Environmental impact of copper smelting on surrounding areas: case study of Kankoyo Township

The impact of copper smelting on an urban settlement in Mufulira District of the Copperbelt Province in Zambia was investigated. The settlement shares a boundary with a copper smelter that was commissioned in the early 1930s and has resulted in the negative impact on the soil and vegetation. The study examined the condition of both topsoil and subsoil layers to support the development of appropriate remediation strategies. A stratified, depth-resolved multivariate approach was used, with topsoil and subsoil analyzed separately to better understand their characteristics. The analysis considered the influence of pH, organic matter, elevation, distance from the copper smelter, and proximity to main roads on soil variability within each layer. The findings revealed that the soils were generally acidic, with organic matter levels below average. Copper concentrations were notably elevated, with mean values of 3780 mg/kg in the topsoil and 1400 mg/kg in the subsurface layer. Furthermore, distance from the smelter emerged as the dominant factor controlling PTE distribution, with Cu, Zn, and Pb concentrations decreasing with increasing distance, confirming the influence of smelter-derived deposition. Elemental patterns distinguished anthropogenic inputs (Cu, Zn, Pb) from geogenic controls (Fe, As). Soil pH and organic matter showed no systematic spatial trends but influenced local PTE retention and mobility. Two contrasting vertical behaviors were identified, with Fe, Cu, and Zn exhibiting strong inter-element associations and deeper soil integration, whereas Pb, Cd, and As showed limited downward migration, indicating differential post-depositional controls on PTE redistribution. Contamination indices revealed pronounced enrichment of Cu and Cd, moderate accumulation of Pb and Zn, and background levels of Fe, with surface soils acting as the primary reservoir of anthropogenic contamination and subsoils reflecting limited pollutant transport. Nonetheless, the amount of unexplained variation indicated that other environmental factors, or local-scale processes not captured in the present study, may also be contributing to the observed patterns. The analysed potentially toxic elements concentrations followed a decreasing order of Fe>Cu>Zn>Pb>Cd>As, with mercury undetectable from all sampled sites.