seasonal variations of electrochemical parameters of surface water from lake alau, maiduguri,...

8/9/2019 SEASONAL VARIATIONS OF ELECTROCHEMICAL PARAMETERS OF SURFACE WATER FROM LAKE ALAU, MAIDUGURI, NI

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Continental J. Environmental Sciences 2: 1- 7, 2008

Wilolud Online Journals, 2008.

SEASONAL VARIATIONS OF ELECTROCHEMICAL PARAMETERS OF SURFACE WATER FROM

LAKE ALAU, MAIDUGURI, NIGERIA

Hati, S. S.1

G. A. Dimari2

B. G. Kolo2

and S. T. Garba2

1Department of Chemistry, Gombe State University, Gombe, Nigeria,

2Department of Chemistry, University

of Maiduguri, Maiduguri, Nigeria

Abstract

Surface water samples from six (6) sampling stations of Lake Alau were monitored for

seasonal variations of electrochemical parameters, pH, redox potential (Eh) and

electrical conductivity (EC). Sampling stations were located on the basis of outlets to

water treatment plant and irrigation, points of water collections for domestic use by

residents around the Lake Area. Determinations were conducted on-site with Jenway

portable meters. Results of determinations show a general increase in the levels of pH

during the dry season period with an average value of 8.00.1, tending towards an

alkaline surface water environment. The general increase in pH level during the dry

season was statistically significant. However, the means of Eh (181.011.3 and

209.811.5 mV) were recorded for dry and wet seasons respectively. EC on the other

hand was higher in the dry season than the wet season, with mean conductivities of

125.610.6 and 169.511.0 S cm-1

respectively. In conclusion, the results of the

electrochemical measurements obtained in this study show that Lake Alau is within the

no problem limits. However further monitoring studies are needed to elucidate the extent

of pollution in terms of toxic heavy metals and certain persistent organic pollutants.

KEYWORDS: water quality, aquatic life, domestic and agricultural wastes

INTRODUCTION

Electrochemical measurement of natural surface water is an important and straightforward way of monitoring

water quality and aquatic life, consequently indicating the level of pollution in such water bodies. Three basic

electrochemical parameters described by Manahan (2005) and Radojevic and Bashkin (2006), and significant

in monitoring both chemical and biological process occurring in surface water are the measure of H+

concentration in water (pH), the measure of oxidizing or reducing properties or power of water, redox

potential (Eh) and, the measure of concentration of ionized substances in water, electrical conductivity (EC).

These parameters, pH, Eh and EC are mainly connected to the quantitative ratio of carbonic acid and its ions

with direct relation to aquatic biota, e.g. fish population, the ability of the aquatic system to supply electrons

to an oxidizing agent and take up electrons form a reducing agent and the approximate measure of the total

concentration of inorganic substances in water.

A number of factors have been attributed to the cause of variations in the electrochemical properties of Lake

surface waters. Major amongst which, is dilution effect following rainfall, leading to an annual seasonal

variation effects (Odo and Ijere, 1997). Others are a wide variety of organic and inorganic pollutants released

into the water from surrounding activities (Manahan, 2005).

Lake Alau receives an average annual inflow of 329,000 m3

of water (Odo and Ijere, 1997). The annual

rainfall in this region ranges from 500mm to 1000mm and relative humidity is about 49%, with evaporation of

2934mm per year and temperature range of 38 to 40oC during the hottest months of March and April. These

factors together with persistent draught, very short rainfall period and desertification had made the water table

very difficult to reach (Idakwo and Abu, 2004). However Lake Alau supplies the municipal water treatment

plant, the major source of drinking water supply to the capital, apart from sporadic water obtained from

boreholes. The Lake supports a significant number of agricultural activities for an estimated population of


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Hati, S. S et al: Continental J. Environmental Sciences 2: 1- 7, 2008

521492 (Maiduguri), and immediate environs 211204 (Jere) and 156564 (Konduga) (FRN, 2007). They areabout sixteen species of fish in Lake Alau (Bankole and Mbagwu, 2000) and several fresh vegetables farming

(Uwah et al, 2007) all year around the Lake.

In view of the challenges vis-a-viz the immense role of Lake Alau to Borno State and Nigeria, it is important

to carry out pollution monitoring on this natural water, particularly because they are very likely to be polluted

with domestic and agricultural wastes (Nikoladge et al. 1994; Diamant, 1980; Wong, 1979), which are

observed to be the major sources of pollutants in Lake Alau. Thus, this work provides monitoring information

concerning the electrochemical properties of the Lake as an indicator of extent of pollution associated with

domestic and agricultural activities taking place in and around Lake Alau in year 2007.

MATERIALS AND METHODS

Study Area, Sample and Sampling

Lake Alau is located on latitude 11o41N and longitude 13

o16E on the South Eastern (SE) part of Maiduguri,

capital of Borno State, Nigeria (Google Earth, 2008; Idakwo and Abu, 2004). Surface water of the Lake was

monitored at six sampling stations (Figure 1) for a period of 8 months. This duration was categorized into

two: dry season (February-May) and wet season (July-October) for the year 2007. Sampling stations were

located on the basis outlets to water treatment plant and irrigation, S1, S2 and S5; points of water collections

for domestic use by residents around the Lake Area S3, S4 and S6.

