Naturally, deep sea dugs are among the most difficult regions of the earth. However, our garbage finds the way there without any problems, as a team around Serena Abel from the Helmholtz Center for Polar and Marine Research found in Bremerhaven. The working group made surprisingly large amounts of microplastics in the western Pacific Kurilen-Kamtschaftka-Graben, as written in the journal "Science of the Total Environment": In each of a total of 13 sediment samples from more than 9000 meters deep, the parties involved between 215 and 1596 small particles per kilogram of mud. "Nobody would have expected such a large amount before," said zoologist Angelika Brandt from the Senckenberg Research Institute and Nature Museum Frankfurt.
Every year, several million tons of plastic waste end up in the oceans. Only part of it is washed back to the coasts; a large amount, on the other hand, remains in the water and gradually breaks down into smaller and smaller particles. These are taken up by organisms, end at the poles in the ice or sink over time into the deep sea. There they also transport currents until they are finally deposited in the deep-sea trenches. Abel and Co were able to detect a total of 14 different types of plastic in the samples. Among the most common substances is polypropylene, one of the standard plastics used worldwide for packaging, as well as acrylates and polyurethane used for coatings.
However, the waste is not distributed evenly over the ground. "Until now, the deepest seabed was considered to be a relatively unaffected and stable environment in which the microplastics are deposited and remain in one place. We were all the more surprised that even samples that were taken only a few meters away from each other had very different structures," says Abel. In addition to currents, animals obviously also contribute to the rearrangements when searching the sediment for food.
In the deepest places of the examined trench, biodiversity during the exploration trips showed even higher than in less deep areas of that trench. And this fulfills the working group with concern: "Exactly this high biodiversity in the deep sea is now particularly at risk due to the strong pollution with microplastics!" Says Brandt.
