Heavy Metal Concentrations in Some Vegetables Grown in a Farm Treated with Urban Solid Waste in Kuru Jantar, Nigeria

Abstract

The use of dumpsite soils as organic manure is wide spread in developing countries like Nigeria. This study investigates the concentration of some heavy metals in vegetables grown in a farm treated with dumpsite soils in Kuru Jantar, Nigeria. Soil samples and vegetables from the farm were collected and prepared using standard analytical procedures. The concentrations of metals in both soil and vegetables were determined using atomic absorption spectrophotometer (AAS). The results showed that the farm was polluted with the metals (Cd, Cr, Cu, Mu, Fe, Pb, Zn, Ni) determined. The Enrichment Factor (EF) showed that some metals had minimal enrichment while Cd (13.93) had significant enrichment at the farm. The Pollution index (PI) calculations showed that at the farm, the contamination pollution ranged from very slight to very severe. The overall order of the metals at the dumpsite was Fe> Mn> Zn> Cu> Cr> Ni> Pb> Cd while the order of the metal concentrations at the farm was Fe> Mn> Zn> Ni> Cd> Pb. The data obtained in the study were analyzed using Pearson correlation analysis. The results showed perfect positive correlation values above 0.9 between the farm and the dumpsite, which indicated that there was a strong association or similarity between them. The metal concentrations in the vegetables analyzed showed that spinach decreased in the order Fe>Zn>Mn>Cd>Pb while in Cabbage, the order was Mn> Fe> Zn>Cu>Cd; in Radish, the order was Fe>Mn>Cu>Cr>Zn while in pepper, the order was Fe>Cu>Mn>Ni. In general, the metal concentrations were below the recommended limit of USEPA and FEPA standards for agricultural soils and vegetables except for Cd in vegetables. The concentrations were however higher in the farm than in the control. Thus, the farm was polluted with heavy metals from the dumpsite soils.