Assessment of Heavy Metals Contamination and Ecological Risks at Tundun Wada Dumpsite, Karu L.G.A of Nasarawa State, Nigeria

Abstract

Municipal solid waste dumpsites constitute major point sources of heavy metal contamination in rapidly urbanizing environments, particularly in developing countries where waste management infrastructure remains inadequate. This study evaluated the physicochemical properties, heavy metal concentrations, and associated ecological risks of soils from the Tudun Wada active solid waste dumpsite during the dry season. Composite soil samples collected from the dumpsite and a designated control site were analyzed for pH, electrical conductivity, organic matter, nutrients, and particle size distribution, alongside metal concentrations of Zn, Fe, Pb, Cr, Ni, Mn, Cu, Cd, Co, Mg, Ca, K, and Na using standard analytical procedures. To comprehensively assess contamination status and ecological implications, multiple pollution indices were calculated, including the Contamination Factor (CF), Degree of Contamination (Cd), Enrichment Factor (EF), Geo-accumulation Index (Igeo), Metal Pollution Index (MPI), and Potential Ecological Risk Index (PERI). Results revealed significantly elevated concentrations of Zn and Cu in dumpsite soils relative to control soils, reflecting strong anthropogenic inputs associated with the indiscriminate disposal of metal-containing wastes, such as batteries, electronic components, and scrap materials. Other metals, including Pb, Fe, Mn, Ni, and Cd, also showed enrichment above background levels, although with varying degrees of statistical significance. The calculated CF and EF values indicated moderate to very high contamination and enrichment for several metals, while the Cd and MPI values confirmed severe overall pollution at the dumpsite. Geo-accumulation index classifications further identified Zn and Cu as major pollutants, with values indicating heavy to significant contamination. The PERI results indicated a considerable ecological risk level, with Cu and Cd contributing disproportionately due to their high toxicity response factors. Overall, the findings demonstrate that soils at the Tudun Wada dumpsite are substantially impacted by anthropogenic metal inputs, posing potential risks to soil quality, ecosystem stability, and human health. The study highlighted the urgent need for improved waste management practices, continuous environmental monitoring, and the implementation of appropriate remediation strategies to mitigate long-term ecological and public health consequences.