Manchester river has worst level of microplastic pollution ever recorded, study finds

Waterways in northwest England found to have 'extraordinarily' high concentrations of harmful pollutant

A river in Greater Manchester has the worst level of microplastic pollution ever recorded anywhere in the world, a study has discovered.

The River Tame in Denton was one of several waterways in northwest England found to have "extraordinarily" high concentrations, with levels of plastic pollution worse than in Hong Kong and South Korea.

Microplastics from these urban rivers and streams are a major contributor to fatal ocean pollution when they flood, the study found.

Researchers from the University of Manchester found microplastics, tiny pieces of plastic debris such as microbeads and microfibres, are shifted into the seas, particularly after flooding.

They are toxic to ecosystems including marine life.

The researchers said their study showed regulations on waste water flowing into urban rivers and streams should be tightened.

In the first detailed study of its kind anywhere in the world, the team took samples from river sediments at 40 sites across the northwest of England, including rural streams in hills and urban rivers in the city centre.

It has long been known that such particles enter rivers from various sources, including industrial effluent, storm water drains and domestic wastewater.

But the new study looked at how they settle in and move out of river basins.

The researchers found microplastic contamination in all parts of the network, including a site on the River Tame, which had concentrations up to 517,000 plastic particles per square metre.

The researchers took new samples following severe flooding – and found levels of contamination fell. The floodwater had removed about 70 per cent of the microplastics stored on the river beds.

“This demonstrates that flood events can transfer large quantities of microplastics from urban river to the oceans,” the study concluded.

One of the study's authors, Professor Jamie Woodward, the University of Manchester’s head of geography, said: “Microplastics in the ocean have recently attracted a lot of attention, but until now science knew little about the major sources of this pollution and the transport processes involved.

“We decided to explore the contamination of urban river beds, as we began to think that they may be the main source of the problem.

“We are only beginning to understand the extent of the microplastic contamination problem in the world’s rivers. To tackle the problem in the oceans, we have to prevent microplastics entering river channels.

“We also need to reduce our use of plastics large and small. We welcome the microbead ban introduced by Michael Gove [the Environment Secretary] earlier this year, and we hope that improvements in wastewater management will be put in place in the future.”

Household sources of microplastics include straws and plastic bags as they slowly break down.

Scientists say they are a risk to all types of life in the sea, from zooplankton to grey seals and even sharks.

The study, published online in Nature Geoscience, said: “A key part of tackling the global microplastic problem is effective regulation to ensure that, in all parts of the world, the multiple sources of microplastics in river catchments are brought under control.”

Discarded fishing gear, which breaks down over hundreds of years, is another source of ocean plastics pollution, killing creatures as large as whales, dolphins, turtles and porpoises.