DETERMINATION OF PHYSICOCHEMICAL AND HEAVY METAL CONTENT OF SOIL AROUND THE VICINITY OF SELECTED INDUSTRIES IN KADUNA METROPOLIS

Abstract

The soaring trend of environmental contamination by heavy metals is a global issue. The continual monitoring of soils around industrial areas becomes necessary. The present study focused on the physicochemical and heavy metal concentration in soil around the vicinity of selected industries in Kaduna metropolis. The mean pH, electrical conductivity, % organic matter, % sand, % clay and % silt obtained were 7.16±0.35, 362.60 ±10.7µS/cm, 2.92±0.50, 76.50±0.81, 17.79±5.51 and 6.13±1.65 respectively. The mean concentrations of the heavy metals investigated ranged between 26.89±0.36 – 77.18±0.40 µg/g for Pb, 29.25±0.7 – 44.20±0.35µg/g for Cr, ND – 1.5±0.02µg/g for Cd, 134.63±1.10 – 217.96±0.16 µg/g for Zn, 9.58±0.7–74.45±0.20µg/g for Cu, 92.14±0.20 – 200.8±0.31 µg/g for Mn and 1185.80±4.66 – 2488.00± 2.37 µg/g for Fe respectively. The highest concentration of Cr in the sampling areas was obtained at the vicinity of textile industry. The concentration of Fe was much higher than those of other elements. Cd was not detected in some of the soil samples. The concentrations of the metals were in the order Cd<Cu<Cr<Pb<Mn<Zn<Fe. The results of geoaccumulation index and enrichment factor showed that the soils were moderately contaminated with most of the metals investigated. The concentrations of the metals examined were significantly higher than the control, which also implied contamination due to anthropogenic contribution. Inter-elemental correlation matrix showed significant positive correlation of Pb with Cr and Mn, but negative correlation with Cd. Pb, Cd and Cu also showed a significant positive correlation with total organic matter of soil. Planned monitoring of the discharge of industrial effluents into the environment as well as avoidance of agricultural activities around the vicinity of these industries was recommended.