Characterization meso- and macroplastic in the River Meuse in the Netherlands – difference in composition and characteristics at two locations

Plastic pollution is a relatively new problem and it is thought increase due to climate change. Plastic litter has various (in)direct effects on factors related to river systems, such as wildlife.
In this study, the focus was on mesoplastic (5 mm – 25 mm) and macroplastic
(> 25 mm) as these categories make up large part of the mass of plastic litter. Samples were collected with a trawl net at different depths (surface, middle, bottom), different sides of the river (left shore and right shore), and at different sides of the boat (port and starboard) at Eijsden between 24th of April until 1st of May 2023.
Plastic particles were categorised using OSPAR and a scan with protractor was made. From these scans, the feret, surface area, and circumference of the plastic particle was determined.
Moreover, the concentration of plastic particles and surface area per 1000 m3 was calculated. Results were compared to samples taken at Sambeek collected between 13th of April until 19th of April 2023. At Eijsden, more identifiable plastic particles were found and particles were bigger. The concentration of plastic particles was higher at Eijsden than at Sambeek. Results showed that fragmentation of plastic occurred whilst traveling downstream. It could be that plastic items were to fragmented (< 6 mm) to be caught by the trawl net. This would also explain the decrease in concentration of plastic particles found. The relationship between discharge and concentration of plastic particles could not be determined in this study, but future research with more data points during the discharge peak could provide a more comprehensive view.
More cooperation between the Netherlands and upstream countries is needed to reduce the concentration of plastic particles found at Eijsden.