Ecological-geochemical assessment of the Sorochinskie Mountains soils (Samara Region)

In this paper we first explain the trivial geographic name «Sorochinskie Mountains», introduced into scientific circulation with the aim of more accurately linking natural (botanical, zoological, soil, geological-geomorphological) objects and etalon areas to a specific locality. Then we describe the types of anthropogenic impact that manifested themselves in different historical periods and allow evaluating modern ecological-geochemical state of the Sorochinskie Mountains soil cover. In the main part of the paper we report about ecology-geochemical research of soils conducted in 2015 in the Sorochinskie Mountains, during which the etalon areas within the main plant communities (birch forest, maple forest, aspen forest, stony steppe, maple oak forest) were laid. Samples of soils were taken from each etalon area to determine the amount of humus, the reaction of the soil solution (pH), and the content of heavy metals (Cu, Zn, Pb, Cd) by the atomic absorption method. As a result of the conducted studies it was established that the soils of the etalon areas of the Sorochinskie Mountains are characterized by a weakly acid or close to neutral reaction and a higher content of humus than the data available in literature. The ecological-geochemical feature of soils is their considerable enrichment of Zn, the level of which in all etalon areas significantly exceeds the local and regional background, in etalon areas of birch forest, maple forest and aspen forest – approximately permissible concentrations (APC). To a lesser extent the soils of the Sorochinskie Mountains accumulate Cu and Pb, the content of which exceeds the regional background, but basically does not reach the level of the APC. The concentration of Cd in soils is also below the dangerous level, but in birch forest and aspen forest it considerably exceeds the local and regional background. In general, the most contaminated with heavy metals are the soils of birch forest, maple forest and aspen forest. The soils of the maple oak forest and stony steppe, lying at a distance from the places of passage of unpaved highways, have a lower level of accumulation of heavy metals. Sources of heavy metals in the soils of the Sorochinskie Mountains are soil formation rocks and man-made streams formed by industrial objects and urban vehicles.