Composition and properties of soils developed within the ash disposal areas originated from peat combustion (Tyumen, Russia)

Electrical power generation by burning fossil fuels leads to the formation of a significant amount of industrial waste that is often stored at ash disposal sites, which leads to a negative impact on the environment. Therefore, studies devoted to soil formation within such areas are rather sufficient for planning their reclamation. The proposed paper presents the results of a study of soil development at the inactive self-grown ash disposal area of Tyumen combined heat and power (CHP-1) plant (Western Siberia, Russia), formed due to the combustion of peat from the local Tarman deposit. Four soil pits representing different areas of ash dumps with grassy and woody vegetation were selected for detailed studies. The laboratory analyses included chemical, mineralogical and microscopic studies. The obtained results showed that the studied soils are characterised by a poorly developed humus horizon and strong stratification of the ash parent material and can be classified as Spolic Technosols. The studied technogenic soils are characterised by neutral and alkaline pH values, high LOI values, diversity of pedogenic carbonates and strong heterogeneity of the profile, due to the alteration of layers composed of fly and bottom ash material. These peculiarities of soils are related to properties of peat ashes, technology of peat consumption, and the intensity of weathering under cold continental climate conditions. The main indicators of pedogenic processes are the formation of humus horizons, the decrease in alkalinity in the upper part of the profile, disturbance of the primary stratification of the parent material, and the formation of pedogenic carbonates. It is possible to suppose further evolution of studied soils towards Andosol-like soils.