Distribution of Polycyclic Aromatic Hydrocarbons in the Soil–Plant System as Affected by Motor Vehicles in Urban Environment

The paper focuses on the interactions among the components of urban natural complex (surface soil layer, rhizosphere, and aboveground phytomass of herbaceous plants) polluted by motor vehicles. The goal of this study is to identify the zone of pollution sources impact and the specific features in accumulation of pollutants in soil–plant systems with different levels of load. The distribution and migration of marker compounds—14 polycyclic aromatic hydrocarbons (polyarenes, or PAHs)—are analyzed in the southwest of Moscow (the campus of the RUDN University and the adjacent area of the Southwest Forest Park) in functional zones differing by the volumes of technogenic loads. The soils of the examined territory according to WRB belong to Albic Retisols (Ochric). The spatial distribution of polyarenes in the system “surface soil layer–rhizosphere–aboveground part of plants” is modeled using data analysis procedures and visualized with the help of the ArcGIS software (Topo-to-Raster tool). The effects of aerial mass transfer of polyarenes into the soil–plant system as the main pathway for the entry of pollutants are evaluated. The prevalent polyarenes and the factors determining the volumes of their accumulation in the functional zones of the studied area are identified. The genesis of polyarenes is assessed according to the abundance ratios of their groups. The differences in the conditions and dynamics of PAH accumulation in soil and plant components are shown. The results are particularly useful to formulate the requirements to soil monitoring in the studied area, to analyze the dynamics of the state of urban territory, and to justify the measures for protection of urban areas under a traffic load.