The Level of Iron in Groundwater

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Published on International Journal of Earth Science
Publication Date: March, 2020

Isewede C. O., Ozeto Halimat, Azama A. A. & Jimoh O. O.
National Institute for Hospitality and Tourism
Benin City, Nigeria

Journal Full Text PDF: The Level of Iron in Groundwater.

Hydro – geochemical analysis is been carried out for the entire area to ascertain the level of Iron and Lead of the groundwater due to it generally shallow overburden with possible effect of pollution. Geochemically, water samples were evaluated and analyzed to determine their potability. A total number of twenty five (25) samples were collected from these hand dug wells and analyzed for their physic- chemical parameters. The concentration of PH, Temperature, TDS, conductivity, colour, turbidity, Iron, are below WHO, FEPA and NAFDAC standard. The result revealed high concentration of Iron ranging from 0.46 – 0.92mg/l in some of the water sample which is much higher than the WHO, FEPA and NAFDAC permissible limit of 0.30mg/l and turbidity also exceeded permissible limit of WHO, FEPA and NAFDAC standard in some of the water samples. It is therefore necessary to treat through boiling, aeration and filtration to make water fit for consumption.

Keywords: Iron, groundwater quality, potable water & human consumption.

Since the commencement of industrial and technological advancement, water quality for both municipal and domestic use has remained a universal issue of discussion amongst scientific disciplines such as the health ministries, environmentalist, planning exports, economists, etc.
Their various contributions has led to a high annual budget for the improvement of a water – base programme including monitoring and reduction of both biological and chemical contamination of the modern day society. Strictly speaking, water is hardly found in a pure state due to the interactive effect with the surrounding lithologies, poisonous components from the atmosphere, dump sites, effluents and industrials discharge. This results in the unusual occurrence of soluble and insoluble matter in the water. These internal and external influences continuously change physic-chemical characteristics of most water bodies by their environment. The pollutants and or contaminants can be natural but more commonly man generated through domestic or industrial process. Depending on the degree of alteration, water can be made unsuitable for use domestically or can become harmful to human beings and / or living organisms in general. Therefore there is the need for periodic check on the quality of water sources for safety purposes.
Ground water is very useful to man and other living organism, hence it is virtually important to detect its occurrence, as well as evaluate it to sustain our domestic, industrial and other uses, especially where surface water is insufficient in terms of quantity and quality (characteristics features) for this purpose.
Water consumption is high in Igarra being the Headquarter of the Akoko-Edo Local Government Area. The town has witnessed a drift or migration from the neighboring environs and villages. The inhabitants depend on both ground and surface water for their domestic and municipal activities. The purpose of this project is to assess the quality of ground water from hand-dug wells in Igarra by comparing their physical, chemical and biological parameters with those local standards such as FEPA and NAFDAC ( AS WELL AS THE GLOBAL STANDARD OF World health organization (W.H.O).
Water is a chemical compound (H2O) on which animals and plants depend for survival, it is also very useful for both domestic and industrial activities. Infact, life as known on earth in non-existence without water. Water can occur in the three states of mater, that is liquid, solid (ice or glacier) and gaseous (steam or water vapour). More that 60% of water available on earth is locked up as ice in the polar regions of the world.
Geologically, water occurs on the earth’s surface in the forms of river, ponds, lakes, streams and in larger bodies such as seas and oceans. Water occurring in this form is generally referred to as surface water whereas in situations where the water occurs in the sub surface in porous and preamble geological formation like aquifers, fractures. Joints and faults, it is described as ground water. The third occurrence of water is rain water, and this is the main source of replenishment for ground water and surface water. Rain water is more abundant during the raining season in the tropics and it is the usual practice in localities that are in short supply of ground and surface water to collect or channel rain water into underground reservoir for use during the dry season.
The Encyclopedia Britannica (1982) and sthelar (1973), have defined ground water as that which occurs below the earth’s surface where it occupies all or part of the void in a geological layer or layers. Waltz (1971) attempts to distinguish between ground water and as any water occurring within the saturation zone (s) where the hydrostatic pressure is greater than or is equal to the atmospheric pressure.
Davis and de west (1966), classified groundwater into different types on the basis of depth of occurring; the classification generally described all forms of water occurring above the water table as either being soil, gravitational or capillary water occurring below the water table as either ground or internal water as shown below.
Soil water
Capillary water
Ground water
Internal water
Fig. 1: Classification of subsurface water (After Davis & Dewies 1966)
The study of the major hydrological systems (under ground and hydrological systems) is referred to as Hydrogeology which incorporate geology, hydrology and fluid mechanics (also see offodile, 1992).
Water can also be described geochemically as heavy water if all or some of the hydrogen atoms have been replaced by deuterium to form deuterium oxide (D20) which has a specific gravity 1.1 freezing point of 8.84 and a boiling point of 101oc as compared to the corresponding value of 1.0, 40c and 100oc respectively in natural water (Chapman, 1964).
Heavy water is not common, but is normally used as a moderator in some nuclear reactions.
The uses of water are too numerous to be listed here and will only suffice, to say that without water, there cannot be life because practically, all biological and chemical process that sustain life are dependent on water.
Water is an inevitable ingredient of life not to man and animal but also to plants.
All industrial process utilizes water. In the agricultural industry, a lot of water is used for irrigation and planting. In the chemical industry, in maintaining fluidity of enzymes in the body, water is used also for the generation of hydro-electric power in the transportation industry water is used as a medium for conveying duty cargo.
Furthermore, in all homes, water is consumed daily as food and used for domestic purpose such as cleaning, washing, cooking, bathing etc; water is the home of fishes and breeding place for amphibians.
The properties of water can be categorized into three namely;
• Physical properties
• Chemical properties
• Biological and / or bacteriological properties.
The physical properties of water can be felt or seen at first sight such as colour, odour, taste, turbidity, (that is colloidal suspensions such as clay and silt). Etc. This in-turn prevents the passage of light through water which is not usual in potable water. Therefore, water should be free from suspensions.
More also, temperature above 25oc renders water unfit or unpleasant for drinking but at temperature of about 10oc, water is regarded fit and potable and density should be at about 4gcm3
The chemical properties of water can be seen from its general formula, H20.
Most underground water is slightly acidic to strongly acidic when tested with a PH meter and / or litmus paper.
The Biological and bacteriological properties of water have led to the decrease in water quality for domestic use in the area. Potable water should be free from any form of life such as algae, bacteria etc. these are organisms of the obligate aerobes and obligate anaerobes. Their presence renders water unfit for domestic use. These organisms can be seen when water is cultured.
Bacteria also differ with regards to the temperature needed for growth. Most of the soil and aquatic organism are mosophilic although there are exceptions.

