INTRODUCTION:

The pollution of the aquatic environments with heavy metals has become a worldwide problem in recent years because they are indestructible and most of them have toxic effect on organism.(Mac Falame and Burchett, 2000).

Among environmental Pollutants, metals are of particular concern, due to its potential toxic effect and ability to bio-accumulate in aquatic ecosystems. (Censi et al, 2006).

Heavy metals are heavy metallic chemical elements that have relatively high density and are toxic or poisonous at low concentration. They include essential and non-essential chemical elements such as Chromium (Cr), Copper (Cu), Zinc (Zn), Arsenic (As), Cadmium (Cd), Mercury (Hg) And Lead (Pb) etc. These heavy metals come in contact with our bodies via food, drinking water and air. They are dangrenous, because they tend to bio-accumulate (increase in concentration in biological cells over time).

There is increasing concern about the quality of foods in several parts of world. The determination of toxic elements in food has prompted studies on toxicological effects of them in food. (Malik A; 2004)

Heavy metals are considered the most important form of pollution of the aquatic environment because of their toxicity and accumulation by marine organisms. (Gurnham. 1975).

Catfish:

These are a diverse group of ray-finned fish. Catfish range in size and behavior from the three largest spacies, the Mekong gaint catfish from southeast Asia, the wels catfish of Eurasia and the Paraiba of south America, to detritivotres (species that eat dead material on the bottom) and ever to a tiny parasitic species commonly called the candiru, vandellia cirrhosa. There are amour-plated types and there are also naked types, neither having scales. Despite their name not all cat fish have promminent barbel. Members of the silurformes order are defined by features of the skill and swim bladder. Catfish are of considerable commercial importance, many of the smaller species, particularly the genus conydors, are important in the aquarium hobby. Many catfish are noeturnal (Wong and Kate, 2001).

Tilapia:

This is the common name for nearly a hundred species of cichlid fish from the tilapiin cichlid tribe. Tilapia are mainly fresh water fish inhabiting shallow streams, ponds, rivers and lakes and less commonly found living in brackish water. Historically, they have been of major importance in artisan fishing in Africa and the Middle East and they are of increasing importance in aquaculture and aquaponics. Tilapia can become problematic invasive species in new warm-water habitats such as Australia (Department of Agriculture, fisheries and forestry) whether deliberately or accidentally introduced, but generally not in temperate climates due to their inability to survive in cold water.

Heavy Metals:

These refer to heavy metallic chemical elements that have relatively high density and are toxic or poisonous at low concentration. They have their R.M.M to be >50mg/g. They include essential and non-essential chemical elements such as Lead (Pb), Cadmium (Cd), Arsenic (As), Zinc (Zn), Copper (Cu), And Chromium (Cr) etc.

These heavy metals come in contact with our bodies via food, drinking water and air, they tend to bio-accumulate increase in concentration in biological call over time. (Johnson, M.O, and Larry E; 2008).

AIMS/OBJECTIVE:

· To determine some heavy metal pollutants in cat fish (Conydors semiaquilus) and tilapia fish (Oreochromis niloticus) samples.

· To know the concentration of these heavy metal in the selected catfish (Conydors semiaquilus) and tilapia (Oreochromis niloticus) samples such as Chromium (Cr) II, Copper (Cu) II, Zinc (Zn)II, Arsenic (As) II, Mercury (Hg) II, Cadmium (Cd) II, and Lead (Pb) II.

· To determine the availability and level of toxic metals in Ndibe beach.

To determine the concentration of the Water body in which the Fishes under study leaves.

METERIALS AND METHOD:

Study Area:

Afikpo North is a Local Government Area of Ebonyi State, Nigeria. Its head quarter is in the town of Afikpo. Situated at 5.89^o North latitude, 7.95^o East longitude and 115 meters elevation above the sea level. It has an area of 240km² and the population of 156, 611 at the 2006 census.

