Millions of tons of plastic waste are dumped into the world’s oceans every year, according tomedia New Atlas, but a new study shows that not all waste plastics pass through the sea in the same way. Scientists studying the movement of sediments under the sea floor have found that so-called underwater “avalanches” are bringing microplastics into the deep ocean, a discovery that could help researchers better map the distribution of waste across the marine environment and help identify future “microplastic hot spots.”
The study, carried out by scientists from the University of Manchester, The University of Durham and the University of Utrecht in the Netherlands, looked at the effects of sediment migration on the seafloor, which they described as the largest current on Earth.
To do this, the team conducted experiments that mixed quartz sand with microplastic fragments and fibers in a sink designed to simulate sediment flow on the seabed. The scientists then analyzed how these flows move disinformation around and distribute plastic material across the ocean floor.
The team’s analysis shows that “avalanches” distribute different types of microplastics in different ways. Microplastic fragments tend to accumulate in the lower part, while microplastic fibers are more evenly distributed and settle for longer periods of time. Scientists believe this is due to the large surface area of the fibers, which also means that they are more likely to fall into the sand and eventually deposit in deep seabed. “This is in contrast to the formation struck by the river, where the floodwaters washed away microplastics. Dr Ian Kane said: “As sediments settle from the current, the high sediment load in these deep-sea streams causes the fibers to become trapped on the sea floor. “
Overall, the team believes that its experiments demonstrate how these sediment streams can move large amounts of plastic waste from nearshore to the deep sea. Understanding this distribution could help scientists understand why different animals eat different types and sizes of plastic, learn more about its consequences, and shed light on how toxins accumulate on the ocean surface.
The study was published in the journal Environmental Science and Technology.