Earthworm and food interactions on bioaccumulation and disappearance in soil of polycyclic aromatic hydrocarbons: studies on phenanthrene and fluoranthene.

The present study describes some novel phenomena with regard to the environmental fate of polycyclic aromatic hydrocarbons (PAHs) in the terrestrial soil environment. Laboratory experiments were conducted on: (1) the influence of earthworms on the disappearance rate of PAHs in soil, and (2) the bioaccumulation of these compounds in the earthworm body. It is demonstrated that the disappearance of phenanthrene and fluoranthene in soil is accelerated by the presence of the earthworm Lumbricus rubellus. Possible explanations and practical implications of this effect are discussed. In the bioaccumulation part of the study it is demonstrated that earthworms may take up and accumulate fluoranthene and, to a lesser extent, also phenanthrene in their body tissues. Bioaccumulation was found to be reduced by changes in bioavailability associated with aging of the PAH-amended soil. Finally, it was observed that earthworms indicate a strongly enhanced bioaccumulation of PAHs under conditions of food limitation.