Determination of Electrochemical Parameters

The electrochemical parameters, pH, redox potential (Eh) and conductivity of surface water of Lake Alau

were determined according to standard analytical methods described by Radojevic and Bashkin (2006), in

addition to instructions in the manuals of instruments used. All determinations were conducted on-site with

portable meters at approximately 25oC. Eh and pH were determined using model 3310 pH meter (Jenway Ltd,

Dunmow, UK). The pH meter and electrode was calibrated with buffer solutions of pH 7 and 4 for pH

determinations, while Eh readings were taken on the millivolt (mV) adjustments of the instrument

accordingly. This was standardized using standard redox solution. Conductivity measurements were carriedout using model 4150 conductivity meter (Jenway Ltd, Dunmow, UK). This was calibrated with standard

potassium chloride solution and results presented in S cm-1

. All observations of parameters at each sampling

stations were made in triplicates. Results obtained were statistically analysed for significance in variations

between seasons by t-test and variations between sampling stations by analysis of variance (ANOVA) with

Bonferroni post hoc test using coupled Microsoft Excel+Analyse-it v. 2.10 (Analyse-it

, 2007). Variations

were considered significant at p


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Contrary to the general increases in pH during the dry season, results of Eh determinations (Figure 2) show a

general decrease in Eh values during the dry season. Of note however is the uniform trend in variations of Eh

between the seasons, along sampling stations, which overall, are not statistically significant. However, the

means of Eh (181.011.3 and 209.811.5 mV) were recorded for dry and wet seasons respectively. These

observations indicate that surface water from Lake Alau at the time of this study, can be characterized as anoxidizing environment further depicted (Figure 4) with the Eh-pH plot.

S2S3

S6

S5

S4

S1

Figure 1: Lake Alau, Maiduguri-Nigeria showing sampling stations

Google Earth Maps (2008)


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Observations in the result of seasonal variations of conductivity determination (Figure 5), shows that

conductivity was higher in the dry season than the wet season, with mean conductivities of 125.610.6 and

169.511.0 S cm-1

respectively. This variation was statistically significant and was effectively contributed by

activities in S1, S3 and S6. Remarkable observations were made at S4 and S5 in which a seemingly no

variations in the conductivity was observed indicating usual activities.

DISCUSSION

Many causes of pollution resulting from heavy metals, strong acids, alkalis and organic compounds affect the

environment and humans (Hammer, 1997; O'neil, 1983). An indication of extent of these can be obtained

from monitoring the electrochemical parameters of a natural water body.

Results of this study generally show the influence of dilution upon the electrochemical parameters studied, as

there were increases in pH and conductivity measurements during the wet season. Naturally aquatic biota

shows sensitivity to extremes of pH largely due to osmotic effects (Strickland, 2007). Knowledge of the level

of pH in such natural water provides control and treatment measures in processes involved in water softening,

disinfection and coagulation. Though the highest pH was observed at outlet points to water treatment plant,yet this level does not pose great demands on pH control during treatment processes. Sulphuric acid produced

from the reaction of pollutant sulfur dioxide which enters natural water as acid rain fall may contribute to the

pH becoming hazardously low a condition that is commonly observed in Lakes of highly industrialized cities

(Uwah et al, 2007). This is hardly the case with Lake Alau situated in an almost no industrial activity region.

Irrigation and intensive agricultural activities have also been known to be responsible for the transport of salts

from irrigated and fertilized land into water bodies, corrosion, leaching and speciation of heavy and toxic

metals in waters have been greatly influenced by the pH (Manahan, 2005). This is likely to be reason of the

significant variations observed in pH values in this study. Since higher agricultural activities takes place

during the wet season.

The EC measure observed in this study, which is simply how easily an electric current runs through water

between two electrodes, shows that factors, such as greater amount of salts, acids and bases are in the water,

which increases conductivity, are within permissible limits. EC is also used to monitor water destined for use

in irrigation, drinking (Carlson and Simpson, 1996; Manahan, 2005) and conductivity is closely related to

salinity, ions that have a major influence on the EC of water are H+, Na

+, K

+, Ca

2+, Mg

2+, Cl

-, SO4

2-, and

HCO3-(Radojevic and Bashkin 2006). Therefore EC increases with increase in mineral contents of a water

sample, thus its use in the measure of mineral contents. In general, conductivity is reduced as runoff increases,

and larger lake watersheds have greater conductivity levels than lakes with smaller watersheds (Manahan,

2005). Other factors that are likely to affect the increase in EC are the increase in temperature, which

decreases viscosity and increases dissociation. Thus the unusual observations at S4 and S5 are very likely to

be caused by these factors.


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Carlson, R.E. and J. Simpson. (1996). A Coordinators Guide to Volunteer Lake Monitoring Methods. NorthAmerican Lake Management Society. A Trophic State Index http://dipin.kent.edu/tsi.htm. Retrieved

12/3/2008.

Comerton, A. M., Andrews, R. C. and Bagley, D. M. (2006) Impact of Blending Reuse and Lake Water on

Treated Water QualityJ Env. Eng. & Sci. (5) 4: 359-363(5)

Dalzell, D.T.B. and Christofi, N. (1999). ATP luminescence used to evaluate the impact Of chemicals and

wastewater to activate sludge. Effluent Eco-Toxicology: An European Perspective. Society of Environmental

toxicology and Chemistry. pp. 14-17 Edinburgh.

Diamant, B.Z. (1980) Environment Health Impacts of water use in Africa. Proc. Water Techn. 13:171-178.

FRN: Federal Republic of Nigeria (2007) Official Gazette. Legal Notice on Publication of the 2006 Census

Report 4 (94) B47-182

Google Earth (2008). Google earth satellite image of Lake Alua, Nigeria. Google Earth 4.3.7204.0836. sever

kh.google.com (Access Date: 12/04/08)

Hammer, J.M. (1977). Water quality and pollution Waste and Water Technology 2nd

Edition, John Wiley &

Sons, New York. Pp. 143-168.

Henry, A.S. (1971). "Metal in the Air". The science of environment B (8) pp.18-31.

Idakwo, P. Y. and Abu, G. O. (2004) Distribution and Statistical Analysis of Bacteria in Lake Alau in the Arid

NorthernNigeria J. Appl. Sci. Environ. Mgt. Vol. 8 (1) 5 - 9

Manahan, S. E. (2005)Environmental Chemistry (8th

Edn). CRC Press LLC, USA. Pp. 169-180; 687

Nikoladze, G.D., Mints, R. D. and A. Kastalsky, (1994). Water Treatment for Public and Industrial Supply.

Pp. 14-16.

Odo, P. E. and Ijere, J. A. (1997) Quality analysis of water from Alau dam area in the north eastern Nigeria

for irrigation suitability and some related agronomic and environmental implications. Issues in environmentalmonitoring in Nigeria. Nig. Geographical Ass. Pp 63-67.


