The geology of Brazil’s volcanic Trindade Island has intrigued scientists for years, but the discovery of rocks made of plastic debris in this remote turtle haven is raising alarm.
Melted plastic has become entwined with rocks on the island, located 1,140 km (708 miles) from the southeastern state of Espirito Santo, which scientists say is evidence of the growing influence of humans on the Earth’s geological cycle.
“This is new and scary at the same time because pollution has reached geology,” said Fernanda Avelar Santos, a geologist at the Federal University of Parana.
Santos and her team ran chemical tests to find out what kind of plastic is in the rocks called “plastiglomerates” because they are made of a mixture of sedimentary granules and other debris held together by plastic.
“We identified (the pollution) comes mainly from fishing nets, which are very common litter on Trinidade Island’s beaches,” Santos said. “The nets are dragged by the ocean currents and accumulate on the beach. As the temperature rises, this plastic melts and becomes embedded in 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 arriving every year to lay their eggs.The only human inhabitants of Trindade are members of the Brazilian Navy, who maintain a base on the island and protect the hatching turtles.
“The place where we found these samples (of plastic) is a permanent conservation area in Brazil, near the place where green turtles lay their eggs,” Santos said.
The discovery raises questions about the legacy of humans on Earth, says Santos.
“We talk so much about the Anthropocene, and this is it,” Santos said, referring to a proposed geological epoch defined by the impact of humans on the planet’s geology and ecosystems.
“The pollution, marine debris and plastics improperly dumped into the oceans become geological material … preserved in the Earth’s geological record.”