Freshwater ecosystem example: Image: Education Images

Study identifies risk of nanoplastics, metals in freshwater

International study is latest in series of startling warnings 

Yet another international study – this time led by a team of researchers from the University of Coimbra – has identified the risks that the contamination of nanoplastics and metals poses to the proper functioning of freshwater ecosystems, the higher education institution said on Monday.

In a press release sent to Lusa news agency, the University of Coimbra (UC) reported that its latest study presents “the possible impacts caused by this co-contamination of freshwaters due to realistic concentrations of these materials, also concluding that the functionalisation of the surface of nanoplastics facilitates the adsorption of metals, thus modulating the impacts caused by metals on aquatic fungi”.

Entitled “Does functionalised nanoplastics modulate the cellular and physiological responses of aquatic fungi to metals?“, the study, carried out by a team of researchers from the Faculty of Science and Technology of the University of Coimbra (FCTUC), in collaboration with Harcourt Butler Technical University (India) and Konkuk University (South Korea), was published in the journal Environmental Pollution.

Juliana Barros, first author, told Lusa how “there has been a growing interest in understanding the combined effects of pollutants on organisms since their coexistence is an inevitable reality.

Nanoplastics are plastic fragments of less than 1,000 nanometres (nm), approximately the size of a virus, commonly used by the pharmaceutical, cosmetics and cleaning products industries”, she added.

According to the study’s authors, freshwaters are particularly vulnerable to contaminants “since they serve as the primary interface between terrestrial and aquatic compartments” and are therefore “often more susceptible to the adverse effects of emerging contaminants than other compartments.

Mining activities contribute to the occurrence of metals in freshwater systems, leading to the coexistence of metals with emerging contaminants such as nanoplastics. 

In small watercourses, the decomposition of organic matter is a crucial process, responsible for the transfer of energy and nutrients through the trophic levels of the food chain,” the study adds, explaining that “aquatic hyphomycetes are the main mediators of this process”.

“These fungi are able to modify the recalcitrant components of the leaf, thus improving its palatability and nutritional quality for consumption by invertebrates.” 

During the research, a laboratory test was carried out with realistic concentrations of nanoplastics, with two types of nanoplastics: regular polystyrene and carboxylates.

The test made it possible to study “their combined effects with copper on the cellular processes and growth of a common and widespread aquatic hyphomycete (Articulospora tetracladia).

“Nanoplastics, copper and their co-exposure to the aquatic hyphomycete A. tetracladia can lead to oxidative stress and rupture of the plasma membrane. In most cases, exposure to treatments containing functionalized nanoplastics combined with copper showed a greater cellular response and suppressed the growth of the fungus”.

All these studies are ‘published’/ announced in the press, and ‘on the world goes’ – with very little in the way of tangible improvements.

Warnings of contamination posed by micro/ nano plastics have been sounded for years. Back in 2019, researchers at Porto University published their conclusions that there were “more microplastics in the Douro estuary than fish”.

Earlier this year, a study also carried out at Coimbra University revealed that microplastics in aquatic systems have been found to accumulate dangerous bacteria resistant to antibiotics.

There have been repeated warnings about the condition of the country’s rivers too.

Source material: LUSA