Paper Title
Investigation of Natural Concentration of Toxic Element in Soil using Instrumental Neutron Activation Analysis

The level of potentially toxic trace element constituents in Zaria soil was assessed using index analysis approach. The indexes employed are enrichment index ( EI ), geo-accumulation index ( geo I ) and pollution load index (PLI). The EI 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 geo I 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 PLI 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. Keywords: Heavy Metals, Soil, Geo-Accumulation Indexes, Pollution Load Index, Nigeria