Environmental changes due to wet disposal of wastes from coal-fired heat power plant: A case study from the Tula Region, Central Russia

Abstract

Long-term disposal of coal combustion residues (CCR) in the environment could change the geochemistry of soils and surface waters of adjacent territories. Aiming to evaluate the environmental impact of CCR we investigated soils and surface waters (12 and 18 sampling points, respectively) in the vicinity of the aged settling pond of the Cherepetskaya Thermal Power Plant in the Tula Region (Russia). The research reports and discusses changes in the composition of readily soluble salts in sod-podzolic soils (Retisols) as well as the content of carbonates and the distribution of potentially hazardous elements (Ni, Cr, V, Sr, Pb, Zn) in soil profiles. The mineralization of surface waters was also measured. For performing analyses, methods of HPLC, XRF, ICP-AES, and ICP-MS were used. The research revealed that the introduction of technogenic material into soils had 1.5–3 times increased the content of readily soluble salts compared to natural Retisols and changed the composition of ions. Carbonates in amounts of up to 1.9% were determined in all Retisols with introduced CCR which is never observed in natural acid soils. Differentiation in the content of V, Cr, Ni, Zn, Sr, Pb in soil profiles corresponded to leaching patterns of these elements from the CCR stated by the other researchers. Their concentrations in soils generally did not exceed the standards stated in the Russian Federation. Natural waters and waters with technogenic impact had the well-defined differentiation in the ratio of sodium and potassium in total cations. The study showed that the area of the environmental footprint of the settling pond with CCR differed in soils and surface waters. Changes in the geochemistry of surface waters were noticeable at greater distances and probably reflected the transformation of the geochemistry of groundwater. Changes in the geochemistry of soils were very local and were observed at a distance of fewer than 200 m from the settling pond.