This study is to examine heavy metal contamination of topsoil around the western flank of the Oban Massif and environs, southeastern Nigeria. Soil samples were collected in seven locations in farming and quarrying land use locations across the study area. Heavy metals (Al, Fe, Zn, Cu, Mn, V, Pb, As, Cr, Co, Ni, and Mo) were analyzed in soil samples using ICP-Ms. Computation of enrichment factor (EF) and Pollution index (PI) was performed on concentration values of potentially toxic heavy metals (Zn, Cu, Pb, As, Cr, Ni and Co), to determine the extent of pollution caused by human activities in topsoil of farming and quarrying areas. The concentration values of heavy metals in soils were also compared with world average background values of heavy metals. Results showed that the potentially toxic heavy metals enrichment factors and pollution index values were below values considered to be harmful to human health. The soil samples with respect to PI can be classified as deficient to minimal enrichment factor. With exception of Pb, Cr and Co which had PI values slightly above 1 and mean values exceeded 1, other potentially toxic heavy metals do not pose any health threat. The heavy metals: Pb Cr and Co are a health threat. Excess Pb and Co are carcinogenic to human system, while excess chromium causes diabetes and bronchitis. Sources of Pb, Cr and Co should be further investigated to institute appropriate remediation measures and also the bioavailability of these heavy metals be conducted in the human population inhabiting the study area.
Keywords: Enrichment Factor; Pollution index; potentially toxic; carcinogenic; bioavailability; remediation