Geologically, the area under investigation or study comprises the Precambrian basement complex rocks of south western Nigeria, which fall within the mega mobilize belt, east of the west Africa craton described as polycyclic metamorphic terrain by Rahaman (1970).
The major rock types occurring in the area can be grouped into three;
• The metasedimentary rock
• The Granitic rocks or older Granites
• The Minor intrusive
The metasedimentary rocks occurring in the Igarra area represents the oldest rocks in the area that are infolded into the older migmatite Gneiss complex. They occur as synformal troughs with a dominantly north – south strike. The main metasedimentary rocks in Igarra area metaconglomerates, low grade quartzites, quartz biotite shists of various mineralogy, quartzitic schists and low grade marbles tec. Both the palaeoecological and geological age of these metasedimentary rocks remain a controversy. The granitic rocks are the major intrusives bodies in the area. They generally intrude the metasediments and form sharp contact with some of them. In most cases they occur as boulders or as a massive ridge. They attain the highest topographic heights of the rocks in the area. At some outcrops, xynolith of the metasedimentary rocks occur in the granitic bodies. These rocks form part of the older granite suite of Nigeria and consists various rock types including, Biotite granite, biotite-hornblende granites etc. in terms of relationship, they cross – cut the metasediments and are therefore younger in age. The minor instrusives do not belong to the older granite suite but are younger in age and include both metasediments and the granitic bodies. They include the pegmatite dykes quartz vein etc.
The various rock types have been intensively and deeply weathered into laterites and lateritic soil columns of overburden in places over the crystalline basement rocks. The overburden varies in thickness from place to place. The base of the overburden serves as the main aquifer for the groundwater although quite appreciable amount of the water is also known to be stored in the faults and joints within the crystalline rocks.
The bedrocks play a significant role in the determination of the physical, chemical and biological characteristics of the groundwater as well as the liquid content. The provisions of good quality water supply from these wells are controlled by the hydraulic conductivity distribution and the quality of ground/water and surface water within the area. This is why the geology of the area cannot be over looked.

Fig 2: Map of the area showing sampling points

Fig 3: Geological map of the study area.

