Ecotoxicological assessment and comparison between metal and nano-metal oxides in different aquatic organisms: laboratory surveys.

The increasing production and application of engineered nanomaterials (ENM’s), metal oxides (>100 nm) and nano metal oxides (NPs; size: 1-100 nm) in consumer products over the past decade will inevitably lead to their release into aquatic systems (specially the coastal environment) and thereby cause the exposure to aquatic organisms. Their likely fate in marine systems is sedimentation following hetero-aggregation with natural organic matter, sediment-dwelling and filter feeding organisms most a risk. The aim of this study is understand if the toxicity of metal depends on the size particles, making comparison between metal and nano metal oxides. In this context, the ecotoxicology of four different metal and nano metal oxides (CuO, ZnO, TiO2 and CeO2) on amphipods Ampelisca brevicornis, sea urchin Paracentrotus lividus and clam Ruditapes philippinarum was investigated. These organisms are excellent bioindicators of marine coastal toxicity. The dissolution of nano and no nano metal oxides was evaluated in water and sediment matrices. Biological responses were assessed using biological assays in three marine species: chronic bioassays for A. Brevicornis and R. philippinarum; acute bioassay for P. lividus. Different biological characteristics were assessed in test organisms, survival and bioaccumulation for amphipods; fertilization and embryo-larval development for sea urchins and bioaccumulation in clams, of metal and nano metal oxides in these marine coastal organisms, exposed to increasing concentrations. Acute and chronic effects, associated with the concentrations of metal and metal oxides NPs, were observed. The results show that the metal toxicity is not dependent on the size of particles but appear to be a concentration-dependent factor.