Olga Vyacheslavovna Nikolaeva

Bioassay is a popular method for the ecotoxicological state assessment of various components of urban ecosystems — soils, water bodies and air. However, little is known about the potential of bioassay application to determine the ecotoxicity of urban dust — a complex heterogeneous media composed of natural and technogenic particles.
Many components of urban dust are known to pose toxic eff ects to living organisms. The aim of this article is to review the existing practices for the ecotoxicological assessment of urban dust and to identify the key trends in the development of the bioassay. The existing studies revealed a high potential of bioassay methods as they are sensitive to a wide range of pollutants present in dust; able to refl ect the dust toxicity selectively depending on environmental factors, and can be implemented using organisms of diff erent trophic levels. The following dust characteristics should be taken into account for the bioassay method proper choice: sample mass, wettability, pH, water-soluble ions and organic matter content. Due to complexity of urban dust composition and diff erent potential for the transition of its components into water extracts, it is recommended to prioritize the bioassay realized on solid dust substrates
instead of extracts. For the comprehensive assessment of dust impact on urban ecosystem, a set of organisms of different
trophic levels should be considered instead of one. Standards should be developed for dust bioassay in order to unify the results obtained by diff erent researches. Th e choice of the control sample is one of the most important
methodological questions.

A significant factor contributing to the degradation of turfgrass in urban areas is the use of chloride-sodium anti-icing agents (AIA). Despite extensive research on the salinization of urban soils, studies assessing the impact of sodium chloride on turf grasses are insufficient. This work evaluated the phytotoxicity of the most common grasses used for lawns in Moscow: red fescue (Festuca rubra L.), creeping bentgrass (Agrostis stolonifera L.), perennial ryegrass (Lolium perenne L.), and white clover (Trifolium repens L.), using the laboratory phytotesting method. The plants were exposed for seven days to soil mixtures with sodium chloride concentrations of 0.1%, 0.5%, and 1.5% (w.). The observed parameters were «root length of seedlings», «shoot length of seedlings», and «seed germination». The studied species showed different levels of sensitivity to soil salinization, and the study highlighted the importance of simultaneous analysis of various growth and development parameters for making informed decisions on the optimal plant species for urban greening. The greatest differences in phytotoxicity were found in the «root length» parameter at high concentrations of AIA (1.5%) and in the «seed germination» parameter across the entire range of salt contamination. The proposed algorithm for selecting optimal plant species in saline soil conditions suggests starting by analyzing phytotoxicity results based on germination, selecting plants with minimal inhibition of this parameter. Then, among these, choose those that also showed the lowest phytotoxicity in terms of root and shoot length. Based on the results of the study, creeping bentgrass is recommended as a universal salt-tolerant species, along with perennial ryegrass at sodium chloride concentrations of 0.1% and 0.5%.

The study investigates the profile distribution of a complex of pollutants in roadside soils. The research was conducted in the Moscow Region, within the territory of the Educational and Experimental Soil and Ecological Center of Lomonosov Moscow State University "Chashnikovo". Soil samples were collected along a transect perpendicular to the Leningrad Highway at distances of 2 m (roadside), 7 m (a depression in the terrain before the forest belt), 50 m (a field behind the forest belt), and 175 m (the central part of the field) from the road surface, at depths of 0–5 cm, 15–20 cm, 30–35 cm, and 45–50 cm. The 2–7 m zone was characterized by technogenic soils, while the 50–175 m zone consisted of sod-podzolic soils used for agriculture. The contents of heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), as well as chlorides (Cl⁻)—key components of deicing agents—were determined. Additional analyses included particle size distribution, organic carbon content, soil pH, and electrical conductivity. It was found that the distribution of different pollutants in the soil profile was not uniform and depended on soil properties, pollutant characteristics, and the landscape design. The 2–7 m zone was characterized by intense contamination with all types of pollutants. PAHs showed a decreasing or bimodal vertical distribution (from top to bottom); HMs showed a decreasing pattern for Cu and Zn, while for Ni and Pb, an increase in concentration was observed in the lower layers or a uniform profile distribution was noted. PHCs showed a decreasing profile, and Cl- exhibited either a decreasing or bimodal distribution. Among soil properties, organic carbon content and particle size distribution were the main factors influencing the vertical differentiation of pollutant concentrations. Exceedances of the maximum allowable concentrations were observed for the mobile forms of Cu and Zn, as well as for petroleum hydrocarbons and PAHs. In the 50–175 m zone, the dynamics of soil contamination were different. Concentrations of all pollutants gradually decreased with depth, reaching background levels. Pollution was detected only in the surface soil layer for PAHs, the concentrations of which slightly (up to twofold) exceeded regional background values. The study highlighted the importance of investigating soil profile contamination near roads. Certain pollutants (Ni and Pb, PAHs, and Cl⁻) may show complex vertical distributions with increasing concentrations in deeper soil layers. It was also shown that the design of the roadside landscape played a crucial role in the distribution of pollutants. An artificially created depression a few meters from the Leningrad Highway can intercept runoff from the road surface, preventing pollutant migration to agricultural areas located upslope. Additionally, a living windbreak in the form of a forest belt reduced the airborne migration of pollutants. Intensive sedimentation of PAHs in front of the forest belt resulted in a nearly 20-fold decrease in their concentrations in soils behind it. Such landscape design can be an effective solution for protecting agricultural fields adjacent to highways. However, the study also emphasized the need for remediation measures to reduce extremely high pollutant levels in close proximity to the road, as surface dust can act as a secondary source of soil contamination near roads and also affect pedestrians and drivers