Masses of toxic litter pours from Rhine into North Sea each year, research finds | Pollution

Thousands of tonnes of waste flow into the North Sea via the Rhine every year, poisoning the waters with heavy metals, microplastics and other chemicals, research shows.

These wastes can be harmful to the environment and human health: tires, for example, contain zinc and other heavy metals that can be toxic to ecosystems in high concentrations.

“Even less persistent natural materials, such as worked wood, paper, cardboard and food waste, can contain toxic or harmful additives,” said Dr. Leandra Hamann, a zoologist at the University of Bonn and lead author of the study.

Rivers play an important role in transporting waste to other aquatic and marine environments. The researchers said the composition of the waste found in the Rhine was very similar to that found in other European rivers, including the Thames. These large quantities of waste can also damage crucial infrastructure such as drainage systems, leading to an increased risk of flooding.

Citizen scientists and researchers from the University of Bonn analyzed waste collected in the Rhine between November 2022 and November 2023. They found that the river carries up to 4,700 tonnes of “macrolitter”, pieces larger than 25 mm, each year. They said more research was needed to understand the full extent of the problem.

Hamann said the Rhine was one of the main contributors of European macro-waste to the sea, but added that many other rivers had not yet been studied.

A floating waste trap was anchored in Cologne to monitor the amount of waste flowing into the Rhine. Of the nearly 2,000kg caught by the trap, 15% was plastic and 28% was food or drink related.

Hamann highlighted the “really great work” done by citizen scientists on the project, tasked with collecting waste from the trap, transporting it to the monitoring site and recording individual waste on a custom-made app.

The study was published in the journal Communications Sustainability.