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POLYCYCLIC AROMATIC HYDROCARBONS LEVEL IN SOILS OF THE EMISSION ZONE OF THE NOVOCHERKASSK ENERGY PLANT

Svetlana Sushkova

Abstract

The aim of the work is to study the levels of polycyclic aromatic hydrocarbons (PAHs) in a 20-cm layer of soils in the Novocherkassk energy plant (NEP) emission zone, based on the results of monitoring studies conducted in 2017. In order to study the PAHs levels in the soils of the anthropogenic emission zone an annual sampling of soil samples of 10 monitoring sites located at a distance of 1-20 km from the NEP was carried out. Samples of soils were selected from a depth of 0-5 and 5-20 cm. In the selected soil samples, PAHs was determined by high performance liquid chromatography (Agilent 1260 Germany 2014) with fluorimetric detection. Soil samples were prepared for chemical analysis in accordance with the state standard requirements [1]. Extraction of PAHs from soils and plants of the investigated objects was carried out by saponification [2]. Repeatability of the determination is 3-times. Also, as in previous years, the maximum PAHs content falls on the monitoring sites closest to the emission source in the direction that coincides with the prevailing direction of winds in the terrain over the study period (T4, 1,6 km to nw). A sharp decrease in PAHs content in the soil of the T8 monitoring site (5.0 km to nw) is 1484.9В±27.4 ng/g, compared to T4 (1.6 km to nw) ? 2352.9В±17.6 ng/g (more than 3.5 times), indicates that the maximum deposition is carried out at a distance of about 1.6 km and decreases at a distance of 15.0 km in the north to 1090.9В±12.9 ng/g. The levels of PAHs content and distribution along the soil profile were more dependent on the type of soils that caused the peculiarities of pollutant uptake. Most of the soils of monitoring areas are represented by Haplic Chernozem of heavy loam or light-clay granulometric composition. The physical and chemical properties of soils, mainly their granulometric composition, affected the PAHs distribution along the profile. The average concentration of PAHs in the upper layer of which is 1.5-2 times higher than its content in the lower layer. The only exception was the monitoring site (T2, 3.0 km to the sw) with sandy Fluvisoil, where the levels of PAHs in the upper 0-5 cm and the lower 5-20 cm layers were very close - 42.1В±2.4 - 45.6В±3.8 ng/g, respectively. Thus, PAHs levels in the soils of the monitoring sites located around the NEP remain largely unchanged for many years. The territory of the most dense smoke plume containing a significant amount of PAHs was up to 5.0 km in the direction from the emission source with a maximum accumulation of 1.6 km in the SW direction from plant.

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