Distribution and accumulation patterns of tire-derived particles in coastal and lake sediments.

Tire and road wear particles (TRWP) are the largest source of microplastics. These particles are generated through friction between tires and road surfaces during use, enter aquatic environments, and may affect aquatic organisms. In this study, TRWP in sediments from 11 different water bodies in Japan were analyzed using pyrolysis gas chromatography/mass spectrometry. TRWP were detected in 32 out of 36 samples, with concentrations up to 4260 µg/g dry weight. TRWP concentrations exceeded the estimated predicted no-effect concentration threshold at 30 out of 36 sites, indicating that potential ecological risks cannot be ruled out. A correlation was found between TRWP concentration and mud content, total organic carbon, or terrestrial organic carbon (terrOC) at sites where mud accumulates. The correlation between TRWP and terrOC was significant even at sites with a notable contribution of marine-derived mud. These findings suggest that TRWP are transported with terrestrial mud and organic matter in aquatic environments. Moreover, sedimentation patterns, as deduced from sediment properties such as mud content and elemental composition, may serve as indicators of TRWP distribution. This study contributes to transport modeling, environmental risk assessments, and development of future pollution control strategies for TRWP.