ASSESSMENT OF BIO-ACCUMULATIVE HEAVY METALS IN WATER, SEDIMENT AND FISH OF AWBA DAM, NIGERIA

Abstract

Metallosis has attracted public health interests; the affected victims often exhibit health behaviors which are similar to those affected with persistent toxic chemicals. Accumulation of heavy metals in fish tissues is a major human exposure route to metal toxicity, the severity of which is dependent on the contaminants’ concentrations and the exposure period. In this study, samples of water, sediment and fish tissues were collected from Awba Dam in University of Ibadan to analyze their metal contaminations. The metal (Zn, Fe, Mn, Hg, Pb, As, Co, Cu and Cd) concentrations in all the samples were analyzed using Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). The results obtained were compared with national and international benchmarks. The mean metal concentrations (mg/L) in water were; Zn (0.582 ± 0.009), Fe (0.780 ± 0.021), Mn (0.324 ± 0.021), Hg (0.067 + 0.011), Pb (0.082 + 0.015), As (0.078 + 0.014), Co (0.090 + 0.015), Cu (0.122 + 0.036), Cd (0.047 + 0.007). Hence, were lower than the metal concentrations (ppm) in sediment; Zn (47.79 + 3.398), Fe (330.49 + 9.442), Mn (63.030 + 4.081), Hg (0.22 + 0.007), Pb (14.47 + 0.012), As (0.022 + 0.008), Co (3.900 + 0.012), Cu (21.15 + 0.045), Cd (0.34 + 0.007). However, the metal concentrations (ppm) in the sediment were higher than those bio-accumulated in fish tissues; Zn (4.222 + 0.023), Fe (8.71 + 0.047), Mn (0.067 + 0.008), Hg (0.007 + 0.001), Pb (0.069 + 0.006), As (0.008 + 0.002), Co (0.003 + 0.001), Cu (1.530 + 0.004), Cd (0.008 + 0.002). The concentrations of all metals determined in water samples were below the WHO limits for drinking water, and this showed that Awba Dam water could be safe for drinking when treated. The concentration of heavy metal recorded in fish indicate a certain degree of bioaccumulation. Therefore, regular monitoring of heavy metal levels in water and fish in Awba dam is necessary.