Researchers have discovered a new type of plastic pollution floating in Earth's oceans and strewn on beaches. The plastic, which resembles stones and pebbles, was found in the South-West of England, Scotland, Spain, and Canada.
Researchers are calling this type of material pyroplastic because the plastic was formed by fire. Unlike other fragments of plastic broken down by the Sun, wind, and water, these appear to have been burned before being discarded into the sea and then shaped by the elements. They are remarkably similar to stones found in many coastal areas, with a worm even burrowing in some of them. The only difference is that they float. Details of the discovery are reported in the journal Science of Total Environment.
The team looked at 165 plastic pebbles collected on beaches around Whitsand Bay in Cornwall as well as 30 chunks from the Orkneys Islands in Scotland, County Kerry in Ireland, and the North West of Spain.
"Pyroplastics are evidently formed from melting or burning of plastic and are distinctly different from manufactured (primary and secondary) marine plastics in terms of origin, appearance and thickness," the researchers write in their paper. "Since pyroplastics have been retrieved by colleagues from Atlantic beaches in Spain and Pacific beaches of Vancouver, they are not a regional phenomenon, and it is suspected that their distribution may be widespread but that documentation is lacking because of a distinctly geogenic appearance."
The team can’t say for certain where the pyroplastic comes from and why it was burned, but they do present some ideas. There’s the possibility the plastic comes from campfires, barbeques, people burning used fishing equipment, leakage from landfill sites, or even from burned waste that was dumped into the sea.
The “stones” analyzed by the researchers were composed of polyethylene and polypropylene (common plastics), but the team also found traces of lead and chromium. This suggests the plastic pollution is not recent. Decades ago, before it was banned, lead chromate was used for coloring purposes. Follow-up tests in the lab suggest that burning plastic containing these substances does indeed alter their color and create a grayish-melt like the pebbles. The plastic was likely also smoothed by the elements, something that wouldn’t have happened overnight, even though plastic is more malleable than rocks.
The researchers do not know how common these pieces of plastic are, so for now they cannot assess their environmental impact. Given the evidence of calcium carbonate tubes created by marine worms, some of the material has already entered the food cycle. More research is necessary to understand the effect that pyroplastic has on the ocean.
[H/T: National Geographic]