Assessment of Heavy Metals in Muscle of Tilapia zilli from Some Nun River Estuaries in the Niger Delta Region of Nigeria

This study investigated the heavy metal concentration in muscle of Tilapia zilli from River Nun in Bayelsa state, Nigeria. The samples were collected from the brackish environment in the Nun river estuary. Tilapia zilli were collected from creek lines traversing five communities at Obama, Tebidaba, Clough creek, Ogbainbiri and Samabiri. The samples were preserved in ice chest and transported to the laboratory. The fish samples were prepared by oven-drying, dry-ashing and digested using a mixture of 5 ml of 1 N nitric acid and 10 ml of 1 N hydrochloric acid, afterwards, the acid digest was filtered and made up to 20 ml by diluting to volume with distilled water. The fish sample digests were analyzed using flame atomic absorption spectrometry. Result of the fish ranged from 0.380 – 21.555mg/kg (lead), <0.001 mg/kg (copper), 0.190 – 1.670 mg/kg (chromium), 0.290 – 22.67 mg/kg (manganese), 2.785 – 30.340 mg/kg (zinc), 40.860 – 195.905 mg/kg (iron) and 0.205 – 1.145 mg/kg (nickel). Statistically, there was significance difference (P<0.05) in the fish collected from the different locations apart from copper. The heavy metal concentration were above the limits recommended by various agencies including Food and Agricultural Organization/ World Health Organization, Median international standard, European Union, United States Environmental Protection Agency and Water Pollution Control Legislation. The high concentration of heavy metals above permissible level suggests the need for caution during the consumption of Tilapia zilli from the Nun estuary due to health implications associated with heavy metals.