The reason we find it difficult to track plastic litter contaminating water bodies is that once it enters the oceans, it is subjected to forces that break it down into tiny fragments called microplastics that measure less than 5mm. As you can easily guess, their monitoring is practically impossible, although new research sheds some light on the matter, showing what role ocean ditches can play in the movement of plastic waste in the oceans. Scientists focused on the Kuril-Kamchatka Riv in the northwestern Pacific, which is 9,750 meters deep, from where eight sediment samples were collected during the 2016 expedition.
This was done at four depths, i.e. 5143 m, 6065 m, 7138 m and 8255 m, and then the necessary analyzes were carried out by mass spectrometry. As a result, 15 different types of plastic have been found in the ocean sediment, including those typical of packaging, such as polyethylene and polypropylene. - The proportions of microplastics in our samples ranged from 14 to 209 particles per 1000 grams of dry sludge. The most frequent occurrence of microplastics was recorded at one of the deepest sampling stations. Apparently, significantly larger amounts of microplastics accumulate in the deeper regions. Probably because the particles can easily get in here, but they get trapped. These ditches act like real plastic traps, the researchers explain.
All the microplastic particles found by the researchers measured less than 375 micrometers and most were less than 125 micrometers. And while they are tiny, scientists say they are probably the missing piece of the puzzle called ocean plastic estimates. - Global estimates of the extent of microplastics in the oceans indicate that there must be a portion that exists outside the water column and is missing from the estimate. The accumulation of microplastics in these regions may represent this missing share. Microplastic at these depths also means that the basics of the food chain are at risk, as many invertebrates feed on sediment, including microplastic. Therefore, future generations will face the consequences of today's environmental pollution for many years, the researchers add.