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Continental J. Environmental Sciences 2: 8 - 11, 2008


BACTERIAL EVALUATION OF LOCAL HARD CHEESE (CHUKU) IN KATSINA- NIGERIA.

1Salihu, M.D.,

1Junaidu, A.U.

1Magaji, A.A.,

1Gulumbe, M.L.,

1Suleiman, A.,

2Ahmed, A, and

1Shittu, A.

1Veterinary Public Health Department, Usmanu Danfodiyo University, Sokoto2National Veterinary Research Institute, Vom, Sokoto Research Laboratory.

ABSTRACT

A study was conducted to evaluate bacterial quality of 288 samples of local haed cheese

(Chuku) procured from various retail outlets and markets in katsina town. The samples

were analysed for the presence of bacterial organisms, using the conventional

microbiological techniques for culture and identification. The results revealed the

presence ofEscherichia coli, Klebsiella sp., Enterococcus sp., Listeria monocytogenes,

Proteus sp. and Staphylococcus aureus. Other isolates are Bacillus sp., Streptococcus

sp., Yersinia sp and Lactobacillus sp. The isolation ofEscherichia coli, Klebsiella sp.,

Enterococcus sp.,Listeria monocytogenes, and Staphylococcus aureus from the samples

are indication of poor hygienic conditions encountered during processing, storage and

marketing of the product which is a possible threat to consumer health.

KEY WORDS: Bacteria, Food poisoning, Isolates, Local cheese, Katsina, Milk.

INTRODUCTION

Milk is inherently a very unstable fluid owing to its high moisture content and the suitability of milk as a

growth substance for contaminants is responsible for the ease with which it becomes contaminated with

microorganism (Salihu, et al., 2005). It is therefore, important to convert milk into various products of milk

such as cheese, fermented milk, whey and other stable products of milk. Milk and milk products play vital

roles in human nutrition and also serve as good medium for growth and transmission of manymicroorganisms to man. (Gill, et al., 1994).

Wherever, cattle are kept the Fulani men milked the cows and thereafter distribute the milk to the individual

women in the encampment (Fulani farm-stead), the women decide on what will be done with the milk

(Belewu and Aina, 2000). The milk is processed into various products such as cheese, fermented milk etc.

There have been reported cases of out break of food poisoning associated with milk and milk products from

developing and developed countries (Sharp, 1987). Although there are no surveillance activities in Nigeria,

laboratory studies have shown the presence of food borne pathogens and high microbial load in some street

food. (Umoh, et al., 1984; Magaji, et al., 2002: Adetunji, et al., 2003). The local cheese (locally called Chuku)

which is thin white to milky in appearance, slightly hard unripened with little moisture is sold in villages,

markets, and crowded points in and around Katsina. Since the milk products constitute an integral part of the

Nigerian diets (Aduku and Olukosi, 1991), attention should be paid more on the hygienic aspects of the

distribution of such foods. Milk and milk products provide a favourable environment for microbial growth.Microbes can contaminate milk or milk products via animals themselves, the surrounding atmosphere,

feedstuff, handling, equipment as well as the milker (ILCA, 1988; Belewu and Aina, 2000).

This study was undertaken to evaluate the bacterial organisms associated with local hard cheese (Chuku) so as

to determine their safety for consumption.

MATERIAL AND METHODS

Preparation of local cheese hard (Chuku)

The local hard cheese is prepared in Nigeria by using vegetable rennet. The cheese is made from milk which

is slowly heated in a pot while vegetable rennet extract of Sodom apple (Calotropis procera) which is

commonly found in the tropics and sub-tropics is added. The plant contains calotropin enzyme which curdles

the milk (Aworth, 1990; Kees, 1995; Anon, 1995). The extract is obtained by crushing the leaves and the


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Salihu, M.D et al: Continental J. Environmental Sciences 2: 8 - 11, 2008

stems of the plant and then rinsed in a calabash with milk. The mixture is strained into warm milk withconstant stirring and heating. Coagulation starts within 15-25 minutes after the addition of coagulant. The

curd is boiled for sometime at least 20 minutes to inactivate the plant enzyme and facilitate whey expulsion

after which the curd is strained through a sieve (usually a small raffia basket which facilitates whey drainage

and gives characteristics shape and size to the cheese) and turned carefully. The fresh cheeses are then spread

on tray or mats or flat wood to dry and become hard in the sun or in the shade.

Collection and processing of samples.

A total of 288 samples used for the study were procured every two weeks and randomly over a period of 24

weeks, from various retail outlets as well as from markets in Katsina metropolis. The procured cheeses were

wrapped in foil papers from the point of collection and transported to the laboratory same day. Care was taken

not to alter the condition of the samples as they are obtained from the sources where consumers purchase them

for direct consumption. The samples were aseptically handled in the laboratory. Samples from each of the

retail outlets were soaked in with distilled water in a beaker and covered with foil paper for 2 to 3 hours to

allowed for the rehydration and softening of the cheese. A loopful each of the softened cheese samples was

then inoculated into peptone water and selenite F broth respectively and incubated at 37OC overnight. A

loopful each from the peptone water was inoculated onto MacConkey agar, Blood agar and Eosin methylene

blue (EMB) agar while a loopful of selenite F broth was inoculated on deoxycholate citrate agar (DCA). The

media were inoculated in duplicate (except the DCA) and incubated aerobically and anaerobically at 37OC for

24-48hrs. Colonies were randomly selected from each medium and restreaked on fresh media plate to obtain

pure culture. Pure cultures of each isolates were stocked in agar slants in MacCarthney bottles. Colonies on

the media were identified based on Bergys manual and classification schemes proposed by Cheesbrough,

(2000). The identification was based on morphology and the following characteristics particularly gram stain,

morphology of the cells, motility and anaerobic condition as well as ability to produce catalase enzyme. Other

tests include biochemical coagulase, oxidase, oxidation and fermentation tests, acid/gas production from

sugar, urease test, hydrogen sulphide test, nitrate reduction test, phenylalamine deamination tests and

haemolysis test.

