New research exposes highly variable microplastic concentrations in UK rivers

Researchers at the University of Nottingham have highlighted highly variable levels of microplastic pollution in UK rivers. The work makes recommendations for the future study of freshwater microplastic pollution so that research can better inform consumers and legislators.

A 12 month study by scientists from the University of Nottingham has found low and highly variable levels of microplastic pollution across three rivers in the Trent catchment, in one of the most comprehensive published records of freshwater microplastic pollution.

Researchers from the University’s School of Geography and Department of Chemical and Environmental Engineering collected samples from 10 sites across the River Trent, the River Leen and the River Soar. Their sample locations enabled the assessment of microplastic particles at the sources of these rivers, as well as sites upstream and downstream of urban centres including Nottingham, Stoke-on-Trent, and Leicester.

Microplastic particles were identified at every site sampled during the study, however, the concentrations recorded were consistently low, particularly near the sources of the sampled rivers. Microplastic concentrations did not once exceed 0.4 particles per litre, and many samples contained no microplastic particles at all.

In addition to being consistently low, by returning to the same sites at regular (4 week) intervals the team found microplastic concentrations to be highly variable. Daily freshwater microplastic discharges varied from as few as 0 particles per day to over 600 million particles per day at one sample site.

The results of the project are published in the journal Environmental Pollution – Freshwater microplastic concentrations vary through both space and time.

This work has implications for the future study of freshwater microplastic pollution. Where previous riverine microplastic studies have reported concentrations from a limited number of samples, the University of Nottingham research highlights the need for more thorough assessments of microplastic prevalence in future work to better inform consumers, industry, regulators and government.

Microplastic particles continue to be identified in freshwater environments all over the world, however, without accounting for the variation identified in our work it is not possible for microplastic research to consider the extent to which its findings are representative of the environments it samples.

He added: “Further research is needed to understand how additional sources of uncertainty, such as variation throughout the profile of a river, can influence our understanding of the role rivers play as sources, pathways, and receptors of microplastic pollution.”

“We do not wish to underplay the potential impacts of microplastic pollution, but we need to make sure that the findings of microplastic research are not misrepresented. Otherwise, legislators, industry, and the general public are not equipped with the information needed to make informed decisions to address the microplastic problem.”

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