Reasons for different environmental effects of technogenic nanoparticles

Abstract

Nanoparticles (NPs) of zinc, zinc oxide, titanium dioxide, iron sized 20-90 nm at concentrations of 0.1-100 g of nanoparticles per ton of seeds were studied. The objects of environmental monitoring were bacterial populations and the family of earthworms (Lumbricina). The toxic effect of nanoparticles under natural conditions depended both on physical-chemical properties of NPs and the type of soil, and on the size, concentration of NPs, and pH of nanoparticle suspensions. When measuring the zeta potential of NPs in aqueous solutions, a decrease in pH of the suspensions due to their composition and size was recorded. There was a direct correlation between the energy produced in cells, which was necessary for the development of living systems, and the increase in the number of protons under the influence of nanoparticles. At NPs sizes less than 20 nm, nanoparticles were much more reactive. They exhibited high biological activity and were safe only at very low concentrations. At concentrations above 10 g/t, they inhibited the growth and development of plants and reduced the survival of microorganisms. It was noted that the ecological effect of NPs oxides was different from the behavior of metal NPs. They accumulated in a living organism, exhibited toxic properties, and were transported along trophic chains, which was not typical for metal nanoparticles. It should be noted that zinc oxide was more soluble than titanium dioxide and had a low aggregation value. Thus, such characteristics as solubility and the ability to aggregate in solutions are important for the environmental safety of NPs.