Seite - 129 - in Freshwater Microplastics - Emerging Environmental Contaminants?

effluents, atmospheric deposition, groundwater, or surface runoff [16, 21]. Several fundamental processes drive the subsequent transport of particles in streams. In fluid mechanics, the collective motion of particles in a fluid is the result of Fig. 2 Schematic representation of the key different processes playing a role in the transport of non-buoyant microplastics (a), buoyant microplastics (b), non-buoyant nanoplastics (c), and buoyant nanoplastics (d) in a river or lake. Processes include (1) turbulent transport, (2) settling, (3) aggregation, (4) biofouling, (5) resuspension, and (6) burial.Aggregates can be formedwith, forexample, sediment, algae,organicmatter, ordissolvedsubstances.Thescalingof thedifferent components is not representative, and not all processes happen to each particle or in a certain order.Other processes, suchas removal by ingestion, relocation, andhydrodynamic alterationby ingestion and excretion (e.g., zooplankton, mussels), can also affect particle fate but are not depicted here Modeling theFate andTransport of PlasticDebris inFreshwaters:Reviewand. . . 129