Distribution of toxic metals in sediments

The study has found that the toxic metals are distributed on the top layer and bottom layer (20 cm) of the river and stream sediments. The levels of toxic metals (Mn, Cu, Cd, Co, Zn and Ni) were determined in sediment from stream that drains New Union Gold Mine tailings dams using Flame Atomic Absorption Spectroscopy. The concentration of the heavy metals were arranged in descending order where Manganese> Copper> Nickel> Zinc> Cobalt> Cadmium. The range of toxic metals in the top and bottom layers were: Mn (99.1 ± 0.1 mg/kg to 203.5 ± 2.1 mg/kg); Cu (8.9 ± 0.1 to 65.7 ± 4.0 mg/kg); Ni (6.1 ± 0.1 to 63.5 ± 1.2 mg/kg); Zn (12.5 ± 0.6 to 36.2 ± 0.3 mg/kg); Co (4.1 ± 0.1 to 18.8 ± 0.5 mg/kg); Cd (0.2 ±0.00 to 1.3 ±0.1 mg/kg). The pH of top soil profile ranged from 3.25 ± 0.01 to 6.28 ± 0.02 whereas the bottom soil profile of ranged from 3.75 ± 0.01 to 6.45 ± 0.03. The pH of the sediments in the stream that drains New Union Gold Mine tailings dams was found to be mainly acidic. The electrical conductivity of top layer sediments in the stream and the Mandzoro River ranged from 8.5 ± 0.20 to 16.3 ± 0.1 mS/cm. and the bottom layer ranged from 8.4 ± 0.20 to 15.3 ± 0.23 mS/cm.