Nanoparticles (NPs) types diffused into the environment are increasing, giving potential damages to terrestrial ecosystems. In this work we investigated the nanoparticles toxicity as pure metal and two oxides (Co, SnO2 and CeO2) on earthworm survival (Lumbricus rubellus). A concentration of 5000 mg kg-1 dry soil of each NP was compared to the chronic dose of 10 mg kg-1. The interaction between NPs and soil microbial biomass was also studied in 7 days length incubation. No mortality was observed at the end of the experiment, but high concentration of Co was found in the 5000 kg-1 dry soil treated. Despite low solubility of all NPs (solid-liquid partition coefficient > 2.8 log l kg-1) pure metal NPs were (Co) more soluble than the metal oxides nanoparticles (SnO2 and CeO2).
