Determination of Heavy Metal Content in Warri River Using Crab as Bio-Indicator

Heavy metal concentrations of Warri river were carried out. Water and crab samples were collected and analyzed for heavy metals concentration using Atomic Absorption spectrometer (AAS). The results obtained indicated that lead ranged from 0.01 – 9.89mg/l with percentage coefficient of variation (CV%) of 109.94% in rainy season and 0.00 – 9.58 with CV% of 153% in dry season in water samples. Lead ranged from 0.06 to 1.32mg/g with CV% of 61.19% in rainy season and 0.00 – 8.25mg/g with CV% of 122.85% in dry season in crab samples. Mercury ranged from 0.00 – 9.82 mg/l with CV% of 169.19% in rainy season and 0.03 – 2.41mg/l with CV% of 128.81 in dry season in water samples. Equally mercury ranged from 0.00 – 2.11mg/g with CV% of 98.30% in rainy season and 0.08 – 2.88 mg/g with CV% of 105.05 in dry season in crab samples. Cadmium ranged from 0.00 – 2.00 mg/l with CV% of 87.50% in rainy season and 0.22 – 1.75mg/l with CV% of 69.87% in dry season in water samples. Also cadmium ranged from 0.03 – 0.90 mg/g with CV% of 75.67% in rainy season and 0.02 – 1.60mg/g with CV% of 83.60% in dry season in crab samples. The concentrations of Zn and Ca were far below WHO recommended limit in the crab and water samples while the concentrations of Cd, Cr, Co, Hg, As, Fe, and Pb in all the samples studied were in excess of the WHO recommended limit for safe water and aquatic foods. These results confirmed that Warri river was highly polluted. For sustainability of development, reduction of the sources of heavy metal pollution should be encouraged so as to reduce health risk to man and aquatic animals