In 2016, Portuguese biologists discovered a new form of pollution that they called “plasticrust." This strange term refers to the plastic fragments that embed themselves on the rocks of the coastlines in some parts of the world, such as Madeira or Hawaii. A similar find has just been identified on the Brazilian island of Trindade, where scientist have discovered what they call “plastiglomerate" rocks.
During an expedition on the island of Trindade, off the coast of Brazil’s Espírito Santo State, researchers from the country’s Federal University of Paraná identified fragments of plastic in the rocks. Their discovery is all the more surprising since this island, located thousands of kilometers from Rio de Janeiro and in the middle of the South Atlantic Ocean, is a protected area that serves as a nesting area for green turtles. The members of the Brazilian navy in charge of protecting this site are its only human residents.
According to the research led by this team of scientists, the melted plastic identified in the rocks could come from fishing nets washed up on the beaches of the island. “The entire structure of these rocks is formed by burned plastic," Fernanda Avelar Santos, a geologist at the Federal University of Paraná outlined in an article by Agencia Brasil published in Folha Nobre. “That molten plastic, similar to volcanic lava, started to incorporate the beach fragments and form these new occurrences in the geology." To reach these conclusions, Fernanda Avelar Santos and colleagues conducted chemical tests that allowed them to identify these “plastic rocks" as a mixture of sedimentary granules and other debris held together by plastic. The researchers call them “plastiglomerates" echoing a previously discovered form of pollution called “plasticrust." And while this word might sound funny, the reality of what it means is much less so.
The term “plasticrust" was used in 2016 by Portuguese scientists from Lisbon’s Center for Environmental and Marine Sciences (MARE), during an expedition to the island of Madeira, located southwest of Portugal in the Atlantic Ocean. On site, the researchers noticed blue fragments embedded in the rocks of the shoreline and took samples to study them more closely. They returned to the island of Madeira several times between 2017 and 2019 and observed that this new form of pollution was widespread. In June 2019, the research team published a study closely detailing the threats posed by these plastic crusts. According to the research, layers of plastic crust could cover 9.46% of the rocky surface of the island of Madeira.