Sediment quality in the Polish part of the trans-boundary Vistula Lagoon: implications for deposition management

Abstract

The Vistula Lagoon is located in Europe and is the second largest lagoon in the Baltic Sea, after Curonian Lagoon. It is a transboundary water basin shared by Poland and Russia. The entire Polish part is a NATURA 2000 area. The whole lagoon area requires economic rehabilitation comprising integrated management involving ecological, social and economic interactions and couplings. Currently most of the actions and investments are devoted to development of local tourism and stimulation of local economy by construction of new marinas and small harbors. In Polish part this is enhanced by the Vistula Spit cross-cut construction. Such activities result in a need for expansion of navigational channels leading to their dredging and necessity of safe management of the dredged deposit. Investigations of sediment quality thus became indispensable. To assess its quality, sediment samples were collected in the Polish and Russian part of the Vistula Lagoon to evaluate and compare soil strength parameters and the concentrations of harmful substances in both parts. Due to the current political situation and interruption of scientific contacts between the Russian and Polish researchers only the results obtained for the Polish part are reported herein. The analysis revealed that the studied sediments are generally very weak in terms of strength parameters but safe as regards the presence of dangerous substances according to EU regulations. This allows for deposition in the form of artificial islands that will ultimately fulfill important ecosystem services and provide long term solution for the excess sediment management.