Zitieren Sie bitte immer diesen URN: urn:nbn:de:kobv:b43-654672
Grinding method and oxidative aging modulate the impact of tire wear microplastics on the reproduction of the nematode C. elegans
- Rationale Tire abrasion is one of the largest sources of microplastic in aquatic and terrestrial environments. Despite this fact, research on tire wear microplastic (TWP) and its effects on soil ecosystems is scarce, especially regarding natural weathering processes. This leaves a large knowledge gap on the interactions of TWP with soil biota. Methodology Cryo-milled tire tread (CMTT) and diamond-ground tire tread (DGTT) were artificially weathered through dry ozone treatment and heat exposure. Particles were analyzed via scanning electron microscopy, particle size distribution, and shape characterization. TWP leachate composition was examined using liquid chromatography–mass spectrometry. The impact on the reproduction of the nematode Caenorhabditis elegans, a widely used toxicological model, was tested for leachate concentration, exposure duration and TWP aging status, using offspring per adult as the endpoint. Results The comminution method significantly influenced TWP particle sizeRationale Tire abrasion is one of the largest sources of microplastic in aquatic and terrestrial environments. Despite this fact, research on tire wear microplastic (TWP) and its effects on soil ecosystems is scarce, especially regarding natural weathering processes. This leaves a large knowledge gap on the interactions of TWP with soil biota. Methodology Cryo-milled tire tread (CMTT) and diamond-ground tire tread (DGTT) were artificially weathered through dry ozone treatment and heat exposure. Particles were analyzed via scanning electron microscopy, particle size distribution, and shape characterization. TWP leachate composition was examined using liquid chromatography–mass spectrometry. The impact on the reproduction of the nematode Caenorhabditis elegans, a widely used toxicological model, was tested for leachate concentration, exposure duration and TWP aging status, using offspring per adult as the endpoint. Results The comminution method significantly influenced TWP particle size distribution, with diamond grinding yielding smaller particles and a more structured surface morphology than cryo-milling. Aging with ozone (180 min) and heat (20 min at 100 °C) reduced DGTT particle sizes by 27-58%, but not in CMTT. Additionally, aging increased carboxylic functional groups and led to a brittle structure in both TWP types. Leachate composition varied with comminution method and aging. Benzothiazole, N-Cyclo-N-phenylurea, and aniline were more abundant in pristine and aged CMTT and aged DGTT. Diphenylguanidine had the highest concentration in all leachates. Aged TWP leachates, regardless of comminution, had significant toxic effects on C. elegans. Leachate from pristine CMTT was more toxic than from pristine DGTT. Nematode offspring correlated negatively with ozone exposure duration in aged DGTT. Tests with aged CMTT leachate showed even short-term exposure reduced offspring numbers. Discussion The results underscore the importance of oxidative and mechanical weathering in TWP toxicity and challenge the use of pristine particles in toxicological assays for risk assessment in the natural environment.…




