Environment: ENEA in the field for the microplastics emergency in Italian lakes

01 June 2022 Last Updated: 08 September 2022

Studying and characterising microplastics in Italian lakes, analysing the microbial communities that colonise their surface and assessing the risks to ecosystems, fish species and human health. This is the objective of a series of studies conducted by a team of researchers from ENEA and CNR in collaboration with Goletta dei Laghi and Legambiente, on some of Italy's lakes to "light a beacon" on microplastics in freshwater - the first survey was only launched in 2012 in the USA - and fill the knowledge gap with respect to the numerous studies conducted instead in the seas and oceans around the world. The activities were presented just days before World Environment Day, which was established by the United Nations in 1972 and is celebrated every year on 5 June to raise awareness about environmental protection.

Despite the fact that water covers almost 70% of our planet, fresh surface water, i.e. the water available to sustain and feed 7.9 billion people, represents a small part of the planet's total water, only 1.2%, but it is the one most used for the various anthropic uses and over the years it is increasingly at risk: according to UN estimates[1] by 2050 there will be more than 5 billion people at risk of a shortage of clean water due to continuous withdrawals, pollution, climate change, contamination by heavy metals, toxic substances and microplastics.

With this objective in mind, starting in 2016 ENEA, in collaboration with Legambiente, undertook a process of analysis, monitoring and study of the phenomenon of microplastics in lakes, the plastic microparticles smaller than 5 mm, now considered emerging pollutants, present in a widespread manner and in close relation with the natural elements present in each ecosystem. The results of the studies were published in 2018 in Science Direct (Environmental Pollution journal, Elsevier).

"The results of the first study in the three main sub-alpine lakes of Northern Italy, Maggiore, Iseo and Garda, during the Goletta dei Laghi campaigns, showed an average abundance of microplastics per km2 of 39,000, 40,000 and 25,000 respectively - comparable with the data of the great American lakes and some Swiss lakes," emphasises Maria Sighicelli of the ENEA Laboratory of Biodiversity and Ecosystem Services. "As far as shapes and materials are concerned, the sampling of 22 transects from which 843 particles were selected, 390 of which were analysed by infrared spectroscopy (FT-IR), also showed the dominant presence of fragments (about 74%), followed by polystyrene pellets, almost 20% of the total, polyethylene (45%) and polypropylene (15%), with higher concentrations near river inputs and reservoir narrowings.

In the subsequent campaigns of the Goletta dei Laghi conducted in the main Italian lakes, the ENEA-Legambiente team was joined by the ENEA-Legambiente team in collaboration with the CNR Water Research Institute (IRSA-CNR) in Rome to study the biofilms associated with microplastics, the so-called platisphere, i.e. the set of microbial communities that colonise the surface, a topic of considerable scientific interest and relatively new. The results of this first study were published in Science Direct (Water Research journal) in 2020.

"By means of molecular biology and laser scanning microscopy techniques that investigated the diversity and structure of the plastisphere, the microbial composition of the bacterial component of these communities was defined, which showed that it differs strongly from that of planktonic communities and is mainly dependent on the lake sampled," says Francesca Di Pippo of IRSA-CNR in Rome. "There is, moreover, evidence of the key role of some species that constitute the 'core' of these communities, and that are characteristic of biofilms present in many aquatic environments. Furthermore, the presence of bacteria involved in the biodegradation processes of plastics has been highlighted, while studies aimed at understanding the adhesion mechanisms of microorganisms to microplastics, the biodegradation processes, and the role of microplastics as a vehicle for transporting and spreading antibiotic resistance genes, pathogenic microorganisms and/or microalgae that are toxic to aquatic organisms and humans are still underway'.

Finally, thanks to an ENEA research team with IRSA-CNR in Verbania, it was possible to assess the potential risks of the presence of microplastics for the health of fish species and, through their consumption, for human health, another aspect of great scientific interest. The results of this first survey in sub-alpine lakes in Northern Italy on the ingestion of microplastics by perch (Perca fluviatilis), one of the most widespread and commercially exploited freshwater species, were published in 2021 in Science Direct (Environmental Pollution journal).

"From Lakes Garda, Como, Orta and Maggiore, we took 80 perch specimens to quantify and analyse the microplastics present in the gastrointestinal tract by means of chemical and morphometric analysis," emphasises Silvia Galafassi of IRSA-CNR Verbania. "In 86% of the individuals we found anthropogenically derived fragments, with lowest averages in Lake Como (1.24 ± 1.04) and highest in Lake Garda (5.59 ± 2.61). The polymers most frequently found were those that are widely used in industry - polypropylene (PP), polyethylene terephthalate (PET), polyamide and polycarbonate; furthermore, fish with a higher microplastics content were found to have a lower frequency of feeding, an effect that highlights how microplastics directly interfere with the predatory activity of perch, as already highlighted for other species.