“DOMINO EFFECT” OF TECHNOGENIC CHANGES OF THE GEOLOGICAL ENVIRONMENT IN THE FORMATION OF THE GEOECOLOGICAL STATE OF THE CHERVONOGRAD MINING REGION

Abstract

The article analyses the state of the hydrosphere and the environment of the largest coal mining complex in western Ukraine before the start of mining operations, changes in the geological environment as a result of more than half a century of hard coal mining, subsidence of the surface over the mined fields, accumulation of coal mining and coal preparation wastes, with their exogenous and pyrometamorphic changes, as well as natural and technological transformation of the Chervonohrad Mining Region (ChMR). On the basis of experimental and geofiltration modelling, assessment of the chemical composition of water in the Upper Cretaceous horizon of fractured marls, and analysis of fluoride intake into groundwater at ChMR water intakes, a hypothesis about the “domino effect” in the formation of the geo-ecological state of the ChMR is put fo rward. The initiating factor of environmental problems is the extraction of hard coal and waste rock from the subsoil with the replenishment of mine water. This activates the formation of voids in the coal deposits without filling them, which, in turn, eventually provokes subsidence of the ground surface above the mined space with the formation of subsidence mounds, swamps and man-made lakes. Waste rock with a high coal content extracted from the subsoil is dumped into waste heaps, and substandard enrichment waste is separated from the enriched hard coal and dumped into a waste heap. Waste rock piles, the waste heap of the concentrator, sludge pits, mine water sumps and other man-made facilities that ensure the functioning of the coal mining and coal preparation complex, together with the deformed surface above the mined area, change the hydrogeological and hydrogeochemical conditions of groundwater. Acidic sulphate waters from the waste heaps and the concentrator dump, which are formed as a result of exogenous oxidation of pyrite, enter the geofiltration field, move from man-made facilities to the Western Bug, Rata and Solokiya rivers, as well as to groundwater intakes in the Upper Cretaceous fractured marl horizon. Acidic sulphate waters actively interact with Upper Cretaceous fractured marls, neutralise them and cause fluoride extraction from the carbonate and clay components of the aquifer with its concentration in groundwater extracted by water intakes. The most unfavourable conditions are inherent in the Sosnivka water intake, whose water in the mid-1990s caused hypoplasia and fluorosis in children.