Detection of natural and synthetic anthropogenic fibers, plastics, and phthalates in Mediterranean marine organisms and environment

This PhD project aimed to investigate different types of anthropogenic pollution in the Mediterranean Sea, specifically focusing on anthropogenic particles (APs) and Phthalic Acid Esters (PAEs). The study included both plastic (PL) and non-plastic (N-PL) particles, with a particular focus on a category of particles that are still understudied: fibers. Fibers are indeed the most common category of APs found in the environment and marine organisms, but they are difficult to sample and analyze. Phthalic Acid Esters (PAEs) are a class of contaminants often used as additives in plastic and other industrial products. Some compounds are considered harmful to humans, and their effects on marine fauna are not yet well understood. The first aim of this PhD project was to investigate the relationship among PAEs, PL ingestion, and environmental and biometric parameters in fish species. Four fish species (Boops boops, Engraulis encrasicolus, Mullus surmuletus, Sardina pilchardus) were sampled in five areas of the Tyrrhenian Sea and Ligurian Sea during two different seasons, spring and autumn, to assess plastic ingestion and the levels of PAEs in the muscles of the selected species. The data obtained have been analyzed to investigate potential correlations between levels of PAEs and factors such as plastic ingestion, sampling season, area, morphometric values, or somatic indices. The results revealed that PAE levels in muscle tissues were not directly associated with plastic ingestion or other factors across all species examined, except for seasonal variability. Specifically, specimens sampled during the spring season exhibited higher PAE levels compared to those sampled in autumn. The second aim was to assess the presence of APs in the water column. For sampling APs, including fibers in the water column, a new methodology was tested, around Capraia Island, using an in-situ pump that allows water sampling at specific depths with minimal air exposure, and isolates particles down to 20 µm in size. This method was compared with sampling using the WP2 plankton net. The best methodology was then applied for sampling the water column in three different areas of the western Mediterranean Sea, characterized by the presence of marine protected areas: the Gulf of Asinara, Capraia Island, and Capo Carbonara. The polymer of all isolated APs was determined by µFTIR. From the results, it emerged that the in-situ pump is the most effective method for isolating APs, including PL and N-PL fibers, and was then applied to sampling the other study areas. Sampling across the study areas revealed that fibers are the most common category of APs, comprising 90% of isolated particles, and that the majority were cellulose fibers. Furthermore, the most impacted area by the presence of APs is the Gulf of Asinara (with an average of 393.7 items/m3 isolated). The third aim of this PhD project was to investigate the ingestion of APs, including N-PL (such as cellulose and rayon), and the levels of PAEs in marine organisms. Eight fish species (Boops boops, Diplodus annularis, Mullus surmuletus, Scyliorhinus canicula, Spicara maena, Spondyliosoma cantharus, Synodus saurus, Trachurus trachurus) and one species of holothurian (Holothuria tubulosa) with six different feeding habits were selected. Organisms were sampled in the same three study areas where water column AP concentration was measured to assess any relationship between APs in the water column and organisms. The ingestion of APs was assessed by analyzing the gastrointestinal content of the organisms, by digesting the organic matter using a 10% KOH solution. Furthermore, the presence of PAEs was investigated in the muscles of the selected species. Additionally, stable isotope analysis of carbon and nitrogen was used to determine the trophic position (TP) and trophic niche of the analyzed organisms to understand whether this factor can influence the ingestion of APs. The results showed that fibers are the most commonly (90% of the APs isolated) found category of APs in the marine organisms analyzed, particularly cellulose, consistent with water column data: specimens sampled in the Gulf of Asinara were found to be the most impacted by the ingestion of APs. PAEs were found in all analyzed specimens, in particular DEHP, DBP, and DIBP. From the statistical analyses, DIBP has emerged as a PAE associated with AP ingestion in the sampled species, thus representing a potential candidate for use as a chemical tracer for APs. The carnivorous and deposit-feeding organisms analyzed appear to be more susceptible to the ingestion of APs, suggesting that feeding habits may influence the quantity of APs in the GI. Additionally, a weak relationship was observed between TP and AP ingestion: organisms with a lower TP appear to ingest a higher number of APs. In conclusion, this PhD underscores the widespread presence of APs, particularly anthropogenic fibers, across the studied marine areas of the Mediterranean Sea, including those within marine protected areas. The pervasive occurrence of both natural and synthetic anthropogenic fibers has been evident in both the water column and within the analyzed marine organisms. Future research on APs in the marine environment should always consider the presence of fibers, encompassing those of natural origin. Furthermore, it is essential to clarify the environmental fate of PAEs and to identify the factors that influence seasonal variations in their levels within marine organisms.