Microplastic contamination of sandy beaches of national parks, protected and recreational areas in southern parts of the Baltic Sea

Highlights: • Microplastics were detected in all the samples along the southern Baltic Sea shore. • MPs abundance in national parks and protected areas is of the same level as on other beaches. • Patchy distribution of MPs is present in any zone of the beach. • The current wrack line was most littered. • About 38% of the collected particles were expanded polystyrene. The distribution of small (0.5–2 mm, S-MPs) and large (2–5 mm, L-MPs) microplastics and mesoplastic particles in 51 samples of surface beach sands at 7 locations along the southern shore of the Baltic Sea was investigated. MPs particles (3267 in total) were found at all the sites and in all the beach zones. The bulk mean MPs (0.5–5 mm) contamination is 68 ± 117 (median 33) items/kg DW (n = 51). The results were confirmed by μ-Raman spectroscopy analysis. National park areas did not differ substantially from other beaches. Expanded polystyrene fragments accounted for about 38% of the total collected particles. Fibres were the predominant type of MPs (55%). The highest contamination was found within the current wrack line (60.1 ± 36.6 items/kg DW of S-MPs). A consistent picture for S-MPs was observed at the beach face, where the mean values in different locations varied between 21.0 and 58.1 items/kg DW, with a bulk mean of 30.4 ± 13.7 items/kg DW.