The latest sign that plastic pollution is a gigantic global problem: rocks fused with melted plastic have been found on a remote Brazilian island, best known as a nesting site for green turtles.
Plastic rocks have been previously found in various parts of the world. Researchers documented plastiglomerates – rock, sand and other debris fused together by melted plastic – in Hawaii in 2014, for instance, and pyroplastics, rock-like pebbles formed out of burnt plastic, on the southwest coast of England in 2019.
Now researchers have discovered a new kind of igneous rock, plastistone, formed almost completely from plastic, on Trindade Island, a volcanic island more than 600 miles east of Espírito Santo in Brazil, said Fernanda Avelar Santos, a geologist at the Federal University of Paraná in Brazil.
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She and others gathered samples in 2019 while studying geology on the South Atlantic island, which also houses a marine reserve. Typically, only 30 to 40 people live on the island and their refuse is recycled or carefully disposed of.
Their research, published in the Marine Pollution Bulletin journal in September 2022, details how they found the new plastic rock, along with samples of plastiglomerates and pyroplastics on the island's beach. Pyroplastics were also found on the island's coral reef.
"These plastic occurrences are an emerging type of marine pollution, and they are a potential source of contaminants for organisms that inhabit or ingest them," Santos, who was the lead author on the study, told USA TODAY. "Finding this kind of marine litter on a nature reserve is an important warning of current human behavior."
Much of the plastic comes from fishing nets, which are made of polypropylene and polyethylene, she said. The nets wash up on the beach and can melt when temperatures rise.