The tiny particles of various sizes from new and old car and truck tyres did not turn out to be neutral surfaces on which bacteria colonise. Rather, they altered the composition of the biofilms – the bacterial layers that cover river stones, sediments and even artificial materials.
‘We were able to show that certain types of bacteria are particularly fond of colonising tyre abrasion, while the diversity of microorganisms decreases overall,’ explains study leader Dana Bludau, who is a PhD candidate in Prof. Dr. Jens Boenigk's research group at the University of Duisburg-Essen (UDE). ‘In particular, the biofilms on larger particles from older tyres differed significantly from those on natural particles from the riverbed.’
The significance of these changes extends far beyond the bacterial community itself. Microbes are key players in aquatic ecosystems: they decompose organic material, control nutrient cycles and form the basis of food chains. ‘If tyre wear particles alter the composition of these biofilms, it affects the entire river system,’ Bludau emphasises.
The results complement current findings by the State Agency for Nature, Environment and Climate North Rhine-Westphalia, (LANUK), which has documented high levels of primary microplastics in the Rhine. Primary microplastics are intentionally manufactured plastic particles such as exfoliating beads in cosmetics or plastic granules used in industry, while secondary microplastics are created by the breakdown of larger plastic items. While LANUK's analyses primarily examined the quantities and sources of input, this study by the universities of Duisburg-Essen and Cologne is the first to demonstrate the specific effects of tyre abrasion on microbial communities in the river.
To date, little systematic research has been conducted into the ecological impact of microplastics. This new study therefore fills an important gap in our understanding of the ecological consequences.
Further Information:
Dana Bludau, Biodiversity, +49 201/18 3-3200,
dana.bludau@uni-due.de
Editor: Birte Vierjahn, +49 203/37 9-2427,
birte.vierjahn@uni-due.de