Distribution of Heavy Metals in Water and Sediment along Abonnema Shoreline, Nigeria

Abstract

The concentrations of Cd, Cr, Cu, Zn and Pb in water and sediment collected along Abonnema shoreline were determined using GBC Avanta flame Atomic Absorption Spectrophotometer version 2.02. The metal concentrations in water ranged from < 0.001 -0.0772 mg/l Cu, 0.1139 - 6.1168 mg/l Zn, 0.0002 - 0.0012 mg/l Pb, <0.001 - 0.0628 mg/l Cd and 0.0632 - 0.1836 mg/l Cr and in sediment 0.1332 - 0.6229 mg/kg Cu, 1.0535 -7.0965 mg/kg Zn, 0.0075 - 0.0520 mg/kg Pb, <0.001 - 0.0526 mg/kg Cd and 0.0762 -0.3071 mg/kg Cr. The concentrations of the metals and their pollution index values in sediment were higher than those in water. The mean metal pollution index values for Cu (0.151±0.140), Cd (0.007±0.0005), and Cr (0.153±0.059) at the high activity area higher than Cu (0.132±0.131), Cd (0.002±0.001) and Cr (0.122±0.0295) at the low activity area while Zn (1.205±1.036) high and (1.478±0.6175) low as well as Pb (0.009±0.008) high and (0.020±0.0185) low showed the reverse. The difference in metal concentrations and metal pollution index values between sediment and water as well as high and low activity areas were not significant (P>0.05). The shoreline was considered critically contaminated as the concentrations of Cr, Zn and Cu exceeded permissible limits set by Rivers State ministry of environment, Federal Envi- ronmental Protection Agency and World Health Organization and therefore pose serious environmental concern. Low pH, high commercial activities, wastes, tidal and wave actions influenced the concentrations of metals in the area. Regular monitoring and evaluation of the water, sediment and sea foods were recommended. Keywords