Concentrations, distributions, and sources of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in bed sediments of the water reservoirs in Slovakia

Dredging water reservoirs is necessary to maintain accumulation capacity and to prevent floodings. As a first step, the quality of the bed sediments in water reservoirs must be determined before dredging operations. In this study, sediment samples from 34 stations of three selected water reservoirs (Zemplinska Sirava, Velke Kozmalovce, and Ruzin) were collected to investigate concentrations, distributions, and hazards of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and to predict their possible sources. Total PCB concentrations were in the range of 20.4 to 2,325 ng/g. The maximum concentrations of PCBs were found in sediments from Zemplinska Sirava, which is in the vicinity of a former manufacturer of PCBs. The composition of PCBs was characterized by tri- and hexa-CB congeners, indicating the influence of contamination from the use of specific Delor mixtures, formerly produced and massively used on the territory of Slovakia. The data showed that the highest total PAH concentrations were associated with the sediments from the Velke Kozmalovce, ranging from 7,910 to 29,538 ng/g. On the other hand, the lowest total PAH concentrations (84-631 ng/g of dry weight) were found in the sediments of Zemplinska Sirava, an important recreational area in eastern Slovakia. The distribution of individual PAHs was similar among the three water reservoirs, and this, together with principal component analysis and diagnostic PAH ratios, suggests mainly pyrolytic contamination of the sediments. However, petrogenic inputs appear to be important in the Zemplinska Sirava sediments.