In the northern hemisphere, the Arctic Ocean virtually is the final destination for micro- and macroplastics, which are not only carried regionally by fisheries, sewage or landfills, but also reach the far north via ocean currents, rivers and winds. Many studies show the heavy impact on the ocean, sea ice, seabed and coastal areas in the Atlantic Sector. Japanese researchers have now published a study in the journal Science of the Total Environment that for the first time in quantified microplastic pollution of the Chukchi Sea in the western Arctic Ocean.
The microplastic concentrations determined by the research team in the Chukchi Sea are significantly lower compared to those on the Atlantic side of the Arctic Ocean. Nevertheless, the values determined are astonishingly high in view of the great distance to human activities.
On average, more than 5,000 microplastic particles per square kilometer float on the water surface in the Chukchi Sea. By comparison, concentrations 30 times higher have been detected on the Atlantic side of the Arctic Ocean, and ten times higher in the global ocean.
In the Chukchi Sea, the research team found the highest concentrations at the northernmost station near the sea ice edge, in the vicinity of Utqiaġvik (formerly Barrow) and in the Bering Strait. The researchers estimated the total amount of microplastic in the Chukchi Sea at over three billion particles. However, this differs significantly from the estimated annual input of 18 billion microplastic particles through the Bering Strait.
The team can only speculate about the whereabouts of the remaining microplastic. They suspect that it is transported further in the Arctic Ocean, temporarily trapped by sea ice or sinks to the seafloor. They emphasize that it is important to clarify what happens to the microplastic.
The researchers most frequently found fragments of formerly larger plastic parts. They did not record fibers, which usually make up the largest proportion in other studies, because of possible contamination from their own clothing. Polyethylene is the most commonly used polymer worldwide and was also the most represented in this study.
The marine ecosystem in the Arctic Ocean is already under severe stress from global warming and the associated sea ice loss and species displacement. Pollution with microplastics could have additional negative effects on the ecosystem.
Julia Hager, PolarJournal
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