HEAVY METALS IN THE MYONEMATIC, HEPATIC AND RENAL TISSUES OF THE AFRICAN CAT FISH (Clarias gariepinus) FROM OGBA RIVER, BENIN CITY, NIGERIA.

The concentrations of heavy metals (Pb, Cd, Zn, Cu, Cr and As) in the myonematic, hepatic and renal tissues of the African catfish (Clarias gariepinus) from Ogba river, Benin City, Nigeria, were determined using a Unicam 929 series atomic absorption spectrophotometer. The concentrations of the aforementioned metals were also determined in water. The mean concentration of Pb ranged from 0.19mg/kg (muscle) to 0.39mg/kg (liver) while the mean concentration of Cd ranged from 0.03mg/kg (muscle) to 0.09mg/kg (liver). The mean concentration of Zn ranged from 0.09mg/kg( muscle) to 0.33mg/kg (liver) while the mean concentration of Cu ranged from 0.23mg/kg (muscle) to 0.76mg/kg(liver). The mean concentration of Cr ranged from 0.19mg/kg (muscle) to 0.41mg/kg (liver) while the mean concentration of As ranged from 0.36mg/kg (kidney) to 0.54mg/kg (muscle). The mean concentrations of the heavy metals in water were Pb(0.09mg/l), Cd(0.04mg/l), Zn(0.01mg/l), Cu(0.53mg/l), Cr(0.38mg/l) and As(0.59mg/l). With the exception of Cu, the mean concentrations of the heavy metals in water were generally above the World Health Organization (WHO) maximum allowable limit for the respective metals in drinking water implying that water from the river is unfit for human consumption owing to heavy metal contamination. The mean concentrations of Cr and As exceeded the WHO maximum allowable limits for fish food. The direct implication of this finding is that people who consume fish from the river are liable to potential health hazards resulting from Cr and As contamination.Â

SOME HEAVY METALS IN SURFACE WATER, SEDIMENT AND FISH (Clarias gariepinus) FROM IKPOBA RIVER BENIN-CITY, EDO-STATE, NIGERIA

Fumes from high vehicular traffic dense areas combined with mixed effluent sources, and run-off waters from some industrial areas channelled into water bodies are possible sources of metal pollutions. Specimens of Clarias gariepinus, surface water samples and sediments from Ikpoba River were collected from two stations, on monthly basis for six months: They were analyzed for concentrations of some heavy metals, using Atomic Absorption Spectrophotometer (AAS). Metal absorption in all three samples revealed a decreasing order of concentration as follows: fish>sediments>surface water. Total mean concentration of metals in samples also showed a decreasing order Zinc>Lead > Copper>Cadmium>Chromiun. ANOVA results revealed that all metals except Chromium and Copper, were higher in fish  harvested from station 1 than those from station 2. Samples of fish, water or sediment harvested in station 1, contained higher concentration of metals than those isolated from station 2. For instance,  Zinc (45.03mg/l) had the highest total mean concentration from fish in stations 1. Surface water in station 1 (0.111mg/l) had higher concentration of lead than station 2 (0.106mg/l) whereas station 2 (0.154mg/l) recorded higher concentration of Copper than station 1 (0.137mg/l). All metals analyzed in sediment samples were higher in station 1 than in station 2 except for Chromium where the value in station 2 (0.29mg/l) exceeded that in station 1 (0.15mg/l). Lead and Zinc concentrations from sediments were highest at station 1 (28.71mg/l) and (24.11mg/l) respectively. The observed concentrations of Lead and Cadmium in fish samples exceeded the WHO maximum permissible limits for aquatic lives, while other metals did not. The results suggest that Ikpoba River is polluted and Clarias gariepinus fish from the river may not be fit for human consumption.Â

An Evaluation of Polycyclic Aromatic Hydrocarbons in Hemichromis fasciatus (Peters, 1857) from an Urban Reservoir in Southern Nigeria

The concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) were analysed in Hemichromis fasciatus netted from the Ikpoba reservoir in Benin City, Nigeria, using Gas chromatographic technique, in order to evaluate the potential ecological risk of these organic pollutants on the investigated ecosystem. The mean concentrations in μg/kg of 2-methynaphthalene,1-methynapthalene, acenaphthylene, acenaphthene, flourene, phenanthrene, anthracene, flouranthene, pyrene, benzo(a)anthracene, benzo(k)flouranthene, benzo(b)flouranthene, indeno(123-cd)pyrene and benzo(ghi)perylene in the fish species were 0.0034, 0.0025, 0.0047, 0.0007, 0.0093, 0.0023, 0.0178, 0.0147, 0.0039, 0.0185, 0.0014, 0.0152, 0.0012 and 0.0027respectively. There were significant differences (P < 0.05) in the mean concentrations of PAHs in fish between stations with the exception of phenanthrene and indeno (123 cd) pyrene. The peak concentrations of the PAHs in H. fasciatus were generally observed in the month of August with the exception of benzo(ghi)perylene, whose peak concentration was observed in October. The Hazard Quotient values for PAHs ranged from 0.0014 for acenaphthene to 0.037 for benzo(a)anthracene while the estimated daily intake of PAHs ranged from 0.000028 mg/person/day for acenapthene to 0.00074 mg/person/day for benzo(a)anthracene. The Toxic Equivalency Quotient (TEQ) values ranged from 0.000014 for benzo(k)flouranthene to 0.00185 for benzo(a)anthracene. The mean concentrations of PAHs detected in H. fasciatus in this study, did not exceed the World Health Organisation (WHO) recommended background concentration of 0.5μg/kg for benzo(a)pyrene in food samples. This finding indicates that the consumption of this fish species by man, does not present an immediate health risk and it is therefore safe to eat as it is relatively free from hazardous levels of PAHs. However, the TEQ values recorded in this study revealed that benzo(a)anthracene poses the greatest potential risk in the reservoir and should thus be closely monitored by relevant authorities in order to avert unwholesome ecological impacts.Keywords: Polycyclic Aromatic Hydrocarbons, Potential Ecological Risk, Ikpoba reservoir, Nigeria

Heavy Metals in Heterobranchus Longifilis (Cuvier And Valenciennes, 1840) Cultured in Earthen Ponds in Selected Communities in Warri Metropolis, Nigeria

The concentrations of Cadmium (Cd), Copper (Cu), Lead (Pb) and Zinc (Zn) in Heterobranchus longifilis (Mean total length= 40.52 cm; mean weight=563.25 g) cultured in earthen ponds in Warri, Nigeria, were determined by Atomic Absorption Spectrometric technique in order to provide baseline data and to ascertain the suitability of such fish for consumption. The mean concentrations of metals in H. longifilis, ranged from 0.13 mg/kg for Cd in January to 72.51 mg/kg for Cu in June with significant differences (p<0.05) observed in the mean concentrations of Cu, Pb and Zn in fish between months. The mean concentrations of metals in H.longifilis, ranged from 0.12 mg/kg for Cd at Jeddo to 69.27 mg/kg for Cu at Ubeji with significant differences (p<0.05) observed in the mean concentration of Zn in fish between stations. The bioaccumulation quotient (BQ) values ranged from 0.50 for Cd at Jeddo to 37.24 for Cu at Oboroke while the hazard quotient (HQ) ranged from 0.39 for Zn to 3.43 for Pb. The maximum acceptable risk (MAR) values anged from 0.02 for Pb at Ekpan to 6.29 for Zn at Ubeji while the estimated average daily intake (EADI) of heavy metals ranged from 0.09 mg/person/day for Cd to  36.13 mg/person/day for Cu. It was concluded that Cd, Cu and Pb were the  metals that presented a potential risk to the consuming public and that the heavy metal content in earthen ponds should be routinely monitored in order to keep metal levels within safe limits.Keywords: Heavy metals, Hazard quotient, Heterobranchus longifili