|
Concentrations
of heavy metals in effluent discharges downstream of Ikpoba
river in Benin City, Nigeria
F. A. Oguzie* and G.
A. Okhagbuzo
Department of Fisheries, University of Benin, Benin City,
Edo State, Nigeria.
*Corresponding author. E-mail:
faoguz@yahoo.com.
Accepted 28 December, 2009 |
|
Various effluent samples were collected from
their sources of discharge to the Ikpoba river in Benin
City, Edo State between September and October, 2008. Six
heavy metals (cadmium, chromium, copper, nickel, lead and
zinc) in the effluents and receiving water were analyzed by
atomic absorption spectrophotometric technique (AAS) in
separate experiments. The concentrations of heavy metals in
the effluents were compared with corresponding heavy metal
values in the water. The results show that metal
concentrations were higher in the effluents than in the
water. Total mean metal concentrations (mg/l) recorded in
the effluents were as follows: Cd = 0.072; Cr = 0.079; Cu =
0.194; Ni = 0.122; Pb = 0.125 and Zn = 0.174 while
corresponding mean values recorded in the water were Cd =
0.043; Cr = 0.072; Cu = 0.152; Ni = 0.091; Pb = 0.110 and Zn
= 0.128. Significant differences (P < 0.05) were recorded
between heavy metal levels in urban run-off effluents and
rubber/brewery effluents. No significant differences (P >
0.05) were recorded between the concentrations of cadmium in
the water procured from the four sampled stations.
Significant correlations (P < 0.05) were recorded between
metals in effluents and water. The concentrations of Cu, Pb
and Zn in urban run-off effluents exceeded the limit
recommended in effluent discharges to surface waters by the
Federal Ministry of Environment (FMENV).
Key words:
Heavy metals, effluent discharges, Ikpoba river, Benin City,
Nigeria. |
