2025 Volume 81 Issue 16 Article ID: 24-16091
A degradation model based on accelerated degradation tests of drink bottle libs under dry and wet conditions was applied to a high-resolution grid-based map considering population distribution and meteorogical conditions (annual cumulative UV radiation and annual rainfall days) to assess the potential for microand nanoplastic (MNP) generation within the class A river basins in Japan. The MNP generation potentials for each grid were aggregated for each class A river basin boundary, and the values for the Tone and Yodo Rivers had large catchment populations and areas. On the other hand, the MNP generation potential per catchment area was found to be extremely high in the Tsurumi River, which has a high population density. The highest generation potential per catchment population was found for the Ota River, which has a Seto Inland climate with low rainfall. In the future, the MNP generation potential should be clarified by taking into account the generation of MNPs due to physical external forces in the basin and the surface runoff effect induced by rainfall.
