The contamination of bottom sediments in water reservoirs in the vicinity of Banska Stiavnica (Slovakia) by potentially toxic elements

Abstract

The Štiavnické lakes located in the vicinity of Banská Štiavnica (Slovakia) represent unique, historical engineering works that are part of UNESCO’s World Heritage. From the scientific point of view, lake sediments from an area rich in silver, gold, lead, and other metals, which have been mined and processed here for over 1000 years, could become a valuable historical research material. Sediment sampling has been performed according to STN ISO 5667-12. Sediment samples were collected from water reservoirs Bakomi, Rozgrund, and Vindšachta. Potentially toxic elements in sediments were analyzed by AAS spectrometry. The Bakomi water reservoir sediments contained on average (in mg·kg-1): Cd 2, Cu 17, Mn 530, Pb 94 and Fe 27,601. Sediments taken from the Vindšachta area contained on average (in mg·kg-1): Cd 2, Cu 30, Mn 980, Pb 96 and Fe 26,884. The sediment in Rozgrund differed significantly from the sediments of other lakes. The sediments of the Rozgrund area, whose reservoir has not been drained in 270 years, contained on average (in mg·kg-1): Cd 6, Cu 39, Mn 1,471, Pb 205 and Fe 37,786. The concentration profile of sediments was examined to the depth of 42cm, while in one case (Mn in the reservoir sediment) the gradual increase of concentration with depth was observed. Concentration anomalies associated with depth were not detected in the examined metals. Concentration anomalies associated with mining or severe air pollution were not detected in the examined metals.