Since 2016, Legambiente and ENEA have been monitoring the problem of microplastics from inland waters to lake basins. Italian lakes are close to densely populated and highly productive areas of the country, in particular subalpine ones, and are an essential and strategic water supply for agriculture, industry, fishing and watering. In addition, they are an important resource for recreation and the local tourism industry.
During Goletta dei Laghi, Legambiente’s national lakes monitoring campaign, investigations were carried out on the microplastics in the lakes of Iseo, Garda, Como, Maggiore, d’Orta, Santa Croce, Cavazzo, Trasimeno, Bracciano, Bolsena, Albano, Paola, Matese and Varano. The investigations’ activities focused not only on the center of the lakes but, following the adopted methodology, also the main tributaries and emissaries, to obtain further information about the phenomenon.
To extend the indicators of the study, Goletta’s technicians also sampled the lakes’ beaches and shores, following another procedure developed with ENEA. Those four-year investigations revealed microplastics in all the samples examined, despite the morphological and ecosystem differences of the selected lacustrine basins.
At the end of the 2017 campaign’s edition, Legambiente and ENEA published a report of the preliminary study done in 2016 and those relating to the analysis, subsequently introduced, on the emissary and inlet water bodies of the main lake basins. In 2016 six lakes of six Italian regions (Lake Maggiore, Iseo and Garda in Lombardia, Piemonte, Trentino Alto Adige and Veneto; Lake Trasimeno in Umbria, lakes of Bolsena and Albano in Lazio) were taken into consideration, in 2017 the study was extended to two other lakes (Como and Bracciano) and focused on entrances and exits of the main river tributaries in order to highlight the influence of water treatment plants.
The concentration of microplastics (measured in number of particles / m3) found in the samples taken downstream to the treatment plant were in some cases up to 80% higher than those detected upstream.
This data was matched to the microbiological analysis Legambiente carried out since the birth of the campaign on lake waters aimed at detecting water treatment plant malfunctions or inadequacy.
The study highlighted the existence of an undeniable relationship between municipal discharges, wastewater, urban outflows and rainwater from the river and lake system reaching the sea. It is therefore important to determine how to reduce the role of the freshwater system as a main source of microplastics for the marine environment.