Deposition of Copper in the Eutrophic, Submontane Dobczyce Dam Reservoir (southern Poland) – Role of Speciation

In order to better understand Cu behaviour in the submontane, eutrophic Dobczyce dam Reservoir (southern Poland), speciation measurements of Cu in the water and the sediment were conducted. To investigate the partitioning of Cu in the main components of the sediment, a scheme of VI-step sequential extraction was used. In addition, other physical and chemical parameters of the water, such as temperature, pH, dissolved O2, nutrients, and suspended particulate matter were determined. Copper content in the water and the sediment was low (1.1–7.4 μg L−1 and 5.5–45.4 μg g−1, respectively). In the water Cu was usually present in the dissolved state (with the exception of the near-bottom water). This was probably the main reason of its small accumulation (cumulation coefficient K = 10687.5) in the sediment of the Dobczyce Reservoir. The seasonal variations in Cu contents in the dissolved and particulate phases as well as observed correlations with the physicochemical parameters of the water are discussed. In the sediment Cu occurred mainly in a strongly bound form. Most Cu found there was in the moderately reducible phase and residual. Therefore, copper (re-)mobilization from the sediment to the water was probably not of importance.