Marine environment plastic litter

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. 

A considerable amount of data had been assembled by 1976 on chlorinated hydrocarbons, petroleum hydrocarbons, heavy metals, and radioactivity [19]. For the first time, littering of the marine environment, primarily by plastics, was identified as an emerging problem. Early toxicity data for both marine and freshwater environments were summarized as well [20]. 

Marine debris is generally defined as any manufactured or processed solid waste material (typically inert) that enters the marine environment from any source. Marine litter and floatables are considered equivalent terms [1], Marine pollution is defined as the introduction by man, directly or indirectly, of substances into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hindrance to marine activities including fishing, impairment of quality for use of sea water and reduction of amenities [2], Marine debris is dominated by persistent synthetic materials, most of which are plastics. 

From this viewpoint, the natural environments should be better identified, in terms of ecological habitats, and test approaches should in turn be based on the typical conditions experienced by the plastic products when entering each habitat, since the microbial population (and thus biodegradation activity) could be quite different. Tosin and co-workers [13] have identified 6 habitats where plastic waste can reside when littered in the marine environment 1) pelagic domain (the plastic products float freely in estuaries and the open ocean water), 2) eulittoral zone (tides and storm waves bring great quantities of plastic waste to the shoreline, where plastic products get partly buried and kept wet by tidal inundation and waves), 3) supralittoral zone (the plastic products are washed onto the beach, exposed to a sandy soil with a low moisture level), 4) sublittoral zone (plastic products settle on marine sandy sediment where they are exposed to the seawater/sediment interface), 5) plastic products can otherwise sink to the bottom of the deep sea and 6) plastic products can be slowly buried within sediments on the sea-floor. 

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]. 

Solid waste disposal environments for plastic materials can include industrial compost, home compost, anaerobic digestion, landfill, litter, and ocean water. Only two disposal environments have both biodegradation standards for test methods and biodegradation performance standards, for example, industrial compost and marine biodegradation environments. Test method standards are available for anaerobic digestion, home compost, and landfill environments. The second necessary performance specification standard for biodegradation performance is not available for anaerobic digestion, home compost, or landfill... 

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