Assessment of Heavy Metals concentration in Soil around Artisanal Gold Mining Site, Osun State, Southwestern Nigeria

Abstract

The concentration of heavy metals in soil samples from artisanal gold mining site at Ijana Osun State South West Nigeria and its effect on the immediate environment was investigated. Soil samples were randomly collected at the Ijana Wasare gold mine site and also few kilometers from the gold mine site where there were no records of mining activities The samples were analyzed for heavy metals such as, copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), chromium (Cr), nickel (Ni) and cobalt (Co) using a Flame Atomic Absorption Spectrophotometer (AAS). The results obtained showed the mean heavy metal concentrations in the mining area for As, Hg, Cu, Zn, Co, Cr, Cd, Pb and Ni as 10.32 mg/kg;, 9.69 mg/kg;, 72.46 mg/kg; 54.73 mg/kg;, 7.54 mg/kg;, 34.32 mg/kg;, ND mg/kg; ND mg/kg and, 20.06 mg/kg, respectively  while the  concentrations in the control area were 3.18 mg/kg;, 1.16 mg/kg; 16.25 mg/kg; 15.12 mg/kg;, ND mg/kg; 18.72 mg/kg;, ND mg/kg; Pb, ND mg/kg and 9.37 mg/kg, respectively. The the mean value of  soil pH was 5.28  in the mining areas and  6.61 in the control sites. The results showed that the concentration of heavy metals in the mining area was higher compared to those in the control area, this suffices to say therefore that the artisanal mining activities have elevated the concentration of heavy metals in the soil within the mine environment.