Materials and Equipment:

Catfish (Oreochromis niloticus), Tilapia pish (Conydors semiaquilus), aluminum foil, working bench, sussors, knife, bowl, freeze, jaw crusher, weighing balance crucible, concentrated trioxonitrate (v) acid HNO₃, Hydrogen peroxide, fume chamber, and Atomic Absorption Spectrometer (AAS)

Sample Collection:

The catfish (orechromis niloticus) and Tilapia fish (conydors semiaquilus) sample were collected from Ndibe beach at Afikpo North Local Government Area of Ebonyi State; sample selected for analysis were catfish (orechromis nuoticus) and Tilapia fish (conydors semiaquilus). These are commercially important and nutrient fish species.

These species are widely distributed in the aquatic environment and have commercial importance. The fish samples were wrapped with aluminum foil and put inside polythene bags and transported the same day to the chemistry laboratory and kept under deep freezer to prevent deterioration till further analysis.

Sample Preparation:

The fish samples were allowed to thaw. The samples were then placed on an aluminum foil to avoid contact with working bench. The samples were cut into small pieces using clean knife into bowl and dried, using microwave drier. This was then grounded into fine powder, using jaw crusher. As much as 0.50g of each of the grinded fish sample was weighed into thoroughly and 1ml Conc. Nitric acid (HNO₃) and 1ml of hydrogen peroxide was added to the weighed samples in a fume chamber and allowed to homogenize.

A blank was also prepared of atomic Absorption spectroscopy (AAS) reading. The plastic containers were then covered and placed in a jacket for microwave digestion. Each digested sample was diluted and made up to 20ml with distilled water after the microwave digestion for AAS readings.

RESULT PRESENTATION:

The result of this analysis shows that concentrations in mg/kg of the heavy metal together with their corresponding world health organization/ food and agriculture organization (WHO/FAO) maximum permissible level (MPL) is presented in Table1

Heavy metals studied: Chromium, Copper, Zinc, Arsenic Cadmium, Mercury and Lead.

Table 1 Adsorption and coefficient of variations of the heavy metals tilapia catfish

Metals ion	Initial Conc. (ppm)	% RSO	(x) mean adsorb	R²	Initial Conc (ppm)	% RSO	X mean adsorb	R²
Cr²⁺	0.300	1.430	0.0038	0.9835	0.382	0.81	0.0021	0.9812
Cu²⁺	0.600	1.830	0.4630	0.9575	0.325	0.73	0.5260	0.9786
Zn²⁺	0.422	1.830	0.4630	0.9613	0.500	0.73	0.5260	0.9805
As²⁺	-	-	-	-	-	-	-	-
Cd²⁺	0.218	1.200	-0.0021	0.9653	0.230	0.72	0.0042	0.9651
Hg²⁺	0.526	-5.018	-0.004	0.9521	0.201	-8.56	-0.0050	0.9621
Pb²⁺	0.421	6.200	0.009	0.9576	0.502	High	0.0086	0.9786

Table2: Heavy metal distribution of cat and tilapia fish of ndibe beach of Afikpo L.G.A., Ebonyi state Nigeria conc (mg/ml) tilapia-fish conc (mg/ml)cat-fish

Metals Ion	Sample Blank	30µm	60µm	80µm	30µm	60µm	80µm
Cr²⁺	0.0085	0.0038	0.0029	0.0018	0.0032	0.0030	0.0020
Cu²⁺	-0.0013	0.4632	0.4300	0.4000	0.5263	0.5000	0.3021
Zn²⁺	0.0037	0.4632	0.4500	0.4300	0.5263	0.5100	0.4012
As²⁺	ND	-0.004	-0004	-0.0038	-0.003	-0.0020	-0.0010
Cd²⁺	-0.0015	0.0030	0.0028	0.0020	0.0018	0.0016	0.0012
Hg²⁺	ND	-0.0050	-0.0020	-0.0020	-0.0020	-0.0010	-0.0010
Pb²⁺	0.00301	0.0088	0.0060	0.0050	0.0086	0.0085	0.0072

ND = Not detected

Table 3: Water analysis of chromium, copper, zinc, arsenic, cadmium, mercury, and lead heavy metals ion conc (ppm)