RESULTS

A total of 10 different bacterial organisms that are of public health importance were isolated from the samples

collected. These organisms include Escherichia coli, Klebsiella sp., Enterococcus sp., Listeria

monocytogenes, Proteus sp. and Staphylococcus aureus. Other isolates are Bacillus sp., Streptococcus sp.,

Yersinia sp andLactobacillus sp.

DISCUSSION

The high level of bacterial isolation in this study is an indication of unsanitary hygienic standard or condition

post processing, storage, handling and retailing of the product. Indicator organisms like Escherichia coli,

Klebsiella sp. and Enterococcus sp. are vital in milk and milk products to evaluate the microbiological safety

and sanitary condition during processing and storage (Belewu and Aina, 2000). The presence ofE. coli which

is usually killed at >55oC in 15 minutes in cheese is suggestive of post processing contamination (Adetunji et

al., 2003). The presence of Klebsiella sp in the product could partly be through air (sneezing, coughing,talking or singing) since the bacteria inhabit the upper respiratory tracts of humans (Belewu and Aina, 2000).

The presence ofEscherichia coli and Klebsiella sp. in milk and milk products has been reported in literature

(Aworth and Egounlety, 1985; Joseph and Akinyosoye, 1997; Belewu and Aina, 2000; Adetunji et al., 2003).

The isolation of enterococcus in this study may be attributed to unhygienic handling as man is the reservoir of

this organism.

The isolation of Staphylococcus aureus (coagulase positive) in this study is similar to the findings of

Adesiyun, (1994) and Adetunji (2003). This bacterium is known to cause major food poisoning in both

healthy and immunosuppressed patients (Alonge, 1993). Staphylococcus aureus produces an enterotoxins that

are heat stable and are generally not destroyed during pasteurization or processing (Tatimi, 1981). Listeria

monocytogenes has been incriminated in meningoencephalities, stillbirth and abortion in humans (Adams and

Moss, 1999). Therefore, the isolation ofL. monocytogenes in this study is an indication that the organism is an


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important contaminant of milk products; this has a serious public health consequence. Lactobacillus sp is alactic acid bacterium that is probably involved fermentation of the products. Proteus sp are usually pathogenic

in cases of wounds, burns, viral infection or similar condition of impaired resistance; their isolation is of

public health significant. This finding is similar to the findings of Belewu and Aina (2000).

The results show high amount of bacteria in the samples and this call for improved storage and retailing of the

product. A high level of sanitary and hygienic condition should be instituted and maintained so as to establish

microbial standards for this product which will go a long way in ensuring safer cheese and other milk

products.

REFERENCES

Adams, M.R. and Moss, R.O. (1999): Food Microbiology. The Royal Society of Chemistry, Thomas

Graham House, Science Park, Cambridge CB 40 WF 3rd

edn. 156-218.

Adesiyun, A.A. (1994): Bacteriological quality and associated public health risk of pre-processed bovine milk

in Trinidad. Int. Food Microbiol. 21: 253-261.

Adetunji, V.O., Ikheloa, J.O., adedaji, A.M. and Alonge, D.O. (2003): An evaluation of the bacteria in milk

products sold in Southwestern Nigeria. Nig. Vet. Jour. 24(3):92-96

Aduku, A.O., and Olukosi, J.O. (1991): Animal Products, Processing and Handling in the tropics. Living

Books Series. C.U. Publication, Abuja, Nigeria.

Alonge, D.O.(1993): Food (meat and milk) Hygiene (2nd

edn). Farmcoe Publications, Ibadan. 58-63.

Anon (1995): Curd and Whey. Spore. 55:1-4.

Aworth, O.C. and Egounlety (1985): Preservation of West African Soft Cheese by Chemical Treatment. J.

Dairy Res. 52: 189-195.

Aworth, O.C.(1990): Upgarding traditional techniques of food processing and preservation: Cheese making.

West Afr. J. Arch. 20: 232-238.

Belewu, M.A. and Anina, O.S. (2000): Microbial Evaluation of Indigenous Milk Products with Special

Reference to the Bacterial Flora of Some Public Health importance in Nigeria. Afr. J. Clin. Exp. Microbiol.

1(1):13-19.

Cheesbrough, M. (2000): District laboratory practice in tropical countries, Cambridge University Press.

ILCA (International Livestock Centre for Africa) (1988): Rural Dairy Tech. Exp in Ethiopia.

Joseph, J.K and Akinyosoye, F.A. (1997): Comparative studies on red sorghum extracts and other chemicalpreservatives for West African soft cheese.Int. Dairy J. 7: 193-198.

Kees, M. (1995): Rural cheese making. Agric and Rural Dev.

Gill, J.P.S., Josh, D.V. and Kwatra, M.S.( 1994): Qualitative bacteriological survey of milk and milk products

with special reference to Staphylococcus aureus. Indian J. Dairy Sci. 47:8.

Magaji, A.A., Salihu, M.D. and Donbou, B.L. (2002): Bacteriological Evaluation of roasted beef suya in

Sokoto Metropolis. Proceedings of the 39th

annual congress of the Nigeria Veterinary Medical Association,

Sokoto 2002.Pp 131-133.


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Salihu, M.D., Junaidu, A.U., Magaji, A.A., Gulumbe, M.L. and Balogun, S.T.(2005): Determination of

phosphatase enzyme activity in yoghurt sold in Sokoto metropolis. Proceedings of the 42nd

congress of

Nigerian Veterinary Medical Association- Maiduguri, 2005. Pp 119-120.

Sharp, J.C.M. (1987): Infections associated with milk and dairy products in Europe and North America 1980-

85. Bull. WHO. 65:397-406.

Tatimi, S.R. (1981): Thermonuclease as an indication of Staphylococcal enterotoxin in food. In: Antinutrients

and Natural Toxicants in Food. Ed. Org. R.C. Food and Nutrition press, Inc. Westport C.T, 53-75.

