An appraisal of heavy metals in water column and bottom substrate of Aba river, Abia state, Nigeria

The level of heavy metals in water and sediment of Aba River was measured in order to determine the pollution status of the river and the effect of riparian influences. Five sampling stations were identified located at coordinates, 05^o 07’ 28.9’’N and 007^o 23’ 12.5’’E; 05^o 07’ 25.0’’N and 007^o 22’ 17.9’’E; 05o 07’ 8.90’N and 007o 22’ 13.4’’E; 05^o 07’ 22.2’’N and 007^o 21’ 844’’E; 05^o 07’ 44.9’’N and 007^o 22’ 836’’E representing stations 1 to stations 5 respectively. Subsurface water and sediment samples were collected for laboratory analysis. A total of 30 samples were collected (15 for water, 15 for sediment). Samples were analyzed for copper (Cu), cadmium (Cd), chromium (Cr), lead (Pb) and nickel (Ni) using standard techniques. Data were statistically analyzed using the Microsoft Excel^® tool pack. Results indicate higher concentrations of heavy metals in sediments than in water. Heavy metals in sediments exceeded the suggested international limits. Apart from Nickel, all the other heavy metals showed low (<0.001) concentrations in water column. There was significant difference between stations in metal parameters in sediments (P=0.05). Ni values were positively correlated in water and sediment (r2=0.25). Based on observation from this study, it can be concluded that Aba River is polluted due to land activities and therefore a need to enact regulatory ordinances to protect its ecology.