Metal Ion	CONC (mg/mL 30mmx1000	60mmx1000	80mmx1000	R2x1000
Cr²⁺	0.0501	0.0060	0.0201	-0.9842
Cu²⁺	0.0862	0.0862	0.0431	-0.8934
Zn²⁺	0.0923	0.0711	0.0600	-0.9892
As₂₊	0.0080	0.0060	0.0050	0.8000
Cd²⁺	0.0050	0.0050	0.0032	0.8921
Hg²⁺	0.0008	0.0008	0.0004	-0.8201
Pb²⁺	0.0088	0.0060	0.0040	-0.8621

Qm = amount of Heavy metal ions distribute in the water and dishes at any time t, (mglg)

Qt = amount of Heavy metal ion on the surface of the fishes and water at any time ‘t’ in (mg/g). Obtained from experiment

Qt = average of qt (mg/g)

Table4: Mean concentration of selected heavy metals in the fish species (cat fish and tilapia from ndibe beach ebonyi state as at August, 2016 selected heavy metals (mg/kg)

FISH SPECIES	Cr²⁺	Cu²⁺	Zn²⁺	As²⁺	Cd²⁺	Hg²⁺	Pb²⁺
TILAPIA FISH	3.80	46.3	46.0	ND	3.0	ND	1.6
CAT FISH	3.20	52.6	50.3	ND	1.8	ND	1.2
WHO/FAO	0.5	33.00	22.00	0.26	0.20	0.50	1.00
MPL/P>0.50

Table 5: Amount of heavy metals present in Ndibe beach water body

Metal Ion	CONC (mg/mL) x 100
Cr²⁺	0.2801
Cu²⁺	0.8620
Zn²⁺	0.8230
As₂₊	0.2058
Cd²⁺	0.1050
Hg²⁺	0.0408
Pb²⁺	0.4088

Fig1: Comparison of heavy metal ion in Tilapia fish with WHO/FAO MPL.

Fig2: Comparison of heavy metal ion in Catfish with WHO/FAO MPL.

Fig3: Amount of heavy metals present in ndibe beach water body

Fig 4: Comparison of heavy metal ion in Catfish, Tilapia fish with WHO/FAO MPL

DISCUSSION:

The results in Table 4.1 shows the concentration of selected heavy metals in two species of fish: Tilapia fish and cat fish (Oreochromis niloticus and Conydors semiaquilus) obtained from samples collected from Ndibe beach in Afikpo North Local Government of Ebonyi State, and compared with standard guideline on food safety by the World Health Organization and Food and Agricultural organization (WHO and FAO). The result in table 5 shows that Ndibe beach as a river contains appreciable amount of heavy metal which is evident in the Fish samples.

Selected Heavy Metals In Tiliapia Fish:

The data is figure 4.1 shows the comparism of heavy metals in Tilapia fish (Oreochromis niloticus) with that of world Health Organization and Food and Agricultural organization (WHO/FAO) guidelines and standard respectively. The result revealed some dissimilar pattern in term of detection limits of the various heavy metals in Tilapia fish (Oreochromis niloticus) which are as follows lead (Pb²⁺)= 1.6mg/kg, Chromium (Cr) = 3.80mg/dg, Cadmium (Cd) = 3.0mg/kg, Zinc (Zn) = 46.0mg/kg, Mercury (Hg) = Not detected, Copper (Cu²⁺) = 46.3mg/kg and Arsenic (As²⁺) = not detected.

From this results, it was observed that Cr²⁺, Cd²⁺, Zn²⁺, and Cu²⁺ are at higher concentration above the maximum permissible level (MPL) of world Health Organization and Food and Agricultural Organization (WHO/FAO) which stipulates for chromium (Cu²⁺) = 1.00mg/dg, cadmium (Cu²⁺) = 0.50mg/kg Zinc (Zn²⁺) 22.00mg/kg and copper (Cu²⁺) = 0.26mg/kg. The concentration of lead was 0.6mg/kg above that of World Health Organization and Food and Agricultural Organization (WHO/FAO) maximum permissible level (MPL).

