The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea

The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

[eng] The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea

Microplastics as vehicles of environmental PAHs to marine organisms: combined chemical and physical hazards to the Mediterranean mussels, Mytilus galloprovincialis.

The ubiquitous occurrence of microplastics (MPs) in the marine environment is raising concern for interactions with marine organisms. These particles efficiently adsorb persistent organic pollutants from surrounding environment and, due to the small size, they are easily available for ingestion at all trophic levels. Once ingested, MPs can induce mechanical damage, sub- lethal effects and various cellular responses, further modulated by possible release of adsorbed chemicals or additives. In this study, ecotoxicological effects of MPs and their interactions with benzo(a)pyrene (BaP), chosen as a model compound for polycyclic aromatic hydrocarbons (PAHs) were investigated in Mediterranean mussels, Mytilus galloprovincialis. Organisms were exposed for four weeks to 10 mg/L of low-density polyethylene (LD-PE) microparticles (2.34x107 particles/L, size range 20-25 µm), both virgin and pre-contaminated with BaP (15µg/g). Organisms were also exposed for comparison to BaP dosed alone at 150 ng/L, corresponding to the amount adsorbed on microplastics. Tissue localization of microplastics was histologically evaluated; chemical analyses and a wide battery of biomarkers covering molecular, biochemical and cellular levels allowed to evaluate BaP bioaccumulation, alterations of immune system, antioxidant defenses, onset of oxidative stress, peroxisomal proliferation, genotoxicity and neurotoxicity. Obtained data were elaborated within a quantitative weight of evidence (WOE) model which, using weighted criteria, provided synthetic hazard indices, for both chemical and cellular results, before their integration in a combined index. Microplastics were localized in haemolymph, gills and especially digestive tissues where a potential transfer of BaP from MPs was also observed. Significant alterations were measured on the immune system, while more limited effects occurred on the oxidative status, neurotoxicity and genotoxicity, with a different susceptibility of analyzed pathways, depending on tissue, time and typology of exposure. Molecular analyses confirmed the general lack of significant variations on transcriptional activity of antioxidant and stress genes. The overall results suggest that microplastics induce a slight cellular toxicity under short-term (28 days) exposure conditions. However, modulation of immune responses, along with bioaccumulation of BaP, pose the still unexplored risk that these particles, under conditions of more chronic exposure (months to years) or interacting with other stressors, may provoke long-term, subtle effects on organisms’ health status

Microplastiche come sorgente di Contaminazione e di rischio Ecotossicologico per gli organismi marini

La presenza sempre più cospicua di rifiuti plastici in mare sta costituendo un problema ambientale emergente. Negli ultimi 10 anniparticolare attenzione è stata rivolta alle microplastiche (particelle<5mm) che, acausa dell’elevato rapporto superficie volume, possono adsorbire differenti classi di contaminanti, rappresentando quindi una rischiosa fonte di esposizione per gli organismi marini. Tale ipotesi tuttavia non è ancora stata supportata da evidenze sperimentali dirette. In questo studio è stata valutata l'efficienza di microparticelle di polietilene (PE) e di polistirolo (PS) di adsorbire pirene, scelto come molecola rappresentativa della classe degli idrocarburi policiclici aromatici; i risultati ottenuti in laboratorio sono stati comparati con quelli relativi alla caratterizazione chimica di microplastiche campionate lungo le coste marchigiane. Esperimenti di esposizione di mitili Mytilus galloprovincialisa plastiche vergini e contaminate hanno permesso di valutare il potenziale trasferimento trofico degli IPA veicolati dalle plastiche e gli effetti cellulari e biochimici indotti. I risultati mostrano una elevata capacità delle microplastiche di adsorbire pirene; lo studio sulla localizzazione tissutale delle microparticelle nei mitili esposti rivela la loro presenza nell’emolinfa, nelle branchie ed in particolare nel tessuto digestivo, dove è stato anche osservato un elevato accumulo di pirene. Le alterazioni cellulari causate dall’esposizione ai polimeri sono state valutate attraverso l’analisi di una ampia batteria di biomarkers, tra cui quelli di proliferazione perossisomiale, stress ossidativo, perossidazione lipidica, alterazione lisosomiale e di danno genotossico. Attraverso un approccio innovativo di DNA-microarray, è stato analizzato anche il profilo di espressione genica nella ghiandola. Questo studio ha dimostrato che le microplastiche possono adsorbire efficacemente i contaminanti come gli idrocarburi policiclici aromatici, evidenziando per la prima volta la loro biodisponibiltà per gli organismi marini che mostrano anche un'ampia gamma di effetti molecolari e cellulari in risposta a polimeri sia vergini che contaminati