A larval perch with microplastic particles in its gutCREDIT:REUTERS
The test were carried out in 2015, and the team also found that around 70 per cent of the microplastics were washed away into the sea following the devastating 2015/2016 floods.
“While that is good for the river beds, because we now know they can effectively cleanse themselves, it is bad news for the oceans,” added Professor Woodward.
“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 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.”
The researchers estimate that the flooding flushed around 43 billion microplastic particles from the River Mersey and Irwell catchments, and into the Irish Sea.
Arecent global estimate put the input of plastic into the oceans at approximately 6.4 million tons per annum.
Much of the plastic floats rather than sinks, so it is swallowed by marine animals who cannot digest it. Chemicals also leach into the water, and it has been shown that even humans who eat seafood ingest 11,000 pieces of microplastic each year.
Although it was believed that 90 per cent of microplastic contamination originated from the land - the rest coming from shipping accidents - the new study is the first to look in depth at where the source may be.
An Environment Agency spokesperson said:“We are working with the water industry and leading academics to investigate the types and quantities of microplastics entering the environment. This research will feed into plans to tackle this type of pollution at the source.
“Plastic pollution is a threat to our natural environment and by working together, we can reduce the amount which enters our land, rivers and the sea and protect wildlife for future generations.”
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