The chemistry of groundwater depends on the geochemistry of the host rocks. As water moves through rocks some exchange takes place, and invariable, the water takes into solution in different concentrations, some elements that make up the rock. The chemistry of groundwater in any geological environment is controlled by several factors viz: the chemistry of the infiltrating water at the recharge sources, the chemistry of the porous medium including the interstitial cements or matrix of the aquifer, the rate of groundwater flow in the aquiferous medium and hence permeability of the aquifer and the travel time of the water through the environment.
The quality of the water, therefore, for various purposes, viz: domestic, irrigation and industry, depends on the concentrations of these substances. The major cations found in groundwater include K+, Na+, Ca2+, Mg2+, Cu2+, Al3+ and the anions are : S042-, CL-, HC03-, N03-, also there are non-ionic constituents like phenols and dissolved gases such as Oxygen (02), and C02. There are international standard in the water industry generally set-up by organizations like the World Health Organization (WHO) and others standard institutions connected with use in agriculture and Industry. Typical standard are outlined as follows:

TABLE 2: International Standard for Drinking Water (after WHO 1994)
Substance Permissible Excessive (PPM)
Magnesium (Mg) 50.0 150.0
Calcium (Ca) 75.0 200.0
Iron (Fe) 0.3 1.0
Manganese (Mn) 0.1 0.5
Zinc (Zn) 5.0 15.0
Chloride (CL) 250.0 600.0
Nitrate (N03) 10 100.0
Sulphate (S04) 200.0 400.0
Lead (Pb) 0.05 –
Carbonate of Na + K – 120.0
pH range 6.5 – 8.5 8.5 – 9.2
Sodium 50 200
Potassium 50 200
Total alkalinity 200 400
Conductivity 1000uS/cm –
Taste absent –
Colour & odour absent –
TDS 1000 –
Hardness as CaC03 500 –
Coliform group absent –

In view of the wide variations in the chemical composition of water in different parts of the world, rigid standards of chemical quality cannot be established. According to FEPA (1991) and WHO (1994) standard for water quality limits designated “permissible” apply to water that would be generally acceptable; value greater than those listed as “excessive” would markedly impair potability. The methods of measuring contamination in extremely concentration is either in parts per million or equivalent per million.
Total Solids 500ppm 1,500ppm
Colure 5 units (pt-Co scale) 50 units
Taste Unobjectionable –
Turbidity 5 units 25 units
Odour Unobjectionable –
Iron (Fe) 0.3ppm 1.oppm
Manganese 0.1ppm 0.5ppm
Lead (Pb) 0.05ppm –
Copper (Cu) 1.0ppm 1.5ppm
Zinc (zn) 5.0ppm 15.oppm
Calcium (ca) 75ppm 200ppm
Magnesium (Mg) 50ppm 150ppm
Sulphate (S04) 200ppm 400ppm
Chloride (CL) 200ppm 600ppm
pH range 6.0-8.5 –
The Sulphate Ma + Na 500ppm 1000ppm
Nolic Substances (As phenol) 0.001ppm 0.002ppm

Groundwater samples were collected from twenty five, 25) hand-dug wells and borehole in Igarra metropolis. The wells samples were chosen randomly, ensuring their fair distribution over the entire study area (fig 2). The choice of a well depends on its distance from a previously chosen well in the locality, the wish of the owner to make the well available for study, and the observed geology. Rubber bucket which locally gives the least contamination (Watt and Wood 1977) was used to draw water samples from all the wells studied. The samples were stored in well drained, clean polyethylene bottles of 2 liters in volumes and rinsed out with the water samples in each location.

To prevent or reduce change in quality of the water samples, physical parameters like Odour, Taste, Colour and Appearance were observed on field. The pH, alkalinity, hardness and the analyses of unstable radicals like nitrite, nitrate, phosphate, silica and bicarbonate were all carried out shortly after collection of each water sample. The sample were then stored in a refrigerator and the temperature kept below 20oC. (Malomo, etal 1990)

This parameter was determined with a thermometer having a calibration from – 10oC to 110oC. Its reading was taken to the nearest ± 1oC.

Chemical analyses of the water sample from hand-dug wells in Igarra were carried out at Tudaka environment consultants limited, Warri. The analyses were carried out based on various standards for water analysis.

Lovibond comparator consists of a housing two glass tube, 15cm deep and 2.5 cm diameter and a disc on which are engraved coloured and permanent glass standard graduated in Hazen units.
Distilled water is put into one of the glass tube and a water sample is put into the other. The readings is to be taken, place the disc over the end of the tube containing distilled water and rotate it until a combination is found that appears to have a colour similar to that of the sample. Record this as the colour of the sample.

