Developing a transport model for plastic distribution in the North Sea.

Dana Elena Stuparu, Myra van der Meulen, Frank Kleissen, Dick Vethaak, Ghada El Serafy

Thursday 2 july 2015

16:15 - 16:30h at Asia (level 0)

Themes: (T) Hydro-environment, (ST) Impacts of pollutants on the water environment

Parallel session: 13G. Environment - Impact

As a result of the rising plastic usage worldwide, the abundance of plastic litter in the sea and ocean has steadily increased over the last few decades. However, there is considerable uncertainty regarding the occurrence and effects of plastic litter on the marine environment. This uncertainty is visible both at the level of physical impacts but also with respect to the adaptation measures to reduce the negative environmental consequences. Aiming for a better representation of this uncertainty, the EU Marine Strategy Framework Directive was published in 2008 and requires EU member states to achieve ‘good environmental status’ (GES) in Europe’s seas by 2020. The present study aims to improve the knowledge regarding the distribution and hot spots of plastic litter in the North Sea. The litter transport in the North Sea is modeled by further development of the Delft3d software. By combining hydrodynamics with particle tracking concepts, the model calculates how the position of plastic particles evolves in time from their release (discharge from points such as the Rhine or the Meuse) until the end of the simulation. The settling velocity of the particles in the water system is dependent on the ambient conditions (temperature/salinity) and also on the particle characteristics (density/size). Different types (polyethylene, polystyrene, PET, PVC) and sizes (10 µm, 330 µm and 5 mm) of plastics were analyzed. The results demonstrate that density is the main determining factor for plastic settlement and that size also has an effect. Modeling results are then compared with field measurements in sediments. Marine litter is a major threat to the marine environment. In this light, modeling can provide a regional or global overview and advice on clear monitoring questions. This work was funded by the European Union Seventh Framework Programme under grant agreement No 308370 (CLEANSEA project) and the Interreg IVa project MICRO.