The contamination of freshwater ecosystems with microfibres has not yet been studied in Poland. We analysed samples from a river and three lakes located in central and northeastern Poland. A significantly higher number of fibres were reported in the river, which runs through large cities, compared with the lake situated within the Landscape Park. Fibres smaller than 1.0 mm dominated, especially in the river where they constituted 39% of all fibres detected. We found more microplastics (⩽ 4930 fibres·m⁻³) by using a mesh size of 20 µm compared with other studies of inland waters. The use of Raman spectroscopy allowed us to identify conventional plastic polymers: polyethylene terephthalate, polyester and polyurethane. We estimated that up to 25 g of microplastic in the form of fibres might be in the lake water under the surface. We found microplastic fibres in Majcz Lake situated within the Masurian Landscape Park. This suggests that microfibres are carried by the wind and rain and enter freshwater isolated from sewage outlets. By using the control sample and an air-test of microfibres in the laboratory, we observed that there is a high probability of contamination with microplastic in the field samples (up to 30% of all fibres detected). The contamination risk noted from the samples cannot be ignored; this could be particularly important for analysis of microplastic in remote freshwater ecosystems.

Microplastics (MPs) have even been detected in remote environments, including high-latitude regions, where human activities are restricted or strongly limited. We investigated the surface water of the bays of the Barents Sea and the freshwater lakes that are located close to and several kilometers from a year-round resident field station in the remote tundra region of the Kola Peninsula. The microplastics’ presence in aquatic environments in this region has not been indicated yet. Microplastics were detected in all samples collected from the Barents Sea (<4800 items·m⁻³) and the lakes (<3900 items·m⁻³). Fibers made from polyethylene terephthalate (PET)—the most common thermoplastic polymer of the polyester family—and semi-synthetic cellulosic rayon were the most dominant. This indicated that the source of fiber contamination may come from protective clothes, ropes, ship equipment, and fishing nets. Small microplastics can spread through current and atmospheric transport. The Norwegian Current is likely responsible for the lack of correlations found between MP contamination and the distance from the field station between the studied bays of the Barents Sea. On the contrary, a significant correlation with human presence was observed in the concentration of microfibers in the water of the tundra lakes. The number of MP fibers decreased with an increase in the distance from the field station. This is the first study, to the best of our knowledge, that reports such a correlation in a remote region. We also discuss implications for animals. Our results show that even the most isolated ecosystems are not free from microplastic pollution.