Trinidad (Trindade) is a small (10 km₂) uninhabited volcanic island located in the Atlantic Ocean, about 1,200 km east of Rio de Janeiro (Brazil). A remote place where there are 11 endemic plant species and a geological richness that justifies the periodic visit of numerous scientists.
Fernanda Avelar Santos, a postdoctoral student at the Coastal Studies laboratory at the Federal University of Paraná, in Curitiba, Brazil, was working on the coast of Trinidad in 2019 when she was surprised to see some blue-green rock formations. Intrigued by the color and shape of these stones, she took some samples for her study in the laboratory.
The preliminary data caused a sensation, and soon after, Avelar returned to the island to search for more specimens and complete the investigation.
The definitive results indicate that it is the first location on a remote island of plastiaglomerate formations (with a similar appearance to natural rock conglomerates), that is, rocks formed from remains of plastics such as polypropylene and polyethylene, according to the team led by Fernanda Avelar (along with nine other researchers) in an article published in the scientific journal Marine Pollution Bulletin (September 2022).
"The continuous entry of plastic garbage into marine and coastal environments reaches alarming levels that expose new scenarios in natural systems," recall the authors of the study. There are data on accumulations of plastic waste that have solidified, but until now no samples of these formations have been analyzed at points far from spill areas.
Fernanda Avelar and her team call the remains found in Trinidad "plastipiedras, a new type of homogeneous composition (without incorporated materials), igneous rocks with a geogenic appearance, divided into in situ and clastic types, and formed on rocky surfaces." "We linked pyroplastics, geogenic analogues to clasts, to clastic plastiglomerates/plastistons, thus representing clastic types of plastic debris forms," the authors write in the abstract of their results.
In this case, it is not the geological agents that form the rocks, but their origin is due to the action of humans.
"We conclude that the human being is now acting as a geological agent, influencing processes that were previously completely natural, such as the formation of rocks," explains Avela in statements released by AFP.
"It fits with the idea of the Anthropocene, which scientists are talking about a lot these days: the geological age of humans influencing the planet's natural processes. This kind of rock-like plastic will be preserved in the geological record and mark the Anthropocene," says the lead author of the study. Avelar describes Trinidad as "a paradise: a beautiful tropical island whose remoteness has made it a haven for all sorts of species: seabirds, fish found only there, nearly extinct crabs, the green turtle."
The only human presence on the South Atlantic island is a small Brazilian military base and a scientific research center. "So it was even more horrifying to find something like the plastipiedras on one of their most ecologically important beaches in Trinidad."
