Assessment of Heavy Metals Level of Soil in Kakuri Industrial Area of Kaduna, Nigeria

Aim: To determine the level and distribution of Zn, Cu, Ni, Cr, Pb, Hg and V from soils in the vicinities of Kakuri industrial area of Kaduna state, Nigeria.
Study Design: To compare the soil heavy metal concentrations with regulatory standard values permitted by the Nigerian environmental guideline as well as international standards and also subject the data to descriptive analysis to determine the Geo-accumulation index (Igeo) and contamination factor (Cf).
Place and Duration of Study: Department of Chemistry, Ahmadu Bello University Zaria between February 2012 and July 2013.
Methodology: Twenty six soil samples at 0 to 10cm and 10 to 20cm depths from twelve (12) sample locations and two control samples was collected on the same day at Kakuri industrial area of Kaduna, Nigeria. The total concentrations of Cu, Zn, Pb, Cd Ni, Hg and V was determined using XRF spectrophotometer. Organic matter content (OM), pH, calcium carbonate and particle size distribution of the soil samples were also determined.
Results: The mean concentrations (in mgkg-1) of Zn, Cu, Ni, Cr, Pb, Hg and V are 100.5±19.82, 60.02±3 .60, 26.25±6.44, 42.42±5.21, 32.00±1.68, 28.80±9.35 and 73.08±3.52 respectively. The metal concentrations (in mgkg-1) ranged: Zn, 20-420; Cu, 26-110; Ni, 9-72; Cr, 22-157; Pb, 27-34; Hg, 10-60 and V, 47-120. Zn and Cu correlated positively with pH with values +0.41643 and +0.64447 respectively. Zn and Cu (+0.6142) and also Zn and Hg (+0.6377) had strong correlation which signifies the same source(s) in the soil. The contamination factor Cf values 1.31, 1.40 and 1.70 for Zn, Cu and Pb respectively falls under the classification 1 ≤ Cf Ë‚ 3 indicates the soil is considerably contaminated but the Igeo ≤ 1 for all sample locations with the exception of KGW with 1Ë‚ Igeo ≤ 2.
Conclusion: Significant spatial variation in concentrations was observed for all metals across the locations and the degree of pollution varies with the level of industrial activities but were all within tolerable limit. The contamination factor C and Igeo index confirms the soil is uncontaminated.