New insights into the role of sediments in microplastic inputs from the Northern Dvina River (Russia) to the White and Barents Seas.

The Northern Dvina River is one of the main sources of microplastic pollution entering to the White and Barents Seas. The coastal and bottom sediments of this river play an important role as a transfer link of microplastics. With Py-GC/MS and μFT-IR methods, it was found that the sediments contain up to 350 mg/kg or 650 particles/kg of microplastic (dry weight). The unique hydrologic conditions of the river branching area contribute to the formation of a microplastic pollution hotspot. The hotspot accumulates >30 % of microplastic pollution, mainly ABS plastic particles smaller than 0.3 mm with roughness and cracks, which increases the hazard class (from II to IV) of microplastic pollution. Obtained data and high annual variability of pollution indicates that this area acts as a place of accumulation, degradation and gradual release of microplastics into the White and Barents Seas, i.e. into the Arctic region.