Why are plastic rocks found across 5 continents, and what are the threats?

Subject: Environment

Section: Pollution

Context:

The emergence of plastic rocks across five continents has been catching attention of experts across the world.

More on news:

Plastic rocks are found in various locations across the globe.
They have surfaced on coastlines and inland areas in 11 countries spanning five continents.
In the geological processes, the mass of plastic deposited annually by humans is estimated at 22-48 million metric tonnes.
The direct reason behind the formation of plastic rocks is the plastic pollution humans are pouring into the environment.
These are primarily composed of compressed rock and discarded plastic polymers.

About Plastic rocks:

Plastiglomerate is a rock made of a mixture of sedimentary grains, and other natural debris (e.g. shells, wood) that is held together by plastic.
There is a debate in the scientific community with regard to the nomenclature for these plastic-infused rocks.
Various terms, including plastistone, plasticrust, plastiglomerate, plastitar, anthropoquinas, and plastisandstone have been proposed to describe the diverse ways in which these formations develop.

Discovery of Plastic Rocks:

Geologist Patricia Corcoran discovered the first plastic rock in Hawaii, and coined the term ‘plastiglomerate.’
Recently, Deyi Hou (an associate professor of environment at Tsinghua University, and his team) reported the first plastic rocks found inland, shedding light on the chemical bonding between plastic and rock.
The team’s extensive review confirms the existence of plastic rocks on five continents and in 11 countries.

Formation Of Plastic Rocks:

Hou and his team delve into the diverse methods through which plastic rocks can form.
Burning is one of the common mechanisms through which plastic debris melts during activities, such as campfires or waste burning, solidifying within the mineral matrix as it cools.
Ocean waves also play a vital role in the formation of plastic rocks.. Oil containing large amounts of plastic on reaching beaches after spills,firmly attaches to rocks . They then undergo partial evaporation and solidify.
Chemical binding which is catalyzed by sunlight-induced plastic oxidation also contributes to plastistone generation.
Plasti Stones can be made from a variety of plastic wastes. These include plastic bags, bottles, fishing gear, maritime ropes, and agricultural mulching films can undergo lithification with rocks, giving rise to the formation of plastistones

Where are they currently found?

As per the reports, plastic rocks have been found in Brazil, Bangladesh, Hawaii, China, Japan, India, Italy, Portugal, Peru, the United Kingdom, and Spanish Curry Island.
Their widespread occurrence shows the global nature of the plastic pollution crisis.

What are the environmental implications?

Plastic rocks alter microbial communities within soil and nearby environments, impacting local ecosystems.
There is lower microbial diversity in the plastistone compared to the adjacent soil.
The phenomenon raises concerns about the potential release of microplastics into the environment.
These rocks shed microplastics, tiny pieces of pollution which have spread across the globe and even into human and animal bodies.
Plastic rocks will continue to increase as a part of natural geographical processes and stick around for a long time.
They are likely to increase in places where plastic pollution is worse, like cities, mulched agricultural soils, and plastic waste dumping sites.