The Geo-accumulation Index of Some Heavy Metals in the Roadsides Soils of Onitsha South Local Government Area Anambra State, Nigeria

摘要

Heavy metals have a great ecological significance due to their toxicity and accumulative behaviour. Monitoring of their concentrations in the soils of our environment is very important. The geo-accumulation index (Igeo) in 11 stations in Onitsha South Local Government Area, (i.e Modeebelu Avenue, Ozomagana, Zik Avenue, Port Harcourt Road, Oguta Road, Iweka Road, Venn Road, Niger Street, Creek /Okwaraji Moore Street and Bida Road) were analysed. The soil pollution status of the area was investigated by analyzing the concentration of eight heavy metals (Mn, Ni, Zn, Cd, Cr, Fe, Cu and Pb) using Atomic Absorption spectroscopy (AAS). From the geo-accumulation index (I_(geo)) results obtained were; Mn values were mainly in class 5 for wet season and class 4 in dry season, Ni fell within the range of classes 2-3 in both seasons, Zn was in the range of classes 1-2 while Cr fell within the ranges of class 4-5 for both seasons. Cu was mainly within the range of class 2-3 in both seasons, while Pb fell within class 0 (with the exception of few locations). The Fe geo-accumulation for all locations was within the class of 0. These results revealed that Fe, Cd and Pb did not pollute the area but were polluted by Mn, Cr, Zn and Ni at various levels in both seasons.