INTRODUCTION The iron and steel industry is a crucial corner stone of growth, socio-economic advancement, technological develop- ment and overall industrialization of any nation 1,2 . Among its economic impact is the supply of basic raw materials and products to multitude of industries such as building, construc- tion, machinery, equipment, automobile manufacturing and railways 3 . Metallurgical operations in the iron and steel industry involve series of complex processes, in which iron ore or metallic element is transformed into products 4 . The most vital conversion operation is the extraction process, which involves the reduction of iron ore (haematite/magnetite) to obtain pig iron, by the addition of coke, limestone and other materials in the blast furnace 5 . Other metallurgical operations include smel- ting, refining, steel rolling and casting. These activities have been reported to be point sources of heavy metals release, with potential capacity for heavy metal pollution 6 . For instance, the conversion of iron ore to molten iron produces significant amount of particulate emissions and carbon monoxide. Considerable quantities of metal laden solid wastes i.e. slag; wastewater and air emissions may also be Investigation of Selected Heavy Metals Level in Top Soils Around Ajaokuta Steel Company, North Central Nigeria OLATUNDE S. OLATUNJI 1,* and OLADELE OSIBANJO 2 1 Department of Chemistry, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, South Africa 2 Basel Regional Coordination Centre, Faculty of Science, University of Ibadan, Ibadan, Oyo State, Nigeria *Corresponding author: Tel: +27 822912934; E-mail: snf_olatunji@ymail.com Received: 24 August 2013; Accepted: 5 November 2013; Published online: 10 May 2014; AJC-15163 The concentration of selected heavy metals in top soils around Ajaokuta Steel Company was investigated in order to evaluate the environmental status level of the metals. Top soil samples were randomly collected around Ajaokuta Steel Company between 2003 and 2005. The samples were sorted; air dried, pulverized to < 2 mm grain size and digested using standard methods. The soil digest solutions were quantified for Cd, Cr, Mn, Ni, Cu, Zn and Pb using flame atomic absorption spectrometry. The mean concentrations (mg/kg) of the heavy metals were; Zn, 56.30 ± 11.94; Cu, 42.90 ± 5.84; Pb, 15.62 ± 3.06; Cr, 14.33 ± 2.38; Ni, 11.48 ± 2.13; Mn, 6.53 ± 1.68; and Cd, 0.13 ± 0.16, with soil concentration distribution in the order Zn > Cu > Pb > Cr > Ni > Mn > Cd. The soils were slightly acidic with mean pH 6.54 ± 0.67 and mean organic carbon levels of 2.03 ± 0.72 %. Significant correlation (p < 0.05) exists between the concentration of heavy metals in soils and organic carbon levels, with correlation coefficient for Mn; γ = 0.51 and Cr; γ = 0.63. The transport/availability of metals in soils is strongly influenced by pH and organic carbon levels, and this forms the basis of their fixation with plant growth nutrients. The retention of metals in soil organic matter proceeds by complexation. The stability of the metal-organic carbon complexes depends on the organic carbon type, nature of the complex formed and the degree of stearic effect. Keywords: Heavy metals, Concentration, Top soil, Distribution, Availability, Fixation. generated in the process of making iron and steel 7 . In addition, the wastewater may contain potentially toxic concentrations of phenols, cyanide, thiocyanate, ammonia, sulphide and chloride 8 . Air emissions may include visible smoke, coke-dust, ammonia, hydrogen sulphide, nitrogen oxides and carbon monoxide 7 . If these wastes are not adequately managed it can result into significant degradation of land, water and air with negative environmental impacts 9 . Soil may however become contaminated as a result of heavy metals release from metallurgical operations of the iron and steel industry 10,11 . Soils play major role in material cycling. Hence they could serve as medium of transfer of heavy metals to plants and animals and other environmental medium. Earliest concerns of occupational exposure were of the symptoms peculiar to metal workers of various kinds 12 . Classic effects of heavy metals can be as a result of toxic metal air emissions, which are suggested to be a factor in high lung cancer rates in some areas. Metals such as Hg, Pb, Cd, Cu, Zn and Mn may be deposited at levels toxic to humans, animals and plants 13,14 . According to ATSDR 15 , Pb, Hg and As ranked top 3 toxins with most adverse effects on public, while Cd, Cr and Ni are listed among the deleterious toxic metals of concern. ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY Asian Journal of Chemistry; Vol. 26, No. 10 (2014), 2982-2986 http://dx.doi.org/10.14233/ajchem.2014.16236