Abstract

The level of potentially toxic trace element constituents in Zaria soil was assessed using index analysis approach. The indexes employed are enrichment index ( ),  geo-accumulation index   ( ) and pollution load index (PLI). The  of the elements Co, Cr, As, Mn, Fe, Th, U and Sb was found to be less than 1 thus indicating that these  elements were derived from crustal materials. The  of the metals falls within the class of 0 and 1. Considering permissible levels of metals, this reveals that the soil in Zaria and environ is not enriched in these potentially toxic elements. The calculated   values of the studied region range from 0.49-3.15. This further confirms that Zaria soils are in an unpolluted condition. Enrichment factor analysis and the geo-accumulation index method were applied in order to determine the extent of anthropogenic contamination, and both show that Pb, Cd, and Hg have been significantly increased by human activities. Principal component analysis was used to identify the sources of metals in these soil samples.

Keywords: heavy metals, soil, geo-accumulation indexes, pollution load index, Nigeria