John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
The river’s microplastics concentrations are “among the highest so far studied worldwide,” says a researcher.
Is any ocean, river, lake, or even dang puddle safe from plastic pollution?
Certainly not the Rhine, as it’s the latest body of water found to be choked with microplastics. Researchers at the University of Basel in Switzerland sampled 11 locations along roughly 500 miles of the river’s surface from Basel to Rotterdam. Everywhere they dipped they found plastic—beads, shards, and fibers, in concentrations as dense as 3.9 million pieces per square kilometer, they write in Scientific Reports.
That extraordinary amount of non-biodegradable crud throws the Rhine into the pantheon of most plastic-polluted places on earth. The researchers say in a press release:
“The Rhine’s microplastics concentrations are thus among the highest so far studied worldwide,” says biologist Professor Patricia Holm from the Department of Environmental Sciences at the University of Basel. For the most polluted Swiss lakes, Lake Geneva and Lake Maggiore, 220,000 particles per square kilometer were reported in other studies. As a further example, in Lake Erie in the U.S., only 105,503 items per square kilometer were found….
“Our results show that the Rhine is significantly polluted with microplastics,” says Holm. “If we assume an average microplastics concentration on the day we took the water sample in Rees, we can say that the Rhine contributes a daily load of more than 191 million plastic particles to the North Sea, and that only takes into account the surface. Even though, in terms of weight, this only corresponds to roughly 25 to 30 kilos a day, this adds up to 10 tons a year. Each one of these billions of plastic items can be ingested by organisms and have negative effects on their health.”
The sources of the microplastics are unclear, but the usual suspects include wastewater-treatment facilities (which can’t filter them out), industrial plants, heavy rains washing debris into the river, and accidents. Once in the water they can float around for what seems like an eternity, getting sucked up by hungry zooplankton, fish, crabs, and even baleen whales, with unknown health consequences to the animals and the humans who eat them.