At the Slovenian Water Research Institute, most of our research into microplastics in water has been carried out at sea. The results of this research show that the Adriatic Sea is among the most heavily polluted. As part of the DeFishGear project, in which the Institute for Water is collaborating with 16 partners from 7 countries, fishermen collected almost one tonne of waste from their nets whilst fishing at sea over a 14-month period (larger pieces of waste caught in nets and discarded nets – the latter accounted for approximately 30 per cent). Larger pieces take over 100 years to break down into smaller particles. Each of us can help reduce the input of microplastics into our waters: by sorting waste correctly, choosing non-synthetic clothing (where possible) and opting for microplastic-free cosmetics.
The laboratory of the Slovenian Water Institute has also participated in research on the Danube, the Rhine, the Dal and the Po rivers. Of the rivers analysed, the Po River contributes the largest amount of microplastics to the sea – as much as 360 tonnes per year. Among the largest sources of microplastics via rivers are municipal sewage treatment plants – in other words, each and every one of us. As (micro)plastics break down, they release toxic substances that have already been identified as carcinogens and endocrine disruptors. Seventy per cent of microplastics entering the sea come from land. Land-based sources include tourism and recreation, industry, urbanisation, rivers and sewage discharges. Marine sources of plastic waste include maritime transport, fisheries and mariculture.
Concentrations in Slovenian waters varied greatly, ranging from 150,000 to over 3,000,000 particles per square kilometre. The results are strongly influenced by weather conditions at the time of sampling. Microplastic levels in the Adriatic Sea are comparable to the high levels of pollution found in the north-western Pacific Ocean. Experts from the Slovenian Water Research Institute also participated in analysing currents in the Adriatic – using a specialised model, they identified areas with higher concentrations of waste (‘garbage patches’). Analyses have also revealed the presence of microplastics in the digestive tracts of fish; the next generation of research will focus on even smaller particles – nanoplastics – for the analysis of fish flesh.
The Slovenian Water Institute has a fully equipped laboratory for carrying out microplastic analyses – from sampling and sample analysis right through to the analysis of the chemical composition of the particles. As part of the DeFishGear project, sampling methodologies have been developed for water surfaces, sediments and organisms.
The DeFishGear project is funded by the IPA Adriatic programme, with a total project value of over 5 million euros. In this project, the Slovenian Water Institute is collaborating with 16 partner organisations from seven countries – the project is coordinated by the lead partner from Slovenia: the National Institute of Chemistry.