Fig. 4.

Globally averaged sources of microplastics (A) as inferred using the methods described in Materials and Methods for the three size ranges: big (diamond), medium (triangle), and small (square). For all sources, the 95% confidence limits are shown as vertical lines. Multiple sensitivity studies were conducted (see Materials and Methods for details) with time averaging (cyan) and with each site withheld (green), showing the ranges of values that can be obtained for each source strength extrapolated globally. (B) The total microplastic deposition estimated in the model (µg/m²/year). (C) The modeled budgets for different continents in terms of sources and deposition (excluding coastal grid boxes). Roads (brown), ocean (blue), agricultural dust (white), and population dust (yellow) contributions in Gg/y are shown for each continent using the medium size (base case).