Polycyclic Aromatic Hydrocarbons in Betula nana (Betulaceae, Magnoliópsida) under Exposure to a Thermal Power Plant

Аннотация

Abstract—The content of polycyclic aromatic hydrocarbons (PAH) in Betula nаnа L. and soil organogenic horizons was studied at a control site and sites affected by a thermal power station (TPS) at distances of 0.5, 1, and 1.5 km from the source of pollution. The PAH distribution over the vegetative organs of the dwarf birch was irregular. Different organs of the dwarf birch had similar qualitative composition of PAHs. No significant changes were detected in the PAH content in dwarf birch organs and on the surface of these organs at different distances from the TPS. The PAH content in the organs of plants affected by the TPS was 2–3 times higher than the background value, and the highest excess was found in leaves. The surface PAH concentration on the bark and roots increased threefold under contamination. No excess was revealed in the leaves and branches. The excess over the background value in the soil at contaminated sites was 3–3.5 times with the maximal accumulation at a distance of 1 km. The PAH content in the soil was three times higher than that in the dwarf birch at the control site and 5–6 times that at the contaminated sites. A strong correlation exists between the PAH concentrations in the soil and in B. nana. In the leaves and branches of B. nаnа, the proportion of surface accumulation in the total PAH pool was found to decrease at contaminated sites as compared with the control site. The opposite trend was observed for the bark and roots. Cluster analysis showed a clear separation between the surface and total PAH content in all plant organs under study. Factor analysis of the total PAH content in the organs of the dwarf birch allowed us to determine three main factors affecting the PAH distribution, with the light structures, toxic components, and the other PAHs were allocated in separate groups. Dwarf birch organs can be used as indicators for the contamination level in tundra communities. We suggest using the PAH content in leaves in order to analyze short-term changes in the PAH content and in the bark to assess the long-term impact.