The scientists sampled floating plastic debris from 42 sites in the Arctic Ocean aboard Tara, a research vessel that completed a trip around the North Pole from June to October 2013, with data from two additional sites from a previous trip. They scooped up plastic debris and determined the concentration of particles by dividing the dry weight of the plastic collected, excluding microfibers, by the area surveyed.
Almost all of the plastic, measured by weight, was in fragments, mostly ranging from 0.5 millimeters to 12.6 millimeters. The rest of the plastic appeared in the form of fishing line, film or pellets. This mix of plastic types is roughly consistent with the kinds of plastic that collect in the subtropical gyres, though those parts of the ocean amasses a higher concentration of fishing line.
The researchers did not find many large pieces of plastic, nor did they find much plastic film, which breaks down quickly, suggesting that the plastic has already been in the ocean for a while by the time it gets to the Arctic.
If the plastics were coming directly from Arctic coastlines, it would mean that people in the sparsely populated Arctic were depositing many more times the plastic in the ocean than people in other parts of the world, which is unlikely. Shipping is also relatively infrequent there and, the authors write, there is no reason to think that flotsam or jetsam in the Arctic would be so much higher than in other parts of the world.
The lesson from the study, Dr. Cózar Cabañas said, is that the issue of plastic pollution “will require international agreements.”
“This plastic is coming from us in the North Atlantic,” he said. “And the more we know about what happens in the Arctic, the better chance we have” of solving the problem.