Ljubljana - To highlight the problem of plastic pollution, over 1400 students in 100 Slovenian schools joined forces with scientists within the EU's Plastic Pirates project. Over the course of one year, young people helped scientists to sample microplastics in rivers, which contaminated more than three-quarters of the rivers analysed.

The leader of the Slovenian "pirate mission" was Mateja Grego from the Piran Marine Biological Station of the National Institute of Biology, and she presented the results of the analysis of microplastic content in the 44 samples analysed.

Pieces of plastic smaller than 5 millimetres were found at 75% of the sample-taking points, with most microplastic particles found in the flowing reservoir lake between Krško and Brežice in the Sava River, Ecologists Without Borders reported.

Of the 32 rivers analysed, only six were unpolluted, but only repeated sampling will provide the true picture. The most common material found in the rivers was polyethylene in the form of films, most likely as a result of decaying shopping bags, packaging and agricultural films.

The presence of polystyrene, which is most likely to originate from the packaging and construction sectors, has been detected in the vicinity of cities, for example in the second sampling of the Ljubljanica River near Vrhnika and in the Drava River near Maribor.

"This kind of research clearly reveals key challenges and solutions that must include systemic change. Without our young plastic pirates, we would still be guessing about the level of microplastic pollution in our rivers for a long time," said Mateja Grego.

The project, which originates in Germany, addressed the issue in a holistic way, so the young pirates also analysed waste on the banks of rivers in 19 larger cities and towns across Slovenia, with cigarette butts and plastic bottles being the most commonly found categories of waste there.

The Plastic Pirates from the Valentin Vodnik Primary School shared their thoughts on the project online on Wednesday, while the organisational side of the project was highlighted by the Communications Manager, Katja Sreš from the Ecologists Without Borders association.

"The motivation of Slovenian schools and their additional commitment has exceeded all expectations. We are delighted that confirmation of the excellent cooperation is also coming from abroad, and we are committed to continuing this project," she said.

The project is being finalised under the auspices of the current EU presidency trio, but this is only the first stage, as they aim to develop the project and extend it to other EU member states and beyond, Sreš added.

The online audience was also addressed by Education Minister Simona Kustec and the head of the ministry's Science Division, Peter Volasko.