Two simple washing procedures allow the extraction of positively buoyant microplastics (>500 μm) from beach wrack

So far, no procedure has been established that allows the extraction of microplastics from organic-rich environmental matrices such as beach wrack. Here we present two novel, easy and cost-effective methods for extracting microplastics from Baltic Sea beach wrack consisting of Zostera marina L. or Fucus spp. Samples of either Zostera marina L. or Fucus spp. were spiked with defined amounts of either expanded polystyrene (EPS) or polypropylene (PP) in three size classes (500-1000, 1000-2000 and 2000-5000 μm). Afterwards, we placed the material between two grids inside a water-filled container and tested the separation efficiency by applying two methods. We either moved the grids up and down manually or bubbled the container with air to analyse the influence of a) beach wrack type, b) particle type, c) particle size, d) washing procedure and e) washing effort on particle recovery. Both procedures turned out to be efficient and easy to apply.