Riverine microplastics in the Hungarian Danube: distribution, sources, and characterisation

Microplastics, defined as plastic particles smaller than 5 mm, have become a pressing global environmental issue. Ineffective recycling practices allow plastics to enter and persist in the environment, breaking down into smaller particles that travel through pathways like rivers. These microplastics can accumulate in ecosystems, where they pose significant risks to flora, fauna, and potentially human health. This study focuses on riverine microplastic pollution in the Hungarian section of the Danube River, Europe’s second-largest river, as well as in its tributary system. The Danube is a vital water source for Budapest and plays a crucial role in the region’s economy and ecological balance. Water samples were collected at varying river depths using a Multilevel Manta Net. Advanced laboratory techniques, including Fourier-transform infrared spectroscopy and digital microscopy, were used to identify and characterise microplastics collected. Additionally, flow measurements were conducted to estimate mass-flux rates. These findings contribute to developing practical measures for understanding, managing, and reducing microplastic pollution in freshwater systems. The findings revealed an average microplastic concentration of 0.311 mg/m³, corresponding to 142 particles/m³. The most frequently identified polymers were polystyrene, polyethylene, and polypropylene, which appeared predominantly as fragments, foam, and flakes. The microplastics exhibited a range of colours, including yellow, black, grey, and green.