Ecological and Health Risk Studies of Heavy Metals in Soils around an Abandoned Battery Factory in Ibadan, Southwestern Nigeria

Abstract

Heavy metals on the soil around an abandoned battery site at Wofun, Ibadan, Southwestern, Nigeria were studied for their ecological and health risks. Ten soil samples collected from the soil around the abandoned battery sites were analyzed using Inductively Coupled Plasma –Mass spectrometry (ICP-MS). The data were evaluated using indices such as contamination factor, enrichment factor, geo-accumulation index and pollution index to determine the ecological and health risks posed by the heavy metals. The results showed an average concentration of Pb (7274.4), V (190.63), Cu (77.52), Zn (53.08) and Co (53) in a decreasing order. The enrichment factor revealed high enrichment for Co (12.30) at site one (S1), and extreme enrichment of Pb (61.12). Zn, Rb and Mo showed no enrichment in the soil. All the sites exhibited extremely high enrichment of Pb except at S10 where the enrichment of Pb was only severe. The results of Igeo indicated that all the sites were strongly to extremely polluted by Pb while S6 is moderately polluted by Co. The rest of the metals do not constitute any pollution threats. An evaluation of the ecological risk index (RI) revealed that the mean Er for Co (13.95), Cu (8.61), and Zn (0.56) indicate low ecological risk as they are less than 40 (Er <40). Lead (Pb) with Er value of 1818.60 has a very high ecological risk and accounts for most of the ecological risks in the study area. Lead (Pb) being the most toxic and abundant of all the heavy metals analyzed in the study areas was used to evaluate the potential non-carcinogenic health risk for both children and adults. The hazard index which is the sum of the hazard quotients for children is 26.64 suggesting that non-carcinogenic health risk may occur if there is any form of exposure to the soil. The hazard index for the adult (2.87) indicated a significant potential non-carcinogenic health risk in the study area.