Heavy Metals Accumulation in Leaves and Tubers of Cassava ( Manihot Esculenta Crantz) Grown in Crude Oil Contaminated Soil at Ikot Ada Udo, Nigeria

摘要

Pot experiment was set up to assess the levels of heavy metals accumulation in leaves and tubers ofcassava (Manihot esculenta Crantz) grown in crude oil contaminated soil in the Niger Delta Region of Nigeria. Threecassava cultivars were used for the study viz: NR-8082, TMS-30572 and a Local variety (LV). The crops were plantedin pots and nurtured to maturity. They were then assessed for the concentrations of the following heavy metals: Pb, Cd,Cr, Ni, Zn and Fe in both the leaves and tubers using standard laboratory procedures. Data analysis was carried out usingthe Analysis of Variance (ANOVA) and significantly different means were separated using the Duncan Multiple RangeTest (DMRT). The analysis revealed that TMS accumulated the highest quantities of these metals, followed by NR andlastly, the local variety (V), this being a function of biomass production. Transfer Factors also proved the order ofaccumulation of this heavy metal as: TMS NR LV. Generally, the order of prevalence of heavy metal in both theleaves and the tubers was: Fe Zn Ni Pb Cd Cr. This study revealed that crude oil pollution is increasinglyraising the levels of heavy metals in the soils of Niger Delta and these metals are being taken up by plants includingcassava, which is the most important staple food crop of the area. Consequently, crops farmers are advised againstcultivating at crude oil contaminated sites for the risk of accumulation of heavy metals in plant tissues.