LONDON – Just over 60 years after it was declared “biologically dead”, England’s Thames River had been hailed as an environmental success. But while much of the effluents, chemicals, and heavy metals that used to pollute the river are gone, microplastics have taken their place.
Mammals such as porpoises, seals, and more than 100 species of fish could be endangered after a series of studies by researchers at London’s Royal Holloway University determined that the Thames, which flows through London, had some of the highest densities of microplastics found in any river in the world.
Compared to global estimates of microplastic contamination, the Thames has “very high levels,” said Katherine Rowley, Ph.D. student and one of the authors of the study, published in the journal Science of The Total Environment.
Due to the risk to wildlife, ecosystems and human health, it is of “great importance that the entry of plastic into marine and freshwater environments be reduced,” he added.
The study found that 94,000 microplastics flow through some sections of the Thames every second at a density that is higher than comparable urban rivers, including the Chicago River, the Rhine in Germany, and the Danube in Romania.
Plastic can enter the water in several ways, including improper disposal of packaging, household items, and cleaning products, according to the study. Items that have been thrown in the trash can also be thrown into the water, and items that are improperly flushed down the toilet can enter the waterways. These larger items eventually break down into small pieces known as microplastics.
Washer outlets are another important source of microplastics, as they are emitted from garments made of synthetic fibers such as polyester.
The researchers also fear that the boom in the use of disposable plastic items like gloves, cleaning wipes and masks during the coronavirus pandemic is exacerbating the problem.
While public awareness of the impact of microplastics on the ocean environment is growing, the study shows that it is also a major concern in freshwater.
More than 10,000 metric tons of plastic are estimated to flow into the Great Lakes from the United States and Canada each year, and rivers are believed to be the primary way that plastic reaches the oceans, according to a 2016 study by the Rochester Institute of Technology.
In the UK, plastic was found on the Thames from a variety of sources, including glitter, microbeads, and broken food packaging.
Large numbers of disposable cleaning wipes, containing plastic fibers, were also found on the riverbank in a separate investigation by Katherine McCoy, a master’s student at Royal Holloway University.
Nicknamed “massive wet wipe reefs,” these are believed to have entered the river from people who flushed them down the toilet.
Clams living near the build-up were found to contain high levels of plastic fibers that McCoy suggested might have originated from the wipes.
Crabs living in the river were also found to have as many as 100 pieces of plastic in their stomachs, in a third study by fellow master student Alex McGoran. More than 95 percent of the Chinese crabs examined had plastic present, which could lead to reduced feeding by sending signals that the stomach was full, the study suggested.
Now that the river and its estuary are home to more than 100 species of fish, two species of seals, and even sharks and seahorses, Anna Cucknell, manager of the Thames project at the Zoological Society of London, said she was “shocked” by the findings. .
“We must not allow plastic pollution to threaten their survival,” he said.
Microplastics can also be ingested by organisms that live in water and spread throughout the food chain, damaging the ecosystem and even reaching the food that humans eat.
The problem has become so widespread that a 2019 World Wildlife Fund study estimated that the average person eats the equivalent of a plastic credit card every week.
The increasing use of cleaning products such as disposable wipes, as well as the inappropriate removal of disposable masks and gloves, during the pandemic threatens to exacerbate the problem, according to another study author Dave Morritt, professor of biological sciences at Royal Holloway University.
“Although these studies illustrate the problem on a local scale, plastic pollution is a global problem,” he said.
