(A Peer Review Journal)
e–ISSN: 2408–5162; p–ISSN: 2048–5170


Pages: 478-482
Samuel O. Ajayi, Babawale E. Abiola , Adebayo K. Adekunle, Adewale S. Akintelu and Ojeyemi M. Olabemiwo

keywords: Heavy metals, index of geo-accumulation, pollution load index, Wazo market


A study of heavy metals levels in Wazo market top soils, Ogbomoso was conducted during dry and rainy season in year 2015 to ascertain status of the soils. Soil samples were collected from five different spots within the market in the month of February, March, June and July. Some physicochemical parameters (pH and total organic carbon) of the soils were determined. The samples were further digested with HClO4, HNO3 and H2SO4 mixture, and digests were analysed for heavy metals using atomic absorption spectrophotometry. The mean levels of heavy metals during the dry season were 249±27.85 mg/kg for Zn, 5.5±1.12 mg/kg for Co, 10±6.00 mg/kg for Cd, 196±60.11 mg/kg for Pb, 14.5±7.63 mg/kg for Ni and 28±6.32 mg/kg for Cu, while during the rainy season the levels of 301±23.88 mg/kg for Zn, 5±0.00 mg/kg for Co, 9±7.87 mg/kg for Cd, 198.5±92.38 mg/kg for Pb, 20.5±8.97 mg/kg for Ni and 45.5±9.76 mg/kg for Cu were observed. The levels of metals based on average concentration during the dry and rainy seasons were Zn >Pb> Cu > Ni > Cd >Co and Zn >Pb> Cu > Ni > Cd >Co, respectively. The average concentration of each metal in the soil during rainy and dry season was almost equal except for zinc and copper which were a bit higher in the wet season. Indices of geo-accumulation revealed that the soils were moderately and strongly contaminated with Pb and Cd respectively. The degree of contamination based on contamination factor showed that the soil can be classified as considerably contaminated with heavy metals during the sampling period. The values of pollution load index obtained during the dry and rainy season indicated that the soil was polluted. In the dry season, at p <0.01, Zn was positively correlated with TOC (0.960). At p <0.05, Pb was negatively correlated with TOC (–0.886) during the dry season while strong correlation exist between Cu-Zn during the rainy season (0.933). This study showed that Wazo market top soil was polluted with heavy metals which may pose serious health challenges on human.


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