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.
Adedosu TA, Adedosu HO & Omotayo KA 2013. Distribution, sources and toxicity potentials of PAHs in soil around vicinity of Balogun-Biiro dumpsite of Osogbo, Nigeria. Malaysia. J. Analy. Sci., 19(3): 636-648. Ata Shakeri, Moore F &Soroush M 2009. Heavy metal contamination and distribution in the Shiraz Industrial Complex Zone Soil, South Shiraz, Iran. World Appl. Sci. J., 6(3): 413-425. Atiemo SM, Ofosu FG, Kuranchie-Mensah H, Osei Tutu, A., Palm Linda NDM & Blankson AS 2011. Contamination Assessment of Heavy Metals in Road Dust from Selected Roads in Accra, Ghana. Res. J. Envtal & Earth Sci., 3(5): 473-480. Chiroma TM, Ebewele RO & Hymore FK 2014. Comparative assessment of heavy metal levels in soil, vegetables and urban grey waste water used for irrigation in Yola and Kano. Int. Refereed J. Engr. & Sci., 3(2): 01-09. Chiroma TM, Ebewele RO & Hymore FK 2012. Levels of heavy metals (Cu, Zn, Pb, Fe and Cr) in bushgreen and roselle irrigated with treated and untreated urban sewage water. Int. Res. J. Envt. Sci., 1(4): 50-55. Edwards H 1976. The correlation coefficient. In: Introduction to Linear Regression and Correlation; W. H. Freeman and Company: San Francisco, CA, USA, 4: 33–46. Emmanuel A. 2013. An assessment of heavy metal contamination in soils and vegetation – a case study of korle lagoon reclamation site. http://ugspace.ug.edu.gh 6- 25. Fakayode SO & Olu-Owolabi BI 2003. Heavy metal contamination of roadside topsoil in Osogbo, Nigeria: its relationship to traffic density and proximity to highways. Envtal. Geol., 44: 150–157. Giwa AA, Bello LA, Amuda OS, Abdus-Salam N & Adelowo FE 2009. Some heavy metals ln urban and rural topsoils of Ibadan, Nigeria. Int. J. Chem..Sci., 2(1): 2006–3350. Guo G, Wu F, Xie F & Zhang R 2012. Spatial distribution and pollution assessment ofheavy metals in urban soils from southwest China, J. Envtal. Sci., 24(3): 410–418. Hakanson L 1980. Ecological risk index for aquatic pollution control, a sediment logicalapproach. Water Res., 14: 975–1001. Holland MD, Allen RKG, Barten D & Murphy ST 1989. Land evaluation and agricultural recommendations for Cross River National Park, Oban Division. Report Prepared by the Overseas Development Resources Institute in Collaboration with WWF for the Federal Republic of Nigeria and the Cross River State Government. Lu X, Wang L, Lei K, Huang J & Zhai Y 2009. Contamination assessment of copper, lead, zinc, manganese and nickel in street dust of Baoji, NW China. J. Hazardous Material, 161:1058-1062. Malawska M & Wilkomirski B 2000. An analysis of soil and plant (taraxacumofficinale) contamination with heavy metals and polycyclic aromatic hydrocarbon (PAHs) in the area of the railway junction IlawaGlowna, Poland. Water, Air & Soil Pollution, 127: 339-349. Muller G 1969. Index of geoaccumulation in sediments of the Rhine River. J. Geol. 2: 108-118. Olawoyin R, Oyewole SO & Grayson RL 2012. Potential risk effect from elevated levels of soil heavy metals on human health in the Niger Delta. Ecotoxicological Environmen Safety. Pekey H 2006. Heavy metal pollution assessment in sediments of Izmit Bay, Turkey. Envtal Monitoring & Asse., 123(1-3): 219-231. Raghunath R, Tripathi RM, Kumar AV, Sathe AP, Khandekar RN & Nambi KSV 1999. Assessment of Pb, Cd, Cu, and Zn exposures of 6- to 10-year-old children in Mumbai. Envtal. Res., 80(3): 215–221. Taofeek A, Yekeen R & Tolulope OO 2012. Evaluation of some heavy metals in soils along a major road in Ogbomoso, South West Nigeria. J. Envt. & Earth Sci., 2: 71-79. Taylor SR & McLennan SM 1985. The Continental Crust: Its Composition and Evolution. Blackwell Scientific Publications, Oxford. Tomlinson DL, Wilson JG, Harris CR & Jeffrey DW 1980. Problems in the assessment of heavy metal levels in estuaries and the formation of a pollution index. Helgolaender Meeresunter, 33: 566–575.