Long-range drift of microplastics towards the Arctic Ocean - discussions on the issue and observations along the North Atlantic current system

Microplastic pollution in the aquatic ecosystems has recently gained considerable attention from both the scientific community and the public. Plastic particles have been detected in practically all marine habitats from surface waters to deep sea benthos and all over the globe, including the Arctic Ocean and adjacent seas. Local microplastic pollution is probably low in the Arctic due to extremely rare coastal human settlements, but long-range drift of microplastics discharged far away might be considered as an untrivial threat for the world’s northernmost marine ecosystems. Significant share of microplastics float on the surface water, and there is a net inward flux of surface waters into the Arctic Ocean due to the deep-water formation processes taking place in the region. Thus, there is a possibility which should be taken seriously that plastics originating from for instance Europe or the USA are constantly transported towards the Arctic Ocean. This study summarizes the main characteristics of the Arctic oceanography and reviews the current knowledge on microplastic distributions in the region. Combining the two aspects, a coherent framework for assessing the issue of microplastic pollution in the Arctic Ocean is provided, long-range drifting from the North Atlantic being an important part of it. Furthermore, a geographically very extensive set of microplastic samples was collected and analysed, ranging from the Baltic Sea to Svalbard and including different sections of the northward flowing current system. All samples contained plastics and characteristic shifts in microplastic compositions in offshore samples supported the idea of long range drifting. However, the dataset was small with respect to the issue in question and definitively more research and expeditions are needed.