Status of Selected Heavy Metals in Soils Samples Obtained From Crown Estate Dumpsite, Okada, Edo State, Nigeria

Abstract

This research work focused on the status of selected heavy metals in dumpsite soil compared with soil samples obtained from a green park area as a control. The research results were also related to threshold limits set by the National Environmental Standards and Regulations Enforcement Agency (NESREA), World Health Organization (WHO) and Food and Agriculture Organization (FAO). Soil samples were collected from a dumpsite inside Crown Estate (made up of residential quarters for both staff and students of Igbinedion University) and a green area of Igbinedion University's permanent site, Okada, Benin City, Edo State in Nigeria. The soil samples were air-dried, ground, sieved, digested and subjected to heavy metal analysis using atomic absorption spectroscopy. The analyzed metal profiles in the dumpsite soil samples are as follows: concentration of Fe, Pb, Cu, Zn, Mn and Ni ranged from 453.26 – 569.28, 0.85 – 1.16, 20.17 – 32.35, 60.98 – 74.26, 5.15 – 9.28, and 5.92 – 9.57 mg/Kg, with mean concentrations of 501.33 mg/Kg, 0.96 mg/Kg, 25.38 mg/Kg, 66.33 mg/Kg, 6.89mg/Kg and 7.90 mg/Kg respectfully, while the status of heavy metal concentration in soil samples collected from the control site ranged from 386.21 – 463.95, 0.82 – 1.32, 20.05 – 26.27, 47.75 – 65.22, 5.77 – 8.73, and 6.35 – 9.87 mg/Kg, with mean concentration of 401.76 mg/Kg, 1.05 mg/Kg, 23.05 mg/Kg, 54.84, 7.39 mg/Kg and 7.78 mg/Kg for Fe, Pb, Cu, Zn, Mn and Ni respectfully. Of all the metals analyzed only the level of Fe in this study did exceed the tolerance limits of NESREA, WHO and FAO. The results also revealed higher heavy metal content in the dumpsite justifiably due to the difference in anthropogenic activities carried out on the two sites.