Аннотация:With the continuous growth of global plastic production and consumption, beach plastic pollution has emerged as a significant environmental challenge. This study if focused on large plastic fragments and meso-plastics (0.5–2.5 cm). Mesoplastics play a crucial role in the plastic degradation process. They are produced mainly by weathering and fragmentation processes of larger plastic items, but also serve as a potential source and precursor of micro/nano plastics. Understanding their physical and chemical characteristics, as well as their distribution patterns, is critical for uncovering the full life cycle of plastic pollution. However, existing research on meso-plastics faces significant challenges due to substantial differences in sampling methods, classification standards, and data recording techniques across countries. It hinders the comparability of the data and complicate the monitoring activities and further development of possible measures to prevent plastic pollution at different levels. In the frame of the joint Russian-Chinese project “Aging and fragmentation of plastic wastes on marine beaches across latitudes” harmonized monitoring protocols were established for macro and mesopastics and the fragments were investigated on the beaches of different areas on the Baltic, White, Barents, Kara and Japan seas. This study represents the results of the field studies including densities, size distribution and types of fragments and also gives the perspective on further laboratory studies of degradation mechanisms of different plastics in different geographical regions.