Polymers and Marine Litter

At sea, the nature of the waste varies greatly depending on whether we consider the beaches, the surface or the seabed, and according to the activities. As a result, managers must consider the specific types of waste characteristics of an area, fishing or tourism, for example and the specific types of activity, industrial, agricultural, urban or harbor. Thus, for a global definition, the diversity of activities, places and future plans requires the consideration of local particularities. 

For polymers, the impact is mainly known at the individual level and not at the population species or ecosystem level. The distribution of plastics at sea, however, remains worldwide, and the potential risk for alterations in communities by transporting invasive species is a reality which can modifiy the balance of ecosystems. The diversity and the complexity of the problem require a thorough knowledge of the nature of litter at sea, transport mechanisms, future possible impacts, and effects on the enviromnent. 

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Typical data shown in Tables 6 and 7 for an E-CO and a corresponding LDPE homo-polymer, demonstrates the similarities between the two resins. In appearance, as film or extruded items, they are also seemingly identical. It is now known that the C=0 groups fit into the PE crystal lattice and hence have little effect on the overall crystallinity. However, E-CO density increases with increases in CO content. It has been noted that at around 16 % CO, E-CO will not float in fresh water, and at about 20% CO, the copolymer will sink in salt water. For rapid photodegradability of marine litter, those CO levels are the upper limitations to assure exposure to the light necessary for photodegradation. 

As shown in Table I, the plastic component of MSW has increased dramatically. Past development of synthetic plastic formulations has focused on reducing the photo, chemical, and biological degradation of the plastic polymers. However, the persistence of plastics in the environment as litter, potential marine hazard, and with concern for global carbon cycling 1,6) has focused recent attention on the recycling of plastics or development of new biodegradable plastic formulations. 

Potential uses for photodegradable polymers, such as E/CO, will exist wherever plastics littering occurs. It has been estimated that almost a billion pounds of plastics find their way into the world s waterways annually [23]. Because E/CO floats and maintains much of its photodegradability when in water, there should be commercial opportunities for E/CO in marine packaging, fishing gear, and similar applications. 

The prevention of marine environment pollution, for instance, is regulated by the MARPOL Treaty. This international convention prohibits the disposal of any plastics waste in the oceans, e.g., from ships or from offshore platforms. The International convention generated activities to check if biodegradable plastics used as an alternative to conventional polymers are suitable to be degraded in a marine environment [2]. A further problem exists from littering, where plastic items are washed away to the sea by rivers or blown by wind from tbe shores and can cause the death of numerous marine animals [3]. 

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