By Christoph Driessen
Cologne, Germany – The Rhine river is full of much more rubbish than previously thought, German researchers have warned.
A study released on Thursday indicated that between 3,000 and 4,700 tonnes of rubbish measuring at least one centimetre in length float past the German city of Cologne every year.
This is drastically more than in some earlier estimates, researchers from the Universities of Bonn and Tübingen wrote in the journal Communications Sustainability.
That amounts to 53,000 pieces of rubbish per day, study leader Leandra Hamann from the University of Bonn told dpa.
Most of the waste in the oceans comes from rivers, Hamann, who is a biologist, explained. However, there have been very few studies in which the waste has been collected and measured individually. The long-term study now being conducted in Cologne has been particularly complex.
Volunteers played an important role in the project
In addition to researchers, numerous volunteers, known as “citizen scientists,” were also involved in the study.
This was made possible by the “RheinKrake” (Rhine octopus) rubbish trap installed on the Rhine in Cologne. For years, it has been collecting so-called macro-rubbish from the Rhine waters across a width of three metres and a depth of 80 centimetres.
“The volunteers do the real hard work,” explained Hamann. “These are people who do this in their spare time. Some bring their children, others are pensioners; it’s a very mixed group that meets every other Saturday, whatever the weather, to either retrieve the rubbish from the water or spend two to three hours sorting and measuring it, weighing everything and taking photographs. No one else could finance this manual labour.”
About 10% of all items were fireworks
Over the course of a year, the rubbish trap collected 17,523 pieces of rubbish with an estimated total mass of 1,955 kilograms. About 70% of the individual items were made of plastic, but these only accounted for 15% of the weight.
More than half of all objects found came from private consumers, and about 28% of these were related to food or beverages.
“On the one hand, I was surprised by the sheer volume, that there really is so much rubbish, and on the other hand, that the amount of rubbish fluctuates greatly over the course of the year,” said Hamann.
The study covers the twelve months between November 2022 and November 2023. Around 10% of all objects fished out of the river during this period were fireworks.
“When you realise that this is only fired off on a single day, it’s crazy,” said Hamann.
In addition, you can find everything from children’s toys to sex toys. “We once found a wallet with several identity cards and took it to the lost property office.”
‘RheinKrake’ continues to fish
Wine bottles, champagne bottles and bottle caps make up a large part of the flotsam, some of which are returnable bottles. “So there is still room for improvement,” Hamann said. “The deposit could be increased to motivate people not to leave empty bottles on the riverbank.”
The “RheinKrake” is still in operation, and the researchers are already working on a further evaluation.
“About two years ago, the EU introduced a requirement for bottle caps to be attached. It would be interesting to see if and to what extent this has had an effect,” Hamann explained.
