The geology of Brazil’s volcanic Trinidad island has fascinated scientists for years, but the discovery of rocks made of plastic debris in this remote turtle refuge is sparking alarm.
Melted plastic has mixed with rocks on the island, located 1,140 km (708 miles) off the southeastern state of Espirito Santo, in what researchers say is evidence of humans’ growing influence on Earth’s geological cycles.
“This is new and terrifying at the same time, because the pollution has reached geology,” said Fernanda Avelar Santos, a geologist at the Federal University of Paraná.
Santos and his team ran chemical tests to find out what kind of plastic the rocks contained, called “plastiglomerates,” because they are made of a mixture of sedimentary granules and other debris held together by plastic.
“we identified [the pollution] mainly comes from fishing nets, which is very common debris on the beaches of the island of Trinidad,” Santos said. “The [nets] are carried by ocean currents and deposited on the beach. When the temperature rises, this plastic melts and mixes with the natural material of the beach. Trindade Island is one of the world’s most important conservation sites for green turtles, or Chelonia mydas, with thousands coming each year to lay their eggs. The only human inhabitants on Trinidad are members of the Brazilian Navy, which maintains a base on the island and protects the nesting turtles.
“The place where we found these samples [of plastic] There is a permanently protected area in Brazil where green turtles lay their eggs, Santos said.
The discovery raises questions about humans’ legacy on Earth, says Santos.
“We talk a lot about the Anthropocene, and this is it,” Santos said, referring to a proposed geological era defined by humans’ impact on the planet’s geology and ecosystems.
“Pollution, marine trash, and plastic mishandled into the oceans are becoming geological material … preserved in Earth’s geological record.”