Environmental risk assessment in selected dumpsites in Abakaliki metropolis, Ebonyi state, southeastern Nigeria

Abstract

Metal leaching into adjacent agricultural soil from dumpsites continues to hamper the quality of produce around the world. Three strategically located major solid waste Dumpsites within Abakaliki metropolis were selected and assessed for potential environmental risks of heavy metals. Samples of the soils from the dumpsites were collected from 0 to 15 cm and 15 to 30 cm soil depth. Multivariate approaches, descriptive statistics and contamination indices were employed. Metal concentrations were compared with local and international standard and most were found to be within the threshold. The results further showed that phosphate (PO43−), nitrate (NO3−) sulphate (SO42−), lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn) and iron (Fe) varied within depths and across dumpsites. Metal concentration was generally higher at 0–15 cm depth and decreased at 15–30 cm. The distribution trend across the studied dumpsites was Fe > Zn > Cu > Pb > Cd. Anions (NO3−, PO43− and SO42−) concentrations generally increased with depth. We used the world average elemental concentrations as a benchmark for risk assessment. The factor of contamination (CF) and the environmental risk index (RI) indicated high contamination as well as environmental risks. The factor of enrichment (EF), Geo-accumulation index (Igeo) and modified environmental risk index (MRI) indicated very high enrichment and environmental risks of Pb, Cd, and Cu. Phyto-remediation, bioremediation, perimeter fencing, and periodic soil monitoring were recommended to restore the degraded soil for improved agricultural productivity.

Keywords

• Agricultural productivity
• Leachate
• Nitisols
• Soil degradation
• Soil reclamation