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CEH scientists published a study last week showing the first evidence of microplastic particles in UK freshwater environments.  ‘Microplastics’ - plastic particles of less than 5mm diameter - are an issue of growing concern as they persist in the environment. They have been widely studied in marine ecosystems but, until now, no studies have investigated their presence in rivers in the UK, despite the likelihood of microplastics entering and accumulating within rivers. 

Route of microplastics transport | Image credit: Alice Horton

The CEH study found high numbers of microplastic particles at all studied sites within tributaries of the river Thames including ‘clean’ rural sites that have a very low surrounding population and were expected to have very little pollution. The results show not only the extent of plastic pollution within the River Thames catchment – hundreds of microplastics particles per kg sediment even at the least polluted sites - but also identify common sources of microplastic pollution. 

Microplastic sources 
  • Synthetic fabrics 
  • Packaging products
  • Road-marking paints

Particles of road-marking paints have not previously been observed in environmental samples; this illustrates the significance of urban runoff, especially from roads, as a route for microplastic particles to enter the river environment. 

Particulate matter, such as sediment, organic matter, and larger plastic debris moves within river systems. It is, therefore, likely that microplastics entering rivers will be transported downstream from their initial source, with the possibility of eventually reaching the marine environment and with consequences for aquatic ecosystems along the way. Studies to date have shown that organisms have the capacity to eat these particles with potentially harmful consequences, in addition to plastic particles associating with harmful organic chemicals or leaching plasticisers. This study highlights the complexity of determining the extent of environmental microplastic pollution and further research is needed to determine the sources, fate, and effects of these particles within the Thames Basin, and the environment as a whole.

View the peer-reviewed paper in Marine Pollution Bulletin