Abstract:
The purpose of this study was to assess the concentration of some heavy metals:namely Cu,
Cd, Pb, Zn and Cr in abandoned tin mined soils around Du and Zawan, Jos south local
government area, Plateau state. A total of 30 soil samples were collected randomly from the
sites at a depth of 0 to 15cm and two common plants grown (maize and beans) were collected
for this study. Physicochemical properties of the soil samples were determined. The soil
samples were subjected to sequential extraction and total metal determination and the extract
for the heavy metals was analyzed using Atomic AbsorptionSpectrophotometer. The
statistical analyses were conducted using one way analysis of variance. The mean pH and
electrode potential ranged from 5.33 to 6.14 and 49.7 to 82.7 respectively, while the electrical
conductivity and organic matter ranged from 33.7 to 94.3 and 2.04 to 3.81 respectively. The
mean concentration levels of heavy metals ranged from Zn > Cu > Cr >Pb> Cd for total metal
determination and it was observed that the mining sites showed more concentration of heavy
metals than the control. The results obtained for sequential extraction followed the same trend
for copper, chromium and lead which showed higher concentrations at the residual fraction
while cadmium and zinc had more concentration at the non-residual fraction. The pollution
potentials for all the metals were calculated and was observed that cadmium for both Du and
Zawan mining sites were higher than the maximum permissible limit allowed by World
Health Organization (WHO).While chromium, lead, zinc and copper followed same trend of
low contamination. The analysis of the food samples from the 3 sites had low concentrations
of metals and are good for consumption since the metals are below WHO maximum
permissible limits. But there is a gradual build up of cadmium in the abandoned mined sites
and the consumption of food grown on these soils may harm the consumers.
