Influence of earthworms on extractability of metals from soils contaminated with Al2O3, TiO2, Zn, and ZnO nanoparticles and microparticles of Al2O3

Nanoparticles (NPs) of Al2O3, TiO2, Zn, and ZnO, and with microparticles (MPs) of Al2O3 were introduced into garden soil. Adult Dendrobaena veneta earthworms were added to half of the samples. Concentration of the metals was determined after 1 and 10 days in soil eluates (water and EDTA) and in the earthworms before and after gut cleansing. The study showed the influence of soil and earthworm activity on the bioavailability of aluminum and titanium originating from NPs. Extractability of Al by water or EDTA increased after 10 days from aluminum oxide MP- and NP-treated soils. The presence of live earthworms completely abrogated this increase. Waterextractability of Ti from TiO2 NP-treated soils increased after 10 days, while EDTA-extractability remained unchanged. The presence of earthworms was associated with a decrease in Ti extractability. The highest extractability was observed for Zn, with negligible effects of time and earthworms. Al, Ti, and Zn were not substantially accumulated in the earthworm tissues. It was concluded that interaction of the nanoparticles with the soil and activity of the earthworms can affect the bioavailability and, potentially, toxicity of metals originating from nanostructures.