This paper reports preliminary findings on microplastic (MP) presence in Rzeszów Reservoir sediment, Poland, considering ecotoxicological risks. Sediment samples were collected from three shoreline stations, and a custom density-based method was used for MP extraction. The extracted pollutants were identified using the Laser Direct Infrared (LDIR) method, both quantitatively and qualitatively. At stations R1, R2, and R3, a contamination of 120,000, 70,000, and 7500 MPs/kg of dry mass was determined. A total of nine types of plastics were identified: polypropylene (PP), polyamide (PA), polyethylene (PE), polystyrene (PS), polyurethane (PU), polyethylene terephthalate (PET), polyacrylonitrile (PAN), polyvinyl chloride (PVC), and rubber, with PU being the most prevalent. Spatial variation occurred in MP abundance, polymer diversity, and particle size. The station closest to the reservoir tributary was characterized by the highest abundance of MPs, the greatest variety of polymers, and the largest MPs. The calculated PHI (Polymer Hazard Index) indicated a very high ecotoxicological risk at all stations classified in the highest risk category V on a five-degree scale. Further research is needed to assess Rzeszów Reservoir’s MP contamination and its ecological consequences.

This study is a review of current knowledge on microplastics (MPs) in aquatic environments. In addition to identifying the sources of contamination by MPs in water and the hazards of their presence, an attempt is made to systematize the terminology of polymeric microparticles according to their size and to describe other parameters characteristic of MPs, i.e., shape and color. Special focus was placed on a review of the most important methods used to extract MPs from environmental matrices, as well as the latest and most effective analytical methods, highlighting their advantages and disadvantages. The value of the paper is in pointing out important developments in MPs analytics, identifying existing inaccuracies and limitations in the field and providing practical guidance. Thanks to its comprehensive approach, this article is a valuable resource for researchers concerned with the problem of environmental MPs pollution.