Mayday, plastic in the sea!

Marine litter emergency management problems and strategies

A sea of waste: estimates

If the extreme heat waves and intense rains of this summer make us talk about climate change, another emergency, which affects everyone, remains silent in the background: that of plastic pollution and other waste in the seas.

The difficulty in finding reliable data, given the extent of the oceans and the presence of currents and winds that move the visible pieces, does not prevent us from making approximate estimates, which are however alarming: the total is around 150 million tons of waste already reached, with an average of 10 million a year, as if a garbage truck ended up in the sea every minute.

Disposable bottles and bags are the main type of waste, but there is no shortage of damaged fishing nets, cables, sanitary towels, tampons, cotton buds, condoms, cigarette butts, disposable lighters and, because of the Covid-19 pandemic, disposable masks and gloves.

Unlike organic materials, plastic takes hundreds of years to completely degrade; therefore it tends to be transported by ocean currents and to accumulate, to create real floating islands of plastic, such as the famous “Great Pacific Garbage Patch”.

However, UNEP, the United Nations program for the environment, claims that 70% of total marine litter rests on the seabed: an invisible part that threatens the health of the seas and underwater fauna in an even more worrying way.

Microplastics and macro problems

Larger pieces of plastic can trap fish and birds: recurring are the cases of seals, dolphins and turtles getting entangled in plastic residues and nets lost at sea, with more or less serious consequences ranging from minor injuries to death.

But the biggest problem is the ingestion of waste by various marine species, mistaken for food given their spread and size. In fact, plastic, in its long process of fragmentation and with the help of sunlight, salt water and waves, breaks down into smaller and smaller particles, easy to ingest, thus entering the food chain.

Microplastics are not only the result of the fractionation process, but are often already contained within our consumer products, such as toothpaste, cosmetics, and personal hygiene products.

Over 10% of fish contain plastic in their stomach and even plankton, at the base of the food chain, are believed to be able to eat plastic. Humans are not exempt: ingested microplastics release chemicals used during their manufacturing process, such as toxic metals and phthalates, with little-known but certainly harmful consequences for our own health.

Problem management strategies

Prevention policies are clearly the starting point for tackling the problem: the European Union, for example, has adopted policies aimed at reducing waste, such as packaging, or eliminating it in its entirety, as is the case with some products of single-use plastics, and aimed at increasing recycling rates.

And for waste already dispersed at sea? For their collection, technology comes to our aid. This is the case of Crab Robot, a project carried out by the Biorobotics Institute of the Scuola Superiore Sant’Anna in Pisa.

It is a crab robot that does not damage the ecosystem and is able to clean the seabed from plastics and microplastics; the prototype, tested in Livorno, is equipped with six sprung legs that allow it to move around obstacles, up to 200 meters deep.

In addition to the work of “sweeper”, it is equipped with internal cameras that allow you to record images and then explore the seabed; it is also able to interact in real time with researchers, who can guide it remotely.

The idea is to equip it with an additional automated arm to collect bags, bottles and other waste of relative size present in the water. A small but great help in this struggle that is only just beginning.

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