WASTE-INDUCED SOIL DEGRADATION AT UNN: PHYSICO-CHEMICAL AND HEAVY METAL ASSESSMENT

Abstract

Improper waste disposal on land can alter soil physico-chemical properties and increase heavy metal accumulation. This study assessed soil characteristics and heavy metal concentrations at two dumpsites and nearby control sites at Odim-gate and the Faculty of Engineering (FOE), University of Nigeria, Nsukka. Soil samples were collected at 0–20 cm and 20–40 cm depths and analyzed using a 2 × 2 × 2 factorial design. Soils were predominantly sandy loam, ranging from slightly acidic to slightly alkaline, with high available phosphorus but low organic carbon (OC), total nitrogen, exchangeable bases (Ca²⁺, Na⁺, K⁺), and effective cation exchange capacity. Dumpsites exhibited higher total porosity, pH, OC, Ca²⁺, and Na⁺ concentrations but lower bulk density and exchangeable acidity (Al³⁺ and H⁺) compared to control soils. OC and macronutrient concentrations were significantly greater in the topsoil. Heavy metals Fe and Pb were present at low concentrations overall, though Fe was significantly higher at Odim-gate and control sites. However, elevated Zn levels, particularly in the 0–20 cm layer of the FOE dumpsite, may pose environmental and health risks due to potential toxicity