Physicochemical and Metal Analysis of Well Water Samples from Akure, Nigeria

By Ogundele Joan Olayinka
April 2010

The Author is a Ph.D research Student at the Chemistry Department of the Federal University of Technology, in Akure, Nigeria.

The physicochemical and metal analysis of well water samples from different parts of Akure metropolis were carried out. The values of the physicochemical properties vary significantly except for the temperature, colour, chloride and the dissolved oxygen which are closely related. The metals concentrations have mean values (mg/l): Fe (0.18), Mg (33.12), Ca (40.02), Na (60.60), Zn (1.02), K (159.40), while Cu and Pb were not detected. These metal values are within the acceptable values in the World Health Organization Guidelines value for Drinking Water Quality.

Keywords: Physicochemical, metal concentration, dissolved Oxygen

1.0 Introduction

Water is the most essential basic necessity of life. However, pure water needed for human consumption does not always occur in nature, due to the presence of dissolved or suspended impurities in most natural water bodies (Goldface, 1999). Well water is the main source of water for domestic use in Akure metropolis. On several occasions, the well water is pumped into houses or fetched manually. Generally, the water samples are used for washing, cooking and even for drinking. The determination of the metal content of the samples is of great importance, because, despite the fact that trace elements are essential to man, at elevated levels, essential and non-essential elements can cause morphological abnormalities: reduce growth, increase mortality and mutagenic effects (Nkono and Asubiojo, 1998; Asaolu, 2002; Adeyeye, 2000). Comparing the results of the physicochemical and mineral analysis of these well water samples with potable water standards provided by World Health Organization will therefore enable us to know the potability of the well water samples in Akure metropolis.

2.0 Materials and Methods

2.1 Sampling

Samples of water were collected from wells located in five different places in Akure, namely; Shijuade, Obaile, Federal University of Technology (FUTA), Ijoka road and Fiwasaye. Clean plastic containers were used for the collection of the water samples on 7th of September, 2002 and labeled appropriately.

2.2 Analysis of Physicochemical Parameters

The dissolved Oxygen (mg/l), Temperature (°C), pH and Electrical Conductivity (EC) in µscm-1 were determined almost immediately after collection of the water samples, using a Dissolved Oxygen kit, Mercury Thermometer, pH meter and a Conductivity meter. The total dissolved solid or residue was calculated from the relationship: TDS= 0.01 EC

The colour of the water was measured by the use of a visual comparator. Odour and taste were determined using the sense organs for taste and smell. The Total Hardness (mg/l CaCO3) was determined using EDTA Titremetric method, Chloride values by Mohr’s method and other parameters were determined according to Ademoroti, 1996 and Andrew, 1995.

2.3 Metal Analysis

 Atomic Absorption Spectrophotometer (AAS) was used for the determination of metals such including Sodium,Calcium, Magnesium, Iron, Zink, Copper and Lead (Ademoroti, 1996).

2.4 Statistical Analysis

The range, mean, standard deviation and coefficient of variation of the results were carried out. The metal concentrations were comparably analyzed in a bar Chart.

3.0 Results and Discussion

3.1 Physicochemical Parameters

Table 1 shows the physicochemical parameters of the Well Water samples from Akure Metropolis. All the well water samples are clear with unobjectionable taste and odour. The temperature (°C) ranges from (26.00-28.00) with mean value of (27.17). However, the values are closely related with a coefficient of variation (%) of (3.13). These values are close to the temperature values recorded for water samples from major dams in Ekiti during raining and dry season as (26.3 and 26.8)°C respectively (Adefemi et. al., 2007). The conductivity (µΩ) ranges from (110.00-425.00) with mean value (253.83). However, the Electrical Conductivity shows wide variance with a CV% (45.32). Similarly, the Total Dissolved Solid and the Total hardness also show wide variance of 45.19% and 45.32% respectively.

The Total Hardness (mg/l CaCO3) of well water samples from Shijuade, Oba-ile and Ijoka-Road are soft, falling within the stipulated value of 0-75 for  soft water, while the samples from FUTA and Fiwasaye are moderately hard, falling within the given range 75-150 recommended (Ipinmoroti K.O.,,1997; Adeyeye and Abulude, 2004). However, these values falls within acceptable limits (500mg/l)of WHO (1997). The hardness of water indicates its Calcium and Magnesium salt contents. The total concentration of divalent metals ions (primarily Ca and Mg) expressed in mg/l of equivalent CaCO3 is termed the Total Hardness (Abulude, 2007). Hence, on the average Akure well water can be said to be soft and good for domestic uses like washing of cloths, cooking, drinking and bathing on the fact that the mean value for the Total Hardness is 81.60 mg/l CaCO3.

