Small microplastics (<100 μm), plasticizers and additives in seawater and sediments: Oleo-extraction, purification, quantification, and polymer characterization using Micro-FTIR

In this study, the abundance and the distribution of small microplastics (<100 μm, SMPs) and of other components of micro-litter (i.e., additives, plasticizers, natural and non-plastic synthetic fibers, APFs) were investigated in sediments and seawater of three different sites of a transitional environment; different anthropogenic impacts and environmental features characterize these three sites. The pretreatment method developed (oleo-extraction and purification procedures) allowed the collection of particles (SMPs and APFs) in a wide range of densities, e.g., from low-density plastics to high-density plastics, avoiding further degradation/denaturation of polymers. An analytical method for quantification and simultaneous identification of SMPs and APFs via Micro-FTIR was developed. Higher abundances of SMPs were observed in sediments compared to the abundance observed in seawater. SMPs were not the major component of the micro-litter. With natural fibers and non-plastic fibers, additives and plasticizers were quantified and identified in sediments and seawater. These latter are employed to obtain specific characteristics of polymers; hence their presence can be a good proxy of these polymers' presence in the environment. Sources and pathways may influence the abundance and distribution of SMPs and APFs. Differences in abundance and distribution of these pollutants in sediments and seawater of the three sites investigated were statistically significant.