Technogenic and Geochemical Diagnostics of Soils Distributed on the Territory of the "Kremikovtsi" Metallurgical Plant

The content of Rubidium, Strontium, Cesium and Barium in soils with a metamorphic and poorly developed profile, subjected to active technogenic pollution from the activity of the former Kremikovtsi metallurgical plant, was analyzed. Six profiles were included in the study - 5 of Technosols from the plant territory and one external control profile of Rhodic Cambisol. Metal content was determined by the LA-ICP-MS method, with data obtained simultaneously with data for over 50 chemical elements. According to the results obtained, the average content of Rb is (in μg/g) 206.10, of Sr - 156.05, of Cs - 12.97 and of Ba - 1876.80, with the values for Barium, Rubidium and Cesium exceeding the average world reference values by 4, 3 and 2.5 times respectively and those of Strontium are slightly below them. The contents of the four metals are genetically determined and naturally geochemical inherited from the high initial contents in the soilforming proluvial sediments. Contamination has contributed to a very large accumulation of the heavy alkaline earth metals Ba and Sr in all alkalized spolic/carbonate surface horizons of Technosols, where they are present as sparingly soluble sulfates, carbonates and phases adsorbed by iron and manganese oxides. A statistically significant positive correlation was determined between Ba and Pb, based entirely on the technogenic effect, in which part of the accumulated lead was adsorbed by sparingly soluble secondary sulfates and carbonates of the alkaline earth metals and especially Barium. The alkali metals in these soils migrate down the soil profile. In the uncontaminated Rhodic Cambisol, their behavior is similar - they migrate downward and concentrate in the carbonate BCk horizon. This observation allows considering the concentration of the heavy alkaline earth metals Ba and Sr in the surface soil horizons as a sign of irreversible or difficult to reverse technogenic soil degradation manifested in the formation of secondary salts of heavy metals, gradual alkalization of the environment and loss of soil colloids .