An international group of researchers found the highest levels of microplastics ever recorded on the seafloor.
Microplastics are small pieces of plastic less than five millimeters long that are used in consumer products like synthetic clothing fabric, toothpaste and skincare products. The small plastics can absorb and give off chemicals and harmful pollutants like dioxins, PCBs and PAHs.
Microplastics can also easily pass through water filtration systems and end up in water systems throughout the world.
British, German and French researchers found 1.9 million pieces of microplastics in a thin layer covering just one square meter of the bottom of the Tyrrhenian Sea, off the west coast of Italy.
“Almost everybody has heard of the infamous ocean ‘garbage patches’ of floating plastic, but we were shocked at the high concentrations of microplastics we found in the deep-seafloor,” said lead researcher Ian Kane. “We discovered that microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents which concentrate them in certain areas.”
The microplastics can settle on the seafloor slowly or be transported rapidly by underwater avalanches known as episodic turbidity currents down to the deep seafloor. There, microplastics are carried away within large drifts of sediment that carry oxygenated water and nutrients.
“It’s unfortunate, but plastic has become a new type of sediment particle, which is distributed across the seafloor together with sand, mud and nutrients,” said Florian Pohl, one of the project researchers. “Thus, sediment-transport processes such as seafloor currents will concentrate plastic particles in certain locations on the seafloor, as demonstrated by our research.”
Microplastics have also been found in the Great Lakes and its tributaries. Researchers have found microplastic particles in 12% of freshwater fish. It is also estimated that there is one particle of microplastics for every 8 gallons of Great Lakes tributary water. That comes to about 112,000 particles per square mile of Great Lakes water.