Throw a polyester pull in the washing machine and it will come out nice and clean, but not quite on its own. During the rinsing, millions of synthetic fibers will break off and rinse with the wastewater, which will then flow to a treatment plant. Each year, a single installation could pump 21 billion of these microfibers to the sea, where they swirl in currents, settle in sediments and end up as fish food, with unspeakable ecological consequences.
Everywhere scientists look in the world’s oceans, they find microfibers, technically a subcategory of microplastics, which are defined as particles less than 5 millimeters in length. And now, after completing four expeditions across the Arctic Ocean, a team of scientists are reporting just how contaminated even these remote waters have been. Sampling up to 1,000 meters deep, they found an average of 40 microplastic particles per cubic meter of water, 92% of which were microfibers. Almost three-quarters of them were made of polyester, strong evidence that humanity’s addiction to synthetic clothing is corrupting Earth’s oceans.
“It just illustrates how contaminated our planet has become with synthetic polymers,” says Peter Ross, ocean pollution specialist and marine pollution advisor at the Ocean Wise Conservation Association, a conservation NGO, and senior author of a new paper in Nature communications describing the results.
Ross and his fellow researchers at Canada’s Department of Fisheries and Oceans were careful not to sample surface waters, which tend to accumulate floating polystyrene foam and lost fishing gear. For this reason, this water is not a good representative sample of the plastic pollution lurking in the sea. Instead, they had to collect water a few feet below the surface, and – conveniently enough – their Research vessels had ports of admission located at the bottom of their hulls. Scientists also took samples along the water column, up to 1015 meters deep, from six stations in the Beaufort Sea above Alaska.
They had to be sure, however, that they weren’t mistaking natural particles for synthetic particles, so they used a forensic technique called Fourier transform infrared spectrometry, or FTIR. An instrument bombards the particles with an infrared beam, exciting certain molecules in the sample and analyzing the infrared signature reflected by the detector. In this way, scientists could not only confirm whether a particle was synthetic, but also determine what kind of plastic it was. “Even our skilled technicians in our group often mistake these mysterious particles for plastic when in fact they are something natural,” says Ross. “The FTIR is therefore very important to confirm whether the mysterious particle is plastic or not.”
Confirmed particles, the team measured their lengths and diameters, which matched known dimensions of synthetic fibers. Almost 75% of the fibers were polyester, a material common in synthetic clothing, and they were also available in a range of colors. “The roster is striking,” says Ross. “All of this really addresses our concerns about the prospects of a significant role for textiles and linens in contaminating the world’s oceans.”
Since the team had data from four expeditions that took place across the Arctic, they were able to compare their samples from the eastern region (over the Atlantic Ocean) to the western region (above Alaska and the Yukon). They found three times more particles in the east than in the west. The fibers were also 50 percent longer in the east, and their infrared signature more closely resembled that of virgin polyester, indicating that these fibers were newer. “As fibers enter the Arctic or the environment, they are altered, they age over time,” says Ross. “The infrared signature changes with sunlight, with chemical processes, with bacterial decomposition.”