Volumes of plastic waste washing up on an uninhabited South Atlantic island is worsening, with 15 percent more bottles drifting onshore each year since the 1980’s.
Researchers compared surveys of pollution on the remote beach from the eighties with those they undertook in 2009 and 2018.
Single-use plastic bottles were the most prevalent form of debris, most of which were manufactured within two years of being washed ashore.
While most bottles washed up in the eighties came from South America, the team found most now come from Asia instead, having being dumped from ships.
Ornithologist Peter Ryan of the University of Cape Town and colleagues studied plastic bottles and containers that had washed up on the west coast of the remote and uninhabited Inaccessible Island in the central South Atlantic Ocean.
The island had previously been surveyed for litter back in the 1980’s — with the researchers adding their analyses from 2009, when they found 3515 pieces of washed-up jetsam, and 2018, when they reported studying 8084 bits of debris.
The researchers found that drinking bottles made of polyethylene terephthalate — or PET — were the most ubiquitous form of debris.
‘Plastic drink bottles show the fastest growth rate, increasing at 15 per cent per year compared with 7 per cent per year for other debris types,’ the researchers wrote.
The team analysed the washed-up waste for manufacturing dates.
Most of the bottles found on the shoreline dated back to within two years of their having washed up on shore.
The oldest piece of waste that the researchers found in 2018, however, came from a high-density polyethylene canister that was manufactured in 1971.
In the survey undertaken in the eighties, around two-thirds of the plastic bottles that washed onshore at Inaccessible Island originated from South America.
‘By 2009, Asia had surpassed South America as the major source of bottles and by 2018, Asian bottles comprised 73 per cent of accumulated and 83 per cent of newly arrived bottles, with most made in China,’ the researchers wrote.
‘The rapid growth in Asian debris, mainly from China, coupled with the recent manufacture of these items, indicates that ships are responsible for most of the bottles floating in the central South Atlantic Ocean.’
This disposal activity, the researchers note, is in direct contravention of the International Convention for the Prevention of Pollution from Ships.
The full findings of the study were published in the Proceedings of the National Academy of Sciences.