Potential ecological and health risk assessment of dumpsite from Ibadan, Southwestern Nigeria

Abstract

Dumpsites have elevated the contamination and pollution of soils by heavy metals, hence the need to study the potential ecological and health risks impact on the soil and humans. Ten soil samples collected from the soil around the dumpsites at Awotan Ibadan were analysed using the inductively coupled plasma-mass spectrometry (ICP-MS) analytical technique. The data were interpreted using contamination indices such as contamination and enrichment factors, geo-accumulation index and pollution index to determine the ecological and health risks posed by the heavy metals. The results of the spatial distribution of heavy metals across the sampling sites showed the following ranges: Cu (43.71-469.64) with a mean of 113.74 mg/kg, Zn (53.50-615.60) with a mean of 130.52 mg/kg, Rb (83.14-225.35) with a mean value of 145.37 g/kg and Pb (28.38-209.15) with a mean of 68.01 mg/kg in descending order: Zn > Cu > Pb >V. The enrichment factors indicated very high enrichment of Cu (25.07), significant enrichment of Pb (18.78) and moderate enrichment of Zn (15.14) and minor enrichments of Co, Ni, Rb and Cs. The results of the contamination factor showed that Sc, Co, Zn, Rb, Cs have moderate contamination while Cu and Pb indicated high contamination. The results of geo-accumulation (Igeo) indicated that Cu and Pb are positive in contrast to the other metals suggesting some anthropogenic influences of the duo heavy metals in the study area. Cu and Zn indicated low ecological risks however, Cu and Pb showed considerable risks (Er 80-160) and moderate risk (Er 40- 80) respectively in sample site number one. The results of the modified ecological risk index (MRI) revealed that about 62.53% of this sample site number one showed a considerable ecological risk of the heavy metal Cu and 47.61% of the moderate ecological risk of Pb. The health-risk study indicated that hazard quotient HQing, HQderm and hazard index (HI) values were below the acceptable limit of 1×10–6 and 1×10–4 and therefore showed no obvious non-carcinogenic risk and negligible cancer risk from the soils and environment.