Source traceability of microplastics in road dust using organic/inorganic plastic additives as chemical indicators

Shinnosuke Yamahara; Reiji Kubota; Thant Zin Tun; Haruhiko Nakata

doi:10.1016/j.scitotenv.2024.172808

Source traceability of microplastics in road dust using organic/inorganic plastic additives as chemical indicators

Sci Total Environ. 2024 Jul 1:932:172808. doi: 10.1016/j.scitotenv.2024.172808. Epub 2024 May 6.

Authors

Shinnosuke Yamahara¹, Reiji Kubota², Thant Zin Tun¹, Haruhiko Nakata³

Affiliations

¹ Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan.
² Division of Environmental Chemistry, National Institute of Health Science, 3-25-26 Tonomochi, Kawasaki-ku, Kanagawa 210-9501, Japan.
³ Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan. Electronic address: nakatah@kumamoto-u.ac.jp.

PMID: 38719051
DOI: 10.1016/j.scitotenv.2024.172808

Abstract

Microplastics (MPs) are environmental pollutants of great concern around the world. The source of MPs in road dust need to be identified to develop strategies to control and reduce MPs emissions by stormwater runoff, one of the main sources of MPs to the aquatic environment. However, little information on the sources of MPs in road dust is available due to lack of their suitable indicators. In this study organic/inorganic plastic additives were used as chemical indicators to understand the source of MPs in road dust. The polymers, organic additives, and heavy metals in 142 commercial plastic products suspected of being source of MPs in road dust were determined. As the results, 147 organic additives and 17 heavy metals were identified, and different additive profiles were found for different polymer types and use application of plastic products. Further, 17 road dust samples were collected from an urban area in Kumamoto City, Japan. and analyzed the MPs (1-5 mm diameter) and their additive chemicals. Polymethyl methacrylate (PMMA) was the dominant polymer accounting for 86 % in the samples, followed by ethylene vinyl acetate (EVA) and polyvinyl chloride (PVC). In total, 48 organic additives and 14 heavy metals were identified in the MPs samples. The organic/inorganic additive profiles of plastic products and MPs in road dust were compared, and several road dust-associated MPs had similar additive profiles to road paints, braille blocks, road marking sheets, and reflectors. This suggested that the MPs were originated from these plastics on the road surface. Road paint was the most important contributor of MPs in road dust (60 % of the MPs), followed by braille block (23 %), road marking sheet (8.3 %), and reflector (2.4 %). These results indicated that organic/inorganic plastic additives in plastic products can be used as chemical indicators to trace the sources of MPs in road dust.

Keywords: Chemical indicator; Microplastics; Organic/inorganic plastic additives; Road dust; Source traceability.