2024 Volume 34 Pages 61-70
The presence of atmospheric/airborne microplastics (AMPs) has become apparent in recent years, but there are still many unresolved issues, and establishing investigation methods and understanding the actual situation are urgent tasks at present. In this study, we attempted to assess the presence of AMPs in the environment at four different sites, namely Niigata-sowa and Kawasaki in urban areas, Kasahori Dam in rural area, and Ogasawara in remote area, making it the first domestic investigation of AMPs using micro-Raman spectroscopy (μRaman), which excels in sensitivity and spatial resolution. As a result, AMPs were detected under quality control and assurance (n=32). The atmospheric concentration of AMPs was 0.52±0.24 MPs m-3, with polyethylene (PE), plastic resin (RES, including epoxy and phenoxy resin), and polyamide (PA) being the most common types in that order. The particle size (Feret diameter) was 7.6±3.7 μm, and the shapes were particles or fragments, both of which were consistent with previous studies. Results from the intensive sampling conducted from 2023/11/14 to 12/12 (parallel measurements at Niigata-sowa, Kawasaki, and Kasahori Dam) showed little difference in the averaged concentration levels between the sites, while weekly fluctuation of AMPs concentrations showed different trends between urban and rural areas. Although differences in the effects of meteorological conditions, sampling site locations, and potential sources on the weekly fluctuation were not very clear, there was concern about plastic pollution even in clean atmospheric environments. Further improvements in method accuracy and verification through accumulation of observation data including other air pollutants (e.g., particulate matter) are essential.