Abstract

The potential of Vigna subterranean commonly called Bambara beans for phytoextraction of copper in a crude oil contaminated soil was investigated. The contamination levels of crude oil in the soil for this pot experiment were 2, 4, 6, 8 and 10% (w/v). Amendments were added to increase the uptake and translocation of metal to aerial biomass. A range of amendments was tested for copper uptake enhancement with V. subterranean commonly called bambara beans. Safe levels of exposure to contaminants were further investigated using albino wistar rats for 28 feeding trial days to trace inherent biomagnifications. Bambara beans extracted up to 88.88 and 43.38 mg/kg into its shoot and root respectively at 10% contaminant dose while achieving 63.17% Cu removal unamended. Poultry manure was the most effective amendment for enhancing copper uptake and translocation into the shoots of Bambara beans with shoot tissue copper levels of 118.13 mg/kg compared to 98.25 and 93 mg/kg obtained for NPK and UREA amendments. 79.28, 70.07 and 70.99% Cu removal was achieved with poultry manure, NPK and UREA amendment respectively. An assay was carried out with animals on inherent biomagnifications. The results showed that the performance of rats fed diets formulated from contaminated soil differed significantly (P > 0.05) from those of the controls used. Hazard characterization revealed negative effects of potentially toxic copper on organ weight, optimum digestibility and animal growth rate. Weight of pancreas showed pancreatic hypertrophy in rats adapted to diets, which contain higher levels of contaminants compared to controls.

Key words: Bambarra beans, copper uptake, amendments, diets, performance