Heavy metal impact on bacterial biomass based on DNA analyses and uptake by wild plants in the abandoned copper mine soils

The metals contamination in surface soils and their accumulation in wild plants from the abandoned Burra and Kapunda copper mines located in South Australia were assessed, and the predominant bacterial diversity in the contaminated surface soils from these two abandoned copper mine sites were evaluated through polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results showed the average concentration of Cu in soils was 3821.59 mg/kg while wild plants accumulated up to 173.44 mg/kg. The concentration of Cu in shoots of spear grass (Stipa uitida) and berry saltbush (Afriplex semibaccata) was higher than that of roots. The concentration of total and extractable As, Cd, Cu and Pb in soils slightly correlated with of these elements in the corresponding wild plants. The toxicity of Cu in heavily contaminated soils impacted on the quantities of specific microbial populations and no significant change in the microbial diversity of highly contaminated soils.