Heavy Metal Concentration, Physicochemical and Biological Properties of Water Collected from Different Schools Along Airport Road, Abuja

Heavy Metal Concentration, Physicochemical and Biological Properties of Water Collected from Different Schools Along Airport Road, Abuja

*Jibrin Noah Akoji., Ovurevu Oyiza Dorcas

Department of Chemistry, Baze University, Abuja

*Corresponding Author

DOI: https://doi.org/10.51584/IJRIAS.2023.81104

Received: 26 September 2023; Revised: 13 October 2023; Accepted: 18 October 2023; Published: 02 December 2023

ABSTRACT

Fifteen water samples from Well and Boreholes were collected from different schools located in some communities along Air Port road, Abuja and were analyzed for heavy metals concentration, Physicochemical and biological properties using standard methods. The result of the heavy metal concentrations shows; Cd in mg/l (0.0883-0.1113), Fe in   mg/l (0.0300-0.2298), Zn(0.0000-0.8888), Mn in mg/l (0.0497-0.4598), Cu in mg/l (0.000-1.6427)  and Pb in mg/l (0.0000 -1.5453). The physicochemical properties showed; Colour-Colourless, Odour- objectionable, Temperature ^oC (21-31), Alkalinity in mg/ml(1.5-7.3), Acidity in mg/ml(0.8-2.2), Hardness in mg/ml ( 1.2-3.6), Appearance ( Some are clear and some are not clear), pH (5.91-7.56),  TDS in mg/l (80-2080), Turbidity in NTU (0.2-3.1) Conductivity in mg/l(123-9385) NH₃ in mg/l(0.014-0.077), SO₄^2- in mg/l(25.87-186.2) and F^– in mg/l (0-0.38). The microbiological results shows that TBC ranges between 30-TNTC, TCC ranges between Nil-30 and E coli is Nil in all the samples. Total Dissolved Solid was found to be above the SON limits. Concentration of Fe, Cd and Pb were also above SON limits. Total Coliform Counts and Total Bacteria counts were also above the recommended limits by SON. Considering the high level of some of the physicochemical and microbiological parameters and the high concentration of Pb and Cd, the water is presumed unfit for drinking, cooking and pharmaceutical uses.

Key words: Heavy metals, Microbiological, Contamination, School, Physicochemical 

INTRODUCTION

Water is a universal solvent essential to man for various activities such as drinking, cooking, industrial activities, agricultural processes and human recreation. The quality of water is a reflection of the source environment and human activities, including its use and management measures. The safety of drinking water is important for health, and it is affected by various contaminants from chemical and microbiological sources [1]. Water is considered safe for drinking if it is free from contaminants and has properties within acceptable limits [2]. It is essential to humans and other life forms even though it provides no calories or organic nutrients. The earth ecosystems are held and maintained by water which covers about 70.9% of the earth surface. It is a necessity to the human body’s mechanics. Without it, the body does not operate, just like a car will not run without gas and oil. The usual sources of drinking water namely stream, rivers, wells and boreholes are mostly untreated and associated with various health risks [1]. Paucity of infrastructure for effective treatment and distribution of water accounts for the incidence of high morbidity and mortality rate associated with water borne diseases in developing countries. Water pollution is the leading cause of death and disease worldwide [3]. A tremendous amount of attention has been directed toward pollution of water supplies and the subsequent effects on the life of many animals and human. Unless water meets certain physical, chemical and microbiological standards it cannot be described as potable and safe for drinking. Water from boreholes is used directly without any purification as such any forms of contaminants present go undetected. In Nigeria today, the use of ground water has increased many fold because the government is unable to meet the ever-increasing water demand. Thus, inhabitants have had to look for alternative ground water sources such as shallow wells and boreholes. The presence of heavy metals, such as Pb, Mn, Cd, Cu, Fe, Zn, Ni, Hg and As also affects the water quality in boreholes. The contamination of groundwater (boreholes) introduces heavy metals into it.  They are leached into the groundwater when the capacity of the surface soil fails to retain them and through consumption may pass to man and other living organisms. HM are indestructible [4] and have the ability to exist in particulate, dissolved and colloidal phases when found in water [5], although HM also exist naturally underground. Industrial and household waste discharges, directly or indirectly through leakages in sewage systems into water sources, cause excessive pollution in surface and groundwater [6]. They are well known contaminants of underground water, and they constitute one of the major pollutants affecting the underground water (boreholes) system [7].

