Quantification and identification of microplastics in Southern North Sea sediments via FPA-based µFTIR Imaging

Microplastics in marine habitats pose a threat to life owing to their small size, their ubiquitous occurrence and their tendency to adsorb and release pollutants. As microplastic research lacks harmonised analysis methods, inter-study comparisons are limited. So far, only few comparable studies have investigated microplastic burden in the North Sea. This work analysed microplastics in sediments of the Southern North Sea and applied advanced methods with potential for standardisation. Firstly, microplastics were extracted via density separation with the Microplastic Sediment Separator (MPSS) followed by a non-destructive enzymatic-chemical digestion. Secondly, microplastics were quantifed and identifed via FPA-based µFTIR imaging in tandem with a semi-automated analysis. Microplastic concentrations in all samples ranged from 2-174 particles per kg of dry sediment. Particle number tended to increase with decreasing particle size. Most frequently detected polymer types were varnishes, polypropylene, polyester, polyoxymethylene and polyethylene. This study contributes to baseline data provision for future research, monitoring activities and political decision-making.