Assessment of Heavy Metal Species in Some Decomposed Municipal Solid Wastes in Bida, Niger State, Nigeria

Soil samples collected from three decomposed municipal solid waste dump sites located in Esso, Gbangbara and Eyagi areas of Bida town were analyzed for some heavy metals (Cu , Fe, Pb, Mn and Cr), using Atomic Absorption Spectrometer. The analysis of the aqua regia digestion showed an average mean concentration (mg/kg) of Cu (342.22±7.6), Mn (570.00± 1.0) and Fe (371.11±1.2) in the three dump sites were exceptionally high. The variation of these heavy metals across these three dump sites were in the order Pb (EY) > Pb (ES) > Pb (GB), Mn(GB) > Mn (ES) > Mn (EY), Fe (GB) > Fe (GB) > Fe (ES) > Fe (EY), Cr (GB) > Cr (EY) > (ES), Cu (GB) > Cu (ES) > Cu (EY). The analysis of the weak sodium acetate solution digestion showed that Cu (5.47± 0.2), Mn (1.88 ± 0.0) and Fe (1.47 ±0.1) (mg/l) on the average exhibited high concentrations in the dump sites. Most of the Cu, Mn and Fe were found to be associated with the exchangeable fraction, which is very soluble and mobile. Base on Federal Environmental Protection Agency and Land Disposal Restrictions standard regulations, these metals exhibit hazardous concentrations.