Umoh, V.J., Dangena, A. and Umoh, J.U (1984): Isolation of Yersnia enterocolitica from milk and milk

products in Zaria, Nigeria. Int. J. Zoon. 11:223-228.

Received for Publication: 13/06/2008

Accepted for Publication: 15/07/2008

Corresponding Author

Salihu, M.D.

Veterinary Public Health Department, Faculty of Veterinary Medicine, Usmanu Danfodiyo University, Sokoto

Email: [email protected].


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TOXICITY ASSESSMENT OF HEAVY ELEMENTS IN RIVER SEDIMENTS USING ENERGYDISPERSIVE X-RAY FLUORESCENCE TECHNIQUE

Hankouraou Seydou1, I.O .B. Ewa

2

1Gombe State University, PMB 127, Gombe Department of Physics,

2Centre for Energy Research and

Training Ahmadu Bello University, Zaria

ABSTRACT

Trace quantities of thirteen elements have been determined from the aquatic sediments,

of the Kubanni River- principal water way at Zaria, Nigeria. Energy Dispersive X-ray

Fluorescence (EDXRF) Technique was used in determining

Si,Ca,K,Ti,V,Fe,Co,Zn,Rb,Sr,Y,Zr and Nb in the sediments. An AXIL computer

programme was used for the spectral analysis. The degree of pollution of the Kubanni

River was ascertain and compared with the literature toxicity data. The Kubanni River

sediments studied showed relatively low state of pollution for the elements determined

and the River could still be used as a principal potable water source for Zaria

inhabitants.

KEYWORDS: EDXRF, toxicity, heavy metals, River sediments, Kubanni

INTRODUCTION

Naturally occurring trace elements are deposited in aquatic environments either in the soluble form and

eventually settle as bottom sediments along the course of the river (Hankouraou, 1998). The presence of these

trace elements in aquatic environments is not without significance: for some of them are known to be very

toxic and act as contaminants in the sediments. Mans activities have increased the loading of municipal and

industrial contaminants to the nations water ways. One of such water ways is the Kubanni River our studyarea in Zaria.

This river runs as a major principal drainage artery dissecting Zaria town. The increased loading of river beds

with wastes could result in increased concentration of many heavy metal contaminants in sediments adversely

affecting water quality and even the survival of aquatic organisms. Contaminants in sediments have a wide

range of sources, and could be affected by lotic (running water), lentic (standing water), estuarine or lacustrine

conditions, physical properties of sediments, the chemical state and biological composition of the water

involved (Jenett et al 1980).

Most research in aquatic systems has been concerned with the form of contaminants present, rather than the

amount of potential toxic material bound up in the sediments .The low concentration elements are

undoubtedly the most difficult to study because background levels are always present in the environment

masking their presence, and a small perturbation on an ecosystem could bring about rapid increase in the ratesof synthesis of these heavy metals.

The potential impact of trace elements in sediments is determined here strictly with respect to the Kubanni

River sediments. The detection of such elements requires sensitive and accurate analytical methods. In this

work the Energy Dispersive X-ray Fluorescence (EDXRF) is chosen due to its reliability amongst other

merits. This method of analysis offers an easy and sensitive way of determining any trace element in

sediments. Its advantages include:

i) Simple sample preparationii) Non destructive capability for analysis andiii) Ability to determine many elements simultaneously.


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EDXRF analysis suffers from certain set backs such as high investment, rigorous radiation protection, matrixeffects, need for well trained personnel; thus limiting its application to few laboratories and research institutes

such as the Centre for Energy Research and Training, Ahmadu Bello University, Zaria, where this work was

carried out.

This paper was a report on the analysis of some trace elements in the Kubanni river sediments by EDXRF

technique.

The method was checked by analyzing United State Geology Survey (USGS) reference materials: USGS-

AGV-1 (Analyzed Andasite) and USGS-G2 (Granite).

EXPERIMENTAL

In order to study the distribution of trace elements along the Kubanni River, 11sediment samples were

collected at different locations (Fadama along Jos Road 5 samples and for Maje Road Bridge, Tudun Wada

Bridge, Kano-Kaduna Bye-Pass Bridge, Zango Bridge, Ahmadu Bello University Dam and Kampangi Hills,

one sample each). The 11 samples were collected in polyethylene containers .The distance between the

sampling points is approximately 3 kilometers.

The sediments were allowed to dry in an oven at 50o

C for three days and were then homogenized, by manual

grinding in agate mortar. The powder obtained after grinding was used for the preparation of pellets used for

the analysis. A Mettler 100 CA digital balance was used for weighing the powdered samples, with only 2.0g

of each sample required for the making of pellets. A cellulose binder polyvinylchloride (PVC) was added to

each 2.0g of the sediments (powder) sample. The mixture was re-homogenized in agate mortar. The samples

were then palletized (using the specac hydraulic press) by applying constantly a pressure of about 11.5 tones

per cm2. Pellets of 20 mm diameter and constant thickness of 5 cm were obtained from the samples.

Two standard reference materials were used for quality control measurements (USGS- AGV-1 and USGS-

G2). Samples and standards were analyzed using the EDXRF facility of the Centre of Energy Research andTraining (CERT), Ahmadu Bello University, Zaria Nigeria. The spectrometer consists of a Si(Li) detector, a

preamplifier, amplifier and 4096 multi-channel analyzer.

X-rays emanating from two sources (109

Cd,55

Fe) were used for the excitation of the characteristic K- lines of

the analytes.

The non linear least square fitting programme developed by IAEA and called AXIL was used for the

determination of line intensities.

RESULTS AND DISCUSSION

Table 1 shows the average concentrations of the elements down-stream Kubanni River (Hankouraou, 1998).

Bowen (1979) had shown that Ca, Co, Fe, K, and Zn are probably essential to all plants. This could be of usedto the seasonal crops grown at the Kubanni River basin. Elements like Si are essential to some groups, not

necessary for all. Rb, K, Sr, and Ca are known to have a very high toxicity, which only arises when a large

proportion of the essential ion has been replaced. Elements like Co are known to be very toxic to seed plants.

