Geochemical Evaluation of Soils and Road Deposited Sediments of Benin City Using GIS and Multi-variance Approaches'

Abstract

This study was carried out to determine the concentration and sources of trace elements in top soils, road deposited sediments and filling station dusts in Benin metropolis in order to evaluate the effect of increased urbanization on the environment. Ninety-nine (99) samples were collected from the study area. These samples were air dried, disaggregated and digested using aqua regia. They were subsequently analyzed for metallic ion concentrations using inductively coupled plasma emission spectrometry (ICP-ES). The physico-chemical parameters were determined using appropriate probe to measure the pH, EC and TDS of the soil and dusts samples. GIS and multi variant analyses were used in the interpretation of the data analyzed. The results of the analyzed topsoil in ppm showed that Cu ranged from 4 - 1125, Pb from 9 - 2889, Zn, from 29 - 5022, Ni, from 2 - 52, Co, from 1 - 12, Mn, from 53 - 132, Cd, from below detection limit (BDL) - 27.2, V, from 17 - 108, Cr, from 15 - 90, Ba, from 6 - 530 and As, from BDL - 6. The pH of the topsoil samples ranged from 5.5 to 7.8, Electrical Conductivity from 37. 0 - 860.0 μS/cm, while TDS ranged from 24.0 - 328.25mg/L. The results of the concentrations of these metals in the Road deposited sediment, equally showed varied concentrations at different location. The geochemical results of both media are more than the background concentration for most of the elements.