Comparative Assessment of the Concentration of Heavy Metals in Concrete and Earthen Fish Ponds in South – East, Nigeria

Abstract

Comparative assessment of the concentration of heavy metals in concrete and earthen fish ponds was carried out in south – east, Nigeria. Water samples using column sampling bottles were collected from 15 randomly selected concrete and earthen fish farms at different locations in Anambra, Enugu and Imo States for 6 months (3 months each in the dry and the wet season) for analysis. The specific locations of the farms were obtained using Global Positioning System (GPS) model extrex (FERMIN). The heavy metals analyzed using Atomic Absorption Spectrophometer (AAS) with Buck Scientific Model 210 VGP, were copper (Cu), zinc (Zn), arsenic (AS), chromium (Cr), iron (Fe), manganese (Mn), lead (Pb) and mercury (Hg). The main objectives of the study were to screen the ponds for presence of heavy metals and compare their concentrations in the two set of farms. Multivariate statistical method was employed using independent t-test to analyze the results. The results showed presence of heavy metals in varying amount in both concrete and earthen ponds with significant differences (p <0.05) inthe mean values of Cu, As, Cr, Fe, Mn, Pb and Hg between the concrete and earthen pondsin dry and wet season. However, there was no significant difference (p> 0.05) in the values of Zn, Cr and Fe between the two seasons. Their mean values (ppm) ranged from, 0.11 ± 0.08 (dry season) and 0.00 ± 0.00 (wet season) Hg respectively to 2.34 ± 1.48 (dry season) and 1.27 ± 0.20 (wet season) Pb.The concentrations of all the metals in concrete and earthen fish ponds across the states were above the normal natural background of these metals. The detection of heavy metals well above the optimal levels and permissible limits in both concrete and earthen fish ponds suggests environmental pollution and underscores the need to periodically monitor our fish rearing environment for possible remediation. This study suggests a further research to determine the levels of these heavy metals concentration in fish ponds.