Study of heavy metals bioaccumulation in the process of vermicomposting

The bioaccumulation of heavy metals (Cd, Zn, Ni, Pb and Cr) and the relationship between them was investigated on earthworm ( Eisenia fetida ) physiology during the process of vermicomposting. The soil samples were obtained from Roudehen city in the eastern area of Tehran. E. fetida specimens were exposed to a mixture of metal compounds in various concentrations to estimate the rate of heavy metal bioaccumulation. After 14-days of (the results of the experiments showed that earthworms accumulated this elements in 14 days) exposure, the metal accumulation was measured using atomic absorption spectroscopy. Cluster analysis was used to interprete the data. Analysis of the 14-day experimental results revealed a strong relationship between the bioaccumulation of Pb and Cr and between Ni and Cd (correlations 0.8 and 0.63). Key words: Earthworm, Eisenia fetida, vermicomposting, heavy metal, bioaccumulation.