ABSTRACT
This study was designed to investigate
the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc,
cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia) and the
associated fungi from vials treated with soil from e-waste dumpsite and soil
without e-waste. E-waste is electronic waste which contains valuable metals as
well as potential environmental
contaminants. The heavy metals in soil and fish samples were determined
using flame atomic absorption spectrophotometer (AAS) after homogeneity and
digestion of samples. The associated fungi were identified using standard
microbiological methods. The genera of the associated fungi were: Penicillium, Candida, Articulospora, Aspergillus, Aspergillus, Aspergillus, Rhizopus, Mucor, Zoopage, Varicosporium and Rhodoturula. The quantity of fungi isolated from each pollution treatments showed
that the number of fungi were inversely proportional to the quantity of e-waste
soil pollution and directly proportional to the quantity of soil without
e-waste pollution. The occurrence of the fungi species revealed that the
untreated (control) vial had the highest occurrence (191) while the lowest
occurrence (103) occurred in the vial polluted with the highest quantity of
soil from e-waste dumpsite. The pH and the biochemical oxygen demand (BOD) of
the vials were significantly affected by the pollutions. Variations were also observed
in the bioaccumulation of the heavy metals by Oreochromis niloticus. Cadmium (0.01 mg/kg) and nickel (0.02 - 0.08
mg/kg) were the least recorded metal in the tissue of the fish while cobalt was
not detected after the five weeks period. The sequence of the heavy metals
concentrations in Oreochromis niloticus tissue samples was Zn > Mn > Pb > Cr > Ni > Cd > Co. The accumulation
of the metals in the fish tissue were, however, lower than the international maximum
guidelines, except for manganese (0.29 - 3.13 mg/kg) that exceeded the 0.01 - 0.05
mg/kg threshold levels for manganese by Federal Environmental Protection Agency
(FEPA). Protecting the environments from toxic metals is necessary, hence a
need for public awareness on the dangers of these toxic metals and law for
proper disposal of e-waste.