Distribution And Enrichment Of Heavy Metals In Soils From Waste Dump Sites Within Imoru And Environs, Southwest Nigeria

Abstract

Soil samples from waste dump sites from Imoru and the towns around it were analyzed for their cadmium, chromium, copper, manganese, nickel, lead and zinc contents in order to determine the distribution and enrichment of these metals in the area. Results show the average metal content as Cd (1.18 mg/kg^-1), Cr (0.69 mgkg^-1), Cu (9.61 mgkg^-1), Mn (93.41 mgkg^-1), Ni (2.94 mgkg^-1), Pb (12.24 mgkg^-1) and Zn (78.82 mgkg^-1).Using Enrichment Factor (EF) the soils were classified as deficient to moderately enriched with Cd and Cr while they are deficient to minimally enriched with Cu, Mn, Ni and Zn. Calculated Geo-accumulation index (Igeo) shows the soil to be unpolluted to moderately polluted of all trace metals analyzed for. The C / P index places the soil as very slightly contaminated to slightly contaminated by Cr, Pb and Ni; severely contaminated to moderately polluted by Cd; and very slightly to severely contaminated with Cu. Generally, the average concentration of the trace metals are below international guideline values for environmental quality criteria.

Keywords: heavy metal, soil, enrichment factor (EF), geo-accumulation index (Igeo), contamination / pollution index