Morphological and chemical properties of soils within geological complexes affected by sulfuric acid in forest-steppe of the Central Russian Upland (Russia)

Abstract

In the Central Russian Upland, black soils become contaminated by toxic substances containing sulfuric acid, which leak from non-recultivated stockpiles of coal mines. Sites for studying properties of soils that represented main geocomplexes of this region were selected using GIS analysis. Background Haplic Chernozems occupy interfluves and slopes; Phaeozems are located at dry gullies. Stockpiles serve parent materials for Spolic Technosols (Arenic/Loamic, Dystric, Sulfidic, Phytotoxic) characterized by high contents of sulfates and total organic carbon (TOC). Burned stockpiles were occupied by less toxic Spolic Technosols (Loamic, Eutric, Phytotoxic), which had a neutral reaction in topsoils and relatively low contents of sulfates and TOC. Remediation with different substrates and phytoremediation resulted in the creation of Technosols (Dystric, Loamic, Molic, Organotransportic). Deluvial/proluvial deposits were occupied by soils with lithic discontinuities that were identified as Regosols over Phaeozems. Near to stockpiles, there were Dystric Colluvic Stagnic Regosols (Arenic/Loamic, Lamellic, Loaminovic, Sulfidic, Phytotoxic), which had strong and moderate acidity and the high content of sulfates that was lower than that in Spolic Technosols (Dystric). Phaeozems (Loamic, Loaminovic, Phytotoxic) within impact zones of stockpiles had lithic discontinuities due to the surface redeposition of materials washed off the tips, decreased acidity and increased contents of sulfates.