Fractional Composition of Hydrocarbons as an Indicator of Soil Contamination in the Traffic Zone of the City of Moscow

Abstract The composition of hydrocarbons in the upper horizons of replantozems in the traffic zones of the Eastern Administrative Okrug of Moscow was studied. Based on the proposed analytical approach, the contents of high-temperature boiling hydrocarbons (technogenic hydrocarbons), biogenic hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) were determined in the soil samples. The content of biogenic hydrocarbons was associated with the amount of organic matter in the soils, and proportion of biogenic fraction increased when moving away from the source of transport pollution and reached 45% of the total hydrocarbon content in the upper horizon. The PAH content in the upper horizons of replantozems varied from 0.347 to 16.466 μg/g, the content of benzo(a)pyrene—from 0.008 to 0.957 μg/g. It was found that the total PAH content, the content of individual PAHs, and their ratios in soils were not related to factors responsible for the distribution and accumulation of actual hydrocarbon pollution in the traffic zone. For the analysis of actual pollution from motor transport, a convenient diagnostic indicator is the content of a fraction of high-temperature boiling hydrocarbons. For the replantozems studied, the content of technogenic hydrocarbons varied from 45 to 3563 μg/g. Within the traffic zone, the content of this fraction in the upper soil horizon was significantly influenced by the distance of the soil from the place of transport emissions.