I looked up what constitutes a unit of microplastics and the definition I found in this article was “any synthetic solid particle or polymeric matrix, with regular or irregular shape and with size ranging from 1 μm to 5 mm, of either primary or secondary manufacturing origin, which are insoluble in water”.
Because “microplastics” is a broad term that covers particles of varying size, structure, and weight, researchers refer to them in terms of number of particles per unit or total mass of microplastics per sample.
I looked up what constitutes a unit of microplastics and the definition I found in this article was “any synthetic solid particle or polymeric matrix, with regular or irregular shape and with size ranging from 1 μm to 5 mm, of either primary or secondary manufacturing origin, which are insoluble in water”.
Because “microplastics” is a broad term that covers particles of varying size, structure, and weight, researchers refer to them in terms of number of particles per unit or total mass of microplastics per sample.