Abstract
Purpose Lacustrine sedimentation is a global issue, reducing the water volume and accumulating matter in reservoirs. The study focuses on the metal(loid) composition of subaquatic sediments of the Berthelsdorfer Hüttenteich reservoir, located in an ore mining affected, siliceous and sulfidic catchment in the Erzgebirge, Germany. Materials and methods Based on high-resolution subaquatic sampling of sediment cores up to 2 m thick, the granulometric spatial distribution of Al, As, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, U, V, and Zn was determined. A modified BCR sequential extraction was performed for sand and silt/clay to characterize the chemical bonding fractions of the metal(loid)s. Results and discussion Aqua regia digestion reveals significant amounts of Al (maximum 30,400 mg kg − 1 dry mass), Fe (26,100 mg kg − 1 ), Pb (2,400 mg kg − 1 ), Zn (1,700 mg kg − 1 ), Cu (158 mg kg − 1 ), As (135 mg kg − 1 ), and Cd (18 mg kg − 1 ). The granulometric spatial distribution of the metal(loid)s and their bonding fractions are primarily affected by the catchment and the sources. There is evidence that Cd, Co, Cu, Mn, Ni, Pb, U, and Zn are locally more associated with sand than with silt/clay. The non-mass-dominating metal(loid)s are bound from 31% to nearly 100% non-residual. However, with increasing depth, the non-residual concentrations are depleted. Despite the reservoir’s sink function for metal(loid)s, their concentrations in the reservoir water are negligible, indicating a slow desorption into the reservoir. Conclusions The study shows the necessity to adjust treatment and recycling strategies of these secondary raw material deposits according to their spatial distribution characteristics.