Evaluation of distribution, chemical speciation, and toxic effects of CuO and ZnO nanoparticles in Daphnia magna and Danio rerio

Abstract

The use of products with nanoparticles has been growing in recent years. Currently, there is the application of nutrients in nanoparticulate form in agriculture. With this growth, it is important to safely expand their use and assess the environmental risk caused by them, as discharges may occur near water flows. In this work, the toxicity, distribution, concentration and chemical speciation of CuO and ZnO nanoparticles in ecotoxicology model organisms, Daphnia magna and Danio rerio were evaluated. Copper and zinc were chosen due to their agronomic importance. In this study, higher toxicity was determined in CuSO4 and in smaller nanoparticles of CuO, for both organisms. For ZnO, the toxicity depended on the particle size and the presence of surfactant, also higher for smaller nanoparticles. The chemical speciation analysis showed that there was biotransformation of CuO (25 nm) and CuSO4 into Cu3(PO4)2 in D. magna; however there was no transformation in D. rerio. The distribution of copper and zinc was similar for organisms, with the highest concentration occurring in the intestinal and gastrointestinal systems for D. magna and D. rerio, respectively. In this study, there was no ZnO clearance in D. magna observed for 24 h.