Fig. 1

(A) Geographical distribution of TRWP in marine sediments. Byfjord, the innermost basin in the fjord system between the island of Orust and the mainland, and the city of Uddevalla on the Swedish west coast (58,35359° N, 11,89502° E). Islands protect the system from the wind-driven influx of marine plastics from the wider North Sea, enabling local sources and transport in the area to be studied. Sampled concentrations of TRWP larger than 50 µm are shown by circles with area proportional to abundance. Procedural blanks (n = 5) are shown for comparison where only one black elastomer were found in one sample (Blank 4) (Fig. S4). (B) The occurrence of TRWP in relation to other identified polymeric microplastic particles, are shown for the different groups of sample stations away from the city