Fe, V and Zn are moderately toxic while Ca, K, Rb and Sr are only toxic to very high concentration which was

not the case with regard to Kubanni River. Zn is the element most frequently concerned with plant damage

from industrial emissions, e.g.: on mine wastes, near smelters, sewage sludges, river dredgings, near galvanized

steel buildings and where rubber tyres are burnt (Patterson, 1971). Excess of it inactivates soil enzymes

(Bowen, 1979) and reduces the bacterial population (Griffiths, et al 1975), but does not have marked effects on

the fauna. The Kubanni River level of zinc was found to be in the range 56 ppm to 665 ppm as shown in Table

1, which was less than 900 ppm an upper toxic limit for animals as given by (Jenett et al 1980) but can be

toxic to plants according to Bowen (1979). Most of toxicity problems encountered with zinc are due to

cadmium associated with zinc. As cadmium appears to be highly toxic to aquatic organism in the 0.02- 2.0 ppm


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range, where a dose of 4 ppm in the diets of humans is normally considered to be toxic ( Jenett et al. 1980).Some specified values have been accepted as the tolerated level in rivers. For example in Missouri the

maximum allowed value as given by Jenett et al. (1980) was 150 ppm, while the Kubanni River mean value of

zinc was obtained to be 149 ppm peaking up with the quoted value.

However, the results of this analysis show that the Kubanni River water might not pose any hazards and are

quite suitable for drinking purposes if well treated.

The quality assurance results (Table2 and 3) shows that the determinations for most of the elements were in

good agreement with the UGSG- AGV-1 SRM and UGSM-G-2 RSM literature values. The values of the

relative errors ranged from 1 to 30% for most of the elements this is within the permissible limits (IAEA,

1988). For Co our results were too far from the recommended values of IAEA. The relative errors were 83%

for USGS AGV-1 and 133% for USGS-G-2, but they were within the values of the participants (Tran Van et

al, 1989).

Table 1: Average concentrations of the elements detected in Kubanni River sediments. (Values in ppm

otherwise as specified).

Elements Mean value of the elements Toxicity to plants by Bowen

(Values in ppm or as stated) (1979) (in ppm)

SD

Si% 30.3 (5)

K% 2.0 (0.5)

Ca% 0.4 (0.2)

Ti% 0.5 (0.1)

V 242 (220) 10 -40

Fe% 1.2 (0.1) 10-200

Co


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Table 3: Determination of Elemental Content of USGS G-2 SRM (Values in ppm otherwise as specified)Elements Literature values This work Relative error%

Si% 32.2 32.0 1

K% 3.71 3.58 4

Ca% 1.40 1.28 9

Ti% 0.28 0.20 29

V 36.0 36.5 1

Fe% 1.60 1.11 31

Co 4.60


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Received for Publication: 07/09/2008Accepted for Publication: 15/10/2008


Hankouraou Seydou

Gombe State University, PMB 127, Gombe Department of Physics, Gombe State

Email: [email protected]


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SEASONAL DYNAMICS OF HEAVY METAL POLLUTION OF NIGER DELTA RIVER SEDIMENTRECEIVING INDUSTRIAL EFFLUENTS

V. C. Eze and G.C. Okpokwasili

Department of Microbiology, University of Port Harcourt, P. M. B. 5323. Port Harcourt, Rivers State, Nigeria.

ABSTRACT

The heavy metal changes of Okpoka-Woji River serving as a sink of effluent of

industries located in its vicinity within the Trans Amadi Industrial area were monitored

over rainy and dry season months in order to follow the seasonal dynamics engendered

by the dumping. Sediment samples from six sampling stations located along the river

were collected for the determination of heavy metals. The mean values for the heavy

metals were as follows: lead ranged from 17 - 67.2 mg/kg and 22.3-67.8 mg/kg; iron

7,995.5 - 17024.2 mg/kg and 6949.3 - 21,403 mg/kg; chromium 0.8-2.3 mg/kg and 16-

3.4 mg/kg; Zinc 3195.1 - 4455.5 mg/kg and 1713.4-3417.3 mg/kg; manganese 22.5 -

100.6 mg/kg and 20.8 - 121.7 mg/kg; nickel 2.4 - 9.2 mg/kg and 2.0-6.9 mg/kg;

vanadium 25.6 - 42.2 mg/kg and 26.1- 50.2 mg/kg; copper 19.5 - 46.9 mg/kg and 36.7 -

67.5 mg/kg; cadmium 0.3 - 1.6 mg/kg and 0.8 - 1.6 mg/kg; barium 21.1 - 77.6 mg/kg

and 22.6 - 34.0 mg/kg respectively for the rainy and dry season months. These results

showed that seasonal changes as well as industrial effluent discharges influenced the

heavy metal values of the river.

KEYWORDS: Seasonal dynamics, heavy metals, pollution, industrial effluents,

sediment.

INTRODUCTION

A pollutant is a substance that occurs in the environment at least in a part as a result of human activities and

which has a deleterious effect on the environment (Moriarty, 1990). Pollutants are now unfortunately part of

our environment as a result of industrial and other sources. There have been substantial increases in the

industrial and agricultural development in the Niger Delta with the attendant population growth. These

activities have resulted in the direct discharge of organic and inorganic substances including crude oil and

refined products through normal operations (effluents), operational failures and sabotage to facilities into the

adjoining water bodies. Other times as these components get into the water body, they finally settle at the

sediment which acts as sinks of contaminants in aquatic systems (Chindah et al., 2004; Muncha et al., 2003).

Sediments are important substrates for heavy metals attachment in any aquatic environment (Horowitz, 1985;

Deely et al., 1992). The degree to which water systems withstand heavy metal pollution is frequently

dependent on the concentration of suspended sediment in the water column. Suspended sediment in the water

particularly clay (< 4 m) act as sponges adsorbing metals directly from the dissolved settles, the bottom

sediment will build up a record on metal pollution in an area (Cauwet, 1987; Forstner, 1989).

