Abstract
The aim of the project provided by the Hamburg Department for Urban Development and the Environment (Freie und Hansenstadt Hamburg - Behörde für Stadtentwicklung und Umwelt) and agreed by the International Commission for the Protection of the Elbe River (ICPER) was to identify the significance of old polluted sediments in the Elbe River and its side structures (old meanders, cut lakes, oxbow lakes) between Pardubice and Mělník (confluence with the Moldau River). The contaminants bound to the sediment particles can be stabile, but under changes in hydrological regime and water quality (floods, changes in pH, redox-potential, presence of complex substances etc.), they can be released and remobilized again.
Within the project, two localities were selected - the area of Neratovice (chemical factory Spolana, Inc.) and Pardubice (chemical factory Synthesia, Inc.; refinery PARAMO). The chemical factories situated close to these towns represented the most problematic polluters of the Elbe River especially during 2nd half of 20th century.
On the basis of a background research and pilot monitoring, sediment sampling was carried out. The chemical analyses were focused on substances identified by ICPER as well as chemicals considered as significant in the previous explorations (heavy metals, PCB, DDT, HCH, PAHs etc.).
The results of grain structure analysis were used for modelling the remobilization of contaminated matter during floods. At the selected river sections, maps of overflow and discharge velocity (Q1, Q5, Q20, Q100) were created.
To summarize, the results of the project provided information of the amount of polluted sediments in the most contaminated localities in the middle course of the Elbe River and described the possibility of remobilization of the polluted sediments during floods. On the basis of these outcomes, the risk management and environmental measures were suggested to protect the ecosystems from contamination stemming from these old pollution loads.