Uptake of Heavy Metals by Dioscorea rotundata (White Yam) and Ipomoea batatas (Sweet Potato) from Enyigba Lead-Zinc Derelict

The levels of heavy metals in Dioscorea rotundata (white yam) and Ipomoea batatas (sweet potato), in addition to the soil, were examined using X-ray Fluorescence (XRF) technique. The results revealed that heavy metal in soil decreased in the order Pb > Zn > Cu > Mn > Cd > Ni > As > Cr. The mean concentration (mg kg-1) of metals was found in the range of Pb (0.04-0.14); As (0.02-0.04): Cd (0.02-0.04); Cu (40.12-62.12); Cr (0.01-0.21); Zn (24.18-74.60); (Mn 18.46-84.90); and Ni (8.24-14.86). As and Cd were not detected in leaves of Dioscorea rotundata. Generally accumulation of metals was observed to be higher in the root than in the leaves and the Translocation Factor (TF) was highest (2.0) in Ipomoea batatas and lowest (0.22) in Dioscorea rolundala. High Pollution Indices (PI > 1) of As and Pb was observed in the two investigated tubers. The variation in the parameters determined were found to be statistically significant (p < 0.05) as determined by one way analysis of variance.