Researchers from the Department of Geography and Environmental Science at Queen Mary University of London have found some shocking things about plastic pollution in our oceans. Their new study dives deep to illuminate the scope of this important issue. The paper suggests that macro-plastic waste could remain floating on ocean surfaces for more than 100 years. This groundbreaking research highlights the persistence of plastic in marine environments and offers insights into why much of the expected plastic at the surface remains elusive.
Dr. Nan Wu, the lead author of the paper titled “Coupling fragmentation to a size-selective sedimentation model can quantify the long-term fate of buoyant plastics in the ocean,” explains that plastic pollution does not simply vanish or sink. Large plastic items like flip-flops, six-pack rings, and food containers eventually fall apart under the effects of sunlight and wave action. This grinding process results in microplastics that can remain suspended in the water column indefinitely.
The Mechanism Behind Plastic Pollution
Scientific studies indicate that buoyant plastics break down very little and very slowly at surface of ocean. Over the course of decades, they slowly disintegrate into smaller and smaller particles. Dr. Wu notes, “People often assume that plastic in the ocean just sinks or disappears. Our model shows that most large, buoyant plastics degrade slowly at the surface, fragmenting into smaller particles over decades.”
These microscopic particles easily edible and can even hitchhike on marine snow. In doing this, they are carried along in the water column and settle out into the deep ocean over time. This process is not instantaneous. Here, Dr. Wu explains his approach in more detail. It can take days for these tiny plastic fragments to attach themselves to larger aggregates and hitch a ride down with marine snow to the ocean floor. Even after a century, nearly 10 percent of the original plastic still remains at the surface.
In the paper, they employed a simple model to illustrate the settling behavior of buoyant plastic through the water column. This novel approach has allowed us to gain unprecedented insight into the long-term fate of these materials within marine ecosystems.
Intergenerational Impact of Microplastic Pollution
These findings highlight the fact that microplastic pollution is not just an environmental problem of today but rather an intergenerational problem. Co-author and project supervisor, Professor Kate Spencer, Queen Mary University, goes on to explain that even if we halted all new plastic from entering the ocean today, buoyant plastic debris would remain for more than a century and still be shedding microplastics.
“This is part of our wider research that shows how important fine and sticky suspended sediments are for controlling microplastic fate and transport,” Prof. Spencer states. “It tells us that microplastic pollution is an intergenerational problem and our grandchildren will still be trying to clean up our oceans even if we stop plastic pollution tomorrow.”
Informed by this lens, the perspective we bring to the work strengthens the understanding that solving plastic pollution is bigger than the next big idea. Yet it takes significant political will and a long-term approach to address the pervasive and chronic intrusion of microplastics into marine ecosystems.
Understanding the Missing Plastic
This research is crucial to helping understand the mystery of missing plastic at the ocean surface. This improved understanding sheds light on why so much of the plastic we assume should be there isn’t. Professor Andrew Manning, a co-author and Principal Scientist at HR Wallingford, explains, “This study helps explain why so much of the plastic we expect to find at the ocean surface is missing. As big plastics break down into smaller pieces, they can become small enough to adhere to marine snow and sink. But that transformation takes decades.
According to him, even in one hundred years’ time, pieces of plastic would continue to be found floating on the surface. “To tackle the problem properly, we need long-term thinking that goes beyond just cleaning the surface,” Prof. Manning urges.
This study is more than an academic exercise. To make that a reality, it calls on policymakers, environmental advocates and society as a whole to act and adopt ambitious plans that will significantly diminish the widespread impacts of plastic pollution.