Heavy metals are collectively grouped as environmental toxins because they are potentially poisonous and constitutes health hazard even at a very low concentration. It is therefore pertinent that environmental samples need to be periodically investigated for the presence of these toxic metals. These heavy metals are much toxic and have tendency to accumulate in the body and may result in chronic impairment. Determining the concentration of this heavy metal in water is very much helpful in understanding the role of pollutant and nutrient elements. Monitoring the quality of groundwater is important for environmental safety. The analysis of potable drinking water for physico-chemical properties and metal content is also very relevant for public health and pollution studies.

The aim of this research is to determine the amount of heavy metals and physicochemical characteristics of the water samples from different schools along Airport Road, in Abuja Metropolis in order to ascertain the quality of the water for domestic and agricultural use. This study is the first of its kind in accessing the water quality of different schools in this part of Abuja Metropolis and it will provide a baseline data of water quality in the schools to inform the administration and the concerned authorities and consequently aid them in proper treatment and purification of the contaminated water.

MATERIALS AND METHODS

2.1 Sample Collections:

Sterilization

Petri-dishes, test tubes and other instruments like flasks etc. were sterilized using alcohol and also put in an autoclave for 45minutes at 121 degrees Celsius for proper sterilization. The sample bottles were washed properly and dried prior to the water sample collection.

The water samples were collected in duplicate from boreholes and wells in selected schools along Airport road during the morning hours in sterile universal sampling bottles from 15 different schools and labelled. A total of 15 water samples were collected from taps and wells located within the schools premises and taken to the Baze University Chemistry laboratory for analyses. 

The Study Area

Figure 1: Map of Abuja, Nigeria Showing the Study Areas.

Analysis of the water samples was carried out in THREE
different categories namely:

1. Physical Analysis
2. Chemical Analysis
3. Microbological Analysis

2.2 Sample preparation for Heavy metals Analysis: 100ml of each water samples was measured using measuring cylinder and poured into a beaker and was heated to evaporation at 100^oC in a fume cupboard. It was then removed from the heating mantle and allowed to cool. 10ml of aqua regia was also added to the beaker and its content was heated to dryness. The beaker was removed and allowed to cool. Then 25ml of distilled water was added to the beaker, stirred and filtered in 100ml volumetric flask and made to mark. The digested sample was transferred to the sample bottles and labelled ready for analysis. The heavy metals such as Cu, Fe, Mn, Zn, Cd and Pb were determined using Shimadzu AA-3000 model of Atomic Absorption Spectrophotometry (AAS).

2.3 Determination of Physicochemical properties

Chloride

Chloride was determined in a natural or slightly alkaline solution by titration with standard silver nitrate, using potassium chromate as an indicator. Silver chloride is quantitatively precipitated before red silver chromate is formed.

Chloride mg/L = (A-B) x N x 35.45 x 1000/ ml sample

Where A = ml AgNO₃ required for sample

 B = ml AgNO₃ required for blank

 N = Normality of AgNO₃ used

2.4 Determination of pH of the Water Sample

The pH meter was calibrated; the instrument was brought to standby mode. The electrode was removed from the second buffer solution and rinsed thoroughly with distilled water, dried and immersed in water sample in a beaker. After the equilibrium between electrode and sample was established (by stirring gently and waiting for 1 minute), the pH of sample was measured when reading was constant. Where the sample temperature is different from the temperature of standard buffer, then temperature of pH meter was adjusted using temperature compensation before recording the pH of the sample. pH and temperature was noted and recorded. The electrode was rinsed and immersed in standard buffer until the next measurement. The pH measurement was repeated to get two concordant readings. On completing experiment, the electrode was returned to storage solution after rinsing with distilled water.

