Technogenic impact of acid tar storage ponds on the environment: a case study from Lviv, Ukraine

WA number of countries keep acid tar in the open air in spent quarries, barns, storage ponds (USA, UK, Netherlands, Belgium, Germany, Latvia, Slovenia, China) or near landfills (Zimbabwe). Storage of acid tars in open areas leads to an increase in regional environmental hazards. In Ukraine, acid tars are also stored in open spaces in storage ponds, in particular, in the city of Lviv near the municipal landfill. After the Lviv experimental petroleum-refining plant began to dispose of oil-refining waste at the Lviv city landfill, two ponds of acid tars were formed. Their total area is 6.8 ha. They were formed by constructing dams in the upper reaches of deep ravines, originating near the landfill. In total, about 300 thousand tons of acid tars have been accumulated in these earth basins. In 2004, the dams of the acid tar storage ponds got cracked. As a result, acidic water flows to the soil surface 1 km southwest of these storage ponds. Sampling for the study of acid tar migration was carried out from 4 sites of anthropogenic origin: 1 - acid tar storage pond No.1; 2 - acid tar storage pond No.2; 3 - technogenic water body at the foot of the landfill containing leacheate; 4 - technogenic water body on the north side of the landfill containing leacheate. The simulation was made by Surfer software. It was found that even after many years of their creation, a very high content of sulfuric acid is observed in the ponds (1,108- 3,862 mg / kg), and they remain a major environmental hazard. The simulation results made it possible to assess the migration of toxic components contained in the tar to the components of the biosphere - the hydrosphere and ecotope. It was established that, unlike other investigated technogenic water bodies, acid tars in the storage ponds have high content of petroleum products, sulphates, phosphates, suspended substances, and high rates of chemical oxygen demand. The high content of petroleum products suggests that acidic tars can be processed into liquid fuel by freeing them from excess water and salts. At the same time, these large quantities of petroleum products pose an environmental threat to soil and groundwater, thereby reducing regional environmental security.