So far, the bottom of the deep sea has been considered a stable environment unaffected by humans. But a research team also found a surprising number of microplastic particles in sediment samples from a depth of up to 9,450 meters. "No one would have expected such a large amount before," reports one scientist.
The seabed of the deep sea is even more heavily contaminated with microplastics than previously thought. This is the conclusion reached by scientists from the Senckenberg Nature Research Society, the Goethe University in Frankfurt and the Alfred Wegener Institute (AWI) in Bremerhaven. In 2016, they took sediment samples in the West Pacific Kuril-Kamchatka Trench. In these, between 215 and 1596 of the tiny plastic particles were detected per kilogram of sediment, more than before, the Senckenberg Society announced. The great biological diversity at the deepest seabed is severely endangered by pollution.
A large part of the plastic waste in the seas comes from land, via rivers or our wastewater, for example. Larger pieces of plastic are ground down into smaller and smaller pieces over the course of decades. Some of the rubbish collects in huge piles of rubbish on the surface of the oceans, but most of it sinks down into maritime trenches thousands of meters below the surface. "We took a total of 13 samples at seven different stations of the trench, at depths between 5740 and 9450 meters. Not one of them was free of microplastics," said the marine biologist from the Senckenberg Research Institute and Natural History Museum in Frankfurt, Serena Abel. "Nobody would have expected such a large amount before."
"Every year, an estimated 2.4 to 4 million tons of plastic end up in the sea via the rivers as a result of extreme global plastic consumption and poorly organized waste disposal," said researcher Angelika Brandt. The deep sea is becoming the "repository of garbage". A total of 14 different types of plastic were discovered. The researchers presented their results in the journal Science of the Total Environment.
"Until now, the deepest seabed has been considered a comparatively unaffected and stable environment in which the microplastics are deposited and remain in one place," said Abel. The researchers were amazed that samples taken a few meters apart had a very different structure. "This shows what a dynamic environment the deepest reaches of the deep sea actually are." Eddies, currents and organisms would keep the sediment moving. The flood of garbage is likely to increase in the future. According to earlier data from the AWI, global plastic production is expected to double by 2045.