Marine Plastics: New Evidence Shows That They Are Here To Stay

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Posted by on December 26, 2006 at 19:14:04:

What happens to your coffee cup top after you put it in the garbage at work? Or what about your plastic car bumper after an unfortunate fender-bender? Or the top for your tube of toothpaste? Plastic is a sturdy and durable material that has changed the world in innumerable ways. However, few of us consider plastics throughout the course of their lifespan, but rather are only aware of plastic from when we need it until when we throw (or recycle) it away.

The very qualities that make plastic such a great building material also mean that plastic takes an incredibly long time to break down. Recent studies demonstrate that it might never fully decompose. Scientists discovered particles of marine plastic smaller than 20 microns in diameter, thinner than a strand of human hair! Large pieces of plastic, which we use on a daily basis, are called macro-plastics. Macro-plastics over time weather from the UV radiation of the sun and from wave activity, similar to weathering patterns that create erosion on land. As the macro-plastics are weathered they form smaller and smaller pieces of plastic, micro-plastics or "mermaids’ tears," which float in the water column, drift at the surface, or sink to the ocean floor. The quantity of ocean plastics is difficult to ascertain, but some scientists believe that on average as much as 300,000 plastic items drift per square kilometer at the sea surface and 100,000 pieces of plastic fall to a square kilometer of the seabed.

Scientists estimate that roughly 80% of plastics found in the marine realm originate on land from tourism-related litter, sewage outflows, and coastal waste facilities. The other portion of marine plastics correlates with ship discharge and loss of fishing gear. While plastics are not the only form of trash affecting the world’s oceans, monitoring shows that plastic makes up 60-80% of marine debris. In 1988 the international community tackled the problem of marine plastics by creating the International Convention of the Prevention of Pollution from Ships (MARPOL). Annex V prohibited at-sea dumping of most trash and all plastics. However, recent study results demonstrate that this international legislation is not sufficient to curbing the rising marine plastic problem.

The affects of large quantities of plastic existing in the oceans is evident in numerous portions of the marine environment. Plastic, by nature, interacts with its surroundings. Scientists discovered that floating pieces of plastic attracted other marine pollutants, effectively concentrating marine pollution. While this may seem like an advantage, it is important to remember that micro-plastics are the same size as plankton. Marine organisms consume large quantities of marine micro-plastics wrongly perceiving them as food. The amount of plastics present in a marine organism increases up the food chain, resulting in a high concentration of plastic and marine pollutants in top predatory species. Macro-plastics are also associated with drowning, suffocating, strangulation, starvation, and injuries to multiple marine organisms.

The problem of marine plastics is invasive throughout the world’s oceans and will be extremely difficult to address in the future. One of the best actions to take against marine plastics is to personally reduce the amount of plastics that you buy and throw away. Greenpeace published a comprehensive report on the state of marine plastics internationally. The report, "Plastic Debris in the World’s Oceans," can be seen at oceans.greenpeace.org/raw/content/en/documents-reports/plastic_ocean_report.pdf. The negative affects of marine plastics was well presented in Maggie Ayre’s 7 December 2006 BBC series which can be read at news.bbc.co.uk/2/hi/science/nature/6218698.stm.

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