Sink and Source Functions for Metal(loid)s in Sediments and Soils of Two Water Reservoirs of the Ore Mountains, Saxony, Germany

Abstract

Since reservoirs can act as sinks for potential contaminants, such as metal(loid)s, sediment management is a challenge for reservoir operators. To exemplify the variability of concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn), the sediments of two differently constituted reservoirs located in the Ore Mountains (Saxony, Germany) were comparatively investigated. In the sediments of the Einsiedel Reservoir, which has a catchment area dominated by forestry, the median values showed an enrichment of Cd (6.7 mg/kg), Co (31.4 mg/kg), Hg (0.57 mg/kg), Ni (39.0 mg/kg) and Zn (283 mg/kg), mainly due to an elevated geogenic background and a preferential input of these elements from the soils of the catchment area. Sediments of the Berthelsdorf Smelter Pond, which has a predominantly agricultural catchment, had relatively high median concentrations of As (62.9 mg/kg), Cd (10.3 mg/kg), Cr (43.1 mg/kg), Cu (50.2 mg/kg), Hg (0.51 mg/kg), Pb (204 mg/kg), V (57.0 mg/kg) and Zn (626 mg/kg), which was due to an elevated geogenic background and heavy anthropogenic metal(loid) inputs over the past. Statistical analyses indicated that site-specific differences (e.g., in the content of organic matter or in the physicochemical properties of sediments) may influence the sink and source functions of the reservoirs for metal(loid)s. In this context, a strong influence of the specific catchment characteristics on the sediment composition of the reservoirs was concluded. Based on the German Federal Soil Protection Ordinance, the status quo of the metal(loid) contamination of the two reservoirs was evaluated and recommendations for further management and investigations were derived.