Determination of some heavy metals and physicochemical properties in contaminated soils of open waste dumpsite in Awka, Anambra State

Abstract

The current study was designed for the assessment of cadmium, chromium, lead, nickel, zinc and manganese and some physicochemical properties of soils collected from an open dumpsite in Awka, Nigeria. Soil samples at the depth (0-20 cm) were randomly collected at the dump field and were analyzed for physicochemical parameters and heavy metals using standard analytical methods. The results show that the main dumpsite had a high sand content (91.48% ± 0.26%) with a low silt 4.07% ± 0.03% and clay 4.65% ± 0.00%. The pH of the dumpsite soils was 6.07 ± 0.04 which is an acidic pH. Organic matter (%) and organic carbon (%) were 3.84 ± 0.06 and 2.23 ± 0.04 respectively. The EC (µS cm-1) was 476.9 ± 0.00 while the ECEC (cmol/kg) 18.93 ± 0.04. The bulk density (g cm-3) was 1.32 ± 0.00 and the porosity (%) of the dump soil was 41.40 ± 0.00. Total metal concentrations of Cd, Cr, Pb, Ni, Zn and Mn were also analyzed and the concentrations of the heavy metals at dumpsitewas obtained (28.35 ± 0.21 to 149.10 ± 0.01 mg/kg). Metal contamination at dumpsite was in the order of Mn ˃ Zn ˃ Pb ˃ Cd ˃ Cr ˃ Ni. The study evidently indicates the presence of heavy metal contamination in the dumpsite even though some of them fell below the critical permissible concentration level. However, it is their accumulation and persistence in the soils of the dump site that may be a cause of concern for their surrounding environment and organisms.