Table 1 · Physicochemical Parameters of Well Water Samples from Akure Metropolis
Location Temp
pH Appearance Taste Odour
Shijuade 28.00370.0072.00259.0031.007.805.005.72ClearU.OU.O
Oba-ile 28.00190.0057.00133.0020.0010.205.006.52ClearU.OU.O
FUTA 28.00425.00124.00297.5021.0015.605.007.12ClearU.OU.O
Ijoka Rd 26.00148.0035.00103.6023.009.505.005.65ClearU.OU.O
Fiwasaye 26.50110.00120.0077.0030.
Range 26.00-
Mean 27.17253.8381.60177.4324.3310.995.006.38ClearU.OU.O
S.D 0.85115.0336.9880.174.462.770.
C.V.(%) 3.1345.3245.3245.1918.3325.
U.O. = Unobjectionable, S.D. = Standard Deviation, C.V. = Coefficient of Variation.

The range of the Total dissolved solid (77.00-297.5) and the Chloride (20.00-31.00) with mean values of (177.43) and (24.33) mg/l CaCO3 respectively. These values fall within the acceptable limit of 1000 mg/l (TDS) and 250 mg/l (Chloride) set by WHO. Similarly, the mean values of the TDS (177.43mg/l) and the Chloride (24.33 mg/l) are close to the mean values recorded for Ekiti dam water as (173.6mg/l) and (18.8 mg/l) respectively (Adefemi, 2007).

 The D.O values ranging from (7.80-15.60) mg/l with mean value of (10.99) mg/l . These values are close to the range (7.4-18.2)mg/l and mean (11.2mg/l) reported for some drinking water in Akure  byAbulude 2007. The pH values for well water samples from Oba-ile, FUTA, and Fiwasaye fall within the acceptable standard of WHO (pH 6.5-8.5). The other two values are a little more acidic with values 5.72(Shijuade) and 5.65(Ijoka Rd). Adeyeye and Abulude (2004) reported similar result of pH range of 5.90-7.60 on their sturdy of some surface and ground water resources in Ile-Ife. The acidic water should best be treated with lime to increase the pH value before drinking. Most treatment of drinking water are done with Alum, Calcium hypochlorite and lime (Babatola, 2009). However the knowledge of the pH value of the water before treatment is an important determining factor for the type of treatment to be best made on the drinking water.

Table 2 · Metal Concentrations of Well Water Samples from Akure Metropolis
Location Fe Mg Ca Na Zn K Cu Pb
Ijoka Rd0.3022.2025.0037.001.00136.00NDND
CV (%)44.0058.7935.3744.7834.198.68--
ND = Not Detected

3.2 Metal Concentration

Table 2 shows the concentration of the well water samples. Copper and Lead were not detected.The range of the values of Sodium mg/l (30.00-102.00), Zinc mg/l (0.50-1.60) and Iron mg/l (0.05-0.30). These values are acceptable for drinking water according to WHO set limits for Sodium (200mg/l), Zinc (5.0mg/l) and Iron (0.3 mg/l).  Iron is an essential trace element for the human body; however, a high concentration of Iron gives water a bad taste and reddish colour (Caircross, 1990). The well water sample from FUTA has the highest values for Magnesium (58.90 mg/l) and Calcium (58.00 mg/l). The well water sample from Shijuade has the highest  Sodium(102.00mg/l) and Zinc(1.60mg/l) Values . Potassium values ranges from 136.00 mg/l(Ijoka Rd) to 171.00 mg/l (Oba-Ile). There is little variation (8.68mg/l) among the Potassium values of the well water samples.

Fe Mg
Ca Na
Zn K

4.0 Conclusion

The well water samples in Akure metropolis are of acceptable physicochemical and metal values according to World Health Organization Standards for drinking water. There is 40% possibility of some of the water being slightly acidic and will not need hypochlorite treatment as is commonly practiced in this area. It is therefore important to determine the pH of well water samples before knowing the possible treatment to be made on such well water. In conclusion, this study shows that most of the well water samples in Akure metropolis are suitable for domestic use like washing, cooking, bathing and drinking. However, there is the need for constant routine analysis to ensure safety and non-contamination of the wells.



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