Nikolai Maximenko and Jan Hafner of the University of Hawaii explain the results of their studies on plastic in the oceans and the movement of debris caused by currents, at the Wwf in Milan.
Every year around eight million tonnes of plastic end up in the world's oceans, of which only eight thousand are removed by associations and volunteers. As time passes and water erosion takes its toll, the waste becomes ever smaller, breaking down into particles that are practically invisible to the naked eye, known as microplastics. What results is a veritable "plastic soup". That is how scientist Nikolai Maximenko described it; he, together with Jan Hafner of the International Pacific Research Center, presented their studies on waste islands and the microplastics contained in the oceans at the Friday 22 September presentation held at the Wwf headquarters in Milan, entitled L'inquinamento della plastica attraverso gli occhi della scienza.
The scientists stressed that the accumulations of debris forming in the waters are extremely dangerous for navigation, for tourists and for marine species, which can not only ingest microplastic particles but can even colonise the larger ones and thereby travel from one place to another, altering entire ecosystems.
Maximenko and Hafner spoke about the difficulty of creating models to study the movement of microplastics in the oceans, due above all to wind patterns. This is why highly sophisticated instruments are needed, along with satellites and floating buoys that make it possible to collect debris. Moreover, much of the waste is impossible to trace: there are several hypotheses as to this "disappearance". Some particles settle on the seabed, others break down into even smaller fragments known as nanoparticles, while others still end up in Arctic glaciers, on beaches or in uninhabited areas of the Earth. We must not forget, too, that large quantities are ingested by fish, birds and other marine animals.
Researchers at the University of Hawaii created a model to find out where the debris carried by the tsunami that struck Japan on 11 March 2011 had ended up. The scientists formulated hypotheses about its trajectory based on observations and mathematical analyses. Confirming the predictions of Maximenko and Hafner, in September 2011 the Russian vessel Pallada discovered a Japanese fishing boat in waters off Midway Atoll, to the west of Hawaii. The tsunami transported 1.5 million tonnes of material, including large containers, fishing nets, parts of refrigerators and pieces of wood, carrying them to Canada and the United States. Remarkably, an entire dock section from the port of Misawa was found in Oregon: on this floating platform more than one hundred animal and plant species had travelled, including starfish, crabs, algae and even insects.
"Whereas for other ills, such as cancer, there is unfortunately no solution, for replacing plastic a solution does exist," said Marco Astori, founder of Bio-on, the company that promoted the event and has created a biopolymer capable of biodegrading in water, which could therefore be a valid alternative to plastic. Bio-on intends to promote research into microplastics in the Mediterranean as well.
"If we don't act at the source, whatever we clean up will be created again and will keep coming back," is the warning from the Hawaiian oceanographers — not to mention that microplastic particles also end up in drinking water. According to Maximenko and Hafner, it is essential to press ahead with research, and it is encouraging that there are young scientists engaged with this issue.
"It is impossible not to see the problem, and it is time to become aware of it," the two researchers added. And some have truly become aware: there are, in fact, a considerable number of cities moving in the right direction. San Francisco has banned the sale of plastic bottles, in London the well-known Borough Market will do the same within a few months, and from 2012 Costa Rica will gradually phase out single-use plastic.
