Divergent responses of earthworms (Eisenia fetida) in sandy loam and clay soils to cerium dioxide nanoparticles

The reported biological effects of cerium dioxide nanoparticles (nCeO 2 ) in soils range from toxic to protective. However, divergences of nCeO 2 toxicity in soils of different textures are not known. In this study, the availability of nCeO 2 on earthworms ( Eisenia fetida ) in sandy loam soils and clay soils was discussed, and the biological effects of nCeO 2 (0–1000 mg/kg) on earthworms in two soils were investigated. The results showed the bioaccumulation and biological effects of Ce on earthworms in the two soils were inconsistent. The European Community Bureau of Reference (BCR) sequential extraction revealed that the major portions of Ce in both soils were in the residual form (98–99%), and the acid-soluble Ce fraction was greater in clay soils. However, nCeO 2 was more toxic to earthworms in sandy loam soils than that in clay soils as assessed by earthworm biomass, morphology, and antioxidative damage. Thus, the high ecological risk of nCeO 2 in sandy loam soils with higher pH and lower clay contents needs to be avoided, being used in agriculture to improve both crop yield and quality.