Accumulation of Polycyclic Aromatic Hydrocarbons in Sealed Soils and Their Environmental Hazard for Eastern Moscow

The contents of 11 PAHs in asphalt concrete of road pavements and in sealed soils of Eastern Moscow have been determined and compared with those in the unsealed urban soils and in background natural soils. Sealed soils and asphalt concrete have the naphthalene type of pollution, whereas phenanthrene predominates in the background soddy-podzolic soils (Retisols). The prevalence of low-molecular-weight PAHs in sealed soils indicates the pronounced effect of emissions from diesel-powered vehicles and from asphalt bitumen, in which the total PAHs content varies from 14.8 to 128.1 mu g g(-1). The total PAHs content in the soils sealed with road pavements averages 14.5 mu g g(-1), which is 4.5 times higher than in the unsealed urban soils and 142 times higher than in the background soils. The enhanced accumulation of PAHs in the sealed soils is explained by the conservation of PAHs by the soil organic matter under the anaerobic conditions. Mapping the sum of PAHs and benzo[a]pyrene in the upper part of the profiles of sealed soils showed the formation of several contrasting human-induced anomalies of polyarenes that are mainly confined to highways. Their environmental hazard was assessed via carcinogenic potential of PAHs, which exceeds MPC for benzo[a]pyrene by 10-13 times.