Recently, the impact of plastic waste on the environment has increased significantly. Plastic can change the microbial load of the environment and transfer heavy metals into the natural system. The thesis aimed to determine the load of plastic and sediment with marine heterotrophic bacteria and Vibrio before and after the tourist season at Sakarun beach. Additionally, the sediment was tested for microbiological indicators of faecal pollution. The next goal is to determine concentrations of Zn, Cd, Pb and Cu adsorbed on the surface of plastic waste on the beach, as well as concentrations of these metals in the intertidal sediment using differential pulse voltammetry of anodic dissolution. The analysis of the plastic additionally included the determination of the type of polymer by the method of Fourier transform infrared spectroscopy (FTIR). The sediment was analysed using basic sedimentological methods and was described as sand with a very high proportion of the carbonate component (>95%). After the tourist season, an increased abundance of marine heterotrophic bacteria on plastic waste was measured. No pathogenic bacteria for humans and animals were found on the plastic, but the species Vibrio harveyi was identified in the sediment, which can be pathogenic for marine organisms and humans if they consume raw seafood. Most of the sampled plastic fragments belong to polypropylene (PP), which is in line with the trend in the data collected in the Adriatic region. The results of heavy metal loading of Sakarun sediment are below the recommended limits, and we classify it as an unpolluted Adriatic sediment. On the other hand, plastic is much more contaminated with heavy metals cadmium, zinc, lead, and copper, which can lead to the transfer of these heavy metals into the environment