Macrophyte Beds as Microplastic Traps in Freshwater Environment

The aim of this work was to examine the causes and mechanisms by which plastic microparticles that have entered a water body are trapped in macrophyte thickets. The retention rate of plastic microparticles by macrophytes depends on the material of their origin; particle hardness, size, and concentration; the material density; and the morphological and ecological characteristics of the plants. For various species of macrophytes, the retention rate of microparticles in the size range of 1–5 mm ranges from 22% to 100%. The appearance of additional resistance to the movement of water and air masses promotes the slowing of the movement of microparticles, their sedimentation, and their retention by plants. Decreasing the kinetic energy of wind waves and raindrops via thickets of macrophytes prevents the repeated movement of already trapped microparticles. Mechanical retention of plastic microparticles occurs as a result of irregularities in the structure of plants, sieve-like structures made of interweaving stems and leaves, the bulk of plant litter, and the adhesion of plant surfaces and microparticles, which is enhanced by the sticky surfaces of the periphyton. The attraction and adhesion of plastic microparticles to plants and to each other occur as a result of the interaction of electric fields.