Sampling and processing methods of microplastics in river sediments - A review

Microplastics (MP) in marine environments attract widespread attention due to their small particle size and potential hazardous impacts on aquatic and terrestrial ecosystems. Compared to marine sediments, knowledge about the occurrence of MP in freshwater sediments, especially in river sediments, is limited. Although MP concentrations in sediments and soils have been reported in a considerable number of studies, no standardized method is available for sampling and sample processing. Thus, a comparison of results is hardly possible. The present study reviews over 47 articles to evaluate reports of MP in river sediments and current sampling and processing techniques by highlighting various techniques, equipment and approaches for implementing quality assurance and quality control procedures. The authors emphasize that MP quantification techniques could lead to overestimation or underestimation depending on how sampling and sample processing is conducted. Standardization and harmonization of these techniques are crucial to underpin monitoring decisions aimed at safeguarding the ecological integrity of freshwater environments.