Abstract

The levels of bioaccumulation of heavy metals (Pb, Cr, Zn, Cd, Mn and Cu) in Eleusine indica and waste soil samples from ten refuse dumpsites located in Kaduna Metropolis was assessed using atomic absorption spectrophotometer (AAS). The soil pH, electrical conductivity (EC), organic matter (OM) and available phosphorus (AP) were also determined. The results of analysis of the waste soils from the refuse dumpsites indicated that levels of the metals were in the range of; 131.93 to 205.18 mgkg^-1 (Pb), 27.13 to 94.198 mgkg^-1 (Cr), 259.30 to 354.708 mgkg^-1 (Zn), 27.23 to 45.498 mgkg^-1 (Cd), 151.68 to 227.568 mgkg^-1 (Mn) and 42.09 to 132.11 mg kg^-1 (Cu). The concentration recorded for E. indica ranged widely from 116.40 to 239.74, 6.97 to 24.84, 86.94 to 261.40, 5.10 to13.24, 90.22 to 318.51 and 41.11 to 103.84 mgkg^-1for Pb, Cr, Zn, Cd, Mn and Cu respectively. The results of soils pH, EC, OM and AP were found to be 7.85 to 8.60 and 0.54 to 3.22 S cm^-1, 2.77 to 6.32% and 42.11 to 175.55 mgkg^-1 respectively. The bioaccumulation factors (BCF) of these metals were less than unity for all the metals except for Pb. The trend in bioaccumulation for metals in E. indica followed the sequence: Zn>Cu>Pb>Mn>Cd>Cr. Though the results indicated low bioaccumulation of metals by E. indica, however, further dumping of toxic waste could lead to toxicity to man through the food chain.

Key words: Waste soils, Refuse dump, Metals, Kaduna.