The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters.

Giuseppe Suaria,Gwendolyn L Lattin,Francesco Regoli,Charles J Moore,Annabella Mineo,Carlo G Avio,Genuario Belmonte,Marcello G Magaldi,Stefano Aliani

doi:10.1038/srep37551

Abstract

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.

Highlights

Global production of plastic materials increased twenty-fold in the last fifty years, exceeding 300 million tonnes in 20151
Global models consistently predict some of the highest concentrations of floating plastics in the world to occur in the Mediterranean Sea[12,18], to the extent that together with the main five oceanic gyres, it has been proposed as the sixth great accumulation zone for marine litter[19]
Owing to limited outflow of surface waters, a densely populated coastline and intensive fishing, shipping, touristic and industrial activities, substantial amounts of marine litter are accumulating in the Mediterranean basin, which according to the most recent simulations is retaining between 21% and 54% of all plastic particles and between 5% and 10% of the global plastic mass[20]

Summary

Introduction

Global production of plastic materials increased twenty-fold in the last fifty years, exceeding 300 million tonnes in 20151. Over 92% of all plastic items found at sea are generally smaller than 5 mm[12] These tiny particles – hereinafter referred to as microplastics – may either result from the breakdown of larger objects, or they can directly enter the marine environment as granules, pellets and fibers. Global models consistently predict some of the highest concentrations of floating plastics in the world to occur in the Mediterranean Sea[12,18], to the extent that together with the main five oceanic gyres, it has been proposed as the sixth great accumulation zone for marine litter[19]. Owing to limited outflow of surface waters, a densely populated coastline and intensive fishing, shipping, touristic and industrial activities, substantial amounts of marine litter are accumulating in the Mediterranean basin, which according to the most recent simulations is retaining between 21% and 54% of all plastic particles (i.e. between 3.2 and 28.2 × 1012 particles) and between 5% and 10% of the global plastic mass (i.e. between 4.8 and 30.3 thousand tonnes)[20]

Methods

Results

Discussion

Conclusion