Assessment of heavy metal contamination in soil and native vegetation at municipal solid waste dumpsites in Akure North, Nigeria

This study evaluated heavy metal (Zn, Fe, Cu, Cd, Pb) concentrations and physicochemical composition across four dumpsites in Akure North Local Government and compared them to those of the WHO and the National Environmental Standard and Regulation Enforcement Agency (NESREA) standards. Two soil samples (0-15 cm and 15-30 cm) and two plant samples were analysed alongside controls to assess pollution indices and metal bioaccumulation. Control samples were taken 1 km away. Heavy metal levels in dumpsites significantly exceeded control sites and regulatory limits, reaching up to 55,850 mg/kg in soil and 49,050 mg/kg in plants. While multiple pollution indices confirmed severe environmental contamination, bioaccumulation patterns varied: iron exhibited the highest soil concentration but the lowest plant transfer, whereas cadmium showed the highest transfer coefficient. Furthermore, dumpsite soils displayed higher electrical conductivity, organic matter, and acidity (pH 5.50–6.47) than controls. These findings indicate that waste disposal activities are progressively degrading soil physicochemical properties and driving heavy metal bioaccumulation in surrounding vegetation, highlighting both phytoremediation potential and associated human health risks.