Assessment of trace metal contamination of soils around Oluyole Industrial Estate, Ibadan, Southwestern Nigeria

Abstract

This study was carried out to determine the level of metals contamination of the soils around Oluyole industrial estate in Ibadan. Oluyole industrial estate has heavy concentration of manufacturing industries that generate a lot of waste products capable of introducing metals into the environment. Consequently, twenty-one topsoil samples were collected and analyzed for Molybdenum (Mo), Copper (Cu), Lead (Pb), Zinc (Zn), Nickel (Ni), Cobalt (Co), Manganese (Mn), Scandium (Sc), Arsenic (As), Strontium (Sr), Cadmium (Cd), Vanadium (V) and Chromium (Cr) using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique. The degree of contamination was assessed using geoaccumulation index, contamination factor and degree of contamination. The mean concentration of metals was in the order: Mn>Cr>Zn>V>Pb>Cu>Ni>Sr>Co>Sc>As>Mo>Cd. Factor analysis indicated three factor groupings. Factor 1 included Mo, Cu, Pb, Zn, As, Sr and Cd. Factor 2 is made up of Ni, Co, Mn, Sc, Sr, V and Cr while Factor three included Sc and V. These elemental associations were influenced mainly by lithology, geochemical affinity and anthropogenic activities. The geoaccumulation index showed that the soils were Practically uncontaminated to Moderately contaminated by Zn, Mn, Sc, and Cr, Moderately contaminated by Mo, Cu, Pb, Ni, Co, As, Cd and Moderately to heavily contaminated by Ni and Sr. Results of Contamination factor also showed that the soils have moderate contamination factor for all metals studied excepting Ni which has considerable contamination factor. The considerable degree of contamination with a value of 28.23 showed that the soils were highly polluted by the metals studied posing a potential health risk to human life and the environments.

Keywords: Oluyole Industrial Estate, Contamination Factor, Degree of Contamination, Geo-accumulation index, Soils