Heavy Metal Profile of Cross River: Cross River State, Nigeria: Using Bioindicators

The heavy metals profile (Zn, Cu, Fe, Co, Pb, Cd and Cr) in water, sediments and fish was assessed using Atomic Absorption Spectrophotometer at Cross River, Cross River State, Nigeria. The heavy metals profile was observed in the order of Sediments > Fish > Water and Ikom Station I > Obubra Station II > Ekori Station III > Ikot Okpora Station IV > Ikot Offiong Station V > Calabar Station VI respectively. Most of the heavy metals were below the maximum allowable levels set by the WHO, FEPA, and USEPA except Zinc with mean concentration of 0.099±0.00404µg.g⁻¹ which is above recommended limit of 0.0766 µg.g⁻¹ of USEPA in the sediment at Ikom. This implies that the waste assimilation capacity of the river is high, a phenomenon that could be ascribed to dilution, sedimentation and continuous water exchange. This is an indication that an urban and industrial waste discharged into the Cross River has a significant effect on the ecological balance of the river. Thus fish species from the Cross River harvested are safe for human consumption.