Evaluation of soil toxicity using a battery of biomarkers on the earthworm Eisenia andrei

Earthworms (Eisenia andrei) were utilised as model organisms to assess biological effects induced by exposure to different agricultural soils in the Biodiversity-Bioindication project The tests have been performed by exposing animals in climate chambers for 10 days to different soils sampled in three agricultural sites, Cà Orsine, Cà Nuova and Cà Novella (Pavia, Italy), at two different seasons (fall and summer). The three soils were subject to different agricultural treatments: soil sampled at Cà Orsine was subject to biological treatment; soil coming from Cà Nuova was treated with a traditional approach; whereas soil collected at Cà Novella was treated with biological muds. The stress syndrome was investigated in adult E. andrei with a set of four biomarkers of stress: lysosomal membrane stability, lysosomal accumulation of lipofuscin and neutral lipids, Ca ²⁺-ATPase activity, and one biomarker of exposure, AChE activity. Data were compared with results obtained in a parallel study, where earthworms were exposed to soil collected from an industrial area (Alessandria, Italy). The results demonstrated that the mortality of earthworms was not affected in individuals exposed to the three soils sampled in two seasons. Only a minimal level of oxidative stress, as sublethal physiological impairment, was detected in the animals exposed to Cà Novella and Cà Orsine soils, with statistical significant changes lower than 20%, revealing a minimal biological injury.