Assessment of the Chemical State of Bottom Sediments in the Eutrophied Dam Reservoir in Poland

The aim of the presented research was to examine the concentration of biogenic compounds and heavy metals in the bottom sediments of the Sulejów Reservoir (Central Poland) from October 2018. Based on the obtained research results, maps of the spatial distribution were prepared. The following parameters were analyzed: total phosphorus (TP), total Kjeldahl nitrogen, total organic carbon (TOC), ratio of total organic carbon to nitrogen (C:N), organic matter content as well as Cd, Cr and Pb concentrations. The sediments were collected at 28 sampling sites, covering the whole area of the reservoir. The differences in the content of individual biogenic compounds result from the composition of the debris applied by the supplying rivers, as well as the content of this elements in the water, long retention time (40 days) and depth from which the tested sediments were taken. The distribution of examined compounds was largely influenced by the agricultural activity in the studied area, as well as the presence of ports and recreational points. Based on the measurements, the highest amounts of biogenic components deposit in sediments of deep parts in slow-flowing waters, in stagnation zones, areas adjacent to arable land, and the sites where fine-size fractions prevail in the deposited material. Biogenic compounds in sediments of the Sulejów Reservoir showed a pattern of gradual increase along the reservoir from lower values in the back-water part. A similar relationship is visible for heavy metals. Referring to the ecotoxicological criteria, it can be stated that bottom sediments from the Sulejów Reservoir collected in 2018 are not toxicologically contaminated in terms of cadmium, lead and chromium content.