2.5 Measurement of Conductance of Water Sample

The meter was first calibrated. The cell was rinsed first with distilled water then with sample water. The sample water was put in a dry beaker with the conductivity cell dipped in it. The meter switch was shifted to READ. The conductance of sample water was read and noted together with the temperature to nearest 0.1°C. Then, the meter switch was shifted at CAL position and the cell was rinsed thoroughly with distilled water after measurement. The conductance measurement was repeated to get at least two concordant readings. Most of the modern instruments are direct reading.

2.6 Acidity

50 ml sample was added in a conical flask and 3 drops of methyl orange indicator solution was added. The burette was filled with 0.02 N NaOH solution and titrated till the color of solution changed to a faint orange color, indicating the end point. The volume of titrant consumed was recorded as V₁ in ml. The methyl orange acidity was calculated.

Methyl orange acidity (or Mineral Acidity) = (V₁×1000)/ (Sample volume)

When the 0.02 N NaOH solution, used in titration is not standardized, mineral acidity is calculated using the following Eq:

Methyl orange acidity= (V₁×N×50×1000)/ (Sample vol.)

For phenolphthalein acidity test, 2-3 drops of phenolphthalein indicator solution was added to water sample and the titration was continued till the faint pink color develops in the solution (i.e., the end point of titration). The volume of titrand consumed was recorded as V₂ (mL) and total acidity or phenolphthalein acidity was calculated.

Total acidity (or Phenolphthalein Acidity) = (V₂×N×50×1000)/ (Sample vol.)

2.7 Determination of Ammonia by Titrimetric Method

1% amount of wet sample was weighed, equivalent to approximately 1g dry weight, in a weighing bottle or crucible. The sample was washed into a 500-mL kjeldahl flask with water and dilute to 250 mL. A piece of paraffin wax was added to distillation flask and only 100 mL distillate was collected. Ammonia in distillate was titrated with standard 0.02N H₂SO₄ titrant until indicator turns a pale lavender. A blank was carried through all steps of the procedure and necessary correction to the results was applied.

2.8 Determination of COLOR by Spectrophotometric Method

The spectrophotometer was verified to be zeroed. The cell was rinsed with a small amount of the filtered sample, and discarded. Enough of the filtered samples was transferred to the sample cuvette, filling to the reference line. The absorbance was measured and recorded at 465 ηm and discarded. Rinse the cell thoroughly with deionized and/or distilled water. The spectrophotometer was periodically verified to be zeroed.

Calculation/Result 

The linear regression equation from the calibration curve was used to calculate the corresponding color value of the samples.

y=mx+b

where: y is the absorbance, m is the slope, b is the y-intercept., x is the calculated color value.

2.9 Determination of Fluoride using Ion Selective Electrode

The electrode was immersed for 1 h in the cell which contains the reference solution-V. After rinsing with the first solution to be measured, the electrode was ready for use. 25 mL of the buffer solution, followed by 25mL of the water sample were pipetted into a measuring cell. The pH was adjusted with hydrochloric acid solution to 5.2 ± 0.2. All the solutions were measured according to the same procedure at a constant temperature of 25 ± 0.5°C. A stirring bar was added to the measuring cell and placed on the magnetic stirrer and the electrodes were inserted into the solution fixed in place. The stirring rate was adjusted to about 180 min/L to 200 min/L. The stirrer was switched off at near constant potential and the value obtained was recorded. The stirring bar and the electrodes were rinsed with the next solution to be measured, before starting the next measurement.

2.10 Total Dissolved Solid (TDS)

To measure total dissolved solids, a clean porcelain dish was used, washed and dried in a hot air oven at 180 degrees celsius for one hour.  The empty evaporating dish was weighed in analytical balance. The sample was mixed well and poured into a funnel with filter paper. 80mL of sample was filtered. With the use of pipette, 75mL of unfiltered sample was transferred into the porcelain dish. The oven was switched on and allowed to reach 105°C. The oven and furnace temperatures was checked and regulated frequently to maintain the desired temperature range and placed in the hot air oven with care to prevent splattering of sample during evaporation or boiling. The sample was dried to get constant mass. Drying for long duration usually 2 hours is done to eliminate necessity of checking for constant mass. The container was cooled in a desiccator.  Desiccators are designed to provide an environment of standard dryness. The dish was weighed as soon as it has cooled to avoid absorption of moisture due to its hygroscopic nature.

