Ecotoxicity of Copper, Nickel, and Zinc Nanoparticles Assessment on the Basis of Biological Indicators of Chernozems

Ecotoxicity of nanoparticles (50-100 nm) of Cu, Ni, and Zn has been assessed by changes in biological indicators of an ordinary chernozem (Haplic Chernozem (Loamic)) of Rostov-on-Don in the laboratory model experiment with incubation of soil samples with nanopowders of these elements added to soil in concentrations 100, 1000, and 10 000 mg/kg. The effects of biological indicators have been determined 10, 30, and 90 days after soil contamination. The addition of Cu, Ni, and Zn nanoparticles led to a decrease of the total number of bacteria, abundance of Azotobacter bacteria, catalase and dehydrogenase activities, and germination and length of roots of radish sown. Reliable cases of hormesis were not detected. Nanoparticles of Cu and Zn showed higher toxicity than Ni nanoparticles, and this was inconsistent with the hypothesis, according to which the toxicity of nanoparticles depended only on their size and did not depend on chemical nature of the element. According to the integral indicator of biological state of soil, maximal toxicity of Cu, Ni, and Zn nanoparticles was observed on the 30th day after contamination.