How we go about cleaning up the mass of plastic pollution in the ocean is a mind-bogglingly difficult question, and one that will take a range of innovative approaches to solve. A new study has cast doubt over one of the more publicized solutions in floating trash-collection barriers, finding that these devices are unlikely to put a dent in the overall problem, even if left to run well into next century.
The new study was carried out by scientists in the UK and Germany and focuses solely on floating plastic. How much plastic waste lingers below the surface of the ocean is something of a great unknown, with plastic fragments often breaking down into tiny pieces known as microplastics that are nearly impossible to track, let alone locate for retrieval.
The team developed a model to estimate the total mass of floating plastics both current and into the future, based on how much washes into the oceans through river systems and mismanaged landfills. According to its analysis, the current total of 399,000 metric tonnes will double to more than 860,000 metric tonnes by 2052, at which point the rate of plastic pollution may finally hit zero (according to previous research).
Next, the scientists examined what kind of impact trash-collection devices, such as the one developed and operated by The Ocean Cleanup Project, could have. These floating barriers are designed to be positioned in the Great Pacific Garbage Patch and passively collect plastic waste on the surface, which can then be hauled back to shore.
The important message of this paper is that we can't keep polluting the oceans and hoping that technology will tidy up the mess
According to the team’s modeling, if 200 of these floating barriers were deployed for 130 years without downtime, they would reduce the amount of floating plastic debris by 44,900 metric tonnes, or around five percent of the total. This calculation takes into account the length of the devices at 600 m (2,000 ft) apiece, along with the average flow speed that brings plastic debris into the barrier.
"The important message of this paper is that we can't keep polluting the oceans and hoping that technology will tidy up the mess," says study author Dr Jesse F. Abrams, from the University of Exeter. "Even if we could collect all the plastic in the oceans – which we can't – it's really difficult to recycle, especially if plastic fragments have floated for a long time and been degraded or bio-fouled. The other major solutions are to bury or burn it – but burying could contaminate the ground and burning leads to extra CO2 emissions to the atmosphere."
Skepticism over this approach is nothing new. Plenty of scientists have cast doubt over the feasibility of using large floating booms to collect floating plastic, suggesting it would have a negligible impact, particularly considering the huge amounts of waste that wash into the ocean everyday anyway. The Ocean Cleanup itself acknowledges that this is only part of the solution, but insists that we need to clean up what has already accumulated in the ocean anyway.
It is also taking steps to limit the plastic waste that enters the ocean via the world’s river systems through its own studies and its “Interceptor” system, which can be installed in waterways to trap the trash closer to the source. Most plastic waste in the ocean enters via these routes, and the authors of the new study say that if these kinds of barriers were installed in key polluting areas, they could prevent “most” of the pollution expected to wash into the ocean in the coming decades.
But with global shipping relying on major waterways to move goods, installing these types of barriers on a large enough scale is not likely to be feasible either. The researchers point to a need to develop and use more eco-friendly materials in place of plastics, and alter our behavior around plastic consumption, as a vital parts of the long-term solution.
"Plastic is an extremely versatile material with a wide range of consumer and industrial applications, but we need to look for more sustainable alternatives and rethink the way we produce, consume and dispose of plastic," said study author Professor Agostino Merico, of Leibniz Centre for Tropical Marine Research.
The research was published in the journal Science of the Total Environment.
Source: University of Exeter via EurekAlert