Sediment is composed of a combination of lithogenic, antigenic and biogenic components such as mineral

grains, organic matter, iron and manganese oxides, sulphides and carbonates. Heavy metals may be attached

to any of these phases in proportions, which depend on the physicochemical conditions prevailing in the

sediment and associated water. It has been seen that as the grain size decreases, the concentration of metals

adsorbed onto sediment component increases particularly across the transition zone from silt to clay. The flat

platy structures of clay minerals have high surface areas, surface charges and cation exchange capacities,

which readily attract metals and metals carrying substrates (Forstner and Wittmann, 1981; Horowitz, 1985;

Cauwet, 1980; Deely et al., 1992)

Various heavy metals other than mercury including tin, cobalt, chromium, nickel, cadmium and thallium are

used in metal alloys or as catalysts. Their mining, smelting and ultimate disposal causes heavy metal pollution


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V. C. Eze and G.C. Okpokwasili: Continental J. Environmental Sciences 2: 17 - 25, 2008

problems. All these metals are substantially toxic to plants, animal and many microorganisms (Atlas andBartha, 1993).

The trace metals that enter the aquatic environment from both natural and anthropogenic sources may be as a

result of direct discharge into both fresh water and marine ecosystem or through indirect routes such as dry

and wet deposition and land runoff. The important natural sources include coastal supply such as rivers,

glaciers wave action and erosion; deep sea supply which included volcanic activities, tectonic activity and

chemical processes in sediment and atmospheric mainly particles and vapours (mercury). The anthropogenic

sources include direct processes such as mining, smelting and refining and indirect processes, which include

electroplating catalysts and petrochemical industry. Other atmospheric sources include fossil fuel burning

(Kiely, 1998).

The aim of this work is therefore to determine the effect of season on the heavy metal of the river receiving

industrial effluents.

MATERIALS AND METHODS

Study area

The Okpoka-Woji River is situated in the coastal environment of the Niger Delta Rivers State, Nigeria. It

arises from the bifurcation to the left of the Okpoka River, which drains into Bonny River. The area has a

mean water depth of 4.8m, which is tidal and gradually transits from fresh to salt water at the head. The

freshwater biotope flows unidirectionally downstream from the Rumuodara swamp forest transversing Port

Harcourt - Aba express road bridge through Rumuogba (Mini-Okoro Police Station) where tidal effects begin,

hence the beginning of the incursion of salt water (Figure 1).

Collection of sediment samples

Sediment samples were collected from the river at the discharge point once in a month from April 2001 -

March 2002. The sediment samples were collected using soil grab and were put in sterile black polyethylene

bags. All the samples were analyzed immediately on reaching the laboratory.

Chemical Reagents

The chemical reagents used in the study were of analytical grade and were products of BDH Chemicals,

Pooles, England; Sigma Chemical Company, St. Louis, Missouri, USA and Hach Company Ltd, Colorado,

USA.

Heavy Metal Analysis

The sediment samples were air dried for 5 days and sieved with a sieve size of 1.70mm. The samples were

digested using the methods adapted from ASTM (2003). This was done by weighing accurately 1g of the

sieved sample, which was placed in the digestion container. Exactly 10ml of water, 5ml, HCL (S. G. I. 19)

and 1ml of HNO3 (S.G.I. 42) were added and swirled gently to mix. The containers were loosely capped and

placed in a rack, which was then put in an autoclave. The samples were autoclaved for 30 minutes at 121o

Cand 15 psi. The digestion containers were then removed from the autoclave and allowed to cool at room

temperature. The contents of the digestion containers were quantitatively transferred to a 100ml volumetric

flask and made up to volume with distilled water. The digests were analysed for heavy metals using atomic

absorption spectrophotometer Model 969, Unicam. The statistical methods used were ANOVA and standard

deviation. The determination was done three times.

RESULTS

The seasonal changes in the heavy metal contents of the Okpoka-Woji River sediment are shown in figures 2a

to 4b. The mean values for lead, iron chromium and zinc where shown in Figures 2a - 2d. The mean value

ranges were lead, 17 - 67.2 mg/kg and 22.3 - 67.8 mg/kg; iron, 7,995.5 - 17024.2 mg/kg and 6949.3 - 21,403

mg/kg; chromium, 0.8 -2.3 mg/kg and 1.6 - 3.4 mg/kg; zinc, 3195.1 - 4455.5 mg/kg respectively for rainy and

dry season months. The mean values for lead, iron and chromium were observed to be higher in the dry


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20

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Stn 1 Stn 2 Stn 3 Stn 4 Stn 5 Stn 6

Stations

Lead(mg/Kg)

Rainy Dry

0.0

5.0

10.0

15.0

20.0

25.0


Stations

Iron(mg/Kg)x103

Rainy Dry

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0


Stations

Chromium(mg/Kg)

Rainy Dry

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0


Stations

Zinc(mg/Kg)x103

Rain Dr

Fig. 2: Changes in the monthly mean values of lead, iron chromium and

zinc levels of Okpoka-Woji River sediment across the stations.

2a 2b

2c2d


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21

0

20

40

60

80

100

120

140


Stations

Manganese(mg/Kg)

Rainy Dry

0

1

2

3

4

5

6

7

8

9

10


Stations

Nickel(mg/Kg)

Rainy Dry

0

10

20

30

40

50

60


Stations

Vanadium(mg/Kg)

Rainy Dry

0

10

20

30

40

50

60

70

80


Stations

Copper(mg/Kg)

Rainy Dry

Fig. 3: Changes in the monthly mean values of manganese, nickel, vanadium

and copper levels of Okpoka-Woji River sediment across the stations.

3a3b

3c 3d


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22

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80


Stations

Cadmium(mg/Kg)

Rainy Dry

0

10

20

30

40

50

60

70

80

90


Stations

Barium(mg/Kg)

Rainy Dry

Fig. 4: Changes in the monthly mean values of cadmium and barium levels of

Okpoka-Woji River sediment across the stations.

