Microplastics in Polish freshwater ecosystems: Current state of knowledge and research gaps

Microplastics (MPs, <5 mm) have been detected since the 1970s in various environments, including freshwater ecosystems. This review compiles and compares data on MPs in surface waters in Poland based on studies published up to 2024. In total, 65 aquatic ecosystems were analysed: 47 lakes, 13 rivers, and 5 dam reservoirs. Most Polish studies focused on MPs in water (73%), with fewer addressing bottom sediments (14%) or shoreline sediments (9%). Only 4% examined both water and bottom sediments simultaneously. The level of MP contamination varied widely, from 0 to 245,000 MP∙m–3 in water and from 4 to 120,000 MP∙kg−1 dry mass in sediments, with 11.5 MP per sample in riverine shoreline sediments. The highest levels occurred in rivers, particularly the Nida and Vistula. Identified particles differed in shape (mainly fragments and fibres), size (most often <1 mm), and colour (predominantly red, blue, and black). Considerable variation in analytical methods was observed, hindering direct comparison of results and highlighting the need for methodological standardisation. Given the heterogeneity of aquatic environments in Poland, further research on MPs is essential. Careful selection of study sites will help identify critical contamination hotspots more efficiently. Such an approach is necessary to develop effective mitigation strategies and protect Poland’s freshwater resources from further deterioration of microplastic pollution.