Clues emerge in ‘missing’ ocean plastics conundrum
VIENNA (AFP) — It’s a puzzle that has perplexed scientists for years: humanity dumps millions of tons of plastics into the world’s oceans annually, yet only a tiny fraction remains visible on the surface.
Now an international team of researchers believe they may be closer to determining where Earth’s “missing plastics” end up, using an unprecedented global effort to track and draw down one of the most polluting materials ever invented.
As images of plastic-clogged beaches and swirling gyres of detritus bobbing on the high seas are prompting governments and cities to curb their throwaway culture, a growing body of evidence suggests a deeper problem of plastic permeating all ocean depths.
Of the between four million and 12 million tons that enter the oceans each year, just 250,000 tons are thought to stay at the surface.
Overall, more than 99 per cent of plasdied tics dumped at sea over several decades are currently unaccounted for.
As plastics degrade through erosion, UV light and microbial decay, their density changes, putting them at the mercy of ocean currents — and, once they get pulled lower in the water, much harder for experts to track.
”It’s quite difficult to decide where it all is because there are so many processes at work,” Dr. Alethea Mountford, from Newcastle University’s School of Natural and Environmental Sciences, told AFP.”
Even plastic at the surface can sink down and go back up again — it’s moving between different possible sinks in different areas of the ocean at any time.
”In a potential breakthrough, Dr. Mountford used a computer model of ocean currents for plastics of three different densities to project where most of the world’s fragments collect once they start to sink.