Contamination and Possible Health Risks of Polycyclic Aromatic Hydrocarbons in Soil and Crops from Cultivated Floodplains of Some Rivers in Ekiti State, Southwest Nigeria

Abstract

The demand for food in Nigeria has increased pressure on land use including floodplains despite possible contamination from the river catchments. The objective of this paper is to evaluate the contaminations and possible health risk of polycyclic aromatic hydrocarbons (PAHs) in soil from Irintan (Ogbese), Omi-Eye (Erio) and Egbigbu (Ayetoro) cultivated floodplains in Ekiti State, Nigeria using standard techniques. The soil samples were collected from 0-30cm depth at 5m, 25m and 45m perpendicular distances to the river course at lower, middle and upstream. The crop samples randomly collected on the floodplains were Talinum triangulare, Caspicum annum and Zea mays from each farm. Samples were appropriately treated and analyzed for polycyclic aromatic hydrocarbons and results used to estimate the possible health risk. PAHs concentration at each of the farm sites was found to be more than their corresponding controls.The ∑PAHs (µg/kg) in soil ranged 0.62-3.20, 0.38-2.33 and 0.09-1.75 at Irintan (Ogbese), Omi-Eye(Erio) and Egbigbu (Ayetoro) floodplains respectively and these values were categorized unpolluted. The ∑PAHs (µg/kg) was 1.24, 0.64 and 21.15 for T. triangulare, 2.62, 2.76 and 18.43 for C. annum and 0.70, 1.78 and 1.31 for Z. mays at Irintan, Omi-Eye and Egbigbu floodplain respectively. All the Benzo (a) pyrene equivalent concentration were less than the cancer screening value except in T. triangulare and C. annum at Egbigbu floodplain suggesting possible carcinogenic health concern in T. triangulare and C. annum at the floodplain. There could be a cause for concern for the consumption of these food crops by the exposed population.