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Olatunji AS, Asowata TI and Abimbola AF
Forty-two (42) composite soils samples and fifty- seven (57) dusts samples were collected from within Benin City metropolis, southern Nigeria. All the samples were air dried, disaggregated and subsequently analyzed to determine the concentration of heavy metals using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The pH, Electrical conductivity (EC) and Total Dissolved Solids (TDS) of the samples were also determined. The pH ranges from slightly acidic to alkaline (5.5-7.1) and (6.0-7.2); EC (37.0-860.0 μS/cm) and (100.0-1437.0 μS/cm) as well as TDS (24.1-559.0 mg/L) and (65-934 mg/L) for soils and dusts respectively. Metals concentration in the soils and dusts are: Cu (4-1125 ppm) and (31.0-210.0 ppm); Pb (9.0-2889.0 ppm) and (40.0-440.0 ppm); Zn (29.0- 10000.0 ppm) and (116.0-729.0 ppm); Ni (2.0-52.0 ppm) and (10.0-28.0 ppm); Sr (4.0-969.0 ppm) and (10.0-196.0 ppm); Cd (Below Detection Limit, Bdl-27.2 ppm) and (Bdl-1.20 ppm); Cr (15.0 ppm-90.0 ppm) and (32.0-64.0ppm) and As (Bdl-6.0 ppm) and (Bdl-4.0 ppm) respectively. The geochemical and geo-accumulation index maps produced showed large variability in the spatial distributions of elements in topsoil and dusts respectively as well as their pollution status. Further evaluation of the results using contamination indices revealed that Pb, Cu, Zn, Cr, Cd, Ni and As are enriched in soils and dusts obtained from areas with dense human and vehicular population as well as areas with considerable commercial activities.