Speciation study of copper, lead, chromium, cadmium and nickel in waters from fish pond and stream of Oke-Osun Farm Settlement, Osogbo, South Western, Nigeria
Speciation of copper, lead, chromium and nickel in waters from a fish pond and stream of a farm settlement in Osogbo, Southwestern Nigeria, was investigated. Wet digestion was used for the extraction of Pb, Cr, Cd, Cu and Ni prior to the determination of their concentrations by Atomic Absorption Spectrophotometry (AAS). Packed Amberlite XAD-A16 resin column was used for the pre-concentration and separation of the various species of metals in water samples. The total mean concentration of heavy metals in the pond and stream were: Cu, 0.317 ± 0.005 and 0.218 ± 0.031; Pb, 0.026 ± 0.001 and 0.032 ± 0.009; Cr, 0.043 ± 0.002 and 0.050 ± 0.003; Cd, 0.004 ± 0.001 and 0.010 ± 0.005 and Ni 0.233 ± 0.001 and 0.233± 0.003 mg/L, respectively. Speciation analysis showed that the concentrations (mg/L) of all the metal species were in the order: Cu > Ni > Cr > Pb > Cd in both the fish pond and stream. There was a significant difference between the mean concentrations of metals in water samples from fish pond and stream (P ≤ 0.05) which strongly suggested that the metals might not have come from the same source. Cluster analysis of metals in the pond and stream samples revealed that the metals could have originated from agricultural runoff, activities on the surrounding farmlands, and vehicular emission, on one hand, and leaching from underlying bedrocks on the other hand.
Keywords: Speciation analysis, fish pond, water, metals, farm settlement, Osogbo