Whereabouts of Missing Ocean Plastic.

Every year, several million tons of plastic end up in the ocean, yet there is an imbalance in the amount found floating at the surface, which is in the order of hundreds of thousands of tons. In the past, scientists have explained this difference by assuming that floating plastic does not persist at the ocean surface and that the missing plastic now would be in the form of microscopic particles at the bottom of the sea.

However, this contradicts numerous reports of decades-old objects floating in oceanic garbage patches, suggesting that floating plastic pollution is highly persistent in these regions. An international team of scientists at The Ocean Cleanup presents an alternative explanation for the missing ocean plastic in Scientific Reports.

To better understand the journey of ocean plastic, the team began registering samples taken from the Great Pacific Garbage Patch for their age. Many objects were clearly marked with production dates from the 1970s-1990s, making it unlikely that the plastic entering the oceans since the 1950s has fragmented completely and settled on the seabed. Resolving this conflict led to the development of a box model that helps to predict the age and path of ocean plastic.

When positively buoyant plastic is introduced into the marine environment, it may be transported to sea by currents...