform Bacteria

No. of Groundwater Sources/Samples 14 Nos. hand-dug wells (HDWs)

Acidity; Na2+, Mg2+, Fe2+, and EC

21 Nos. groundwater samples

Kulinkina et al. (2017)

Rural communities/Ghana

pH, turbidity, manganese, chloride and iron. Concentrations of total dissolved solids (TDS) EC, turbidity , FC , and FS

94 and 68 Nos. boreholes in the dry season and wet season respectively

Mkwate et al. (2017)

Balaka District/Malawi

Sojobi (2016)

Omu-Aran/Nigeria

NO3 −, Mg, TH, pH and Mg, Pb, TH, pH and DO

10 Nos. bore-holes and 3 Nos. hand-dug wells

Wanke et al. (2015)

Omusati/Oshama, Okongo/Ohangwena, Omatjete/Omaruno, Okanguati/kutnene/Namibia Myingyan and Tha Pyay Thar/Asia Sagamu, Mosimi, Ogijo and Odogunyan/Nigeria

F, NO3, SO4, TDS, E-coli

15 Nos. deep wells (up to 30m) and 44 Nos. shallow wells (1-3m)

As, Mn, U, F, Fe

20 Nos. wells

TSS and TS Pb, Ni, Cr, and Cd, Coliform Bacteria

72 Nos. samples

Rao (2014)

Andhra Pradesh/India

30 Nos. samples

Akhtar et al. (2014)

Lahore/Pakistan

EC, Na+, Cl-, SO42-, Mg2+, Ca2+ TDS, Turbidity

Akinyemi & Souley (2014)

Abeokuta North, Ifo, Obafemi, Obafemi Owode, Odeda/Nigeria

Porowska (2014)

Owamah et al. (2013)

Bacquart et al. (2015) Dahunsi et al. (2014)

Srinivas et al. (2013)

Total of 11 boreholes and shallow wells

Recommendation(s) Treatment of HDW water of the study area before use Regular monitoring of groundwater Treating water in locally sustainable ways

Large scale adoption of house hold water treatment and continued monitoring of the water sources Provision of proper sanitary system , restriction of domesticated animals from boreholes and wells and household treatment Regular monitoring and relevant treatment

Regular monitoring and testing of drinking water Public outreaches/workshops, properly design and construction of wells There is need for remediation

340 Nos. wells

Regular monitoring and protection of aquifer against contamination

pH, Mg

1 No. spring, 1 No. well, 1 No. borehole

To be treated prior to drinking and irrigation.

Otwock/Poland

HCO3−, Cl−, Ca2+, Mg2+, Na, K, Fe, DOC

32 Nos. samples (1–2.7 m)

Provision of engineered landfill

Isoko North Local Government Area, Delta State/Nigeria Tuticorin/India

pH, Coliform Bacteria, Pb and Cd

144 Nos. samples

EC, pH, TDS, Ca, Mg, Na, K, TH, Cl TDS, EC, Na+, Cl−, HCO3− K+, F−, pH, SO42−, , Br−

21Nos. wells (10-m depth)

Public workshops. Proper design and construction of wells Groundwater unsuitable for irrigation

Vasanthaviger et al. (2013)

Thirumanimuthar/India

Oyelami et al. (2013)

Ido –Osun/Nigeria

Cl-, Na, Mn

20 Nos. wells

Oni & Hassan (2013)

Aba-Eku (Ibadan)/Nigeria

Pb, Cd, Fe

2 Nos. wells

194 Nos. samples

Groundwater has hydrogeochemical regimes Regular monitoring & better domestic waste management required Landfill to be provided plus adoption proper

Al-ahmadi & El-Fiky (2009) This study

Wadi Marwani/Saudi-Arabia Emevor/Nigeria

pH, TDS, Mg, Na, SO42-, Cl-, NO32pH, Ba, total coliform

16 Nos. wells (5–15.3 m) 10 Nos. each of boreholes and hand-dug wells

waste management practice None as groundwater was safe for drinking Regular monitoring and testing of drinking water, public workshops, proper design and construction of wells

Source: Adapted from Sojobi (2016) after slight updates

6009’E

6023’E 5037’N Aniocha Oshimilli North North Ika South Ika North East Aniocha South Oshimilli South

Abia shaka

Ethiope West Warri North

Sapel e Okpe

Warri SouthWest

Warri South

Ndokwa West

Ethiope East

Uvwie

Ndokwa East

Ellu

N

Owhelogbo

Isoko Ughelli North North Isoko South

BomadiUghelli South

Otibio Otor-Owhe

Patani

0

Idoni

Lake Ora

Udu

Burutu

Aradhe

Ukwuani

25Km

Study Area

Lake Okparo Ozoro

Ofagbe

Ivrogbo Oruovo Akiewe

Orie

Emevor Owevwe

Okpe Oghara Ivede Ogheneore Iyede Ivorogbe

N KEY Towns Study Area Town Boundary Main Road River

0

25Km

5020’N

Fig. 1a: Map of Isoko North showing Study Area Source: Ministry of Lands, Surveys & Urban Development, Asaba, (2013)

6009’E

6023’E

Fig. 1b: Map of Nigeria showing Delta State

7 6 5

pH

4 3 2 1 0 Series1

BH Wet

BH Dry

HDW Wet

HDW Dry

5.12

4.9

6.12

6.2

Well Type and Season

Fig 2a. Average value of pH in boreholes and hand-dug wells for wet and dry seasons

1.4 1.2

Ba (Mg/L)

1 0.8 0.6 0.4 0.2 0 Series1

BH Wet

BH Dry

HDW Wet

HDW Dry

1.1

0.5

1.22

0.66

Well Type and Season

Fig 2b. Average concentrations of barium in boreholes and hand-dug wells for wet and dry seasons

120 100

EC(µS/cm)

80 60 40 20 0 Series1

BH Wet

BH Dry

HDW Wet

HDW Dry

84.51

92.74

69.91

65.1

Well Type and Season

Fig 2c. Average concentrations of electrical conductivities in boreholes and hand-dug wells for wet and dry seasons

• • • • •

Baseline information on the quality of groundwater of rural Nigerian communities is scarce. This study provides a first time comprehensive report on the quality status of groundwater in Emevor. The groundwater was found acidic with elevated concentration of Ba, and coliform bacteria. ANOVA (p<0.05) showed a significant difference in the concentration of parameters that exceeded regulatory limits Correlation analysis showed that the main cations influencing the groundwater TDS were Ca, Mg, Ba, Fe, Na and K.