Lead at high concentration, interferes with a variety of body processes and is toxic to many organs and tissue including the heart, bones, intestine, kidneys, reproductive and nervous syst. Other symptoms include abdominal pain, confusion, headache, anemia, irritability, and in severe cases seizures, coma and death (Ekong et al, 2006)

Selected heavy metals in catfish:

The following data where obtained from heavy metal concentration in catfish (Conydors semiaquilus) Lead Zn²⁺ = 1.2mg/kg, chromium (Cu²⁺) = 3.2mg/kg, cadmium (Cu²⁺) = 1.8mg/kg, Zinc (Zn²⁺) = 50.3mg/kg, Mercury (Hg) = Not detected (ND), Copper (Cu²⁺) = 52.6mg/kg, and Arsenic (As) = not detected (ND).

From the results of the analysis, it was observed that Cr²⁺ Zn²⁺ and Cu²⁺ are at higher concentration above that of World Health Organization and Food and Agricultural Organization (WHO/FAO) maximum permissible level (MPL) which stipulates; for chromium (Cr) =0.50mg/kg, Zinc Zn²⁺ = 22.00mg/kg, and copper (Cu²⁺) = 0.26mg/kg.

Lead is 0.2mg/kg above the World Health Organization and Food and Agricultural Organization (WHO/FAO) standard which is 1.00mg/kg. Cadmium is 1.6m/kg higher than World Health Organization (WHO/FAO) standard which stipulates 0.2mg/kg-Mercury and Arsenic were not detected.

REFRENCES:

1. Andrews, N.C. (1986)., Disorder of iron metabolism. New England Journal of Medicine; 341:1986-95

2. Aurnham, A.S. (1975)., Journal of fish resources. 11:920-925.

3. Bengum, A., Harikrisha, S., and Khan, I. (2009). International journal of pharm Tech. Research, 1(2):245-249.

4. Brandes, E.A., Greenaway, H.T., Stone, H.E.N. (1956)., “Ductility in chromium” Nature. 178(587):587.

5. Canli, M., and Atli, G. (2003). Environmental pollution. 12:129-136.

6. Censi, P., Spoto, S.E., Saiano S., Sprouieri M., Mazzola, S., Nardine, G.D.,Geronimo, S.I., Punturo, R., and Ohonello, D. (2006)., Heavy metals in coastal water systems. A case study from the northwestern Gulf of Thailand chemosphere, 64:1167-1176.

7. Dobaradarna, S., Naddafi, K., Nazmara, S and Ghaedi, H. (2005). African Journal of biotechnology. 9:(3):6191-6193.

8. FAO/WHO. (2011)., Joint FAO/WHO food standard program iodex committee on contaminants in foods, fifth session Pp64-89.

9. Khalifa, K.M., Hamil, A.M., Al-Houni, A.Q.A., and Ackacha, M.A. (2010), International journal of pharm. Tech. research 2:(2)1350-1354.

10. Khalifa, K.M., Veerisingam, S., Suresh, G., Marichamy, G., and Venkata C. (2009)., International journal of animal and veterinary advance. 1(1):10-14.

11. Macfarlane, G.B., and Burcheltt, M.O. (2010)., Cellular distribution of Cu, Pb, and Zn in the Arey mangrove Avicemnia marina (forsk). Vierh Aquatic Bofanic, 68:45-59.

12. Malik, A.(2004)., Environmental international. 30:261-278.

13. Mc-Henry, C. (1992)., The newencyclopedia Britannica. Chicago Encyclopedia Britannaica

14. Raja, p., Veeriasingam, S., Suresh, G., Marchamy, G and Venkata C. (2009)., International journal of animal and vertinary advance. 1(1):10-14

Received on 02.11.2016 Modified on 18.02.2017

Research J. Science and Tech. 2017; 9(2): 224-228.

DOI: 10.5958/2349-2988.2017.00039.0