Scientists have uncovered startling findings about the longevity of plastic pollution in ocean surfaces, predicting that it could persist for over 100 years. The study offers critical insights into the “missing plastic” problem and highlights the intergenerational challenge of oceanic pollution.
Scientists from Queen Mary University of London have developed a new model predicting that buoyant plastics could pollute the ocean’s surface for more than a century, even if all plastic inputs were halted today.
Published today in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, the study concludes a trilogy exploring the long-term fate of microplastics in the ocean.
This impactful research builds on previous papers published in the journals Nature Water and Limnology & Oceanography, providing a comprehensive understanding of how plastic pollution transitions from the ocean’s surface to its depths.
Using advanced computational models, researchers from the Department of Geography and Environmental Science at Queen Mary University of London, in collaboration with HR Wallingford Ltd, simulated the degradation and movement of plastics over time.
Combining expertise in marine geochemistry, fluid dynamics and environmental modeling, the team illuminated the persistent nature of this global issue.
“People often assume that plastic in the ocean just sinks or disappears. But our model shows that most large, buoyant plastics degrade slowly at the surface, fragmenting into smaller particles over decades,” lead author Nan Wu, from the Department of Geography and Environmental Science, said in a news release. “These tiny fragments can then hitch a ride with marine snow to reach the ocean floor, but that process takes time. Even after 100 years, about 10 percent of the original plastic can still be found at the surface.”
The research underscores why there is a significant discrepancy between the estimated amount of buoyant plastic entering the ocean and the relatively lesser amounts observed at the surface. This phenomenon, known as the “missing plastic” problem, has puzzled scientists for years.
Co-author Kate Spencer, a professor of environmental geochemistry in the Department of Geography and Environmental Science who supervised the project, emphasized the far-reaching implications of the study.
“This is part of our wider research that shows how important fine and sticky suspended sediments are for controlling microplastic fate and transport. It also 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,” she said in the news release.
The study’s insights indicate that finding a solution to the microplastic crisis requires long-term strategies. Short-term clean-up efforts, while essential, may not be sufficient due to the enduring nature of plastic pollution.
“This study helps explain why so much of the plastic we expect to find at the ocean surface is missing. As large plastics fragment, they become small enough to attach to marine snow and sink. But that transformation takes decades. Even after a hundred years, fragments are still floating and breaking down,” added co-author Andrew Manning, a principal scientist at HR Wallingford and an associate professor at the University of Plymouth. “To tackle the problem properly, we need long-term thinking that goes beyond just cleaning the surface.”
Worryingly, the research also suggests that as plastic production continues to rise, the biological pump — the ocean’s natural method of conveying carbon and particles — could become overwhelmed. This interference could have cascading effects on oceanic biogeochemical cycles, further stressing marine ecosystems.
Source: Queen Mary University of London