Search

The concentrations of potentially toxic elements (PTEs) and their contamination indices were determined in urban soil from five different land-use zones, namely municipal solid waste landfill (MWL), industrial area (INA), heavy traffic area (TRA), residential area with commercial activities (RCA), and farmland (FAL) in Osogbo Metropolis. Ecological and human health risk assessments were also evaluated. Based on the average concentrations, the highest values of As, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were found at INA, while the maximum concentrations of Ba, Cd, and Co were observed at MWL. The average enrichment factor (EF) values of Cd, Cu, Pb, and Zn showed very high to extremely high enrichment in the soils of INA, MWL, TRA, and RCA, while the EF values of Ba, Co, Cr, Fe, Ni, and V were significantly to moderately enriched in the aforementioned land-use zones. This trend was consistent with the average contamination factor (Cf) values of Cd, Cu, Pb, and Zn, which indicated considerable to very high contamination at INA, MWL, TRA, and RCA. However, Cf values of Ba, Co, Cr, Fe, Ni, and V had moderate contamination variously at the different land-use zones. Furthermore, the potential ecological risk factor (Er i ) values for all the PTEs were < 40, which indicated low Er i , except for Cd and to some extent Pb. The Er i value of Cd was high to very high at MWL, INA, TRA, and RCA, and low at FAL, while Er i of Pb was only moderate at INA. Assessment of health quotient (HQ) of non-carcinogenic health risks was within acceptable limit (< 1) for most of the PTEs in the different zones for adults and children, except the maximum HQ value of Pb at INA (HQ = 1.0), which was beyond the acceptable limit for children. The carcinogenic risk was within the acceptable limit (1.0 × 10 -6 ) in all the zones, except INA. This may pose health challenges to children in the vicinity of the pollution sources. Continuous monitoring of PTEs to reduce exposure to PTE should be considered., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Increased growth of industrial activities, especially in urban centers, is one of the main sources of toxic substances in Nigeria. The level of these impacts is not well known. Soil and sediment samples from one such industrial area were examined for their mineralogical composition and heavy metals contents in order to assess the level of contamination and potential ecological risk status., Methods: Mineralogical composition of the media and their heavy metals concentrations were determined using X-ray diffractometry and inductively coupled plasma-mass spectrometry methods, respectively. Ecological risk assessment was carried out using single (contamination factor, geo-accumulation index, enrichment factor) and multi-elemental (contamination degree, pollution index and modified pollution index) standard indices., Results: The average heavy metal concentrations in soils and sediments followed the order magnesium (Mn) > chromium (Cr) > lead (Pb) > copper (Cu) > cadmium (Cd) > cobalt (Co) > nickel (Ni), with corresponding values for soils and sediments of 324.3, 79.9, 66.1, 40.7, 14.3, 9.1, 6.8 mg kg -1 and 266.8, 78.6, 40.6, 39.8, 12.9, 8.4, 4.6 mg kg -1 , respectively. Principal component (PC) analysis of the results indicated three main sources of metals (industrial, vehicular activities and geogenic input). Evaluated contamination factor (Cf), enrichment factor (E f ) and geo-accumulation index (Igeo) revealed very high contamination for Pb, Cd and Cu in all of the samples, with calculated pollution index (PI) and modified pollution index (MPI) revealing that all the samples were severely polluted. Calculated potential ecological risk factor (ER i ) within the industrial area demonstrated a strong potential ecological risk for Cd, Pb and Cu., Conclusions: Activities in the industrial area have affected the quality of the analyzed environmental media, with possible detrimental health consequences. Regular environmental monitoring of the industrial area and the formulation of appropriate policies that support reduction of contamination are strongly recommended. However, due to the limitations of comparing site samples with a single control sample in this work, further study is recommended to compliment this preliminary study., Competing Interests: The authors declare no competing financial interests.