Rocks formed from plastic found on Trindade Island – Planeta

The archipelago that hosts Trindade belongs to a chain of seamounts in the Atlantic in a straight line that goes from the State of Espírito Santo to Africa and has an area of ​​9.2 square kilometers. The island emerged about 3 million years ago after a series of volcanic explosions. Credit: Brazilian Navy

The increase in the production and consumption of new materials, based on technological development, has increased the ability of human beings to influence the earth’s geological cycle, making us capable of irreversibly altering these processes. Pollution, present above all in the marine environment and largely caused by plastic materials, can also alter the faunal and floral scenarios of the terrestrial environment.

That’s what you suggest an article published by scientists from the Federal University of Paraná (UFPR) and other Brazilian institutions in the journal Marine Pollution Bulletinfrom the ScienceDirect platform (Elsevier). The authors found new data demonstrating that man acts as a geological agent and causes the generation of new rocks from marine pollution.

The study reports the presence of rocks identical to natural ones, but composed of plastic, in the Parcel das Tartarugas, region of Ilha da Trindade – a volcanic island located 1,140 kilometers from Vitória (Espírito Santo) and administered by the Brazilian Navy. The site is an important marine reserve in the South Atlantic and a unit of Brazilian natural monuments. Rocks made of plastic have been identified near the largest nesting region of the green sea turtle (chelonia mydas) and sea snail reefs in Brazil.

The plastic rocks were found in Parcel das Tartarugas on Trindade Island. Credit: Fernanda Avelar Santos

Natural habitat of seabirds

Belonging to the so-called Blue Amazon – an area with natural wealth and abundant minerals that only Brazil can exploit economically –, the island is a natural habitat for seabirds and hosts a fragile and unique ecosystem that includes endemic species of fish and different sets of rocks.

The discovery by Fernanda Avelar Santos, a doctoral student in the UFPR’s Graduate Program in Geology, occurred during geological mapping activities on the island.

“We identified four types of plastic debris shapes, distinguished by composition and appearance. Plastic deposits on the coastal shelf covered volcanic rocks; current beach sediments composed of gravel and sand; and beach rocks with an irregular surface due to hydrodynamic erosion,” the researcher describes.

Pyroplastics found on the island: Natural processes such as erosion act on the plastic rocks and create this type of fragment. Photo Fernanda Avelar Santos

decades of existence

Plastiglomerates, analogous to sedimentary rocks, were first reported in Hawaii in 2014. Another material identified on the Brazilian island was plastistone, similar to igneous rocks and with a predominantly plastic composition. The element was found covering existing volcanic rocks in the region, which record the last episode of active volcanism in Brazil.

“We also observed pyroplastics, which were first described off the coast of England,” Fernanda reveals.

The materials portrayed in the article were viewed in the field in 2019 and are at most two decades old. The collected samples were subjected to laboratory analyzes which made it possible to recognize different forms of plastic debris. The author explains that the single site phenomenon occurs above two different types of substrates – which establish the connection between the geological substrate and the plastic forms.

Man as a geological agent

The main contribution of the article is the recognition that humans behave as geological agents and influence sedimentary deposits. Based on human interventions, the authors warn that it is necessary to question what is truly natural.

For researcher and co-author Giovana Diório, a Master’s student in Geology at the UFPR, the current behavior of people in relation to marine pollution is causing a paradigm shift in classical geology, which has a pre-anthropocene perspective, i.e. that understands the ancient processes of the Earth’s history from a conception based on the period before the significant interference of human beings in natural processes.

“The events demonstrate that human impact, as well as its residues, are so present in the environment that they have begun to influence processes previously considered essentially natural, such as rock formation”, reflects Giovana.

“Throughout geological time, the major transformers of Earth’s records have been natural. For example, tectonic processes and climate change. However, human action in current times is so pervasive that it is changing the planet at a faster rate than natural processes”, declares the lead author of the article, which exemplifies: “when we destroy mountains for mining exploration or build road construction, in weeks or a few years this mountain can be flattened. In a context of natural erosion, this process would take thousands or millions of years.”

need for conservation

The process of formation of a rock from marine pollution, for example, is fast and depends on three phases, in which the human being acts as the main geological agent: availability of plastic waste in the marine or coastal environment; disposal and disposal of waste in a seaside resort, which occurs when people collect waste to discard it or start a fire; and increasing the ambient temperature by means of fire, which melts the plastic and interacts with the beach sediments forming plastic cement and, consequently, these rocks.

For the geologist Carlos Conforti Ferreira Guedes, professor in the UFPR’s Geology Department and collaborator in the published article, it is necessary to stratigraphically preserve the human impact on the Earth. Sedimentary and stratigraphic analysis is the study and description of sediments and sedimentary rocks to interpret how they formed.

He explains that, with non-natural materials, such as garbage and plastics, occurring indiscriminately in nature, they have begun to participate in sedimentary processes and accumulate together with classical rocks, preserving themselves in what is called the geological record. “When geologists of the future analyze rocks from this period, they will be able to recognize human impact on the Earth by identifying these unnatural materials alongside natural materials,” he reflects.

Although it is not yet possible to define the impacts of these rocks composed of plastics on the environment and how they will behave in the geological record, Fernanda suggests that geosciences are starting to consider human action, as well as anthropogenic materials, as fundamental attributes in recent processes .

Anthropocene: human impact on the Earth

“Currently, the classical concepts of geology consider only natural factors as preponderant to define terms, such as the definition of rock. From an Anthropocene perspective, these criteria need to be updated and include human action as a fundamental aspect. In this way we will be able to understand how we are impacting the current Earth system and look for solutions to soften and build a geological future in harmony with natural systems”, warns the scientist.

Human impact on planet Earth is the field of study of Anthropocene researchers, a perspective that represents the moment in which humanity is becoming the active geological agent of current geological processes.

Geological time, which supports important fundamental theories of modern science – such as the Theory of Evolution – represents the recognition of a chronological scale that divides the 4.5 billion year history of the Earth and is fundamental for understanding the evolution of the planet , from its inception to as we know it today.

* This article was originally published on the journal’s website UFPR sciences. Read the original article here.

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