ABSTRACT

This study evaluated the physicochemical properties and heavy metal concentrations in soil samples from a solid waste disposal site in Oluku,Ovia Northeast, Benin City, Edo State Nigeria. Soil samples were collected from in triplicates from different depths (10cm, 20cm, 30cm, 40cm) and analyzed for pH, porosity, bulk density, electrical conductivity, and heavy metal concentrations (Pb, Cd, Zn, Fe).

 The heavy metals analysis was carried out by using the Atomic Absorption Spectrophotometer, the soil bulk density was determined using the sand replacement method, the porosity of the soil sample was determined through water retention method, soil pH was measured using a 1:1 soil-to-water ratio, the soil electrical conductivity was measured using a 1:5 soil-to-water ratio.

The results showed significant differences in physicochemical properties and heavy metal concentrations between the dumpsite and control site. The dumpsite soil samples had higher porosity(44-56%), lower bulk density(1180.17-1247.12 kg/m³), and higher electrical conductivity (252-290 µS/cm) compared to the control site. The pH values in the dumpsite ranged from 7.12 to 7.62. This range indicates a neutral to slightly alkaline soil condition. Such pH levels may be influenced by the decomposition of organic materials and the presence of various waste products, which can alter the chemical composition of the soil. In contrast, the control site exhibits pH values ranging from 6.12 to 6.86. These values suggest a slightly acidic to neutral condition, typical of healthy, undisturbed soils. Heavy metal concentrations were also elevated in the dumpsite soils, with Cd and Zn exceeding the World Health Organization (WHO) permissible limits. The study highlights the potential environmental risks associated with solid waste disposal and suggests the need for proper waste management practices to mitigate soil pollution.