Copper is used in the production of biocides in agriculture and micronutrient fertilizers to protect wood. Scientists from Russia and Turkey were the first to study how copper compounds of different sizes affect soils and barley. It turned out that large particles of several millimeters in size increase the concentration of metal in the plant up to eight times, while nanosized particles - up to ten, which reduces the performance of the plant and its yield.
The research findings could help maintain soil fertility and develop new agricultural fertilizers. Scientists published their conclusions, made with the support of the Presidential Program of the Russian Science Foundation (RSF), in the journal Environmental Geochemistry and Health. Heavy metals are among the most hazardous pollutants released into the environment. Unlike organic pollutants, which decompose, heavy metals can only be distributed among the individual components of water systems and soils. To assess the effect of metals on the soil and bottom sediments, it is necessary not so much to determine the increase in the total concentration of elements as to study their mobility.
In addition, the degree of dispersion of heavy metals in the environment, that is, the degree of particle size reduction, becomes an important aspect. The higher the degree of dispersion, the smaller the particle size. Researchers from the Ivanovsky Academy of Biology and Biotechnology of the Southern Federal University (SFU), together with colleagues from Ondokuz-Mayis University (Turkey), are studying such processes occurring at the level of atoms and molecules.
“The safety issues of using copper-based materials, including nanodispersed ones, are especially important, because they are widely used in the production of biocides in agriculture and micronutrient fertilizers for wood protection. Accumulation of heavy metals, including copper, in soil can potentially lead to accumulation in plant tissues. In varying degrees of dispersion, they are toxic not only for plants, but also for human cells,”says Marina Burachevskaya, project manager for a grant from the Russian Science Foundation, Ph. D. on-Don).
In the new work, soil scientists looked at how copper changes in ordinary chernozem depending on the particle size, and also assessed its toxic effect on the growth of spring barley. The samples were examined using synchrotron radiation - this is electromagnetic radiation that is generated by large electron or positron accelerators. Synchrotron radiation differs from ordinary X-ray radiation in high intensity, that is, the experiment is carried out many times faster. Scientists took soil samples from the Rostov region and added copper oxide of varying degrees of dispersion (3-5 millimeters and 30-50 nanometers) to them.
Various amounts of copper compounds were added as a dry powder and thoroughly mixed with the soil. These contaminated samples were planted with barley seeds and closely monitored. The copper content was determined using X-rays in powder from already dried plant parts. It turned out that copper compounds led to an increase in the content of mobile metal compounds in the soil. Such compounds can penetrate plants and are able to move along the food chain, as well as migrate to neighboring environments: groundwater, rivers, lakes.
The results showed that the share of isolated mobile copper compounds from contaminated samples is 20-2322 times higher than the amount of metal compounds taken from uncontaminated (control) soil. The more metals were introduced into the soil, the more mobile the metals were. The concentration of particles depended on how firmly the copper was fixed in the soil and its availability for plants.
“The influence of a large dose of copper of different dispersion consisted in the fact that the development and productivity of spring barley were inhibited. Considering the greater negative effect on biometric, cytomorphometric, ultrastructural parameters and data on the metal content in plants, in general, we can conclude that copper in nanodispersed form better penetrates from the soil into the plant and is able to accumulate in it in large quantities, "concludes Marina Burachevskaya … The research results can be used in such a branch of agriculture as crop production, for example, to control the ecological situation, maintain soil fertility and develop new fertilizers.