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Microfibers vary between 3 to 8 mm but are extremely fine, with less than a 0.1 mm diameter, and which come mainly from home and industrial washing machines. Credit: Lucy Woodall/London Natural HIstory Museum.

Science

A new collaborative study by researchers at the University of Barcelona, Spain, and the University of Plymouth, United Kingdom, has revealed that two thousand meters below the seas of southern Europe, marine sediments act as a sink for textile microfibers.

A washing machine can release up to 700,000 microfibers to wastewaters in one use, making it one of the most common forms of plastic pollution in the marine environment. But despite their bright colors and vast quantity, microfibers have barely been studied. The little research that has been done has already begun to demonstrate that these tiny strands of material are being ingested by both bottom-dwelling and open-water organisms, making further research into the pollutant extremely important.

The researchers gathered 29 seabed sediment samples from southern Europe, an area which spanned from the Cantabrian Sea to the Black Sea. Upon analysis, their results showed that cellulosic fibers, for example, cotton and linen, dominated over synthetic polymers and that higher densities of fiber are found in the Cantabrian Sea compared to the Black Sea. They also discovered that depth was no barrier to the spread of microfibers with 20 percent of those analyzed originating from sediment two thousand meters below the surface. “Textile microfibers seem to concentrate at the bottom of submarine canyons, while the quantity in the continental slope is significantly lower. This suggests microfibers, probably coming from the ground are accumulated in the continental platform, from where they are swept and taken by several oceanographic processes to marine hollows through the natural conducts -marine canyons" says Anna Sánchez Vidal, lead author on the study.

Some of these synthetic microfibers such as polyester are made of plastic, which does not degrade quickly and can be easily incorporated into the food chain. “Recent results show ingests of microplastics by different organisms and in different ecosystems, but the specific impact on the organisms is unknown," highlights Anna Sánchez Vidal. "It can depend on a wide range of factors, such as features of the microfibers (size, abundance) or these chemical substances these absorbed, as well as the physiology and ecology (size, feeding, whether they excrete or accumulate, etc.) of marine organisms."

Interestingly, the researchers note that the ability of a fiber to shred may play an important role in controlling the spread of fibers to the deep sea. The higher abundance of cellulose fibers over synthetic ones, despite only making up 35 percent of the world market, could be explained if fibers such as cotton or linen shed more easily. Furthermore, cellulosic fibers are significantly denser than seawater and are thus more likely to sink. Understanding how the function and shape of microfibers affect their ability to pollute is going to be an important area of new research. "We need to advance in research and innovation in the textile industry, in the design of effective filters for washing machines, in the treatment of wastewaters, and the promotion of sustainable clothing," concludes Sánchez Vidal.

By Ellis Moloney

Sanchez-Vidal, A., Thompson, R., Canals, M., & de Haan, W. (2018). The imprint of microfibers in southern European deep seas. PLOS ONE, 13(11), e0207033. doi: 10.1371/journal.pone.0207033

This research has been supported by Ministerio de Economía, Industria y Competitividad, Ministerio de Educación, Cultura y Deporte, Agència de Gestió d’Ajuts Universitaris i de Recerca, Institut d'Estudis Catalans (IMarCat) and Directorate-General for the Environment.