Tellurium, a rare chemical element, is a growing threat to ecosystems, as its content in the environment has increased dramatically, and its effect on living organisms remains poorly understood. The main sources of tellurium pollution include the mining, metallurgical, glass, rubber, electronic and pharmaceutical industries, as well as the production of solar panels.

Currently, in some territories, the tellurium content in the soil exceeds the background level by 30 or more times. Environmental pollution with tellurium has led to its being classified as a new pollutant that poses a danger to the environment and humans.

"The ecotoxicity of tellurium has previously been underestimated. We have found that it manifests itself with a significantly lower excess of background concentrations in the soil than other heavy metals considered highly toxic, such as mercury, cadmium and lead," said Sergey Kolesnikov, Head of the Department of Ecology and Environmental Management at the Academy of Biology and Biotechnology of the Southern Federal University.

According to the scientist, soil pollution with tellurium leads to a decrease in soil fertility, which affects crop yields. In addition, tellurium is able to enter plants from the soil, and then into the body of animals and humans, causing their diseases.

In a recent study by the Southern Federal University, the results of which are published in the journal Emerging Contaminants, have established concentrations of tellurium in the soil, exceeding which leads to a decrease in fertility. To do this, they simulated contamination with different doses of tellurium, starting from very low (1.5 background concentrations).

The study showed that even minimal amounts of tellurium reduced the activity of soil microorganisms, which play an important role in plant nutrition, by 20-30%. The activity of microorganisms decreased by 50-70%, and at the highest concentrations of tellurium - by 80-90%. At the same time, tellurium in the form of nitrate turned out to be twice as harmful as in the form of oxide.

The scientists also drew attention to the fact that the negative effect of tellurium increased over time: 10 days after contamination, the activity of microorganisms was 10-20% lower than after 30 days.

The results of this work can be used to predict environmental risks from tellurium pollution and to develop standards for tellurium content in soils of different properties. The uniqueness of the results obtained lies in the fact that environmentally safe concentrations of tellurium in the soil were established for the first time in the world.

"The use of the research results will contribute to the production of environmentally friendly agricultural products, ensuring food and environmental safety of the Russian Federation," the authors of the study added.

They used the author's methodology for assessing the ecotoxicity of pollutants according to the degree of disturbance of the ecosystem functions of the soil. At this stage, scientists plan to continue work on assessing the ecotoxicity of rare chemical elements, the level of pollution of which is steadily increasing, and the potential danger to the environment has not yet been fully studied.

The research was supported by a grant from the Russian Science Foundation and performed at the Youth Laboratory for Environmental Soil Quality Regulation, established at Southern Federal University as part of the strategic academic leadership program "Priority 2030" (national project "Science and Universities").