1–4 Direct toxicity to humans and aquatic life and indirect toxicity through accumulation of metals in the aquatic food chain are a focus of concern. Heavy metals are serious pollutants because of their toxicity, persistence and non-degradability in the environment. Heavy metals in natural waters and their corresponding sediments have become a significant topic of concern for scientists and engineers in various fields associated with water quality, as well as the general public. This will help guarantee the health of the aquatic ecosystem, humans and the environment. Stream and fishpond sediments should be analyzed at regular intervals as a quality assurance process to ensure that there are no toxic substances in the ponds, leading to possible bio-accumulation and magnification. Pollution has reached levels hazardous to human health compared to standard limits for aquaculture development. The concentrations of accumulated heavy metals depended on the textural class of the sediment.Ĭonclusion. The selected streams and their associated fishponds were fairly polluted, with the Yah fishpond (Ilesha) having the highest heavy metal pollution compared to Arula fishpond (Osogbo) and Ewuru/Rara fishpond (Yakoyo). A closely related order of Fe>Mn>Ni>Zn>Cr>Cu>Se>Pb>Mo>Cd was observed in River Eku. There was a significant difference (pCu>Ni>Zn>Pb>Cr>Mn>Co in Ilesha, Fe>Cu>Ni>Zn>Mn>Co>Pb>Cr in Osogbo and Zn>Fe>Ni>Mn>Cu>Co>Cr>Pb in Yakoyo. Metal concentrations recorded in bottom sediment varied widely and exhibited fluctuations among the different ponds and streams, especially in the values of Fe, Cu, Mn, Cr, Zn and Pb.
Particle size distribution and textural class of the samples were also determined. Sediment samples were collected in triplicates from the streams and their associated fishponds and the accumulations of nine heavy metals (lead (Pb), cobalt (Co), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), manganese (Mg), zinc (Zn)) in the sediment were investigated seasonally. Heavy metal and particle size determinations were used to determine the sediment quality of three fishponds in Osun State, Nigeria and their feeder streams. Heavy metals in water systems are a human health concern as they can enter the food chain.
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