RUDN University researchers have shown that technogenic toxicants in the ecosystem are distributed unevenly. The reason for this is that they come from the source in “portions”. Further, an active interaction of technogenic and natural factors begins: soils temporarily deposit pollution and create conditions for the transformation of toxicants. Further, the buffer role of the roots is switched on, which do not allow some pollutants to pass through. From a practical point of view, these data are important for optimizing the traffic load in urban ecosystems and developing technologies for cleaning soils in the city. Results published in Applied geochemistry.
Newswise — Due to the activities of transport (exhausts, abrasion of tires and road density), substances entering the atmosphere and accumulate in snow, soil and plants. There they interact with natural factors, and the spread of pollutants takes on a complex form. RUDN researchers conducted a detailed analysis of pollution in one of the districts of Moscow. Based on experiments at the site (snow survey, numerous analyzes of snow, soil and vegetation samples), the authors traced the path of toxic substances and showed that the resulting pollution is uneven.
“Technogenic evolution in soil and plants has specific features. Mainly, it is the specific dynamics of pollutants. Pollutant flows deviate from natural trajectories. These deviations are very noticeable, and propagation models are needed to investigate them. We have built theoretical models and verified them in practice with experimental data. It is obvious that the intensity of pollution and the severity of consequences should decrease with distance from the source. However, in reality, the dynamics of technogenic changes is not the same in different directions,” said Professor Alexander Khaustov, Doctor of Science in Geology and Mineralogy, Leading Specialist of the RUDN Institute of Ecology.
Ecologists have studied how polycyclic aromatic hydrocarbons (PAHs) are distributed in soil, roots and stems. These are persistent toxic organic compounds that have two or more benzene rings in their structure. Such substances serve as an indicator of sources of environmental pollution. The object of the study was the RUDN University campus in the south-west of Moscow. This is one of the most environmentally friendly areas of Moscow, and the campus itself is recognized as the greenest in Russia. However, the territory is surrounded by busy highways, which have a serious impact on ecosystem. The researchers studied the distribution and accumulation of toxicants in the soil and plants in the area. It turned out that the complex of 14 detected PAHs carries its own information and makes it possible to very clearly describe the source of the release. This fundamentally changes our understanding of the flows of pollutants in natural environments.
The authors showed that the distribution of PAHs in the soil-root and root-stem systems is largely uneven and variable. The distribution of PAHs turned out to be undulating. The reason for this is the specific interaction of technogenic and natural factors, which forms "mosaic" structures. In this case, the roots play the role of a "filter" in the distribution of PAHs in the soil, which prevents the movement of PAHs, depending on their molecular weight. PAHs with 2-3 cyclic fragments pass this barrier, while larger compounds do not overcome it.
“We were able to evaluate the relationship between the mobility and availability of toxicants for living organisms and the physicochemical properties of these substances and the properties of media. Such models are necessary to assess the state of the soil and plant systems of the city, optimize the traffic load, and create environmental protection technologies. We continue research at our test site. The next task is to evaluate the relationship of especially toxic compounds with solid microparticles migrating in the air. Our test site is a good platform for such research: we can trace in detail the diversity of processes in the urban ecosystem in a compact area,” said Margarita Redina, Doctor of Economics, Professor of the Department of Environmental Safety and Product Quality Management, RUDN University.
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