Sources of meso- and macroplastic pollution in the river Meuse and the effect of the sup directive

Plastics have become a serious environmental hazard. Compared to marine plastic contamination, riverine plastics is relatively new and understudied. In response to the accumulated waste, the European Union implemented the Directive on Single Use Plastics (SUP), which aims to reduce plastic waste from the TOP 10 most commonly found plastic items on European beaches. In the Netherlands, research on macro- and mesoplastic present in the water column of the river Meuse has been conducted by Rijkswaterstaat since 2022. However, sources of plastics and the effect of the SUP Directive on plastics in the Meuse have not been investigated. This study therefore aimed to assess the sources of meso- and macroplastic litter in the river Meuse and to assess the effect of the recently implemented plastic regulations on plastic in the Meuse.

Data on macro- and mesoplastic present in the water column of the river Meuse was collected with trawl nets on starboard and port side of a boat in April 2024. Samples were taken at the surface, middle and bottom of the river, at locations Eijsden (baseline for plastic entering the Netherlands) and Sambeek (halfway through the Meuse). Data was first spatially compared between Eijsden and Sambeek to determine the source countries. Sources were defined as locations, pathways or activities from which plastics enter the river. These were quantified by three characteristics: the ratio between meso- and macroplastic objects, the country of origin, and the potential pathway derived from the OSPAR River Monitoring method. Data on plastics that fall under the SUP Directive were then temporally compared with existing data from 2022 and 2023, and with data from the current study of 2024. Two plastic characteristics that were used were the age of plastics and the plastic concentration in plastic pieces per 1000 m3. Differences between years provide information on the effect of the SUP Directive on the plastic objects in the Meuse.

Spatial differences showed that macroplastics were more prevalent than mesoplastics in Eijsden, whilst in Sambeek this was the reverse. The prominent country of origin for plastics in Eijsden were France, Belgium, and the Netherlands, whilst for Sambeek this was Germany. No plastic pieces from the Netherlands were found. Evident pathways were consumer food waste and consumer hygiene waste. Temporal differences showed that the plastic concentration in Eijsden decreased from 9.10 pieces per 1000 m3 in 2023, to 5.74 pieces per 1000 m3 in 2024. Plastic concentration in Sambeek increased from 2.99 pieces per 1000 m3 in 2022 to 7.43 pieces per 1000 m3 in 2023 but decreased in 2024 to 6.55 pieces per 1000 m3. The age of plastics was found to be approximately 1 year. Plastics under the SUP Directive that decreased at Eijsden were ‘cups for beverages’, ‘cigarette filters’, ‘food containers’, and ‘packets and wrappers’, whilst at Sambeek these were ‘cups for beverages’, ‘food containers’, ‘wet wipes’, and ‘cutlery and straws’. Increased items were ‘plastic bags’ and ‘wet wipes and sanitary items’ at Eijsden and ‘cigarette filters’ and ‘plastic bags’ at Sambeek.

Sources of plastics were mainly from countries that were part of the Meuse River Basin. Plastic input was mostly from outside the Netherlands, pertaining to consumer waste from food packaging and sanitary products. These may come from toppled waste containers, public rubbish bins, accidental loss, or landfills, and combined sewage system overflow during heavy rain events or insufficient working sewage systems. Plastics are retained for one year in the Meuse. A decrease in the concentration of plastics compared to previous years has been observed at Eijsden, which suggests that the SUP Directive is slowly showing the first signs of positive change. However, at Sambeek no decrease was found. However, at Sambeek no decrease was found. Continous monitoring of plastics in the vertical water column is therefore needed to observe changes in concentrations, pathways during different seasons, and trends in the SUP Directive.