Additives, plasticizers, and small microplastics (< 100 µm) in seawater: a comparison of three sampling methods

Microplastics (MPs) are ubiquitous, persistent emerging pollutants that have been observed in every environment and in different animal species (from invertebrates to mammals). MPs are part of the micro-litter, together with additives, plasticizers, natural fibers, non-plastic synthetic fibers such as rayon (APFs). The main concern is that invertebrates can ingest all these particles according to the size of their mouthparts, and filter-feeders can collect these particles together with the seston. In particular, all the particles smaller than 100 ?m are actively ingested or filtered; hence, these particles can enter the trophic web, where they can be bioaccumulated and biomagnified. Besides, due to their size, these particles can be transferred from the gastrointestinal tract to other organs or other tissues, such as muscle tissue. Therefore, they can pose a health threat to humans who use them as a food source. There are currently no standardized and harmonized methods for the sampling, pretreatment, contamination control, and analysis of SMPs and APFs (< 100 ?m), which are often overlooked in marine environments. Consequently, a lack of knowledge regards the abundance and chemical characterization of these particles in the seawater and their pathways and fate. Awarenessraising projects and citizen science help spread scientific knowledge and raise the consciousness of more people about crucial environmental issues such as microplastic pollution. SEA Plastics [7] has organized a cruise expedition in the Thyrennian Sea and has offered to collect samples to investigate SMPs and APFs. Seawater samples were collected at two sites in South Italy during the 2021 expedition. Three different sampling systems were employed: manta net, plankton net, and Niskin bottles. Samples were filtered on-site and stored at 4 °C till the arrival at the laboratory of CNR-ISP. An elutriation method was developed to retrieve all the particles collected. A pretreatment method previously developed was performed. All the operations were performed in a plastic-free Clean Room Iso 7. SMPs and APFs were quantified and simultaneously identified via Micro-FTIR. Pyrolysis-gas chromatography was employed as an inter-calibration technique to confirm the identification of specific polymers. The first results show differences among the samples collected with different sampling devices.