University researchers lead study of nanoplastics in Portugal's rivers

A team of scientists from Science and Technology faculty of the University of Coimbra have been studying the damage that nanoplastics have been generating in Portugal’s freshwater ecosystems.

The results have been published in the scientific journal Fungal Ecology, focused on the process of leaf decomposition, considered a crucial indicator for assessing the function and quality of freshwater systems. For this, the team used five species of hyphomycetes - aquatic fungi that play the main role in the decomposition of leaves.

In experiments carried out in the laboratory, with fungi isolated from Swiss streams and leaves harvested in Coimbra's Parque Verde, on the bank of the Mondego river, researchers found that exposure of the fungi to nano-sized plastics (100nm and up to ~ 100mg / L), interferes with their ability to break down the leaves.

"We have shown that nanoplastics reduce the ability of fungi to decompose leaves at concentrations of 1.6 mg / L. This value is about four to six times higher than the concentration of microplastics reported in the U.S. and Europe," said Seena Sahavedan, a researcher at the Center for Marine and Environmental Sciences at Coimbra and the principal author of the scientific paper.

"Our findings document that nanoplastics can interfere with ecological functions in aquatic ecosystems. However, since different fungi differ in their sensitivity, it remains to be seen what would happen in a natural multispecies system," notes the researcher.

Pollution from plastics is known to be a serious threat to aquatic environments. Plastics production is estimated at 8,300 million metric tons and it is predicted that by 2050, about 12,000 million tons of waste plastic will either be in landfills or in the natural environment.

It is estimated that every year, from the rivers of the world, between 1.15 and 2.41 million metric tons of plastic will enter the ocean. Plastics can be fragmented into particles of very small sizes (‘nano,’ that is, one hundredth of a millimetre) whose environmental effects are still unknown, but of great concern.

Sahavedan points out that nanometre-sized plastics are also used in a wide range of products such as toothpaste, water paints and biomedical products, also, polystyrene, “which is a very versatile type of plastic and is nowadays used in a wide range of products - food packaging, cosmetic containers, medical pipettes, etc- which are single-use products and are not biodegradable with the polystyrene molecules contributing significantly to the debris found in aquatic systems."

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