The Norwegian coastal current (NCC) is the main pathway of surface water out of the North Sea, making the Norwegian coastline highly exposed to buoyant marine debris. The NCC can bring litter from land bordering southern parts of the North Sea, as well as litter from Atlantic waters, which are a major contributor to the water masses of the North Sea. Due to the complex geometry of the coastline, Norwegian fjords can act as a sink for marine litter (Deng., 2015). In this work an assessment of the contribution of transboundary plastics passing along the coast of western Norway is made through numerical modelling. Emissions of buoyant plastics (Meijer et al., 2021) from major rivers in Europe are used as an input to a Lagrangian particle model, with background currents from a 4 km resolution model of the North Atlantic (Lein et al., 2013), to compute the discharge fluxes of plastics ending up in the NCC. We then use the computed particle fluxes from the NCC as input to a Lagrangian model fed with currents from a hydrodynamical model with 160 m resolution (Dalsøren et al., 2020) to track the pathways into and out of the fjords near Bergen in western Norway. We find estimates for the fraction of plastics moving into the fjords, and establish transboundary connectivity metrics for selected regions. We also assess the relative influence of windage, ocean currents and other oceanic processes known to be important for far field and intermediate scale transport. The results are of relevance to agencies working on laws for trans-national pollution and with ocean clean-up initiatives.

Primary Presenter: Prithvinath Madduri, University of Bergen (prithvimadduri@gmail.com)

Authors:

Prithvinath Madduri, University of Bergen  (prithvimadduri@gmail.com)

James Clark, Plymouth Marine Laboratory  (jcl@pml.ac.uk)

Guttorm Alendal, University of Bergen  (guttorm.alendal@uib.no)

Anna Oleynik, University of Bergen  (anna.oleynik@uib.no)

Helge Avlesen, NORCE Norwegian Research Centre  (heav@norceresearch.no)