Preliminary assessment of soil contamination by trace metals in peri-urban municipal landfills in Ibadan, Nigeria

Abstract

Background: Soil contamination by trace metals as a result of improper waste management and disposal in Ibadan, Nigeria has been evaluated in this study. Several studies have shown the link between trace metal soil contamination and improper solid waste disposal.Methods: Soil samples were taken from two major landfills in Ibadan, in the south-west of Nigeria, and subjected to laboratory analysis using inductively coupled plasma-optical emission spectrometry (ICP-OES) as part of a wider study to evaluate the waste management practices in the city.Results: The results of this investigation, without taking into account the background values of the trace metals at both landfill sites, showed that the quantified levels of lead at both sites exceeded threshold levels. The quantified values of zinc and copper metals exceeded the threshold levels specified in the Finnish government decree on the assessment of soil contamination and remediation needs, at 1098 mg/kg and 233.20 mg/kg in the Aba-Eku landfill site, and 1205 mg/kg and 476.55 mg/kg in the Lapite landfill site, respectively. This calls for a comprehensive risk assessment.Conclusions: It is hoped that the results of this study will serve as a basis for a wider risk assessment of all landfill sites within the city.