the "pellets" experiment in the Gulf of La Spezia – Repubblica.it

Use plastics to combat plastic pollution. It seems almost a paradox but it is possible thanks to small grains of virgin plastic that could help us understand how much the sea is really polluted and to develop future "cures" for its health. She is convinced of this Silvia Merlino, researcher at the Institute of Marine Sciences of the Cnr which, together with a team of experts and with the collaboration of Stefania Giannarelli of the University of Pisa has recently concluded a first curious experiment in the Gulf of La Spezia. Thanks to virgin plastic, it has in fact managed to trace the quantity of polluted sea in a much more effective way than with traditional methods, namely the analysis of muscles and mussels.

In January 2019, when a graduate student in chemistry contacted Dr. Merlino for a thesis on microplastics, the idea was born to study the impact of some pollutants on pellets, essentially the granules of four millimeters of virgin plastic and main constituents of plastics, of which too little is still spoken.

They are the raw material for producing most of the plastic products that we know, used both on an industrial and a household level. "The problem is that these pellets, often during transport by producers, both on land and by sea, are dispersed. In nature there is a huge quantity of pellets: from a sampling we did on the beach it was almost 30% of the various microplastics. Really many if you think that they do not come from plastics that are fragmented over time, but have been dispersed from the source ".

"The Japanese have noticed that they absorbed everything and started to think that they could be used instead of muscles, which in environmental research are real tracers to understand the pollution levels of the sea. But the mussels are complex to treat – he explains Merlin – while the pellets no. Hence the idea, similar to that of an attempt made in San Diego, but enriched by more tests, to create a first experiment in the world in the Gulf of La Spezia: to place nine cages in three different sites and at three different depths, to succeed – thanks to plastic – to trace marine pollution.

"The first results say that the values ​​of absorption of pollutants are the same in muscles and pellets, a fact which confirms that these plastics can be used as tracers for science. Pellets reach a chemical balance with water very quickly: if the water gets dirty, the pellets immediately reveal it, while the molluscs take much longer to detect it, about 20 more days ".

If nature pellets become a vehicle of important pollution, given that they move through the currents, placed in the cages used by researchers, they can therefore become a "fast and effective system to understand if a sea area is polluted. In the Gulf of La Spezia these plastics have mainly absorbed IPA (polycyclic aromatic hydrocarbons), which are derivatives of partial combustion of carbon but often come from anthropogenic sources such as coal-fired thermo-electric power stations or petrochemical plants and can cause serious damage to the environment ".