Dataset on settling of polystyrene microplastic aggregates through density transition between distilled water and saltwater

Settling experiments were conducted in a water column consisting of an upper layer (distilled water), a lower layer (saltwater—NaCl solution in distilled water), and a density transition between the two. The sinking of aggregates formed by polystyrene microplastics was examined using visualization methods to track the position of the aggregate centroid over time, as well as the evolution of size and shape factors during sinking. The dataset includes (1) measurements of settling dynamics, (2) measurements of size and shape factors of sinking aggregates, and (3) density profiles of the water column. The experiment demonstrates delayed settling of porous aggregates through the density gradient of the surrounding liquid, illustrating diffusion-limited retention and the evolution of aggregate shape during sinking.