Assessment of Heavy Metals in Some Marine Fish Species Relevant to their Concentration in Water and Sediment from Coastal Waters of Ondo State, Nigeria

Abstract

Due to oil exploration activities and urbanization as well as continuous industrial and agricultural growth in Ondo State, Nigeria. The coastal water has been heavily impacted by a number of pollutants originating from different sources including heavy metals. This investigation assessed and monitored accumulation levels of ( Cr, Cd, Pb, Cu, Zn, and Ni ) in different organs ( Gill, Head, Bone, Muscle and Eye ) of five fish species (Pentanemus quinquarius, Pseudoltolithus senegalensis, Trichirus lepturus, Plectorhynchus meditarraneus and Pseudotolithus typus together with water and sediment collected from the ocean shoreline in the coastal waters of Ondo State, Nigeria. Heavy metals concentrations in fish tissues, water and sediment samples were analyzed after treatment using atomic absorption spectrophotometer. Dissolve total metal in water (in mg/l) Zn 0.12-0.22 , Cu 0.26-0.27 and Ni BDL-0.01 recorded in the water samples in this study were low and within the maximum permissible level (MPL) recommended by WHO and USEPA, while higher concentrations above the MPL were recorded for Cr 0.31-0.34 Cd 0.08 -0.21 and Pb 0.57-0.79. The concentrations of these metals in sediment in (mg/kg) were in the range Cr (0.16-4.19, Cd 0.35-0.38, Pb 0.9-1.00, Cu 0.24-1.44, Zn 2.12-3.11 and Ni BDL-0.01. They are all lower than their probable effect concentrations (PEC) in sediment. Mean Concentrations of the heavy metals in fish species were of the order: Zn>Cu>Cr>Cd>Pb>Ni. Levels of heavy metals varied depending on different tissues in the fish species. Correspondingly, high concentrations of the metals were found in gills and eye compared to other tissues. While the concentration of Zn (0.34 mg/kg-1.29 mg/kg), Cu (BDL-1.88 mg/kg), Ni (BDL-0.01 mg/kg) , and Cr (BDL-1.28) in the fish tissues were within the maximum allowable level (MAL) for a food source, the findings of this study shows higher value above the allowable limit for Cd(BDL-1.14 mg/kg) and Pb (BDL-0.71 mg/kg), thus constituting potential health hazard to consumers of these fish species.