Heavy Metals in Soil and Plants During Revegetation of Coal Mine Spoil Tips and Surrounded Territories

Coal mining in Donbas is a global problem as it causes the destabilization of ecological landscapes. Spoil tips, covering almost 52% of the territory, alter the topography of the land, affect the ecosystem, and decrease soil fertility. The soils become degraded and are unsuitable for agricultural use. The occupation of the Donetsk region by the Russian Federation has suspended the observation and research of man-made influence on this territory, which is a major concern for the scientific community. To reduce the negative impact of spoil tips, it is necessary to slow down the process of pyrite oxidation and the formation of toxic substances, as well as the migration of heavy metals due to erosion. Biological reclamation with grass and woody plants can help in achieving this goal. Another urgent issue is the constant supervision and assessment of the suitability of the bedrock of coal mines for agricultural use. The study investigated the total and mobile content of heavy metals in the rock samples from the "South Donbaska-1" mine, ordinary chernozem (background soil), and vegetation growing on the spoil tip. The results showed that the content of Co, Cr, Cu, and Fe in the rock of the spoil tip is higher than in the background soils. The content of heavy metals gradually decreases as the distance from the spoil tip increases. The content of Pb in ordinary chernozem and rock is practically the same, indicating its active migration. An analysis of the biomass of plant samples growing on the spoil tip showed that the content of Co, Cu, and Zn was within the limits of the threshold limiting values. However, the content of other studied elements exceeded the permissible norms. The research results provide information on the ecological state of the spoil tip and can be used for recreational as well as reclamation works in these areas.