If seas and oceans risk turning into plastic soup, Italy's lakes and rivers are no exception: microplastics in the country's inland waters are now an established fact. A comment from the president of Legambiente.
The presence of plastics in water is not a problem weighing heavily only on the marine ecosystem, but also on those of lakes and rivers. The particular enemies of freshwater are microplastics — plastic particles measuring less than five millimetres. An increasingly widespread form of pollution, yet one that is difficult to quantify and impossible to eliminate entirely, precisely because of their small size. Microplastics come from the fragmentation of waste dispersed in the environment, but they can also be a primary form of waste, as in the case of pre-production industrial pellets, textile fibres from washing machines, or microbeads used in cosmetics.
While the study of the dispersal of these microparticles at sea dates back to the 1970s, the awareness that inland waters are not immune to this phenomenon is far more recent. The consequences of their presence in aquatic environments are manifold: ingestion by organisms, with the resulting false sense of satiation that leads them to stop feeding; bioaccumulation in the food web; toxicity from the absorption of pollutants present in the environment, as well as from additives contained in the plastic; and the transport of alien species that travel on the fragments.
It is for this reason that, for two years, Legambiente and Enea (the National Agency for New Technologies, Energy and Sustainable Economic Development) have, during the Goletta dei laghi campaign, launched a specific monitoring programme to study the problem of microplastics in inland waters. During 2017, six lakes were sampled (Iseo, Maggiore, Garda, Como, Trasimeno and Bracciano), covering a total of almost 50 kilometres traversed by the manta trawl, a special net used to capture micro-pollutants.
For the first time, a number of inflowing and outflowing watercourses were also sampled, both upstream and downstream of water treatment plants — true conveyor belts for everything they inappropriately receive along their course as they pass through inhabited areas: the River Oglio for Lake Iseo, at both its inlet and outlet; the Adda for Lake Como; the Sarca at its inlet into the Trentino section of Lake Garda; and the Mincio as the outflow.
Lake Como and Lake Maggiore proved to be the most polluted — that is, those with the highest average particle density per square kilometre, at 157,000 and 123,000 particles respectively. In general, the highest concentrations were found precisely at the mouths of inflowing rivers and downstream of the discharges from sewage treatment plants. Worrying results were also recorded for Lake Bracciano, which, marked by a particularly dry summer and excessive water abstraction, has an average of 117,000 particles per square kilometre, and for Lake Iseo, with 63,000 particles. Somewhat better results were recorded for Lake Garda, with 10,000 particles, and Lake Trasimeno, with 7,914 particles. Among the rivers, the Oglio, a tributary of Lake Iseo, recorded the highest particle concentration, with an increase of 81 per cent downstream of the treatment plant.
In short, lakes and rivers are heavily contaminated by microplastics. This is due to poor waste management upstream and the low quality of sewage treatment, whose discharges, even today, far too often end up in water without undergoing the necessary treatment. Tackling this problem requires action on multiple fronts. The recent approval by Parliament of laws banning microplastics in cosmetics from 2020, and non-biodegradable and non-compostable cotton buds from 2019, is an excellent signal and places Italy at the forefront on this issue; however, a significant tightening of waste management is needed immediately, just as it is necessary to launch widespread awareness-raising and prevention initiatives to reduce the input of these insidious pollutants.