Great Pacific Garbage Patch

garbage patch

The Great Pacific Garbage Patch refers to marine litter trapped in gyre (a system of rotating ocean currents) in the central North Pacific Ocean. The patch extends over an indeterminate area, with estimates ranging very widely depending on the degree of plastic concentration used to define the affected area.

The Patch is characterized by exceptionally high concentrations of plastics, chemical sludge, and other debris. Despite its size and density, it is not visible from satellite photography; it consists primarily of suspended particulates in the upper water column.

Since plastics break down to even smaller polymers, concentrations of submerged particles are not visible, nor do they appear as a continuous debris field. Instead, the patch is defined as an area in which the mass of plastic debris in the upper water column is significantly higher than average. As the plastic flotsam degrades into smaller and smaller pieces, the plastic ultimately becomes small enough to be ingested by aquatic organisms that reside near the ocean’s surface. Thus, plastic waste enters the food chain. Some plastics decompose within a year of entering the water, leaching potentially toxic chemicals such as bisphenol A, PCBs, and derivatives of polystyrene.

The Great Garbage Patch was predicted in a 1988 paper published by the National Oceanic and Atmospheric Administration (NOAA). The prediction was based on results obtained by several Alaska-based researchers between 1985 and 1988 that measured plastic in the North Pacific Ocean. The garbage patch occupies a large and relatively stationary region. The gyre’s rotational pattern draws in waste material from across the North Pacific Ocean, including coastal waters off North America and Japan. As material is captured in the currents, wind-driven surface currents gradually move floating debris toward the center, trapping it in the region. It takes six years for currents to carry debris from the west coast of North America to the gyre. Debris from the east coast of Asia can make the trip in under year.

There is no strong scientific data concerning the origins of plastics in the pelagic zone (the ‘open sea,’ water not near the coast or sea floor). Ship-generated pollution is a source of concern, since a typical 3,000-passenger cruise ship produces over eight tons of solid waste weekly, a major amount of which ends up in the patch, (however most of the waste is organic). Pollutants range in size from abandoned fishing nets to micro-pellets used in abrasive cleaners.

Some of these long-lasting plastics end up in the stomachs of marine birds and animals, and their young, including sea turtles and the Black-footed Albatross. Besides the particles’ danger to wildlife, on the microscopic level the floating debris can absorb organic pollutants from seawater, including PCBs, DDT, and PAHs. Aside from toxic effects, when ingested, some of these are mistaken by the endocrine system as the sex hormone estradiol. These toxin-containing plastic pieces are also eaten by jellyfish, which are then eaten by larger fish. Many of these fish are then consumed by humans, resulting in their ingestion of toxic chemicals. Marine plastics also facilitate the spread of invasive species that attach to floating plastic in one region and drift long distances to colonize other ecosystems. On the macroscopic level, the physical size of the plastic kills birds and turtles as the animals’ digestion can not break down the plastic inside their stomachs.

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