<p><strong>Abstract.</strong> Polycyclic aromatic hydrocarbons (PAHs) and particularly benzo(a)pyrene (BaP) are toxic compounds emitted from various anthropogenic sources. Understanding the BaP concentrations, dynamics and decomposition in soil is required to assess the critical loads of BaP in urban environments. The first attempt to evaluate all major input and output components of BaP balance and to calculate the permissible load on the urban environment in different land-use zones of the Eastern District of Moscow was done. BaP contamination of the snow cover in the Eastern District of Moscow was related to daily BaP fallouts from the atmosphere. In 2010 the mean content of the pollutant in the snow dust was 1942 ng g<sup>−1</sup> whereas the average intensity of its fallout was 7.13 ng m<sup>−2</sup> per day. Across the territory BaP winter fallout intensities varied from 0.3 to 1100 ng m<sup>−2</sup> per day. The average BaP content in the surface (0–10 cm) soil horizons was 409 ng g<sup>−1</sup>, which is 83 times higher than the local background value and 20 times higher than the maximum permissible concentration (MPC) accepted in Russia. The variations in soil and snow BaP concentrations among different land-use zones were examined. A significant contribution of BaP from the atmosphere to urban soils was identified. Based on the measurements of BaP atmospheric fallout and BaP reserves in the soils, the critical loads of BaP for the land-use zones of the Eastern District were calculated for different values of degradation intensity and different exposure time. It was established that, at annual degradation intensity of 1–10 %, the ecologically safe BaP levels in soils of all land-use zones, excluding the agricultural one, will be reached only after many decades and centuries.</p>

Results of 21-year-long (1989–2010) observations of the concentrations and the spatial distribution patterns of nine heavy metals (HMs) in topsoils of the Eastern district of Moscow are presented. The quantitative parameters of soil pollution include the annual increase rates of HM concentrations in several land-use zones. The maps of geochemical anomalies were compiled using the data collected in 1989, 2005, and 2010. The growth of the total volume of industrial and vehicles’ emissions between 1989 and 2005 caused significant deposition of Pb, Zn, Cu, and Cd. The additional input of Cd to the soils is attributed to the application of sewage sludge as fertilizers. The relative increment of concentrations was the highest for Pb, Co, Cu, Ni, and Cr. In 2005–2010, the relative annual increment rate was the highest for Cr, Cd, Co, and Ni, and it increased by an order of magnitude as compared to the previous period. By contrast, Pb and Cu concentrations decreased owing to the soil reclamation, the exclusion of leaded gasoline as a fuel for vehicles and closing some hazardous enterprises. Joint analysis of snow and soil geochemical maps allows identification of the zones of actual, permanent, and relict pollution.

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