Microplastics are everywhere. The tiny plastic particles pollute almost every ecosystem on earth. The oceans are particularly affected. Maritime trenches thousands of meters below sea level have become the “final resting place” for a disturbingly large amount of the smallest plastic particles.

A new study by scientists from the Senckenberg Nature Research Society, the Alfred Wegener Institute and Goethe University Frankfurt examines pollution by microplastics in the Kuril–Kamchatka Trench in the west Pacific Ocean. The scientists investigated sediment samples from depths of up to 9,450 meters and found between 215 and 1596 microplastic particles per kilogram, which is more than has ever been detected before. The study, which was published in the journal “Science of The Total Environment”, shows that the deep sea is already highly polluted with microplastics and that this is a threat to the high level of biodiversity on the seabed. The scientists used infrared spectroscopy to detect the microplastic particles. They found a total of 14 different types of plastic, including polypropylene and acrylates. Interestingly, they saw big differences between the samples, even if these had been taken just a few meters apart. This shows that the deepest parts of the deep sea are a dynamic environment where the microplastics are not only moved around through currents, but also by organisms. 

The scientists warn of the impact of increasing plastic pollution on deep-sea biodiversity: “Every year, an estimated 2.4 to 4 million tons of plastic reach the sea via the rivers as a result of the extreme world-wide plastic consumption and the badly organized waste management. A considerable part of this sinks to the bottom of the sea and collects there as sediment or is transported further down by currents to the deepest regions, where it finally settles down.