CALCULATION AND RESULT

Tabulation for Total Dissolved Solids (TDS):

Weight of the clean porcelain evaporating dish (g) = W₁

 Weight of the dish and the residue (g) = W₂

Weight of residue (g) = W

The volume of the sample (mL) = V

Weight of residue (g) W = W₂ – W₁

Weight of residue in mg (To convert W (g) to W (mg), multiply W (g) with 1000) W (mg)

Description Total Dissolved Solids (mg/L) V = Volume of the sample (mL) (To convert mL to L, multiply by 1000)

2.11 Total Hardness:

100 ml of the sample was taken and 2 ml buffer solution was added to it, and then, 3 drops of Black T was added and Titrated with standard EDTA solution (with continuous stirring) until the last reddish color disappears. At the end point the solution turns blue. The volume used was noted.

Hardness will be calculated as follows:

Hardness (in mg/L as CaCO₃) = (V× N × 50 ×1000) / (SV) (5)

Where: V = volume of titrant (mL); N = normality of EDTA; 50 = equivalent weight of CaCO₃; SV = sample volume (mL)

2.12 Sulfate

250 mL of the sample was taken in a conical flask .The acidity was adjusted with HCl to 4.5 using a pH meter. Then an additional 1 to 2mL HCl was added. The solution was heated to boiling and stirred gently, barium chloride solution was added slowly until precipitation appear to be completed. Then about 2 ml of barium chloride solution was again added in excess. The precipitate was digested at 80°C overnight for not less than 2 hours. The content was filtered in the flask through an ash less filter paper. The precipitate was washed with small portion of warm distilled water until the washing is free of chloride as indicated by testing with silver nitrate-nitric acid reagent. The precipitate was placed along with filter paper in a crucible after finding its empty weight and dries it. The crucible was kept in a muffle furnace and ignites at 800°C for 1 hour and was cooled in a desiccator and weighed. Weight of the barium sulfate precipitate was found.

Calculation

SO₄ in mg/L =

2.13 Bacteriological analysis:

For Bacteriological analyses, various tests were performed in a step-wise pattern to confirm the presence of Pathogens in Water samples. Presumptive Coliform Test was applied to determine Most Probable Number (MPN) of Coliform through Multi-tube technique. The samples positive for Presumptive test was subjected to different tests for confirmation of E. coli presence. For this purpose, EMB agar was used to culture the samples. The samples were streaked on agar plates, labelled with a specific source code and incubated for 24-48 hours at 37 ⁰C. The 24-hours positive samples were cultured. Each positive sample was cultured on Lactose broth and Nutrient agar slant and incubated at 37 ⁰C for 24 hours.

Total Bacteria Counts

28 grams of nutrient agar was suspended in 1000ml of distilled water by heating and stirring. It was autoclaved for 15 minutes at 121°C, refrigerated and divided into Petri dishes and allowed to cool down at room temperature.  The spread plate method was used. Serial dilution of each of the samples of water was prepared. Of each water sample, 0.1ml was spread on the nutrient Agar plate and incubated for 24 hours at 37°C. The number of colonies per plate, and the units of colony formation per ml (CFU/ml) were calculated. For the identification of bacterial species, sub cultures was carried out on MacConkey and mannitol salt Agars.

Total Coliform Count

The total coliform count was determined by most probable number (MPN) index method. Serial dilution of the sample was prepared. The 1^st set of five tubes had 10ml of double strength MacConkeybroth, the second and third set had 10ml single strength of lactose broth with all the test tubes containing Durham tubes. All the tubes received 1ml of the water samples. These were incubated at 37°C for 24 hours for total coliform count. Acid production was determined by color changes in the tubes to yellow and gas production was determined by the gas trapped in the Durham tubes.

