Fig. 3

Plastics dispersal through Earth surface reservoirs from 1950 to the year 3000, following a halt on production and discard in 2025. This unrealistic model scenario illustrates over what timescales discarded microplastic (P, > 5 mm), large microplastic (LMP) and small microplastic (SMP, < 0.3 mm) potentially disperse via rivers and air into oceans, remote terrestrial surfaces, beach and marine sediments. A P and LMP disappear in all transitory reservoirs within 100 and 200 years due to fragmentation at an annual rate of 3%. The prolonged dispersal of SMP in all reservoirs is driven by cyclical marine emissions to air, deposition to terrestrial surfaces, runoff to surface oceans, and re-emission to air. Only a small fraction of SMP sinks to shelf sediments and to the deep ocean, followed by slow sedimentation to deep ocean sediments. SMP mass, and concentrations, in the surface ocean and atmosphere, where human SMP exposure is relevant, only return to 2025 levels towards the year 5000 (Fig. 4)