How much plastic is at the bottom of the oceans? Scientists are finding the first

For the first time, scientists have estimated how much plastic is on the ocean floor. According to scientists, this may be a hundred times greater than what is currently visible on the surface.

We've known for some time that there is a lot of plastic floating in the ocean. A study was recently published on how many microplastics are found on the ocean floor. However, no research has ever been done on how many large objects pollute the ocean floor. But that's changing now: In a large-scale study, scientists have made a preliminary estimate. Scientist Denise Hardesty contributed to the research. “We know that millions of tons of plastic waste end up in the oceans every year,” she explains. However, what we didn't know before was how much of it eventually ended up on the seafloor. During this research we discovered that the seabed has become a reservoir for the vast majority of pollution. For example, we estimate that there are currently approximately 3 to 11 million tons of plastic hiding in the depths of the ocean. This research is the first part of a larger research project aimed at better mapping ocean pollution. The research has been published in the journal Deep Sea Research Part I: Oceanographic Research Papers.

Forecasting models
Scientists have built two models to predict research. The first prediction model is based on data from Remotely Operated Vehicles (ROV), such as underwater drones that spotted plastic during a survey. The second prediction model is based on data focusing on plastic extracted from trawl nets. Ultimately, the first ROV-based prediction model turned out to be particularly interesting: it showed that approximately 46% of all plastic in the ocean lies at a depth of less than 200 metres. The opposite is also true: 54% of all plastic in the oceans is found at a depth of more than 200 metres. This area reaches the ocean floor. Finally, scientists have also made one last shocking discovery: According to prediction models, inland and near-coastal seas together are likely to contain almost as much plastic as all other oceans combined.

Knowledge gap
The study's findings are important because they attempt for the first time to shed light on the pollution of the seafloor itself. Fellow scientist and team member Xia Zhou also contributed to the study. “Our findings help fill the knowledge gap regarding the behavior of plastic in the sea,” she says. “It is very important to understand how exactly plastic is transported and accumulated in the deep ocean. The ocean surface is actually a temporary repository for plastic. Our research shows that plastic will eventually sink to The bottom, where it will remain lying around. Hardesty notes that this waste will break down into smaller parts over time. These smaller parts can mix more easily with seafloor sediments, which will also become contaminated more quickly.

Researchers point out that approximately one truckload of plastic waste ends up in the oceans every minute. Yet all is not lost. For example, the scientists wrote in their paper that there is an important reason why the estimates are so high: There are currently no projects aimed at cleaning plastic from the seafloor. Therefore, scientists in the study call for better monitoring of the seabed. “We expect there will be a way to reduce the amount of plastic on the seabed,” concludes Zhou. “This method essentially consists of preventing plastic waste from reaching the sea.”