​Fecal Coliform Count

The fecal coliform count was estimated using EMB (Eosin Methylene blue Agar) streaking method. A loop of broth from the positive tubes was streaked on EMB Agar. The plates were incubated at 37°C for 24 hours. The Colonies on the EMB plate is metallic green which confirmed the presence of Escherichia coli strains.

RESULTS AND DISCUSSIONS

3.1 Results for Heavy Metals

The Table 1.0 shown below is the result of mean concentration of some Heavy metals in the samples as determined using Atomic Absorption Spectro photometer

 Table 1: The mean concentration of the Heavy metals in the water samples

3.1.1 Manganese

The mean values for both well and borehole water samples from the fifteen locations which fall within the WHO and NSDWQ standard value (0.1mg/l) include, Samis-borehole, Bu-borehole, AVS-borehole, JSS-borehole and JSS-Well. Drinking water containing high levels of manganese can lead to Neurological disorder [8].

 3.1.2 Iron

It was found that the mean values of both well water and borehole water samples from all the fifteen locations are above the WHO, USEPA and NSDWQ standard value (0.3mg/l). However the mean values for borehole water samples shows they have higher values when compared to that of well water. Presence of iron in drinking water may be due to the use of various iron salts as coagulating agents in water-treatment plants and where cast iron, steel, and galvanized iron pipes are used for water distribution. The commercial activities of automobile mechanics, artisans and carcasses of abandoned and unserviceable cars could be seen in the neighbourhood of sampling sites, High presence of iron in water promotes undesirable bacterial growth (“iron bacteria”) within a waterworks and distribution system, resulting in the deposition of a slimy coating on the piping. Aeration of iron-containing layers in the soil can affect the quality of groundwater if the nitrate leaching takes place.

3.1.3 Lead

The mean value of lead in the well and borehole water samples is above the WHO and NSDWQ standard value (0.01mg/l), except for AVS- borehole, BU-borehole and RHLC-borehole which is within the standard value. The presence of high lead concentration in water samples for the six locations might be due to the pesticides used decades ago or industrial activities that contaminated the soil and groundwater. Additionally, this could also result from household plumbing activities around the sampling sites. Excessive amount of lead in water can cause cancer, kidney disease, memory problems, high blood pressure, brain damage, hearing loss and behavioural problems [8]

3.1.4 Cadmium

The mean value of all water samples is above the WHO, USEPA and NSDWQ standard value (0.003 and 0.005mg/l). The results of animal studies suggest that very small amounts of cadmium in water can produce nephrotoxic and cardiovascular effects and large amount can damage the kidney, liver and heart and in severe cases may cause death. Higher levels of cadmium in water from the fifteen locations can result from the use and disposal of items containing cadmium. Cadmium may be derived from natural or industrial sources, or from cadmium compounds used in the production of plastic water pipes [9].

3.1.5 Zinc

The result shows that the values are below the USEPA, WHO and NESREA standard value (5 and 3 mg/l). Adverse effects of high zinc intake include nausea, vomiting, loss of appetite, abdominal cramps, diarrhoea, and headaches. Intakes of 150–450 mg of zinc per day have been associated with such chronic effects as low copper status, altered iron function and reduced immune function. Zinc can also interact with certain medications such as antibiotics, diuretics, and penicillamine (a drug used to treat rheumatoid arthritis) (NIS).

3.1.6 Copper

The mean value of Copper in the well and borehole water samples is below the WHO, USEPA and NESREA standard values (2.0 and 1.0 mg/l). The major source of copper in drinking water is corrosion of household plumbing and water fixtures. Copper is an essential micronutrient. The body requires copper in very small amounts. However, very large single or long-term intakes of copper may be harmful to your health [10]. Excess copper in the human body can cause stomach and intestinal distress such as nausea, vomiting, diarrhea and stomach cramps.

3.2 Result of Bacterial Count in the water Samples

The Table 2 shown below is the result of Total Bacteria Count, Total Coli form Count and E Coli in the samples as determined.

 Table 2: Bacterial Count on the Water Samples