2025 Volume 48 Pages 105-114
In the Dainineya River, located in the central area of Osaka City, microplastics were collected and analyzed regarding their density, polymer types, shapes, and colors. The investigation followed the “Guidelines for Microplastic Investigation in Rivers and Lakes (Ministry of the Environment, Government of Japan) .” Microplastic collection was conducted by the natural water flow method, and under low flow conditions, the net towing method (an original method) was employed. Sample analysis was performed according to the guidelines. Upon comparing the results of the natural water flow method and the net towing method for microplastics sized 1–5 mm, the densities were found to be 41.0 particles m-3 and 9.68 particles m-3, respectively. While questions were raised regarding the quantitative comparison between the net towing method and the natural water flow method, the former was considered to capture the characteristics of microplastics in the target river equally well from a qualitative perspective.
