Contamination of beach sediments of a subalpine lake with microplastic particles

microspectroscopy which allows for analysis of particles down to the µm-range (Supplemental information). We found the majority of plastic particles at the north shore of Lake Garda with 483 ± 236 macroplastic particles/m ² and 1,108 ± 983 microplastic particles/m ². At the south shore, extrapolations revealed 8.3 macroplastic particles/m² (only one replicate contained macroplastic) and 108 ± 55 microplastic particles/m ² , respectively. The high concentration of particles at the north shore may result from the strength of the wind 'Ora' blowing from south to north, resulting in a strong surface circulation and a counter clockwise rotating eddy at the northern tip of Lake Garda (Supplemental information). Our results are in concordance with a study from Lake Huron (Great Lakes) were 94% of plastic pellets were found at a single beach [7]. The found numbers of microplastic particles are in a similar range as reported in studies performed on marine beach sediments (0.21–77,000 particles/m²), though not as large as in cases of highly contaminated marine beach sediments [8]. Nevertheless, our results indicate a similar relevance of microplastic contamination in lakes. Similar to marine environments and the Great Lakes, with ocean-like characteristics, we found primarily low density polymers, namely polystyrene (45.6%), polyethylene (43.1%) and polypropylene (9.8%). However, in the size class of very small microplastic particles (9–500 µm), also polyamide and polyvinylchloride were identified (Figure 1). Polyvinylchloride was ranked among the five most hazardous plastic polymers and by far the most additives are used for its production [9]. In general, the particles we found were fragments of larger particles, most likely originating from post-consumer products. The found fibres (2.3%) rather originate from lakeside sources (e.g. rope, fishing gear) as fibres were not in the size range found in sewage effluents [3] (Supplemental Information). An exemplary examination of nine randomly chosen plastic particles (0.781–3.016 mm) using scanning electron microscopy revealed diverse surface textures which closely resembled degradation and fragmentation marks of plastic particles found in marine environments (Figure 1) [8]. Signs of degradation in Plastic waste is of increasing concern in marine ecosystems [1–3]. Buoyant plastic particles accumulate in pelagic habitats whereas non-floating debris accumulates on the seafloor and in beach sediments, posing risk to the respective communities [1–4]. Microplastic particles (<5 mm) are either directly introduced via sewage discharge or formed by biofouling and mechanical abrasion, making them more prone to consumption by aquatic organisms [2,3]. As a consequence, they …