Plastics: the urge to stop the path to the sea

Implementing methods that effectively detect plastic pathways1 from land to sea and developing innovative upstream collection and retention systems, without producing additional plastic waste, is crucial as, once it reaches the sea, collecting it becomes a much more diffi cult and above all wasteful undertaking.

The massive use of plastics has spread globally during the second half of the last century, with plastics production reaching 322 million tonnes in 2015 worldwide2 (58 million tonnes in Europe). Plastics have become an indispensable component of our lives due to their many advantages, including light weight, strength and relative resistance to water. However, these advantages become a problem when plastic is not properly disposed of (or reused) and released into the environment, where it can be transported over long distances.

Plastic waste can be substantially reduced into two categories: microplastics (MicP) with dimensions <5 mm and macroplastics (MacP) with dimensions ≥5 mm. A third category of plastic fragments can also be considered perhaps even more insidious given their microscopic size which makes them difficult to sample and monitor: nanoplastics (1-100 nm). Plastic, not decomposing in a short time and slowly degrading into smaller and smaller fragments, risks persisting for hundreds (if not thousands) of years in ecosystems and entering trophic nets and then ending up on our tables. According to a 2014 study3, it has been estimated that at least 5.25 trillion plastic particles float in the world’s oceans, weighing close to 270 thousand tons. MicPs can also become vectors for harmful substances, such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), and by dispersing in the water column, thanks to their small size, can also be ingested by a multitude of organisms. Plastic pollution in watercourses and seas is therefore an environmental problem that affects everyone globally. Initially it was thought that marine litter was mainly derived from fishing and tourism-related recreational activities, however, as research progresses, it has been determined that most of the pollutants in the sea come from land-based litter that is mainly transported through rivers. Numerous studies have also shown that plastics account for the majority of marine litter. A recent research project4 has revealed the highest levels of microplastics ever recorded on the seabed. The sea in question is the Tyrrhenian Sea: up to 1.9 million fragments deposited in a thin layer were found in just one square metre. The study also showed that these fragments were transported in a closed sea, such as the Mediterranean, even by ocean currents.

As we have understood, the plastics released into the environment represent a serious danger to aquatic ecosystems (and not only) all over the world, with inevitable implications for our health.

 

 


1Yasuo Nihei, Takushi Yoshida, Tomoya Kataoka, Riku Ogata. High-Resolution Mapping of
Japanese Microplastic and Macroplastic Emissions from the Land into the Sea. Water, 2020; 12
(4): 951 DOI: 10.3390/w12040951

3Eriksen, M.; Lebreton, L.C.M.; Carson, H.S.; Thiel, M.; Moore, C.J.; Borerro, J.C.; Galgani, F.;
Ryan, P.G.; Reisser, J. Plastic pollution in the world’s oceans: More than 5 trillion plastic pieces
weighing over 250,000 tons afloat at sea.
 
4Ian A. Kane, Michael A. Clare, Elda Miramontes, Roy Wogelius, James J. Rothwell, Pierre
Garreau, Florian Pohl. Seafloor Microplastic Hotspots Controlled by Deep-Sea Circulation.

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