On the origin of Arctic Plastic: Interconnectivity between the Pacic and Atlantic Ocean and implications for plastic accumulation and transport in the Arctic

Abstract

Abstract Plastic pollution in the ocean is a growing concern. Yet, less than 1% of the total load of plastic going into the ocean is located, hence the quest for the lost plastic is still ongoing. Currently, microplastics are even found in remote areas such as the Arctic. Not only is plastic found oating in surface waters, but also in increased concentrations in sea ice. Even though many global modelling studies on plastic in the ocean have been performed, mechanisms for transport of plastic in the Arctic sea ice specically, and entrainment of microplastic in ice, have not been studied yet by numerical modelling. The Arctic is especially interesting because it is changing rapidly under global warming. This thesis aims to study transport mechanisms of plastic and interconnectivity between the Atlantic, Arctic and Pacic Ocean using Lagrangian techniques and identifying accumulation zones in sea ice and the ocean. Floating particles that enter the Arctic Ocean from the Pacic side accumulate in the Beaufort Gyre and very rarely (0.3% of the particles) cross the Arctic to the Atlantic side when traveling in sea ice. Floating particles from the Atlantic Side either accumulated in the Barents Sea or are advected back to the Atlantic by the Transpolar Drift Stream, but do not enter the high Arctic. These results indicate the necessity of a realistic data set to simulate plastic transport and a parametrization for the entrainment of plastic in ice, and more research on accumulation of plastic in ice.