Nature and quantity of litter reaching the sea

Landfills, especially marine sites or those near the coast, sometimes pose serious environmental problems because they can give rise to deferred impacts. In the open air, storms can dump thousands of plastic bags close to the sites, sometimes into the sea. These contributions, however, remain localized, in contrast to those due to the abandorunent of waste which is mainly related to human behavior. The latter constitute a significant part but one which is not quantified in the statistics. Experts speak of aroimd 10% of waste that would eventually finish up in the sea. Discharges from ships and rivers constitute a significant part. 

Emerging in the 1950s and revolutionary at the time, polymers represent the largest proportion of marine htter which can constitute up to 100% in the case of floating debris. Their diversity and their properties make the imderstanding of the evolution of this htter in the sea more complex [THO 09]. The typological analysis 

Degradation prodncts from macrolitter have different properties at sea, different effects and different futnies from the original products. Eventually, they form microparticles, usually made of plastic, which constitute a veiy important aspect of the problem of marine litter. They comprise an assembly of objects of varying size, shape, color, density and chemical composition [HID 12]. With densities ranging from 0.8 to 1.4 g cm , the plastics in the sea and on the surface are mainly polyethylene (density 0.92-0.97 g cm ), polypropylenes (0.85-0.94 g cm ) and polystyrenes (from less than 0.05 in the case of foamed polystyrene to 1.00 g cm ) [LES 11]. The denser plastics such as poly (vinyl chloride) (PVC) and polycarbonates, if they do not aggregate with the organic material, tend to sink. 

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