Why does Britain have the world’s most polluted rivers?
As researchers discover our water has the highest levels of microplastic in the world, Joe Shute asks what we can all do to help
Standing in Urmston meadows on the southern tip of Manchester you feel relinquished from the grip of the city of industry. Alder trees line the banks of the River Mersey, which meanders between gravel beds and picturesque fields. If you are lucky, you might spot the odd heron or kingfisher flashing across the water. Dig a little deeper into this semi-urban idyll, however, and a very different environment soon emerges. One that is invisible to the human eye but devastating our ecosystems across the world.
Only a few miles upstream, the River Tame, which flows down from Saddleworth Moor and feeds into the Mersey, now holds the dubious honour of containing the highest levels of microplastics currently recorded anywhere in the world.
At a stretch of the Tame near Denton in Greater Manchester, a research team led by Jamie Woodward, professor of physical geography at Manchester University, has recorded 517,000 particles per square metre of riverbed. This makes it twice as polluted as the Incheongyeonggi beaches in South Korea and the Pearl River estuary in Hong Kong, the previous holders of the questionable accolade.
According to Prof Woodward, a single pint glass sample of riverbed sediment taken from the spot where we are standing in the River Mersey would roughly contain a staggering 20,000 pieces of microplastic. The effects of such a high concentration of pollutant within the river remains untold.
For decades Manchester’s rivers have been slowly recovering from the ravages of the industrial revolution. In the 19th century, as the cradle of British manufacturing boomed, rivers such as the Mersey and neighbouring Irwell were declared biologically dead and even in the Seventies were considered among the worst in Europe.
Following the Toxteth Riots of 1981, a campaign was launched by then environment secretary Michael Heseltine to clean up the Mersey River Basin. Salmon, trout, grayling and even otters have returned, and in December last year the first salmon was caught on the River Tame for a century. But the advent of the plastic revolution has created a new threat that is feared may have even more serious environmental consequences.
Microplastics (comprising beads, fibres and fragments less than 5mm in diameter) have been proven to have a devastating impact on marine life – although as they pass up the food chain, the consequences for human health remain unknown. Scientists fear chemicals contained in microplastics could cause poisoning, infertility and genetic disruption in marine life, and potentially in humans if ingested in high quantities. It has been shown that humans who eat seafood ingest 11,000 pieces of microplastic each year.
The catchment-wide study, the first of its kind worldwide, which has been published this week, was conducted by Prof Woodward, his PHD student Rachel Hurley, and James Rothwell, a reader in physical geography at the university.
In 2015 the team began analysing sediments in 10 rivers within about 12 miles of Manchester. All but one of the 40 sites showed severe microplastic contamination – five, including the aforementioned stretch of the Tame, were deemed severe “hotspots”.
The team collected samples by wading out into the river and retrieving cylinders of sediment to analyse at the laboratory. It was only under the microscope that the scale of the problem came to light.
While Greater Manchester is Britain’s second most populous area with 2.55million people, according to Dr Rothwell the results of this study would most likely be replicated in many other parts of the country. And with 95per cent of plastic polluting the world’s rivers pouring in from 10 rivers in Africa and Asia, elsewhere in the world if the same test is done the problem could be far worse.
“It is just no one has been looking,” he says. “We haven’t been getting a handle on the problem.”
Of the first collected samples, 57per cent of microplastics were fragments, 33per cent microbeads (heavily used in cosmetics before being banned by Environment Secretary Michael Gove in January) and 9per cent fibres – it has been shown that a single polyester fleece jacket can release more than 1,900 plastic fibres per wash.
While the researchers believe sewage plants and industrial sites to be the source, alongside households, they admit they cannot yet pinpoint exactly where the microplastics are coming from – or crucially how to stop them. What they are certain of, however, is where they end up.
The second stage of sample collecting took place after the historic floods of winter 2015-16 and revealed that 70per cent of the microplastics had been washed away downstream into the Irish Sea, representing a total of 43 billion particles.
“It shows if we can clear out the riverbeds we are stopping one of the major sources of plastic pollution to the ocean,” says Rachel Hurley, whose PHD contained the research. “Such high concentrations right here at home show we are very much a part of the microplastic problem.”
The research increases pressure on the Environment Agency to improve the management of wastewater in Britain and record the levels of microplastics across the country. An Environment Agency report published last month revealed 86per cent of English rivers are failing to meet standards and named plastic pollution as a future threat, warning it acts as a “reservoir for toxic chemicals” with the potential to accumulate in freshwater and marine life and enter the food chain.
In a separate study of Salford Quays, the Manchester University team found up to 30per cent of organisms they analysed had ingested plastic. Tubifex worms, which can grow up to 20cm in
length, were found to contain up to four pieces of plastic per organism.
Every single day, approximately eight million pieces wash into the world’s oceans. However, a study in 2015 found that we have no idea where 99per cent of this waste ends up once it starts to degrade. According to Dr Hurley, it is microplastics rather than larger waste items that are of far greater concern.
“The smaller the plastic, the more organisms can ingest it. Animals really low down in the food chain can take in really small pieces which then has a knock-on effect.”
Alan Wright, campaigns manager at the Wildlife Trust for Lancashire, Manchester and North Merseyside, says fish specimens retrieved from the River Mersey and its tributaries are increasingly now being found with microplastics inside them. “Microplastics are going to affect the whole ecosystem,” he says.
In Greater Manchester at least, there remains hope that Britain can be a leader in confronting this global problem. As Mike Tuddy, chairman of the Salford Friendly Anglers Society (reputedly the world’s oldest fishing club) points out, they have already managed to bring these rivers back to life once.
“Everybody who loves nature needs to play their part in reducing the plastic we put into our environment,” he says.
The true scale of the effects of the plastic revolution may only now just becoming clear, but these rivers have weathered human poisons before. As Tuddy points out, we need only give them space to breathe.