Cadmium and lead accumulation in three endogeic earthworm species

The objective of this study was to assess the capability of earthworms from the same ecological group as heavy metal bioindicators. Three earthworm species from the endogeic group were studied: Aporrectodea caliginosa (Savigny, 1826), Perelia kaznakovi (Michaelsen, 1910) and Octolasion lacteum (Örley, 1885). Their accumulation of the heavy metals lead (Pb) and cadmium (Cd) were studied from three stations in Tehran province, Iran. O. lacteum was used to compare metal accumulations in two sites located next to a highway. A. caliginosa and P. kaznakovi were used at a third site located near the edge of a sewage system to compare metal accumulations between the two endogeic species in this area. At both locations, the concentrations of Cd and Pb in earthworms were higher than in the surrounding soil. The results of the study revealed that P. kaznakovi and A. caliginosa were better bioindicators for Pb, but O. lacteum was a better bioindicator for Cd. These earthworms can therefore be used as Cd and Pb bioindicators in environmental assessment.