IMPACTS OF IGBATORO ROAD SOLID WASTEMANAGEMENT SITE, AKURE, ON THE SURROUNDING SOIL AND GROUNDWATERQUALITY

Abstract

The continuous accumulation of solid wastes, poor monitoring and lack of good management had contributed massively into environmental pollution. In order to assess the impact of Igbatoro Road solid waste management site on the surrounding soil and ground water quality, three (3) soil samples were collected randomly from within the dumpsite and three (3) other soil samples, 50 m away from the perimeter fence of the dumpsite. Two (2) water samples were collected from within the site and (4) others from surrounding hand dug wells. The samples were analysed for physicochemical parameters using standard methods. The distribution of heavy metals (Zn, Cu, Pb, Ni, Cd, Cr) in soils from within and around the dumpsite was investigated. The heavy metals both in soil and water were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean concentrations of heavy metals in exchangeable fraction within the waste dump are in the order of Cu > Zn > Cd > Ni > Pb > Cr, in carbonate fraction: Zn > Cu > Ni > Pb > Cd > Cr, in Fe-Mn oxide fraction: Zn > Cu > Pb > Ni > Cd = Cr, in organic fraction: Cu > Zn > Ni > Cd > Pb > Cr, while in residual fraction: Cu > Zn > Ni > Pb > Cd > Cr. Also, the mean concentration of heavy metals in exchangeable fraction in the surrounding soil follows the order: Zn > Cu > Pb > Cr > Cd > Ni, in carbonate fraction: Zn > Cu > Pb > Cr > Cd = Cr, in Fe-Mn oxide fraction: Cu > Zn > Ni > Cr = Cd = Pb, in organic fraction: Cu > Zn > Ni > Pb > Cd = Cr, while in residual fraction: Cu > Zn > Ni > Cr > Pb > Cd. The calculated contamination factor/pollution load index (CF/PLI) revealed that the soils were contaminated by the metals in both soil locations. The mean value of potential ecological risk (PERI) around the dumpsite indicated a low level of potential ecological risk. The total concentrations of the metals were lower than their corresponding target values for both Department of Petroleum Resources (DPR) and international standards except for Cd and Cu. The concentrations of the physicochemical parameters analysed in the water samples in both locations showed values lower than their World Health Organization (WHO) standards limits for drinking except for TDS and sulphate for the surrounding area. The heavy metal concentrations in the water samples in both locations showed values falling within their WHO standard limits. The bacterial loads of the water samples in at the surrounding area were found to be at a concentration greater than their WHO standard limits. The dumping of various wastes at the dumpsite was found to be a contributing factor to heavy metal contamination of soil at the study area. Hence, an engineered landfill for Akure metropolis is recommended to replace the existing practice.