4a

4b


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Figures 3a - 3d show the mean values for manganese, nickel, vanadium and copper. They had the following

mean values ranges manganese, 22.5 - 100.6 mg/kg and 20.8 -121.7 mg/kg; nickel, 2.4 - 9.2 mg/kg and 2.0 - 6

mg/kg; copper, 19.5 - 46.9 mg/kg and 36.7 - 67 mg/kg respectively for rainy and dry season months. It was

observed that the mean values were higher in the dry season months for manganese, vanadium and

copperwhile the mean values for nickel were higher in the rainy season month than the dry season months. It

was also observed that P < 0.05 showed that there was significant difference in the mean values between the

dry and rainy season months for manganese, nickel and vanadium while P > 0.05 showed no significant

difference in the mean values between the dry and rainy season months for copper.

The mean values for cadmium and barium are shown in Figures 4a - 4b. The mean values ranges were

cadmium, 0.3 - 1.6 mg/kg and 0.8 - 1.6 mg/kg; barium 21.1 - 77.6 mg/kg and 22.6 -34.0 mg/kg respectively

for the rainy and dry season months. It was observed that there was no significant difference in the mean

values between the dry and rainy season months for cadmium and barium as P> 0.05.

DISCUSSION

The accumulation of heavy metals in sediments may become the re-pollution source for an aquatic

environment when environmental changes occur. The levels of the heavy metals observed in the sediments

during the study period were higher than those encountered in the surface water. The trace metal content of

recent sediments depends on the anthropogenic inputs as well as the natural characteristics of the sediments

especially in the grain size (Tkalin et al., 1996; Presley et al., 1992). The domestic and industrial effluents

discharge may be implicated in the high concentration of the heavy metals observed. Okoye et al. (1991)

reported anthropogenic heavy metal environment of Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn in the Lagos Lagoon

and implicated land based urban and industrial wastes. Kakulu and Osibanjo (1988, 1992) revealed elevatedlevels of Pb, Cr, V and Zn in Port Harcourt and Warri sediments, which suggest that effluents from petroleum

refineries located in these cities, have contributed significantly to the heavy metal pollution of the respective

aquatic ecosystems.

The high concentrations of these heavy metals call for a serious concern in relation to ecological and human

health. Contaminated sediment can be associated with acute and chromic effects on aquatic life. Sediment also

constitute a major source of persistent bioaccumulative toxic chemicals which may pose threats to ecological

and human health even after contaminants are no longer released from point and non-point sources. Adverse

ecological effects of contaminants in sediment include fin rot skin lesions, increased tumor frequency and

reproductive toxicity in fish, reproductive failure in fish eating, birds and mammals and decreased biodiversity

in aquatic ecosystem. Threat to human health occurs when sediment contaminants bioaccumulate in fish and

shellfish tissues consumed by humans (Armitage, 1997).

The seasonal dependent variation in the sediment of the heavy metals may be associated with seasonal factors

such as nature of the sediment and runoff and water quality (Bryan, 1973; Szefer et al., 1999). It was observed

that zinc, nickel, barium had mean values higher in the rainy season months than the dry season months. The

other metals studied namely lead, iron, chromium, manganese, vanadium, cadmium and copper had meanvalues higher in the dry season than in the rainy season months. The means, that there is much concentration

of organic and inorganic nutrients in the sediment in the dry season than rainy season months. It also shows

that the river water is cleaner in the rainy season dilution of industrial wastes as they enter river from rainfall,

soil erosion and runoff.

This was in contrast with the findings of Chindah et al. (2004) and Biney (1997) who reported consistent

higher concentration of zinc and copper in the dry season than in the dry season months while the rest of the

metals higher mean values in the rainy season than dry season months. The mean values for nickel and barium

were in agreement with their findings as the values were higher in the rainy season than dry season months.

Iron is used in steel production and is a byproduct of combustion and such it is expected to be present in large

quantities. However, it is also found in many primary and secondary minerals in a significant weight, so the


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increases are not necessarily anthropogenic in nature. It is certainly possible that the noted increase explained

as deriving from anthropogenic emissions may to some extent be due to the diagenetic inputs (Varekamp,

1990).

ACKNOWLEDGEMENT

We sincerely thank the management of Quality Control and Testing Laboratories Limited Plot 173

TransAmadi Industrial Layout Port Harcourt Rivers State Nigeria for allowing us the use of their facilities.

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Atlas, R.M. and Bartha, R. (1993). Microbial Ecology Fundamentals and Applications , 3rd

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Forstner, U. (1989) Contaminated Sediments: Lectures on Environmental Aspects of Particle Associated

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Edition, Berlin,

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Horowitz, A.J. (1985). A Primer on Trace Element-sediment. Chemistry, U.S. Geological Survey water

supply paper 2277, pp 6.7

Kakulu, S.E. and Osibanjo O. (1988). Trace Heavy Metal Pollutional Studies in Sediments of the Niger Delta

Area of Nigeria,Journal Chemical Society Nigeria; 13; 9 - 15.

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Muncha, A. P., Vassconcelos, M. T. S. D. and Bordalo, A. A. (2003). Macrobenthic Community in theDouuro Estuaryi Relation with Trace Metals and Natural Sediment Characteristics, Environmental Pollution;

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Okoye, S.C.O., Afolabi, O. A. and Ajao, E.A. (1991). Heavy Metals in the Lagos - Lagoon Sediments,

International Journal of Environmental Studies; 37:35-41.

Presley, B.J., Taylor, R.J. and Boothe, P.N. (1992). Trace metal contamination in sediments of the Eastern

Mississippi Bight,Marine Environmental Resources; 33: 267 -82.

Shell Petroleum Development Company (SPDC), (1986). Street Guide of Port Harcourt

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from the Connecticut Coastline, Weslsyen University E& ES Department.

Received for Publication: 04/10/2008

Accepted for Publication: 25/11/2008


V.C. Eze

Present address: Department of Microbiology, Michael Okpara University of Agriculture, Umudike, P.M.B.7267, Umuahia, Abia State, Nigeria.

E-mail: [email protected]

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