Identification of tire and road wear particles in artificial water bodies in Japan

Tire and road wear particles (TRWPs) are a major source of microplastic pollution in urban environments. While research has largely focused on natural aquatic systems, artificial urban water bodies in Japan remain understudied despite their high potential to accumulate these pollutants. This study provides a detailed evaluation of TRWPs in artificial water bodies across four major regions (Kinki, Chukyo, Kitakyushu/Fukuoka, and Sapporo) in Japan using microscopy, SEM-EDX, and Raman spectroscopy. TRWPs were characterized by distinctive morphologies, elemental signatures (Zn, S, Si, and C), and Raman spectral features, including carbon black and styrene-butadiene rubber (SBR) markers. Quantitative analysis revealed spatial variability, with TRWP concentrations ranging from 291.2 to 489.9 particles/L. The highest abundance was recorded in Sorakuen (489.9 particles/L), while the lowest was observed in Tsurami (291.2 particles/L). Raman spectra from sites like Tsuruma (Nagoya) and Maizuru (Fukuoka) indicated the presence of fresher TRWPs, whereas particles from Shonai (Nagoya) and Maruyama (Kyoto) exhibited signs of advanced weathering. SEM imaging further supported these findings, highlighting extensive surface degradation particularly in high-traffic locations. These artificial systems function both as semi-enclosed ecological habitats and as potential accumulation zones for TRWPs, where prolonged retention promotes particle buildup and transformation. While the findings indicate that such environments can retain substantial TRWP loads, further comparative research is needed to evaluate their relative role within broader urban aquatic systems.