Electronic pH meter Digital Moden Exner GMBH, D4040, NEUSSI was used, it has combined electrode. Known buffer solution of pH 4, and pH 9.20 was used to standardize the equipment. pH is the negative logarithm of the hydrogen ion concentration. It is a method of expressing the acidity or alkalinity of aqueous solution. The solubility of ions in water is strongly influenced by the Ph value of the water.

The conductivity was determined directly from various samples by using conductivity meter (Radiometer Copen-Hagen CDM 83). Conductivity is another important criterion in measuring the electrical resistance of a solution, which is to draw information on the total ionic concentration in the solution. The conductance for water samples is related to the total concentration of dissolved ions, their valences, mobility and temperature measurement. The purity of water is commonly checked by conductivity meter.
Procedure: The equipment makes use of a cell. It operates by detaching the measuring cell from the instruction, cleaned thoroughly with a bottlebrush and rinsed with distilled water occasionally thereafter to remove tenacious deposits.
The cell was rinsed with a small quality of the solution to be tested before filling for measurement. The button was held down while the measuring dial pointer was slowly rotated until the balance indicator was central. The readings were measured in uS/cm.

Apparatus: – Evaporation dish or beaker, oven, desiccators, steam bath, 100ml-measuring cylinder.
Procedure:- 100ml of the sample were measured and filtered into 100ml measuring cylinder using a pre-weighed filter paper; it was made up to 100ml with distilled water. It was later, transferred into an oven at 180oC for 11/2 hours, cooled in desiccators and weighed. The weight of the crucible was recorded as W1, with dissolved solid as W2.
TDS (Mg/l) = W2 – W1 X 103 Mg/l

A buck model Flame Atomic absorption spectrophotometer (AAS) is similar to flame emission spectrophotometer. In (ASS), the sample were aspirated into the flame and atomized.
Standard solution was prepared from the solution in ppm for each metal using suitable metal salts of element to be determined.
The instrument was switched ‘ON’ for about 15 minutes to arm for stability and the required lamp for each metal was fixed. The standard of metal was aspirated simultaneously, as well as the samples serially. The absorbance readings were then recorded under the same condition (Buck Scientific Operations Manual book for ASS).

The results of the chemical composition of hand-dug well water in Igarra are shown in Table 12. In the chemical analysis of the 25 well water, concentration of different ions is expressed in milligram per liter.
Physiochemical Properties of Water in Hand Dug Wells in Igarra
Sample Code pH Temp TDS Cond Colour Turbidity Iron (Fe)
Oc mg/l μs/cm Lu N.T.U mg/l
1 7.63 27.1 74 147 0 1.31 0.22
2 6.89 25.9 29 58.3 1 8.62 0.15
3 8.12 29.9 321 656 0 4.37 0.63
4 7.96 26.2 264 527 0 2.62 0.47
5 7.73 28.7 298 597 1 1.74 0.21
6 7.45 29.1 222 446 0 1.93 0.19
7 8.11 26.6 317 633 1 3.52 0.52
8 7.83 27.1 312 624 1 3.94 0.92
9 8.12 27.5 373 743 1 5.81 0.49
10 7.82 27.3 210 424 0 0.82 0.14
11 7.27 27.1 311 621 0 1.27 0.76
12 7.61 26.8 72 145 0 1.33 0.23
13 6.80 25.7 28 543 1 8.54 0.13
14 7.42 27.6 73 146 0 1.38 0.14
15 6.20 25.2 27 56.8 1 8.64 0.61
16 8.10 29.5 320 653 0 4.73 0.15
17 7.91 26.3 264 528 1 2.83 0.62
18 6.96 24.2 262 525 0 2.60 0.46
19 7.83 28.8 299 598 1 1.82 0.23
20 7.55 29.6 223 448 0 1.96 0.20
21 8.00 26.8 319 655 1 3.54 0.52
22 7.91 27.2 313 628 1 3.96 0.91
23 8.22 27.7 375 745 1 3.96 0.51
24 7.91 28.2 212 426 0 0.94 0.15
25 7.30 28.0 314 624 0 1.30 0.75
The temperatures in well water are somehow uniform and are found to vary between 28oC and 30oC. The condition of the well also has some influence e.g. well depth, whether it is covered or not and nature of material used for cover etc.

Fig 4: Graphical Representation of Temperature in water sample against WHO.

Ground water is usually colourless and the presence of colour in water indicates the presence of impurities which such as decaying leaves. All the sample water tested the colour fall within the range of 0 – 1 and they are all below FEPA and WHO Standard.

Fig 5: Graphical Representation of colour in water sample against FEPA, NAFDAC.

Electrical conductivity is the ability of any substance to conduct electrical current. The electrical conductivity of water indicates chemical quality of water, it is a function of pH, temperature, ionic concentration and species of ion present in water. It is measured in milli ohms or micro ohms. In the study area, the electrical conductivity varies from 145 to 745us|cm were all below WHO Standard for drinking.

Fig. 6: Graphical Representation of Conductivity in water sample against FEPA, NAFDAC and

PH refers to the hydrogen ion concentration in water. A PH of 7 a solution is considered neutral, with PH greater than 7 it is alkaline solution and PH less than 7 is an acidic solution. Ground water is slightly acidic and slightly alkaline.
The PH of most ground water is generally controlled by the amount of dissolved carbon (IV) oxide gas and carbonates. The PH values for WHO standard fall within 6.5 to 8.5.

The total dissolved solid content (TDS) is also known as the total salt concentration of groundwater.
TABLE 14: Groundwater is classified to its TDS content by (HEM, 1970) as follow:
Fresh <1000ppm Moderate 3000-10000ppm Very saline 10000-35000ppm Brine > 35000ppm

Based on this classification, the TDS concentration for all the tested well water samples, which varied from 30 to 800ppm, fall under fresh water. With respect to WHO (1994) desirable limit for drinking water, the TDs concentrations for all the water samples tested are not objectionable, the desirable maximum limit of TDS being 1000ppm. The low concentration of TDS in the area is due to the fact that there is a very minute concentration of salt in the groundwater around Igarra.

Fig 8: Graphical Representation of TDS in water sample against FEPA, NAFDAC and WHO

Fig 9: Hydrogeochemical graph showing the concentration of Iron in water sample against

The assessment of groundwater quality in Igarra and environs has revealed a disparity in the level of chemical constituents associated with groundwater.
The dissolved iron concentrations are generally low with about 48% of the water samples having concentrations not exceeding 0.3mg/l. The WHO maximum concentration (mg/l) limit is 0.3mg/l. 52% of the well water samples are above the WHO standard for Fe, which is 0.3mg/l.
Iron gives a bitter or astringent taste to water. Iron leaves a material with permanent stains. It also influence the development for iron bacterial which them self are not hazardous both are very unpleasant. They form mosses of gelatinous and filamentous organic matters that tract the iron they use for growth.
Increase in concentration of iron in some ground water could be as a result of weathering of minerals like pyronxene, biotite, anphiboles and olivine pleasant in basement rocks.
Higher concentration of iron in groundwater could impact objectionable taste, colour, and stain of plumbing fixtures and laundered close, the brownish colouration in groundwater is caused by precipitation of soluble Fe3+as Ferric hydroxide. Iron is also a vital constituent for red blood cell formation.
The sources of iron (Fe) in groundwater are from igneous rocks, sand, stone, oxides, carbonates and sulphide or iron clay minerals. According to Durfer and Baker, (1964), more than 0.1ppm precipitates after exposure to air, causes turbidity, stains plumbing fixture, laundry and cooking utensils and imparts objectionable taste and colors to food and drinks. Hence only 48% of well water sample tested were okay as per Fe presence
Most of the groundwater in the studied area is odorless and tasteless. Also, the groundwater generally shows that Iron and Lead have little or low level concentrations, but of all the cations it is Iron concentrations that exceeded the WHO recommended limits in some of the water samples.

Conclusion can be drawn that groundwater is dependent on the chemistry of the rock (basement rock), leaching and infiltration and exchange of ions with the reservoir rocks and human activities.
It is also observed that not only the geology, topography, climate, soil and weather alone influence the groundwater chemistry, but man himself has very strong influence on the groundwater chemistry too.

From the earliest times, mankind has relied heavily on water supply from hand-dug wells for their domestic, agricultural and industrial uses.
Over 80% of the populations of inhabitants in Igarra metropolis derive their water supply by harnessing hand-dug well water. Hence, it is very important that proper measures be taken to avoid groundwater contaminations and to enhance suitable water development, since the health of inhabitants in a community depends in large extent on the quality of groundwater supply.
In view of the above, the following measures are recommended: Sanitary disposal site or landfill should be sited in the outskirts of the main town for sustainable development of groundwater.
1. Well location should be at least, 30m away from any source of contamination such as a cesspool or soak away.
2. Shallow hand-dug wells should be ringed or lined with ringed concrete cement to prevent excess contamination from any nearby toilets or soak away.
3. Adequate treatment must be given to well water such as chlorination of the well water or boiling to destroy any bacteria that may be present in it.
4. Establish a policy on land use planning and urban development, to guard against indiscriminate sitting of wells within the centre of the town.

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